CHAPTER 2 Review of Literature - Shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/37191/10/10_chapter2.pdf · use of response surface methodology in development and optimization

Review of literature

6

CHAPTER 2

Review of Literature

This chapter deals with the scientific work carried out by researchers

related to flaxseed physicochemical characteristics and composition, health benefits of

flaxseed and flaxseed incorporated food products. Moreover, the chapter focuses on the

use of response surface methodology in development and optimization of food product.

This chapter is divided into five sections as follows.

2.1 Physical characteristics of flaxseed

2.2 Chemical Characteristics of flaxseed and its fraction

2.3 Health benefits of flaxseed and its fractions

2.4 Antinutritional factors of flaxseed

2.5 Flaxseed based food products and storage stability

2.6 Response surface methodology (RSM) in the development of extruded food

products

2.1 Physical characteristics of flaxseed

Knowledge of the physical properties of linseed is essential to facilitate

and improve the design of equipment for harvesting, handling, processing and storing the

seed. Various types of cleaning, grading and separation equipment are designed on the

basis of the physical properties of grains or seeds. Some of the reported literature on

physical characteristics of flaxseed is discussed below.

The flaxseed is flat and oval with a pointed tip. It is a little larger than a

sesame seed and a smooth glossy surface. The seed consists of a hull, endosperm and

embryo including the cotyledons. The hull is tough and fibrous. Its colour ranges from

pure yellow to deep brown (Nagaraj, 1995). Seed color is determined by the amount of

pigment in the outer seed coat the more pigment, the darker the seed (Freeman, 1995).

Generally oily flaxseeds cultivars have greater dimensions than fiber flaxseeds cultivars


7

(Green and Marshall, 1981). The seeds have a crisp and chewy texture and a pleasant

nutty taste (Carter, 1993).

Coskuner and Karaaba (2007) reported that the physical properties of

flaxseed is function of seed moisture content. The seed moisture content varied from

6.09% to 16.81% (db). In the moisture range, seed length, width, thickness, arithmetic

mean diameter and geometric mean diameter increased linearly from 4.27 to 4.64 mm,

2.22 to 2.38 mm, 0.85 to 0.88 mm, 2.45 to 2.63 mm and 2.00 to 2.12 mm respectively

with increase in moisture content. One thousand seed weight increased linearly from 4.79

to 5.32 g. The true density increased with moisture content from 1000 to 1111 kg/m3

while bulk density decreased 726.6 to 555.6 kg/m3. Also, porosity values of flaxseeds

increased from 27.34 to 57.44%. The highest static coefficient of friction was found on

the plywood surface. The static coefficient of friction increased from 0.537 to 1.073,

0.515 to 0.933, 0.472 to 0.975, 0.499 to 0.877, 0.544 to 0.862 and 0.472 to 0.824 for

plywood, aluminum, stainless steel, galvanized iron, polypropylene knitted bag and kraft

paper surface respectively. The angle of repose increased linearly from 21.60 to 33.4

0

with the increase of moisture content. The physical properties of flaxseeds were

expressed in the linear regression equations as function of moisture content. High

correlation coefficients were found with a significance level of 95%.

Selvi et al. (2006) also studied on the physical properties of linseed as

function of moisture content. As the moisture content increased from 8.25 to 22.25% dry

basis (d.b.), the average length, width, thickness and the geometric mean diameter varied

from 4.57 to 4.86, 2.40 to 2.59, 1.03 to 1.13 and 2.24 to 2.43 mm, respectively. In the

same moisture range, studies on rewetted linseed showed that sphericity, surface area and

1000 seed mass and true density increased from 49.09% to 49.94%, 15.83 mm2 to 18.56

mm2 and 6 to 6.7 g, 1010.1 to 1020.4 kg m

-3, respectively. As the moisture content

increased from 8.25 to 22.25% d.b., bulk density was decreased from 690.5 to 545 kg m-3

whereas the angle of repose, terminal velocity and porosity were found to increase from

21.590 to 26.85

0 and 2.46 to 3.82 ms

-1, 31.64% to 46.59%, respectively.


8

Table 2.1 Physical characteristics of flaxseed

Parameter Range References

Length (mm) 3.0 to 6.4 Freeman, 1995

Width (mm) 1.8 to 3.4 Freeman, 1995

Thickness (mm) 0.5 to 1.6 Freeman,1995

One thousand seed weight (g) 4.79 to 6.7 Selvi et al., 2006;

Coskuner and Karababa, 2007

Bulk density (kg.m-3

) 545.0 to 726.6 Selvi et al., 2006;


Porosity (%) 27.34 to 57.44 Coskuner and Karababa, 2007

Angle of repose 21.590 to 33.4

0

Selvi et al., 2006;


2.2 Chemical composition and characteristics of flaxseed and its

fractions

Flaxseed is mainly grown either as oilseed crop or fiber crop with fiber

linen derived from the stem of fiber varieties. Beyond its oilseed crop and fiber producing

ability, the proximate composition of flaxseed shows the promising potential for

exploration in the food product development. Following various researchers reported on

its chemical composition of flaxseed and its fractions.

Hettiarachchy et al. (1990) reported on chemical composition of eleven

flaxseed varieties grown in North Dakota. The moisture percentage of 7.1-8.3%, oil

content of 31.9 – 37.8 %, protein content of 26.9 – 31.6% and dietary fiber of 36.7-46.8%

were observed in different flaxseed varieties.

Oomah and Mazza (1993) reviewed on the protein content, amino acid

composition, fractionation, and functional properties of flaxseed proteins. Protein values

are generally well above 36%. Differences can be attributed to both genetics and

environment. As in other oilseeds, a negative correlation is observed between the oil and


9

protein contents of the seeds. Flaxseed-protein products were found to have emulsion

stabilizing effects comparable with those of gelatin. The incorporation of flaxseed-protein

products at 3% level produced a smooth and creamy fish sauce devoid of any undesirable

flavor and a marked reduction in its red color. Supplementation of flaxseed-protein

products in ice-cream mixes increased product viscosity, specific gravity, and overrun but

reduced melt-down times with an increasing level of additions from 0.5 to 1%. Thus

flaxseed-protein products have potential as emulsifiers and stabilizers in food systems.

Wanasundara and Shahidi (1994) reported on the functional properties and

amino acid composition of solvent extracted flaxseed meals. Meals extracted with

methanol-ammonia-water/hexane had the highest nitrogen-solubility index. The

minimum solubility of nitrogenous compounds in hexane-extracted and methanol-

ammonia-water/hexane-extracted meals occurred between pH 3.0 and 3.5. Flaxseed

meals had a high water-adsorption value, and the two phase solvent extraction did not

influence it. Fat adsorption of the meals was influenced by the presence of ammonia in

the extraction system, and the pH of these meals was increased by nearly one unit.

Solvent-extracted flaxseed meals had improved emulsifying and foaming properties.

Extraction with methanol ammonia-water/hexane did not change the amino-acid

composition of flaxseed meals. The content of essential amino acids of the meals was

slightly less than the FAO/WHO (1973) reference values. Methionine, lysine, and

tryptophan levels were considerably lower than the reference values. Flaxseed protein

showed an abundance of glutamic acid and had an amino-acid composition similar to that

of canola.

Nagaraj (1995) reported on the quality and utility of oilseeds. Flaxseed

contains 6.5-10% moisture, 20-24% proteins, 37-42% oil, 15-29% carbohydrates, 5-9%

crude fibre and 2-4% ash. The seed composition varies with respect to variety, seed size,

climate and maturity. The oil contains mainly triglycerides with 0.25% phosphatides and

0.5% waxes. The normal linseed oil is a drying oil because of its higher level of linolenic

acid. The seed contains 20-24% protein consisting mainly globulins and glutelins.

Linseed protein is deficient in lysine, and methionine as in any other oilseed. The expeller

cake contains 96.8% dry matter, 30% proteins, 7% fat, 42% carbohydrates, 10% fibre and

7% minerals. The meal is a valuable protein source to poultry and ruminants. It has


10

laxative effect which aids in keeping the livestock healthy. The meal/seeds need to be

processed to remove mucilage and inactivate toxic constituents.

Cui and Mazza (1996) studied on physiochemical characteristics of

flaxseed gum. Hydrocolloidal gums extracted from four flaxseed cultivars were

characterized in terms of loss of weight on drying, ash and nitrogen contents, mineral and

amino acid compositions and intrinsic viscosity. Of the gums extracted from flaxseed,

Omega had the least loss of weight on drying (3.7%) followed by Norman (6.5%), 84495

(11.5%) and Foster (14.4%). Data for loss of weight upon drying from the latter three

flaxseed gums are comparable to those of commercial gums (8-13%). The ash content of

flaxseed gums ranged from 3.3 to 8.4%. Nitrogen levels in flaxseed gums (1.5- 3%) were

higher than those of commercial gums (0.34-1.31%), which may reflect the presence of

more proteinaceous components in these gums. Omega flaxseed gum contained the

highest amount of galacturonic acid (25.1%), followed by gums from Foster (23.9%),

Norman (21%) and 84495 (15.7%) flaxseed. The amounts of heavy metals (cadmium,

lead and copper) were higher in flaxseed gums than in guar gum and gum arabic, but

comparable to the levels of xanthan gum. The amount of manganese varied from 4 to 17

ppm in gums extracted from different cultivars, while the values for commercial gums

were between 6 and 9.5 ppm. Zinc levels were relatively stable in flaxseed gum (15-16.5

ppm) but varied from 4 to 12.1 ppm in the commercial gum samples examined. Glutamic

acid was the major amino acid for all the gums examined. The intrinsic viscosities for

guar and xanthan were very similar, (1135.4 and 1355.1 ml g-l, respectively); however,

they were substantially higher than those of flaxseed gums(434 to 658 ml g-l) and gum

arabic (14.1 ml g-l).

Oomah and Mazza (1998a) studied on the compositional changes during

commercial processing of flaxseed. The physicochemical characteristics of flaxseed

products at four stages of commercial processing, cleaning, flaking, pressing and solvent

extraction, were determined to improve the functional properties of flaxseed products.

The effect of industrial oil extraction on proximate composition, protein extractability,

gel electrophoretic profiles, in vitro protein digestibility and viscosity of eight flaxseed

products was assessed. The processes of flaking, heating, solvent extraction and solvent

removal significantly increased the contents of protein, ash and soluble carbohydrate, and


11

decreased oil content, total phenolics and protein solubility. Pepsin digestibility ranged

from 11 to 72%, and generally increased with processing. Sodium dodecyl sulphate–

polyacrylamide gel electrophoresis of solubilized proteins showed the presence of four

major polypeptide components, with only minimal changes in the protein profiles among

the samples as a result of processing. The viscosity of the slurry was largely unaffected

but shear thinning indices increased with processing. Multiple-regression analysis

showed that protein content was related to carbohydrate content, cyanogenic content, and

viscosity, but not associated with protein solubility and digestibility.

Oomah and Mazza (1998b) reported on fractionation of flaxseed with a

batch dehuller. The effects of microwave treatment and dehulling time were investigated

on yield of fractions obtained on dehulling three flaxseed cultivars, Linola 947, NorMan

and Omega. Four major fractions (medium, fine, mix and hull) varying in composition,

were obtained upon dehulling. The yield of fractions varied significantly between

untreated and microwave-treated seeds, among cultivars and dehulling time. Microwave-

treated seeds produced higher yields of medium and hull fractions than untreated seeds.

The yield of the medium, fine and hull fractions increased with increasing dehulling time.

Neither cultivar nor microwave treatment affected the protein and oil content of the hull

fraction which had a high carbohydrate content. Microwave drying proved to be a useful

conditioning treatment for achieving high yields of hulls and cotyledons by batch size

abrasive dehulling. The hull fraction obtained through this process can be used for food

and industrial applications such as a raw material for the extraction of phytochemicals.

Wanasundara et al. (1999) investigated the changes in flaxseed

nitrogenous compounds during eight days of germination. The dry matter content of the

seeds was reduced by 35% at the end of the germination. During the germination period,

a relatively small decrease was observed in total nitrogen content, but there was an

increase in the content of non-protein nitrogen from 9 to 33.5% of the total amount. An

increase in the total content of free amino acids was also observed. Among individual

amino acids, glutamine showed a marked change during the germination period

indicating that it is the favoured amide donor in the developing flax seedlings. An

increase in the water-soluble protein and a decrease in the salt-soluble protein fractions

was also observed. The content of poly-amines, namely agmatine, spermidine and


12

putrescine, which are important in controlling cellular metabolism and growth, was also

increased during the germination period.

Madhusudhan et al. (2000) reported a dry mechanical method for

concentrating the lignan secoisolariciresinol diglucoside in flaxseed. A Comitrol

processor was used to mill the seed, followed by sieving and aspiration to obtain hull-rich

fraction from Neche and Omega flaxseed cultivars. As a result, the content of

secoisolariciresinol diglucoside (nonfat, dry basis) increased from 12.9 and 14.3 g/kg in

whole Neche and Omega seed, respectively, to 27.6 and 23.8 g/kg (weighted averages) in

the hull-rich fractions. The significant (P<0.0005) inverse correlation between oil and

SDG contents for cultivars. Neche suggests that oil content in dry-milled fractions is a

useful indicator of secoisolariciresinol diglucoside content. Compared to similar reported

processes, this was less effective at producing a hull-free embryo, but the Neche hull

fraction contained much less fat (173 g/kg weighted average) than the other processes.

The hull fraction appears to be a good source of SDG for functional food studies.

Fritsche et al. (2002) reported on-line liquid-chromatography–nuclear

magnetic resonance spectroscopy–mass spectrometry coupling for the separation and

characterization of secoisolariciresinol diglucoside (SDG) isomers in flaxseed. Two SDG

diastereomers were extracted from flaxseed and liberated through alkaline hydrolysis.

Anion-exchange and reversed-phase chromatography were successfully employed to

purify the hydrolyzed flaxseed extract. On-line LC–NMR–MS analyses revealed the

structure of the isolated and purified SDG diastereomers, [2R, 2‘R]-2,3-bis[(4-hydroxy-3-

methoxyphenyl)-methyl]-1,4-butanediyl-bis-b-glucopyranoside the predominant flaxseed

lignan and [2R, 2‘S]-2,3-bis[(4-hydroxy-3-ethoxyphenyl)methyl]-1,4-butanediyl-bis-b-

glucopyranoside, a previously incompletely characterized minor flaxseed lignan. Circular

dichroism (CD) analyses confirmed the presence of two distinguished optically active

compounds present in the flaxseed extract.

Oomah et al. (2006) studied on thermal characteristics of flaxseed (Linum

usitatissimum L.) proteins. Thermal characteristics of ion-exchange protein fractions

from dehulled delipidated meal of four flaxseed cultivars grown at three locations were

evaluated by differential scanning calorimetry (DSC) to examine genotypic and

environmental effects. DSC was performed in a ‗‗dry‘‘ state on four, 0.28, 0.35, 0.45 and


13

0.50 M NaCl lyophilized protein fractions. Flaxseed proteins exhibited two thermal

events between 83 and 115 0C with distinct shoulders present in the 0.45 and 0.50 M

fractions of all cultivars. Cultivar and location effects were significant for the first

thermal transition (T d1) of the 0.28 and 0.35M fractions, and the second transition (T d2)

of the 0.35, 0.45 and 0.50 M fractions. The enthalpy of the first transition ∆H1 of the 0.35

and 0.50M fractions was cultivar dependent, while that of the second transition ∆H2 was

cultivar and location specific for the 0.35, 0.45 and 0.50M fractions. The 0.28 and 0.45 M

fractions displayed the lowest and highest thermal transition temperatures, respectively.

All protein fractions consisted of reversing and nonreversing thermal events as assessed

by modulated DSC. Flaxseed cultivars, when grouped by thermal characteristics of

protein fractions, can be differentiated by principal component analysis.

Morris (2007) reported the proximate composition of flax. An analysis of

brown Canadian flax averaged 41% fat, 20% protein, 28% total dietary fibre, 7.7%

moisture and 3.4% ash, which is the mineral-rich residue left after samples are burned.

The composition of flax is provided in Table 2.2. Alpha Linolenic acid (ALA) constitutes

57% of the total fatty acids in flax, making flax the richest source of ALA in the North

American diet. Linoleic acid constitutes 16% of total fatty acids. Flax oil and canola oil

have the lowest levels of the nutritionally undesirable saturated fatty acids. The level of

the desirable monounsaturates in flax oil is modest. Flax is a very rich source of a lignan

called secoisolariciresinol diglucoside (SDG), which is found in amounts ranging from

1mg/g of seed to nearly 26 mg/g of seed. The composition of flaxseed can vary with

genetics, growing environment, seed processing and method of analysis (Daun et al.,

2003).

Choo et al. (2007) studied on the physiochemical and quality

characteristics of cold pressed flaxseed oils. In this study, the physicochemical and

quality characteristics of seven cold-pressed flaxseed oils sold in New Zealand have been

analyzed. General regulations and specification for edible vegetable oils and cold-pressed

oils were used as a guide. Fatty acid composition, tocopherol composition, moisture and

volatile matter content, free fatty acids, chlorophyll pigments, total phenolic acids, total

flavanoids, acid value, unsaponifiable matter, peroxide value, conjugated dienoic acids,

p-anisidine value and specific extinction in the ultraviolet spectrum of the flaxseed oils


14

Table 2.2 Proximate composition of flaxseed on common measuresa

Form of

flax

Weight

(g)

Common

measure

Energy

(kcal)

Total

fat

(g)

ALAb

(g)

Protein

(g)

Total

CHOc,

d

(g)

Total

dietary

fibre

(g)

Proximate

analysis 100 - 450 41.0 23.0 20.0 29.0 28.0

Whole

seed 180 1 cup 810 74.0 41.0 36.0 52.0 50.0

11 1 tbsp 50 4.5 2.5 2.2 3.0 3.0

4 1 tsp 18 1.6 0.9 0.8 1.2 1.1

Ground

seed 130 1 cup 585 53.0 30.0 26.0 38.0 36.0

8 1 tbsp 36 3.3 1.8 1.6 2.3 2.2

2.7 1 tsp 12 1.1 0.6 0.5 0.8 0.8

Flax oil 100 - 884 100.0 57.0 - - -

14 1 tbsp 124 14.0 8.0 - - -

5 1 tsp 44 5.0 2.8 - - - aBased on a proximate analysis conducted by the Canadian Grain Commission. The fat content

was determined using the American Oil Chemists‘ Society (AOCS) Official Method Am 2-93.

The moisture content was 7.7%. bALA = Alpha-linolenic acid

cCHO = Carbohydrate.

dTotal Carbohydrate includes carbohydrates like sugars and starches (1 g) and total dietary fibre

(28 g) per 100 g flax seeds.

were measured. Color and dielectric measurement of the flaxseed oils were also

estimated using a spectrocolorimeter and a food oil sensor, respectively. The

physicochemical characteristics of the flaxseed oils were found to be quite similar with

only a few significant variations. Four out of the seven flaxseed oils passed all the quality

tests conducted in this study. The p-anisidine values of the seven cold-pressed flaxseed

oils varied between 0.36 and 0.74. Flaxseed oils had Totox values less than three. The

acid values of the seven cold-pressed flaxseed oils were well within the limit of 4.0 mg

KOH/g.

Bozan and Temelli (2008) reported on chemical composition and

oxidative stability of flax, safflower and poppy seed and seed oils. The major fatty acid in

the flax oil was α-linolenic acid, comprising 58.3% of total fatty acids, whereas poppy

and safflower oils were rich in linoleic acid at 74.5% and 70.5% level, respectively. The

amount of total tocols was 14.6 mg/100 g flax, 11.0 mg/100 g poppy and 12.1 mg/100 g


15

safflower seed. Flax and poppy oil were rich in γ-tocopherol as 79.4 mg/100 g oil and

30.9 mg/100 g oil, respectively, while α-tocopherol (44.1 g/100 g oil) was dominant in

safflower oil. Only α- and γ-tocotrienol were found in the oils. Oxidative stability of oils

was measured at 110 0C at the rate of 20 L/h air flow rate, and poppy oil (5.56 h) was

most stabile oil followed by safflower oil (2.87 h) and flax oil (1.57). There were no

correlation between oxidative stability and unsaturation degree of fatty acids and tocol

levels of the oils. All of the seeds investigated provide a healthy oil profile and may have

potential as a source of specialty oils on a commercial scale.

Husain et al. (2008) analyzed the chemical compositions and functional

properties of full fat (roasted and non-roasted) and partially defatted (roasted and non

roasted) flaxseed flour samples. Moisture content of different flour samples showed that

full fat non roasted flaxseed flour is significantly higher (4.53%) in moisture content as

compared to the other three types of flaxseed flours. Partial defattening has significantly

affected the crude protein content of flaxseed flours while roasting showed a non

significant effect on the protein contents. The crude fat content of the full fat non-roasted

flaxseed flour (38.76 %) and full fat roasted flaxseed flour (38.53%) were non-

significantly affected as a result of microwave roasting. Highest significant values of K,

Mn, Mg Na, Ca, Cu and Zn (1369.31, 4.73, 713.04, 58.16, 398.21, 3.45 and 7.86

mg/100g, respectively) were found in partially defatted non roasted flaxseed flour.

Roasting significantly increased the bulk density of flours while defattening in non

roasted flaxseed flour decreased the bulk density. The highest water absorption capacity

(2.34 g/g) was found in partially defatted roasted flaxseed. The fat absorption capacities

were higher in roasted full fat (1.31g/g) and roasted defatted (1.27 g/g) flaxseed flours.

Foam capacity and stability decreased in roasted flours as compared to non roasted flours.

Partially defatted flaxseed flour samples were found to be higher in these parameters.

Strandas et al. (2008) studied on composition and properties of flaxseed

phenolic oligomers. An extract from flaxseed containing oligomeric structures of the

phenolic glucosides secoisolariciresinol diglucoside (SDG), p-coumaric acid glucoside

and ferulic acid glucoside was fractionated into three oligomeric fractions (F50, F60 and

F70) by reversed phase liquid chromatography and further subfractionated by Sepharose

CL-6B. The F50 fraction, which had the highest proportion of hydroxycinnamic acid


16

glucosides, was also fractionated on Sephadex LH-20 according to hydrophobicity and

size. The different separations resulted in complex profiles of UV-absorbing molecules.

HPLC analyses indicated that reversed-phase chromatography separated the oligomers

according to composition of the phenolic glucosides, while the subfractionation revealed

that other structural features of the oligomers were also important. Using the DPPH

radical, SDG and oligomeric fractions showed similar hydrogen-donating abilities

comparable to ferulic acid but higher than α-tocopherol, which suggests that SDG was

the only active antioxidant.

Li et al. (2008) reported on separation and determination of

secoisolariciresinol diglucoside oligomers and their hydrolysates in the flaxseed extract

by high-performance liquid chromatography. In this study, a new gradient reversed-phase

high-performance liquid chromatography (HPLC) method has been developed to be

suitable for the separation and determination of: (1) SDG oligomers extracted from the

defatted flaxseed powder by a 70% aqueous methanol solution; (2) SDG oligomers and

their alkaline hydrolysates, including SDG, p-coumaric acid glucoside and its methyl

ester, ferulic acid glucoside and its methyl ester in an alkaline hydrolytic solution; and (3)

the succedent acid hydrolysates, including secoisolariciresinol monoglucoside (SMG),

SECO, anhydrosecoisolariciresinol (anhydro-SECO), p-coumaric acid and its methyl

ester, ferulic acid and its methyl ester, 5-hydroxymethyl-2-furfural (HMF) and its

degradation product in an acid hydrolytic solution. The content of SDG oligomers in a

defatted flaxseed powder was found to be 38.5 mg/g on a dry matter basis, corresponding

to a SDG content of 15.4 mg/g, which was determined after alkaline hydrolysis.

Furthermore, this study presented a major reaction pathway for the hydrolysis of SDG

oligomers.

Canadian Grain Commission (2009) reported fatty acid profile of flaxseed

oil. It is quite evident that the level of α-linolenic acid is by far the largest component of

the fatty acid profile of flaxseed, but it is when the profile of flaxseed is compared to the

other major oilseed crops that its value as a functional food crop becomes clear. Flaxseed

may be considered a functional food because its high content of α-linolenic acid may

contribute in promoting good health as well as preventing diseases which is discussed

later in Section 2.4. Table 2.3 presents the percentage content of fatty acid.


17

Table 2.3 Percent Fatty acid content of flaxseed oil

Wang et al. (2009) studied on effects of drying methods on rheological

properties of flaxseed gum. Flaxseed gum solutions were extracted and dried by different

methods: ethanol precipitation, freeze drying,105 0C oven drying, 80

0C oven drying,

spray drying, and vacuum drying. The effects of these drying methods on the rheological

properties of flaxseed gum were investigated in present study. Ethanol precipitation

increased the apparent viscosity of flaxseed gum solution, while all the other methods

decreased the apparent viscosity. Most of the drying methods slightly increased the

activation energy, except ethanol precipitation. In frequency sweep test, all the drying

methods reduced the G‘ (Storage modulus, Pa) and G‘‘ (Loss modulus, Pa) values. In

creep–recovery tests, the data were modeled by Berger‘s model. The E2 (Retarded elastic

modulus, Pa) and η1 (Coefficient of viscosity associated with viscosity flow, Pa.s) values

were reduced by all of the drying methods in this study. Some relationships were found

between the parameters in the Power Law model of the frequency sweep test and the

parameters in Berger‘s model.

Khattab and Arntfield (2009) reported on the functional properties of raw

and processed canola meal. Heat treatments significantly increased water and oil

absorption capacities while reduced nitrogen solubility of different meals. Neither

roasting nor water boiling significantly affected the gelation of the meals. Canola meal

showed the best emulsification and foaming properties followed by soyabean meal and

flaxseed meal. Both emulsifying and foaming properties were significantly reduced after

heat treatments. Raw, roasted and water-boiled canola meal revealed unique functional

properties, which could be a base for selection in different applications. This study shows

the potential of canola meal for incorporation into new functional foods and value-added

products.

Palmitic Stearic Oleic Linoleic Linolenic Reference

4.6-6.3 3.3-6.1 19.3-29.4 14.0-18.2 44.6-51.5 Hettiarachchy et al.,

1990

5.1 3.6 19.2 15.5 55.7 Canadian Grain

Commission, 2009


18

Singh and Jood (2009) evaluated proximate composition, in vitro protein

digestibility and anti-nutritional factors of linseed cultivars. Linseed (Linum

usitatissimum L.) cultivars, namely, Laxmi, Padmini, Sheela Sharda and Shekhar were

analyzed for proximate composition, in vitro protein digestibility and anti-nutrients like

phytic acid, polyphenols, trypsin inhibitor activity and oxalic acid. Varietal differences

were observed for all the parameters. Among the cultivars, Sharda cultivar contained

maximum content of crude fat (47.38%), crude fibre (10.48%) and crude protein

(21.18%). It also exhibited lowest amount of phytic acid (770.00 mg/100 g), polyphenols

(610.33 mg/100 g) and trypsin inhibitor activity (22.67 TIU/g) which resulted in

maximum content of in vitro protein digestibility (73.73%). Oxalic acid was found lowest

in Shekhar cultivar and highest in Sheela cultivar.

Cammerer and Kroh (2009) studied on shelf life of linseeds and peanuts in

relation to roasting. Changes in the oxidative status of peanuts and linseeds during

storage were investigated by the ESR spin trapping technique with N-tert. butyl-α-

phenylnitrone. It has proven to be a suitable method for the determination of the radical

generating reactions in the very early stage of fat spoilage and deterioration reactions can

still be detected, before changes in sensory properties are noticeable. Primarily, due to

oxidative reactions of lipids, shelf life of peanuts and linseeds as well as their sensory

quality decreases with storage time. Roasting has a controversial influence on the

stability of linseeds and peanuts, respectively. Roasted linseeds became rancid more

rapidly than fresh seeds. With increasing roasting temperature and time the oxidative

stability of peanuts was improved and shelf life prolonged. This can be attributed to the

formation of antioxidant Maillard reaction products. A correlation was found between the

amount of deoxyosones as reactive Maillard reaction intermediates and shelf life of

roasted nuts.

Khan et al. (2010) investigated chemical composition of six varieties of

linseed (Chandni, LS-29, LS-49, LS-70, LS-75 and LS-76). Proximate composition,

mineral profile and cyanogenic glycosides (linamarin) were determined. Average

proximate composition values for linseed i.e. crude protein, ether extract, crude fiber, ash

and nitrogen free extract were 24.18, 37.77, 4.78, 3.50 and 25.86%, respectively. Higher

values of crude protein, ether extract, crude fiber and nitrogen free extract were observed


19

in varieties LS-49, LS-70, LS-29 and Chandni, respectively. Average mineral contents in

linseed i.e. Ca, Mg, K, Na, Cl, P, Cu, Fe, Mn and Zn were 0.39, 0.09, 1.41, 0.05, 0.08,

0.89, 4.67, 50.56, 8.29 and 13.55 ppm, respectively. Among micro minerals, varieties LS-

29 and LS-70 were higher in Cu contents; LS-75 was higher in Fe content, while LS-49

was higher in Mn and Zn contents. Among macro minerals, level of Ca was higher in LS-

70, levels of Mg, K and Na were higher in Chandni, while P was higher in LS-49.

Average amount of linamarin in linseed was 31.05mg/100 gm DM. The variety LS-75

had the highest (35.22 mg/100 gm) linamarin content, while variety LS-70 had least

(26.22 mg/100 gm) amount of linamarin. In conclusion, there is significant difference in

chemical composition among linseed varieties. The varieties LS-49 showed higher crude

protein content, LS-70 showed greater oil content, while LS-75 had higher content of

linamarin.

A simplified linseed meal fractionation procedure for the extraction of

protein and fibre has been developed by Mueller et al. (2010a). Response-surface

methodology was used to investigate optimal parameters for linseed meal extraction.

Based on the data of this extraction screening, the process technology was transferred to

the pilot scale, obtaining a soluble protein and fibre containing fraction, and an insoluble

fibre fraction. Water-binding and oil-binding capacities, protein solubility, emulsification

capacity and foaming activity of the products were measured. The results indicated

excellent functional properties of the two fractionation products, applicable especially to

bakery products.

Mueller et al. (2010b) also reported on functional properties and chemical

composition of fractionated brown and yellow linseed meal. Considering its high content

of protein and dietary fiber, linseed meal is a remarkable source for food ingredient and

food additive production. In this study, brown and yellow linseed meal were fractionated

via pH control, to obtain five linseed meal fractions rich in protein and fiber. The

fractions were characterized by measuring functional properties, proximate and

carbohydrate composition and lignan contents. Acid soluble protein fractions were

characterized by lower emulsification capacities and foaming activities in comparison to

a commercial soy protein isolate. Alkaline soluble protein fractions showed

emulsification activities comparable to whole egg and relatively high contents of SDG of


20

110 mg/g DM and 56.2 mg/g DM, respectively. The good emulsification and foaming

activities, as well as the enriched concentration of SDG and therefore high nutritional

value, make especially the alkaline soluble protein fraction highly interesting for food

ingredient production.

Toure and Xueming (2010) reviewed on flaxseed lignans. The major

lignan in flaxseed is SDG. Once ingested, SDG is converted in the colon into active

mammalian lignans, enterodiol, and entero-lactone, which have shown promise in

reducing growth of cancerous tumors, especially hormone-sensitive ones such as those of

the breast, endometrium, and prostate. Known for their hydrogen-donating antioxidant

activity as well as their ability to complex divalent transition metal cations, lignans are

propitious to human health. The extraction methods vary from simple to complex

depending on extraction, separation, fractionation, identification, and detection of the

analytes. Flax lignan is also a source of useful biologically active components found in

plant foods, such as phytochemicals, and it is considered a functional food.

Marambe et al. (2012) investigated in-vitro digestibility of flaxseed

proteins. The effect of seed mucilage and oil and thermal processing on the in-vitro

protein digestibility (IPD) of flaxseed protein was assessed under simulated GI digestion.

Protein in ground whole flaxseed that contained both mucilage and oil had the lowest

digestibility (12.61%). Baking and boiling before size reduction significantly (P < 0.05)

improved the IPD (31.77% and 28.04%, respectively). Further increase in IPD occurred

when mucilage (51.00%) and both mucilage and oil (66.79%) were removed. Isolated

flax protein had a similar IPD value (68.00%) as the mucilage and oil–removed flaxseed.

The polypeptide of approximately 13 kDa showed resistance to GI digestion compared

with other polypeptides of all these treated seeds. Removal of oil and mucilage as well as

thermal treatment enhanced protein digestibility of flaxseed.


21

Table 2.4 Chemical characteristics of flaxseed and its fractions

Sr.

No. Author Year Important finding

1. Hettiarachchy

et al.

1990

The moisture percentage of 7.1-8.3%, oil content of

31.9 – 37.8 %, protein content of 26.9 – 31.6% and

dietary fiber of 36.7-46.8% were observed in 11

flaxseed cultivars.

2. Oomah and

Mazza

1993

Flaxseed-protein products were found to have

emulsion stabilizing effects comparable with those of

gelatine. Flaxseed protein modifications involving

succinylation, acylation, or incorporation of lipophilic

molecules that are known to improve surface

properties of the protein have not investigated.

3. Wanasundara

and Shahidi

1994

Flaxseed meals extracted with methanol-ammonia-

water/hexane had the highest nitrogen-solubility

index. Flaxseed protein showed an abundance of

glutamic acid and had an amino-acid composition

similar to that of canola.

4. Nagaraj 1995

Flaxseed contains 6.5-10% moisture, 20-24% proteins,

37-42% oil, 15-29% carbohydrates, 5-9% crude fibre

and 2-4% ash. The seed composition varies with

respect to variety, seed size, climate and maturity. The

oil contains mainly triglycerides with 0.25%

phosphatides and 0.5% waxes.

5. Cui and

Mazza

1996

Gums extracted from flaxseed cultivar, Omega had the

least loss of weight on drying (3.7%) followed by

Norman (6.5%), 84495 (11.5%) and Foster (14.4%).

Nitrogen levels in flaxseed gums (1.5- 3%) were

higher than those of commercial gums (0.34-1.31%).

The intrinsic viscosities for guar and xanthan were

very similar, (1135.4 and 1355.1 ml g-l, respectively);

however, they were substantially higher than those of

flaxseed gums (434 to 658 ml g-l).

6. Oomah and

Mazza

1998a The processes of flaking, heating, solvent extraction

and solvent removal significantly increased the

contents of protein, ash and soluble carbohydrate, and


22

decreased oil content, total phenolics and protein

solubility in flaxseed. Pepsin digestibility ranged from

11 to 72%, and generally increased with commercial

processing of flaxseed.

7. Oomah and

Mazza

1998b

They reported on fractionation of flaxseed with a

batch dehuller. The effects of microwave treatment

and dehulling time were investigated on yield of

fractions obtained on dehulling three flaxseed

cultivars. Microwave drying proved to be a useful

conditioning treatment for achieving high yields of

hulls and cotyledons by batch size abrasive dehulling.

8. Wanasundara

et al.

1999

During eight days of germination period, a relatively

small decrease was observed in total nitrogen content,

but there was an increase in the content of non-protein

nitrogen from 9 to 33.5% of the total amount. An

increase in the total content of free amino acids was

also observed. An increase in the water-soluble

protein and a decrease in the salt-soluble protein

fractions was also observed.

9. Madhusudhan

et al.

2000

They reported a dry mechanical method for

concentrating the lignan secoisolariciresinol

diglucoside in flaxseed. The hull fraction appears to

be a good source of SDG for functional food studies.

10. Fritsche et al. 2002

Two secoisolariciresinol diglucoside (SDG)

diastereomers were extracted from flaxseed and

liberated through alkaline hydrolysis. Anion-exchange

and reversed-phase chromatography were successfully

employed to purify the hydrolyzed flaxseed extract.

Circular dichroism (CD) analyses confirmed the

presence of two distinguished optically active

compounds present in the flaxseed extract.

11. Oomah et al. 2006

They studied on thermal characteristics of flaxseed

proteins by differential scanning calorimetry (DSC) to

examine genotypic and environmental effects.

12. Morris 2007 An analysis of brown Canadian flax averaged 41% fat,

20% protein, 28% total dietary fibre, 7.7% moisture


23

and 3.4% ash. Alpha Linolenic acid (ALA) constitutes

57% of the total fatty acids in flax, making flax the

richest source of ALA in the North American diet.

SDG is found in amounts ranging from 1mg/g of seed

to nearly 26 mg/g of seed.

13. Choo et al. 2007

The physicochemical and quality characteristics of

seven cold-pressed flaxseed oils sold in New Zealand

have been analyzed. The p-anisidine values of the

seven cold-pressed flaxseed oils varied between 0.36

and 0.74. Flaxseed oils had Totox values less than

three. The acid values of the seven cold-pressed

flaxseed oils were well within the limit of 4.0 mg

KOH/g

14. Bozan and

Temelli 2008

The major fatty acid in the flax oil was α-linolenic

acid, comprising 58.3% of total fatty acids, whereas

poppy and safflower oils were rich in linoleic acid at

74.5% and 70.5% level, respectively. The amount of

total tocols was 14.6 mg/100 g flax. Flax and poppy

oil were rich in γ-tocopherol as 79.4 mg/100 g oil and

30.9 mg/100 g oil, respectively.

15. Husain et al. 2008

Moisture content of different flour samples showed

that full fat non roasted flaxseed flour is significantly

higher (4.53%) in moisture content as compared to the

other three types of flaxseed flours. The crude fat

content of the full fat non-roasted flaxseed flour

(38.76 %) and full fat roasted flaxseed flour (38.53%)

were non-significantly affected as a result of

microwave roasting. Minerals were found in higher

amount in partially defatted non roasted flaxseed

flours. Foam capacity and stability decreased in

roasted flours as compared to non roasted flours.

16. Strandas et al. 2008

An extract from flaxseed containing oligomeric

structures of the phenolic glucosides

secoisolariciresinol diglucoside (SDG), p-coumaric

acid glucoside and ferulic acid glucoside was

fractionated into three oligomeric fractions (F50, F60

and F70) by reversed phase liquid chromatography

and further subfractionated by Sepharose CL-6B. SDG


24

was the only active antioxidant.

17. Li et al. 2008

A new gradient reversed-phase high-performance

liquid chromatography (HPLC) method has been

developed to be suitable for the separation and

determination of SDG oligomers, their alkaline

hydrolysates and succedent acid hydrolysates

extracted from the defatted flaxseed powder by a 70%

aqueous methanol solution. The content of SDG

oligomers in a defatted flaxseed powder was found to

be 38.5 mg/g on a dry matter basis, corresponding to a

SDG content of 15.4 mg/g, which was determined

after alkaline hydrolysis.

18. Canadian

Grain

Commission

2009 α-linolenic acid (55.7%) is the largest fatty acid

present in flaxseed oil.

19. Wang et al. 2009

They reported on effects of drying methods on

rheological properties of flaxseed gum. Ethanol

precipitation increased the apparent viscosity of

flaxseed gum solution.

20. Khattab and

Arntfield 2009

Functional properties of raw and processed canola

meal, soya meal and flax meal were studied. Canola

meal showed the best emulsification and foaming

properties followed by soyabean meal and flaxseed

meal.

21. Singh and

Jood 2009

Among flaxseed cultivars, Sharda cultivar contained

maximum content of crude fat (47.38%), crude fibre

(10.48%) and crude protein (21.18%). It also exhibited

lowest amount of phytic acid (770.00 mg/100 g),

polyphenols (610.33 mg/100 g) and trypsin inhibitor

activity (22.67 TIU/g) which resulted in maximum

content of in vitro protein digestibility (73.73%).

Oxalic acid was found lowest in Shekhar cultivar and

highest in Sheela cultivar.

22. Cammerer

and Kroh 2009

Due to oxidative reactions of lipids, shelf life of

peanuts and linseeds as well as their sensory quality

decreases with storage time. Roasting has a


25

From the above cited literature, flaxseed is good source of omega-3 fatty

acid (α- Linolenic acid), protein and dietary fiber. It is also one of the richest vegetarian

source of lignan (specifically SDG). These components of flaxseed are of great interest

both for the food and pharmaceutical industries.

controversial influence on the stability of linseeds and

peanuts, respectively. Roasted linseeds became rancid

more rapidly than fresh seeds. With increasing

roasting temperature and time the oxidative stability of

peanuts was improved and shelf life prolonged.

23. Khan et al. 2010

Average proximate composition values for linseed i.e.

crude protein, ether extract, crude fiber, ash and

nitrogen free extract were 24.18, 37.77, 4.78, 3.50 and

25.86%, respectively.

24. Mueller et al. 2010a

Acid soluble protein fractions were characterized by

lower emulsification capacities and foaming activities

in comparison to a commercial soy protein isolate.

Alkaline soluble protein fractions showed

emulsification activities comparable to whole egg and

relatively high contents of SDG of 110 mg/g DM and

56.2 mg/g DM, respectively.

25. Toure and

Xueming 2010

The major lignan in flaxseed is called

secoisolariciresinol diglucoside (SDG). Known for

their hydrogen-donating antioxidant activity as well as

their ability to complex divalent transition metal

cations, lignans are propitious to human health.

26. Marambe et

al. 2012

Protein in ground whole flaxseed that contained both

mucilage and oil had the lowest digestibility (12.61%).

Baking and boiling before size reduction significantly

(P<0.05) improved the IPD (31.77% and 28.04%,

respectively). Removal of oil and mucilage as well as

thermal treatment enhanced protein digestibility of

flaxseed.


26

2.3 Health benefits of flaxseed and its fractions

Ranhotra et al. (1992) noted that flaxseed oil or blends of flaxseed oil and

sunflower oil promoted cholesterol reduction in hypercholesterolemic rats compared to

diets formulated with hard fats. These authors suggested that a diet with the appropriate

balance of n-6 and n-3 fatty acids was preferred over diets high in n-6 fatty acids.

Ratnayake et al. (1992) studied on chemical and nutritional studies of

flaxseed (variety Linott) in rats. Weanling rats fed diets containing 20–40% flaxseed for

90 days had significantly lower total serum cholesterol and TAG levels than rats on

flaxseed-free diets.

Cunnane et al. (1993) reported that flaxseed was shown to reduce the

postprandial blood glucose response in humans. A consumption of 50 g/day ground

flaxseed by young females over a 4-week period caused a reduction in blood glucose

levels.

Bell and Keith (1993) reported on nutritional evaluation of linseed meals

from flax with yellow or brown hulls, using mice and pigs. Meal from yellow seed

(YLM) ontained less neutral detergent fibre (NDF) than meal from brown seed (BLM:

24% vs 29%). less crude fiber (8.7% vs 11.7%) and more crude protein (CP- 41% vs

38%) in the dry matter. Mice fed 0.33, 67 and 100% LM replacing Soyabean meal (SBM)

in a 2x3x4 factorial experiment showed better growth and feed efficiency with YLM and

commercial LM (CLM) than with brown linseed meal (BLM). Supplemental lysine was

beneficial. Apparent digstibility of CP by 30 kg pigs was 70% and by 60-kg pigs was

75% for both YLM and CLM. Fibre was more digestible in YLM (NDF 39% vs 30%

acid detergent fibre, 16% vs 10%) but digestible energy kg-1

dry matter for 30 kg pigs

was 11.2 MJ for YLM vs. 12.3 MJ for CLM and for 60 kg pigs was 13.MJ and12.3 MJ.

In another experiment, a 23-100 kg pig growth trial comparing BLM with CLM, daily

grains decreased from 677 to 604 g (P < 0.05 ) as dietary LM level increased from 0 to

18% in the grower period (to 57kg ).

Prasad (1997) investigated ability of flaxseed SDG to scavenge hydroxyl

radical (.OH) using high pressure liquid chromatography (HPLC) method. SDG

prevented the lipid peroxidation of liver homogenate in a concentration-dependent


27

manner in the concentration range from 319.3 -2554.4 microM. These results suggest that

SDG scavenges .OH and therefore has an antioxidant activity.

Arjmandi et al. (1998) reported that whole flaxseed consumption lowers

serum LDL cholesterol and lipoprotein concentrations in postmenopausal women.

Significant (p< 0.01) reductions in total cholesterol were observed for both treatments

(6.9 and 5.5% for flaxseed and sunflower seed, respectively). However, only flaxseed

regimen was able to significantly (p<0.001) lower LDL cholesterol (14.7%). Serum

HDL-cholesterol and triglyceride concentrations were unaffected by either of the

treatments. Most interestingly, lipoprotein (a) [Lp(a)], a strong predictor of

cardiovascular disease, concentrations were significantly (p < 0.05) lowered by the

flaxseed treatment (7.4% compared to baseline values). Regression analyses showed the

strongest association between age and both total and LDL-cholesterol concentrations.

Among the dietary variables, total and soluble fiber intakes were negatively correlated

with serum total and LDL-cholesterol concentrations. The cholesterol lowering effects of

flaxseed and sunflower seed may be due to the activity of single or multiple components,

including α-linolenic or linoleic acids, total and soluble fiber, and non-protein

constituents present in these seeds.

Oomah and Mazza (1999) reviewed on health benefits of phytochemicals

from selected Canadian crops. Flaxseed is an abundant source of α-linolenic acid (ALA),

viscous fiber components and phyto-chemicals, such as lignans and protein. These

components of flaxseed are of great interest both for the food and pharmaceutical

industries. In addition, flaxseed incorporation into the diet is particularly attractive from

the perspective of development of foods with specific health advantages. ALA has a

broad spectrum of potential health benefits associated with its consumption. It inhibits the

production of eicosanoids, alters the production of several prostanoids, reduces blood

pressure in hypertensives and lowers triglycerides and cholesterol. Flaxseed

polysaccharide gum or mucilage may have nutritional value as a dietary fiber, which

appears to play a role in diabetes and coronary heart disease risk, preventing colon and

rectal cancer, and the incidence of obesity. It has been observed that flaxseed protein may

influence blood glucose in two ways: by stimulating insulin secretion, which could result

in reduced glycemic response and by interaction with polysaccharides. Lignans and other


28

phenolic are also known to have strong protein-binding properties which may suggest

some partial chemopreventive effect of flaxseed protein in conjunction with phenolics.

The pharmaceutical industry's interest in lignans as a chemical class relates mainly to

their antimitotic activity which led to the speculation that these compounds when

ingested may act as natural anticancer agents.

Prasad et al. (2000) reported that rats fed 22 mg SDG/kg and treated with

the diabetes-promoting chemical streptozotocin had 75% lower incidence of type-1

diabetes than the streptozotocin-treated control group. However, the serum glucose of the

SDG plus streptozotocin-treated rats had significantly higher serum glucose levels than

streptozotocin-treated control group.

Demark-Wahnefried (2001) explored the effect of dietary fat restriction

and flax supplementation on hormonal levels, prostate-specific antigen, and

histopathologic features. The potential effects of flaxseed may be enhanced with

concomitant fat restriction. Twenty-five patients with prostate cancer who were awaiting

prostatectomy were instructed on a low-fat (20% of kilocalories or less), flaxseed-

supplemented (30 g/day) diet. During 34 days of duration, significant decreases were

observed in total serum cholesterol (201 ± 39 mg/dL to 174 ± 42 mg/dL), total

testosterone (422 ±122 ng/dL to 360 ±128 ng/dL), and free androgen index (36.3% ±

18.9% to 29.3% ± 16.8%) (all p <0.05). Daily supplement of flaxseed, which is a rich

source of lignan and ω-3 omega PUFAs, when combined with dietary fat restriction,

results in decreased prostate specific antigen levels and proliferation rate in prostate

cancer.

Prasad (2001) investigated the effectiveness of flaxseed lignan,

Secoisolariciresinol diglucoside (SDG) on the development of diabetes type 2. Incidence

of diabetes was 100% in untreated and 20% in SDG-treated zucker diabetic fatty rats by

the age of 72 days (P < 0.01). The rats that did not develop diabetes by 72 days of age in

the SDG treated group developed diabetes later on (age 72 to 99 days) except for 10% of

the rats that did not develop diabetes for the duration of the study (101 days of age),

suggesting that SDG retarded the development of diabetes.

Lemay et al., (2002) noted that a diet containing 40 g flaxseed/day

improved menopausal symptoms in 25 hypercholesterolemic menopausal women.


29

Glucose and insulin levels were lowered by the flaxseed intake; however, only small non

significant changes in cholesterol levels were observed.

The effects of dietary flaxseed (FS) and defatted flaxseed meal (FLM) on

serum and tissue fatty acid profiles of rat dams and offsprings were investigated by

Wiesenfeld et al. (2003). ALA and eicosapentaenoic acid increased; linoleic and

arachidonic acid decreased; and docosahexaeonic acid was unchanged in serum, ‗gastric

milk‘ and liver. FS more than FLM, changed fatty acids profiles, but FLM and 40% FS

significantly reduced serum cholesterol. Dietary 40% FS may have increased oxidative

stress as evidenced by a reduction in liver vitamin E.

Collins et al. (2003) studied on the effects flaxseed and defatted flaxseed

meal on reproduction and development in rats. High levels of flaxseed (FS, 20 or 40%) or

defatted flaxseed meal (FLM, 13 or 26%) added to AIN-93 diet were evaluated in a two-

phase study: dosed during gestation only or during gestation and maturation in a lifetime

study. At cesarean section on gestation day 20, neither FS nor FLM affected fertility,

body weight gain, litter size, or fetal development. FLM, but not FS, decreased gestation

length. The offspring of dams allowed to litter were observed to postnatal day (PND) 21

or 90. Neither FS nor FLM affected PND 21 survival indices of F1 pups. FS (20 and

40%), but not FLM, increased the anogenital index (AGI) of F1 females at PND 21. The

AGI of F1 males was not affected by either FS or FLM. FLM (13 and 26%), but not FS,

delayed puberty in F1 males. Age and weight at the onset of puberty in females were not

affected by FS or FLM. FS and FLM caused dose-related increases in the number of F1

females with irregular estrous cycles. During PND 21-90, F1 females fed 20% FS, 13%

FLM, or 26% FLM gained more weight than the controls. FS and FLM decreased

thymus/body weight and thymus/brain weight ratios in weanling F1 males and females.

FS and FLM decreased liver/body weight and liver/brain weight ratios in weanling F1

females, and 26% FLM decreased the same two ratios in F1 males. In conclusion, FS did

not affect fetal development but did affect indices of postnatal development such as the

estrous cycle.

Thompson (2003) reported a summary of clinical studies and in general a

positive benefit has been associated with flaxseed oil intake and tumor prevention. A

10% flaxseed oil diet reduced tumor growth and metastasis incidents.


30

Reddy et al. (2003) reviewed on natural products for cancer prevention.

Plant estrogens are found in red clover, black cohosh, rhubarb, and flaxseed and are

highly recommended to reduce breast and prostate cancer. This review focuses on the

many natural products that have been implicated in cancer prevention and that promote

human health without recognizable side effects. These molecules originate from

vegetables, fruits, plant extracts, and herbs.

Lucas et al. (2004) reported that flaxseed reduces plasma cholesterol and

atherosclerotic lesion formation in ovariectomized Golden Syrian hamsters. Seventy-two

6-month-old female Golden Syrian hamsters were either ovariectomized (ovx) or sham-

operated (sham) and randomly assigned to six groups (n = 12): sham, ovx, or ovx plus

either 17 β-estradiol (E2, 10 µg/kg body weight) or semi-purified diet adjusted for

macronutrients and fiber to contain one of the three doses of flaxseed (7.5, 15, or 22.5%)

for 120 days. Ovariectomy significantly elevated plasma total-, HDL-,and free-

cholesterol concentrations. Similar to estrogen, all doses of flaxseed were effective in

preventing the ovx-induced rise in plasma total cholesterol. Triglyceride concentrations

were significantly higher in the flax-fed hamsters. There were no significant differences

in plasma non-HDL- and esterified-cholesterol among the treatment groups. The findings

of this study show that flaxseed is beneficial in reducing plasma cholesterol and plaque

formation induced by ovarian hormone deficiency.

Tarpila et al. (2005) reviewed on flaxseed as functional food. Water-

binding capacity of flaxseed insoluble fiber increases the intestinal bulk which is useful

in the treatment of constipation, irritable bowel syndrome and diverticular disease.

Soluble fiber from flaxseed mucilage delays gastric emptying, improves glycemic

control, alleviates constipation and reduces serum cholesterol. Epidemiological studies

showed that the intake of dietary fiber and colorectal cancer correlated inversely.

Flaxseed lignans and fatty acids have been investigated in several cohort studies for their

effects on breast cancer risk and there is an association between elevated serum

enterolactone and decreased incidence of breast cancer. The flaxseed diet has been shown

to be beneficial on prostate cancer and benign prostate hyperplasia when defined by cell

proliferation indexes and other cancer biomarkers. Alpha-linolenic acid seems to have an

antiproliferative effect on prostate cancer cells. Elevated serum enterolactone level


31

associates with a lower incidence of acute coronary heart disease. Respectively, low

serum enterolactone enhances the risk for coronary deaths. Alpha-linolenic acid has been

shown protective against cerebrovascular stroke and atherogenic carotid plaque

formation.

Prasad (2005) studied on hypo-cholesterolemic and anti-atherosclerotic

effect of flax lignan complex isolated from flaxseed. The objectives of this study were to

determine if lignan complex reduces serum cholesterol, oxidative stress and

atherosclerosis in hypercholesterolemic rabbits. Lignan complex reduced the

development of atherosclerosis by 34.37% and this was associated with a decrease in

serum total cholesterol (TC) by 20%, LDL-C by 14%, TC/HDL-C by 34%, serum MDA

(malondialdehyde) by 35% and aortic MDA by 58%. Serum HDL-C was elevated by

30% in hypercholesterolemic rabbits and by 25% in normocholesterolemic rabbits with

lignan complex. Lignan complex did not affect the TC and LDL-C and serum MDA in

the normocholesterolemic rabbits. These results suggest that lignan complex isolated

from flaxseed reduced the extent of hypercholesterolemic atherosclerosis and this effect

was associated with marked decreases in oxidative stress, serum total cholesterol, LDL-C

and risk ratio, and elevation of serum HDL-C. Lignan complex may, therefore, be

beneficial in preventing atherosclerosis, and reducing risk factors for coronary artery

disease and stroke.

Morris (2005) reviewed on new flax facts. On the basis of several clinical

studies, flax favorably effects on the immune system. ALA and lignans block the release

of pro-inflammatory cytokines. C-reactive protein (CRP) is an acute phase pro-

inflammatory protein formed mainly in the liver in response to acute injury, infection,

hypersensitivity reactions, inflammatory diseases, malignancy, and trauma. CRP is a

sensitive biomarker of systemic inflammation and tissue damage. ALA-rich diets

decrease blood CRP levels. Through these effects, flax consumption may help prevent

and treat disorders characterized in part by an over-stimulated immune system. Such

disorders include atherosclerosis, obesity, the metabolic syndrome, diabetes mellitus,

rheumatoid arthritis, multiple sclerosis and systemic lupus erythematosus.

Tzang et al. (2009) investigated the effects of dietary flaxseed oil on

cholesterol metabolism of hamsters. High-fat/cholesterol diets (HFCD) formulated by


32

addition of butter (BU), coconut oil (CO), or flaxseed oil (FX) enhanced (P < 0.05) serum

lipids of hamsters compared to the low-fat/cholesterol diet (Control). However, FX

groups showed a hypocholesterolaemic effect compared to CO and BU groups. The

hypocholesterolaemic effect of FX might result from increases of LDL-receptor mRNA

expression, and cholesterol catabolism/output.

Ibrugger et al. (2012) evaluated flaxseed dietary fiber supplements for

suppression of appetite and food intake. The study was conducted on 24 and 20 subjects

respectively, to compare (I) Control vs Flax drink; and (II) Flax drink vs Flax tablets.

Flax drink increased sensation of satiety and fullness compared to Control and a

significant decrease in subsequent energy intake was observed after the Flax drink

compared to Control. A small dose of flaxseed fiber significantly suppresses appetite and

energy intake. Furthermore, flaxseed fibers administered as drinks or tablets produce

similar responses.

Table 2.5 Health benefits of flaxseed

Sr.


1. Ranhotra et

al. 1992

Flaxseed oil or blends of flaxseed oil and sunflower oil

promoted cholesterol reduction in hyper-cholesterolemic

rats compared to diets formulated with hard fats.

2. Ratnayake et

al. 1992

Rats fed diets containing 20–40% flaxseed for 90 days

had significantly lower total serum cholesterol and TAG

levels than rats on flaxseed-free diets.

3. Cunnane et

al. 1993

Flaxseed was shown to reduce the postprandial blood

glucose response in humans.

4. Bell and

Keith 1993

Mice fed 13% flaxmeal grew 6% faster than control

mice (P<0.01) and pigs fed 4% flaxmeal grew 4% better

(P>0.05). The possibility that flax mucilage or soluble

fibre may exert both negative and positive nutritional

effects warrants further investigation.


33

5. Prasad 1997

SDG scavenges .OH and therefore has an antioxidant

activity.

6. Arjmandi et

al. 1998

Whole flaxseed consumption lowers serum LDL

cholesterol and lipoprotein concentrations in

postmenopausal women.

7. Oomah and

Mazza 1999

Flaxseed is an abundant source of α-linolenic acid

(ALA), viscous fiber components and phyto-chemicals,

such as lignans and protein. Flaxseed incorporation into

the diet is particularly attractive from the perspective of

development of foods with specific health advantages.

8. Prasad et al. 2000

Rats fed 22 mg SDG/kg and treated with the diabetes-

promoting chemical streptozotocin had 75% lower

incidence of type-1 diabetes than the streptozotocin-

treated control group.

9. Demark-

Wahnefried 2001

Daily supplement of flaxseed, which is a rich source of

lignan and n-3 omega PUFAs, when combined with

dietary fat restriction, results in decreased prostate

specific antigen levels and proliferation rate in prostate

cancer.

10. Prasad 2001

Flaxseed lignan, SDG retarded retarded the development

of diabetes in zucker rats.

11. Lemay et al. 2002

Glucose and insulin levels were lowered by the flaxseed

intake; however, only small non significant changes in

cholesterol levels were observed.

12. Wiesenfeld

et al. 2003

Flaxseed meal and 40% flaxseed significantly reduced

serum cholesterol. Dietary 40% FS may have increased

oxidative stress as evidenced by a reduction in liver


34

vitamin E.

13. Collins et al. 2003

Flaxseed (FS) nor defatted Flaxseed meal (FLM)

affected fertility, body weight gain, litter size, or fetal

development. FLM, but not FS, decreased gestation

length. FS affected indices of postnatal development

such as the estrous cycle.

14. Thompson 2003

A 10% flaxseed oil diet reduced tumor growth and

metastasis incidents.

15. Reddy et al. 2003

Plant estrogens are found in red clover, black cohosh,

rhubarb, and flaxseed and are highly recommended to

reduce breast and prostate cancer.

16. Lucas et al. 2004

Flaxseed is beneficial in reducing plasma cholesterol and

plaque formation induced by ovarian hormone

deficiency.

17. Tarpila et al. 2005

Reviewed on flaxseed as functional food. ALA, dietary

fiber, lignan exerts health benefits if flaxseed products

consumed.

18. Prasad 2005

Flaxseed lignan complex is beneficial in preventing

atherosclerosis, and reducing risk factors for coronary

artery disease and stroke.

19. Morris 2005

Flax consumption may help to prevent and treat

disorders characterized in part by an over-stimulated

immune system and favorably effects on the immune

system.

20. Tzang et al. 2009

Flaxseed showed a hypocholesterolaemic effect

compared to coconut and butter.


35

21. Ibrugger et

al. 2012

A small dose of flaxseed fiber significantly suppresses

appetite and energy intake.

From the above literature cited, the use of flaxseed as a dietary supplement

is increasing in parallel with the research on its multiple effects on human health.

Flaxseed insoluble fiber increases the intestinal bulk which is useful in the treatment of

constipation, irritable bowel syndrome and diverticular disease. Soluble fiber from

flaxseed dietary fiber delays gastric emptying, improves glycemic control, blood glucose

metabolism, alleviates constipation and reduces serum cholesterol. The physiological

benefits of flaxseed oil are attributed primarily to the high content of ALA. ALA has a

broad spectrum of potential health benefits associated with its consumption. It inhibits the

production of eicosanoids, alters the production of several prostanoids, reduces blood

pressure in hypertensives and lowers triglycerides and cholesterol. Flaxseed lignans

(specifically SDG) have been investigated and shown to have anticarcinogenic activity

owing due to its antioxidant and protein binding property.

2.4 Anti-nutritional factors in flaxseed

Keeping an eye on safety of flaxseed, its anti-nutritional factors makes it

always questionable. Cyanogenic glycosides, trypsin inhibitor, phytic acid, anti-

pyridoxine factor are anti-nutritional factors present in flaxseed. Hall et al. (2006)

reviewed on safety of flaxseed. Pyridoxine supplementation in chicks on diets containing

a flaxseed meal was necessary to counteract the vitamin B6 deficiency. Klosterman et al.

(1967) identified the antipyridoxine factor linatine. Although linatine is a problem in

chicks, flaxseed has not been associated with a vitamin B6 deficiency in humans. In fact,

no effect on serum pyridoxine levels in subjects consuming 45 grams of flaxseed per day

over 5 weeks was observed (Dieken, 1992).

Amarowicz et al. (1993) studied on chromatographic techniques for

preparation of linustatin and neolinustatin from flaxseed, standards for glycoside

analyses. Cyanogenic glycosides, which are major antinutrients of flaxseed, were

extracted from the meal using 80% (v/v) ethanol. After silicic acid and subsequent RP-8

chromatography, cyanogenic glycosides along with soluble sugars were separated. Two


36

cyanogenic glycosides, namely, linustatin and neolinustatin, were subsequently separated

on a silica gel column with chloroform/methanol/water (65:35:10, v/v/v). Cyanogenic

compounds so prepared may be used as chromatographic standards for glycoside

analyses.

Bhatty (1993) reported laboratory-prepared flaxseed meals containing 42–

51 units of TIA, which was slightly higher than 10–30 units observed by Madhusudhan

and Singh (1983) and commercially obtained flaxseed meal (14–37 units). The contents

of phytic acid were significantly different among cultivars. AC Linora has a lowest phytic

acid content of 2280 mg/100 g and low ALA yellow-seeded cultivar Linola 947 has the

highest content (3250 mg/100 g seed) among the eight cultivars reported (Oomah et al..,

1996). At the recommend daily intake of about 1–2 table spoons, approximately 5–10 mg

of hydrogen cyanide is released from flaxseed, which is well below the estimated acute

toxic dose for an adult of 50–60 mg inorganic cyanide and below the 30–100 mg/ day

humans can detoxify (Roseling, 1994 )

Wanasundara et al. (1993) reported on removal of cyanogenic glycosides

removal of flaxseed meal. Flaxseed meals were prepared by a two-phase solvent

extraction system consisting of hexanes and an alkanol (methanol, ethanol or

isopropanol) phase with or without added water and/or ammonia. The effect of the

extraction process on the contents of protein and cyanogenic glycosides in the meals was

studied. The crude protein content of the extracted meals varied from 43.5 to 48-6,

compared with a value of 41-2% for hexane-extracted meals. Of the 4.42 mg/g linustatin

and 1.90 mg/g neolinustatin originally present in the meals, over 90% of each cyanogenic

glycoside was removed under optimum conditions using methanolic solutions.

Chadha et al. (1995) determined cyanide content in 10 cultivars of

flaxseed using an autohydrolysis method that required up to 5 hours of hydrolysis time.

The maximum cyanide values were typically obtained by 2–3 hours of hydrolysis.

Linamarin was reported to be present at very low levels (<32 mg/100 g seed) in 8 of the

10 cultivars. Cyanide content was found in the range of 12.4 to 19.6 mg/100 g of

flaxseed.

Feng et al. (2003), who reported that autoclaving and microwave heating

reduced hydrogen cyanide by 29.7% and 83.2%, respectively. In their study, they also


37

reported a 73.8% hydrogen cyanide reduction using a California pellet mill. In addition,

hot air oven heating at 1300C for 10 and 20 minutes resulted in 16.2% and 22.8%

reduction of hydrogen cyanide.

Yang et al. (2004) reported that flaxseed contained cyanide content of

15.8 mg/100 g. They also studied on removal of cyanide reduction with autoclaving,

microwave and solvent extraction. Hydrogen cyanide reductions of 89%, 27%, 82%, and

100% using solvent extraction, autoclaving, microwave roasting, and water boiling,

respectively were reported.

Park et al. (2005) reported on analysis and decrease of cyanogenic

glucosides in flaxseed. Linustatin and neolinustatin in flaxseed which produce acetone,

hydrogen cyanide (HCN) and sugar when hydrolyzed. The HCN is the chemical whose

toxin is being issued in food safety. Linustatin and neolinustatin were found in flaxseed

by 206.5 and 174.2 mg/100 g respectively using RI-HPLC and LC/MS analysis of 80%

methanol extraction. Also HCN (137.38 mg/kg) was found in flaxseed distillate by

autohydrolysis and IC analysis More than 85% of linustatin, neolinustatin and HCN were

removed when flaxseed was heated for more than 2 hours in 2000C. Especially, HCN was

decreased to 98% by heating only 30 min in 2000C.

Singh and Jood (2009) reported antinutritional factors in flaxseed cultivars

namely, Laxmi, Padmini, Sheela, Sharda and Shekhar. Among the cultivars, Sharda

cultivar exhibited lowest amount of phytic acid (770.00 mg/100 g), polyphenols (610.33

mg/100 g) and trypsin inhibitor activity (22.67 TIU/g) which resulted in maximum

content of in vitro protein digestibility (73.73%). Oxalic acid was found lowest in

Shekhar cultivar and highest in Sheela cultivar.

Khan et al. (2010) also determined cyanogenic glycosides (linamarin) in

six varieties of flaxseed. Average amount of linamarin in flaxseed was 31.05mg/100 gm

DM. The variety LS-75 had the highest (35.22 mg/100 gm) linamarin content, while

variety LS-70 had least (26.22 mg/100 gm) amount of linamarin.

Ivanov et al. (2012) investigated effect of effect of microwave heating on

content of cyanogenic glycosides in flaxseed. In spite of its high nutritive value, linseed

has not been effectively exploited in animal feeding, due to the fact that it contains anti-

nutritive components, which are cyanogenic glycosides (CG) and anti-vitamin B6


38

(linatine). CGs are a major limitation in application of flaxseed and its meal in animal

nutrition. Operating frequency of microwave oven was 2450 mHz, and working power

was 240W, 400W, 560W and 800W. Samples were treated for 0, 3, 6 and 10 minutes for

every working power. When microwave power of 560 W and 800 W was used for 6 min

and longer, flaxseed samples were burned and damaged, therefore these treatments

should not be used. Minimal time of heating with microwave power of 400W, which

would provide reduction of HCN content under allowed limits (250 mg/kg of flaxseed:

Serbian regulation), was determined graphically using three-dimensional contour plot

graph and it was 290 s (4 minutes and 50 s). This regime is recommended for treating

flaxseed before usage as a feed compound.

Cyanogenic glucosides, linatine, trypsin inhibitors and phytic acid are

antinutritional factors present in flaxseed. Among all, cyanogenic glucosides has major

concern because of its hydrogen cyanide producing ability. CG can be reduced

significantly by adopting autoclaving, solvent extraction, water boiling and microwave

roasting.

Table 2.6 Anti-nutritional factors in flaxseed

Sr.


1. Amarowicz et al. 1993

Cyanogenic glycosides, which are major

antinutrients of flaxseed, were extracted from the

meal using 80% (v/v) ethanol. Two cyanogenic

glycosides, namely, linustatin and neolinustatin,

were subsequently separated.

2. Bhatty 1993

Laboratory-prepared flaxseed meals containing

42–51 units of TIA, which was slightly higher

than 10–30 units observed by Madhusudhan and

Singh (1983) and commercially obtained flaxseed

meal (14–37 units). Approximately 5–10 mg of

hydrogen cyanide is released from flaxseed,

which is well below the estimated acute toxic dose


39

for an adult of 50–60 mg inorganic cyanide and

below the 30–100 mg/ day humans can detoxify.

3. Wanasundara et

al. 1993

The effect of the extraction process on the

contents of protein and cyanogenic glycosides in

the meals was studied. Of the 4.42 mg/g linustatin

and 1.90 mg/g neolinustatin originally present in

the meals, over 90% of each cyanogenic glycoside

was removed under optimum conditions using

methanolic solutions.

4. Feng et al. 2003

Autoclaving and microwave heating reduced

hydrogen cyanide by 29.7% and 83.2%,

respectively.

5. Yang et al. 2004

Hydrogen cyanide reductions of 89%, 27%, 82%,

and 100% using solvent extraction, autoclaving,

microwave roasting, and water boiling,

respectively is reported.

6. Park et al. 2005

Linustatin and neolinustatin were found in

flaxseed by 206.5 and 174.2 mg/100 g

respectively. HCN was decreased to 98% by

heating only 30 min in 2000C.

7. Singh and Jood 2009

Among the cultivars, Sharda cultivar exhibited

lowest amount of phytic acid (770.00 mg/100 g),

polyphenols (610.33 mg/100 g) and trypsin

inhibitor activity (22.67 TIU/g) which resulted in

maximum content of in vitro protein digestibility

(73.73%). Oxalic acid was found lowest in

Shekhar cultivar and highest in Sheela cultivar.


40

8. Khan et al. 2010

Average amount of linamarin in flaxseed was

31.05mg/100 gm DM. The variety LS-75 had the

highest (35.22 mg/100 gm) linamarin content,

while variety LS-70 had least (26.22 mg/100 gm)

amount of linamarin.

9. Ivanov et al. 2012

Microwave power of 400 W and 290 seconds

reduced cyanogenic glycosides from 320 mg/kg to

250 mg/kg of flaxseed.

2.5 Flaxseed based food products and storage stability

Flaxseed is utilized as a main food ingredient in order to enhance

functional foods (Oomah and Mazza, 1999). Whole or ground flaxseed, flaxseed oil,

deoiled cake can be used in various food products. In this section, end product use of

flaxseed will be discussed.

Chen et al. (1994) investigated the oxidative stability of flaxseed lipids

during baking. When ground flaxseed was heated at 1780C in a sealed tube, headspace

oxygen decreased from 21 to 2% within 30 min, while that of whole flaxseed decreased

only slightly up to 90 min at 1780C. Under the same conditions, the oxygen consumption

of lipids extracted from an equivalent amount of flaxseed was between the whole

flaxseed and the ground flaxseed. After heating to 1780C for 1.5 h, α-linolenic acid

decreased from 55.1 to 51.3% in ground flaxseed, and to 51.7% in lipid extracts, but it

remained unchanged in the whole flaxseed. A muffin mix, containing 28.5 wt% flaxseed

flour, consumed oxygen more rapidly than a control muffin without flaxseed flour at a

baking temperature of 178~ for 2 h, but the α-linolenic acid remained unchanged in both

muffin mixes. Under typical baking conditions, there is minimal loss of α-linolenic acid

from flaxseed, although the manner of incorporation of flaxseed in food products should

be considered to minimize oxidation of α-linolenic acids.

Alpers and Sawyer-Morse (1996) studied on eating qualities of banana nut

muffins and oat meal cookies made with ground flaxseed. The control muffin looked pale

compared with the muffins made with 30% and 50% ground flaxseed. The 50% ground


41

flaxseed muffins were rated nearest to the optimal flavor. 30% and 50% ground flaxseed

muffins were rated as more acceptable than the control muffin. As with banana nut

muffins, the control cookie looked pale compared with 30% and 50% ground flaxseed

cookies. The 50% ground flaxseed cookies were rated near optimum in tenderness and

flavor. Panelists rated the 30% flaxseed cookies as slightly more acceptable than the

control cookies, although all three treatments were very similarly rated in acceptability.

Ahmed (1999) reported on physico-chemical, structural and sensory

quality of corn-based flax-snack. A Brabender laboratory single screw extruder was used

to prepare the extrudates under fixed extrusion conditions. Feed moisture content was

18%, barrel temperature before the die was 200°C, and screw speed was 200 rpm.

Expansion ratio decreased, bulk density and breaking strength increased almost

recilinearly and resulted in a more dense snack. Higher degree of lightness ‗L‘ values

were obtained in blend containing a lower percentage of flaxseed. Water absorption

decreased as the percent of flaxseed increased. Water solubility index showed similar

trend. Sensory evaluation by 15 members sensory panel showed that within the observed

concentration ranges, total score gradually decreased by increasing proportion of added

flaxseed but still acceptable for the panellists. Microscopic examination revealed that

increasing the percentage of flaxseed resulted in a denser product, while a lower percent

gave a more hollow snack. Consequently, there is a parallelism between the flaxseed

percent and the microstructure of the extrudates.

Manthey et al. (2000) investigated the effects of ground flaxseed in

spaghetti. Dough strength significantly decreased, with small particles having the most

detrimental effect on dough strength. However, medium and coarse fractions resulted in

spaghetti that was too brittle whereas the fine particle size flaxseed gave acceptable

spaghetti quality. Flaxseed macaroni was stable during processing and storage.

Flaxseed oil has been proposed to be a valuable ingredient for ice cream

products (Hall and Schwarz, 2002). Flaxseed oil replaced between 10% and 25% of the

milk fat in ice cream formulas has been investigated. The 25% flaxseed product exhibited

an oil-like mouth feel; however, the presence of the oil in product could not be detected

by 60% of the panelists using an informal sensory evaluation. A trained sensory panel

showed that 15% of the milk fat could be replaced in a vanilla ice cream without being


42

detected. The melt time of flaxseed ice cream was not significantly different compared to

control. The 25% flaxseed ice cream product gave a thin consistency compared to

10%product, whereas 10% flaxseed ice cream showed similar properties with control.

Flaxseed oil addition significantly improved the fatty acid profile of frozen dessert.

Lee et al. (2003) tested the effects of boiling, refrigeration, and microwave

heating on ground flaxseed macaroni quality. Boiled macaroni and boiled-refrigerated-

microwave-heated macaroni exhibited similar appearance attributes. Cooked firmness

values were highest with boiled macaroni, intermediate with refrigerated macaroni, and

lowest with microwave-heated macaroni.

Ansorena and Astiasaran (2004) reported that the use of linseed oil

improved nutritional quality of the lipid fraction of dry-fermented sausages. Improvement

of the nutritional quality of the lipid fraction of dry-fermented sausages was achieved by

a substitution of one quarter of the amount of pork backfat present in traditional

formulations by an emulsion in which linseed oil was included. This improvement was

particularly noticeable when 100 mg/kg of butylhydroxytoluene and 100 mg/kg of

butylhydroxyanisole were added. P/S ratio increased from 0.4 in the control sausages to

0.6 in the batch with 3.3% linseed oil and to 0.7 in the batch with linseed (3.3%) and

antioxidants. The n – 6 / n - 3 ratio decreased from 14.1 in control products to 1.7–2.1 in

modified products as a consequence of the α-linolenic acid increment. No oxidation

problems were detected during the ripening process, with TBA values always lower than

0.23 ppm. Hexanal and nonanal showed the highest values in linseed oil containing

products. Addition of antioxidants avoided the formation of decadienals and other

aldehydes from lipid oxidation.

Gambus et al. (2004) explored flaxseed utilization in bread, cookies and

pastry. Bread with 10 and 13% addition of flaxseed meal revealed elevated amounts of

protein (1.1 and 1.4%, respectively) and fat (3 and 4.8%) in comparison to standard

bread. The fatty acid profile exhibited 8-fold increase in α-linolenic acid. Linseed

supplement improved dietary value of bread, enriching it with dietary fibre (5-fold

increase in the case of 13% share), phosphorus, potassium, zinc and doubled the content

of magnesium and copper. A 3% increase in linseed in the recipe for flax hermit cookies

and 5% rise in flax muffins did not influence their sensory assessment and improved their


43

dietary and nutritional value, which was reflected by the amounts of proteins, dietary

fibre, micro and macroelements. The replacement of margarine and oat bran with linseed

in pastry recipes had beneficial effect on α –linolenic acid content. No significant

differences in the dietary enhancement of pastry were found between brown linseed –

Opal and yellow linseed – Hungarian Gold.

Sinha et al. (2004) reported the effects of various levels of flaxseed (0–

20%) on extrusion properties and cooking quality of fresh pasta. Appearance and cooking

quality of fresh pasta made with flaxseed was superior at lower absorption level (29%),

but brightness and yellowness scores were lower whereas redness score increased in fresh

pasta. Flaxseed flour decreased energy requirement to extrude dough, by decreasing

gluten strength. Cooked firmness values varied significantly (p < 0.05). Control sample

yielded the highest firmness and statistically differed from 5% and 10% flaxseed fortified

fresh pasta (p <0.05), whereas 15% and 20% flaxseed fortified fresh pasta gave the

lowest firmness scores.

Hall et al. (2005) reported the shelf life of flaxseed macaroni in terms of

SDG and lipid stability. Processing and drying methods did not affect lipid oxidation as

much as the pretreatment of the flaxseed with steam or addition of the hull component.

Pasta made with hull and steam-treated flaxseed had higher oxidation than pasta made

with ground flaxseed. Pentane was observed to be the most abundant volatile of all

treatments. Propanal significantly increased by week 32 in hull and steam treated

flaxseed, indicating a potential degradation of ALA. Thus, these pretreatments were

detrimental to the oxidative stability of the flaxseed macaroni and were not recommended

as possible alternatives to whole ground flaxseed. Samples did show early signs of

oxidation but no detectable off-aroma was found by week 32. Nevertheless shelf life of

pasta is limited as observed by high hexanal levels in pasta stored over 1 year

Hussain et al. (2006) evaluated physical and sensory attributes of flaxseed

flour supplemented cookies. Full fat flaxseed flour was supplemented with wheat flour @

5, 10, 15, 20, 25 and 30%. Cookies were prepared from composite flours. Cookies

prepared without flaxseed flour were kept as control. The mean quality score of the

cookies decreased with the increase in the level of the flaxseed flour supplementation.

Colour and crispiness of the cookies showed a declining trend as compared to flavour and


44

texture of cookies. Cookies containing 20% and lower level of the full fat flaxseed flour

were acceptable in relation to their overall acceptability. Significant reduction in the

spread factor of the cookies was observed. Addition of the flaxseed flour restricted the

spread of the cookies.

Montesano et al. (2006) tested consumer acceptance of pizza and pizza

crust made with whole wheat flour and added flaxseed. Standard food formulation

included a crust made with added flaxseed, a crust made with added flaxseed and

replacing 50% of the high gluten flour with whole wheat flour, and a crust made with

added flaxseed and full substitution of the high gluten flour with whole wheat flour were

compared. Mean scores suggested that panelists preferred the pizza crust made with only

high gluten flour. However, when the pizza was sampled with the toppings of pizza sauce

and cheese, the consumers could not detect a difference in the crust made with high

gluten flour and the crust made with high gluten flour and flaxseed. Results are favorable

towards the possibility of consumers accepting a pizza crust made with flaxseed.

Bashir et al. (2006) reported on the effect of flaxseed flour

supplementation on the baking properties of cakes and cookies. Wheat flour was replaced

with flaxseed flour at five different levels i.e. 5, 10, 15, 20 and 25% respectively. The

average thickness and width of cookies increased as the amount of flaxseed was

increased but, spread factor was decreased. The overall volume of cakes decreased as the

amount of flaxseed was increased. Supplementation of 10 to 20% of flaxseed flour

resulted in favorable baked products with respect to organoleptic properties. Therefore, it

is highly recommended to explore the potential of flaxseed health benefits to provide

value added products to consumer.

Pohjanheimo et al. (2006) studied on the effect of baking process and

storage on volatile composition of flaxseed breads. Volatiles of flaxseed oil, low fat

crushed grains and three bakery products containing flaxseed in its different forms were

analysed by GC-MS. The volatile compounds identified in flaxseed breads, flaxseed

grains and oil were mainly aldehydes, ketones and alcohols. No clear off-odours were

found in the flaxseed bakery samples after relatively short storage times. The proportion

of hexanal decreased during storage in all bakery samples even though it is a common

indicator of oxidation of lipids. The peroxide value and free fatty acids content showed


45

no significant changes during eleven weeks of storage of the flaxseed oil. Rancidity tests

showed a high stability of flaxseed oil stored at room temperature for eleven weeks.

Valencia et al. (2006) evaluated stability of linseed oil and antioxidants

containing dry fermented sausages. Different packaging conditions (aerobic, vacuum and

modified atmosphere) were studied with a partial substitution of pork backfat by linseed

oil and antioxidants. After 5 months of storage, α-linolenic acid was better preserved by

vacuum and MAP (7.32 and 7.74 g/100 g fatty acids, respectively) than in aerobic

conditions (6.15 g/100 g fatty acids), without significant differences to values obtained

after 2 months of storage for this acid. At the end of the storage, (η- 6)/(η- 3) fraction in

sausages with linseed oil was in all cases lower than 3, in contrast to values obtained for

control products that were all higher than 15. Better PUFA/SFA ratios were also observed

in modified sausages (0.6–0.7 g/100 g fatty acids) than control ones (0.3–0.4 g/100 g

fatty acids). No signs of lipid oxidation measured by TBARs and peroxides were detected

for modified sausages regardless the packaging system used (TBARs values lower than

0.25 ppm and peroxides lower than 4 meq O2/kg), pointing at a high effectiveness of the

antioxidants. Furthermore, vacuum and MAP prevented 2,4-decadienal formation.

Nutritional benefits of linseed oil and antioxidants containing products were maintained

after 5 months of storage.

Chen et al. (2007) reported the interaction between flaxseed gum and meat

protein. Thermal properties, dynamic rheological properties, texture and microstructure

of salt-soluble meat protein and flaxseed gum (SSMP-FG) mixtures were investigated.

Two transitions, 57.00C (TSSMP1) and 63.2

0C (TSSMP2), were observed for SSMP without

FG with differential scanning calorimetry (DSC). Addition of 2% FG to SSMP increased

TSSMP1 and TSSMP2 by 1.90C and 5.9

0C, respectively. Two transitions, 53

0C (TSSMP1) and

750C (TSSMP2), were also observed for SSMP without FG with dynamic rheological

measurement. Addition of 2% FG to SSMP increased TSSMP1 and TSSMP2 by 90C and

140C. These results indicated that addition of FG increased thermal stability of SSMP.

Addition of FG also increased the storage modulus G0, gel strength, decreased syneresis,

and changed the microstructure of SSMP gels with texture analyser and scanning electron

microscope (SEM), respectively, suggesting that an interaction between FG and SSMP

may have occurred. The results of addition of destabilizer to SSMP gels indicated that


46

electrostatic forces seemed to be the main force involved in the formation and stability of

protein–polysaccharide gel.

Pelser et al. (2007) studied on lipid oxidation in ω- 3 fatty acid enriched

dutch style fermented sausages. Products were manufactured with a substitution of 10%,

15% and 20% of pork backfat by flaxseed oil and canola oil, pre-emulsified with soy

protein isolate. The products were sliced, packaged in an oxygen-enriched atmosphere

and stored in the dark for 12 weeks at 70C. No differences were detected in moisture,

protein and fat content between control and modified sausages, with the exception of the

formulation with sodium caseinate. The PUFA/SFA ratio increased from 0.30 in the

control to 0.42–0.48 in the sausages with canola oil and to 0.49–0.71 in the sausages with

flaxseed oil. The ω-6/ ω-3 ratio decreased from 11.20 in the control to 6.94–5.12 in the

sausages with canola oil and to 1.93–1.05 in the sausages with flaxseed oil. In the

samples with addition of pre-emulsified flaxseed oil, especially with sodium caseinate,

lipid oxidation clearly increased during storage. Physical and sensory analysis showed

that the sausages with encapsulated fish oil and flaxseed oil resembled the control most.

Lu et al. (2008) investigated the effects of dietary oil on the fatty acid

compositions of the longissimus and biceps brachii muscles and its effects on cooked

muscles flavour. Seventy-two crossbred barrows (Duroc x Landrace x Large White),

were blocked by weight and randomly assigned to one of three treatments. The three

dietary treatments were: (a) no oil supplement (CON); (b) 3% soybean oil supplement

(SO3); (c) 3% linseed oil supplement (LO3).Dietary linseed oil and soybean oil

significantly increased the contents of C18:3 and C18:2 in the neutral lipids and

phospholipids in both longissimus muscle and biceps brachii muscle, respectively. Aroma

compounds analysis indicated only few aroma compounds were affected significantly by

dietary oil in both cooked longissimus muscle and biceps brachii muscle. The flavour

attributes of cooked longissimus muscle and biceps brachii muscle were not influenced

by feeding 3% soybean oil. Feeding 3% linseed oil did not deleteriously affect the flavor

of cooked longissimus muscle but cooked biceps brachii muscle from LO3 had

significantly lower pork flavour and higher abnormal flavour than CON and SO3.

Wang et al. (2008) investigated the effect of extrusion parameters such as

screw speed, moisture content, temperature and feed rate on in-vitro protein digestibility


47

(IVPD) of the extruded flaxseeds. A central composite design was used with four

controlled variables: screw speed (70, 120, 170, 220 and 270 r/min); moisture content

(4%, 10%, 16%, 22% and 28%); temperature (84, 108, 132, 156 and 180 0C); and feed

rate (25.4, 47.4, 69.4, 91.4 and 113.4 kg/h). The experimental values of IVPD measured

from 69.46% to 77.43%. A second-order model was obtained to predict the IVPD. It has

been found that moisture content and feed rate affect the IVPD more significantly

compared with the temperature and screw speed. In the present study, the maximum

digestibility was obtained when the screw speed, moisture content, temperature and feed

rate were 120 r/min, 10%, 120 0C and 91.4 kg/h, respectively.

Strandas et al. (2008) analyzed phenolic glucosides in bread containing

flaxseed. Three phenolic glucosides, secoisolariciresinol diglucoside, p-coumaric acid

glucoside and ferulic acid glucoside, were analyzed in commercial breads containing

flaxseed. The total phenolic glucoside content ranged from 15 to 157 mg/100 g dry bread.

Secoisolariciresinol diglucoside was the dominating phenolic glucoside with an average

relative content of 62%, followed by p-coumaric acid glucoside (20%) and ferulic acid

glucoside (18%). Strong positive correlations between the phenolic glucosides were

found, indicating no major effect of raw material or bread-making process on the relative

content of the phenolic glucosides in flaxseed.

Bilek and Turhan (2009) reported on enhancement of the nutritional status

of beef patties by adding flaxseed flour. Beef patties were produced with five different

formulations; the addition of 3%, 6%, 9%, 12% and 15% flaxseed flour. Control samples

were formulated with 10% and 20% fat addition. Fat and ash content of raw patties

increased, while moisture and protein content decreased with increased flaxseed flour.

The same trend (except fat content) was also observed after cooking. The addition of

flaxseed flour did not affect pH values of raw and cooked beef patties. The addition of

flaxseed flour improved the cooking loss but, increased the energy value (as kcal/100 g).

L and a values of raw beef patties containing flaxseed flour were close to controls with

10% fat. α-linolenic acid content of raw and cooked beef patties increased as the level of

flaxseed flour increased. The PUFA/SFA ratio increased from 0.04 in the control with

10% fat to 0.62 in the raw beef patties with 15% flaxseed flour. The ω-6/ ω-3 ratio

decreased from 5.76 in the control with 10% fat to 0.36 in the raw beef patties with 15%


48

flaxseed flour. The nutritional status of beef patties was enhanced with minimal

composition and sensory changes with 3% or 6% flaxseed flour addition.

Lipilina and Ganji (2009) determined the optimum amount of ground

flaxseed substitution for flour in bread and muffins. Flaxseed was added to yeast breads

at 15, 25 and 30% and to muffins at 33, 50 and 66% substitution levels for flour on a

weight for weight basis. Breads containing 30% and muffins containing 50% flaxseed

were rated better than their counterparts regarding overall acceptability scores. Linolenic

acid, fiber and folate contents were improved by 28 g, 16 g and 387-mg dietary folate

equivalents (DFE), respectively, in 30% flaxseed bread compared to control. In 50%

flaxseed muffins compared to control, linolenic acid, fiber and folate contents were

improved by 21 g, 17 g and 341-mg DFE, respectively. Flaxseed at 30–50% substitution

for flour greatly enhanced the nutritional qualities of some nutrients without affecting the

overall acceptability of bakery products.

Chetana (2010a) incorporated 20% flaxseed in groundnut chikki.

Tertiarybutyl hydroquinone (TBHQ) at 200 ppm level used as an antioxidant. Results

showed that there were no differences in texture or sensory quality among the samples

with and without antioxidant. The peroxide value of oil in chikki increased gradually at

370C on storage. At the end of 60 days, rancidity developed in samples without

antioxidant. Addition of flaxseed increased α-linolenic acid upto 9%, which were not

present in chikki prepared with only groundnuts. Thus the ratio of 18:2 to 18:3 increased

with addition of flaxseed, which has significant health effects.

Chetana et al. (2010b) reported on the nutritional characteristics of

flaxseed and its application in muffin making. Flaxseed powder contained 21.8% protein

and 42.7% total dietary fiber, which upon roasting reduced to 20.3 and 40.50%,

respectively. Addition of flaxseed powder weakened the dough. Peak viscosity and cold

paste viscosity also decreased. The volume of the muffins gradually decreased from 150

to 145 and 120 cc. Muffins prepared from 20% of raw and roasted flaxseed powder had

10.2 and 9.9% of protein and 12.8 and 11.7% of dietary fiber, respectively. ω-3 fatty acid

contents in raw and roasted flaxseed powder were 55.41 and 50.76%, and the muffins

prepared with 20% raw and roasted flaxseed powder had 12.85 and 11.14%, respectively.

Sodium dodecyl sulfate-polyacrylamide gel electrophoretic pattern and gel filtration


49

studies showed that high- and low-molecular weight protein bands were identified in raw

and roasted flaxseed powder and in the product.

Wu et al. (2010a) investigated rheological properties of the extruded

pastes (dispersions of flaxseed-maize blend) of various extrusion conditions by dynamic

oscillation and creep-recovery tests. Temperature sweep test showed that the starch

gelatinization of non-extruded pastes took place at about 67 0C and no gelatinization was

observed for the extruded sample. Frequency sweep tests could be represented by a

Power law model and the samples showed gel like behavior since storage modulus was

much larger than loss modulus. The creep-recovery data were modeled by the Burger‘s

model. With the addition of flaxseed, the viscoelastic modulii of pastes were increased

due to the formation of starch–protein–fat network, however, with further increasing the

flaxseed content the viscoelastic modulii of pastes were decreased due to excessive fat

which lead to network weakening. The water holding capacity results indicated that the

viscoelastic properties of pastes were depended on the swelled starch–protein complex

granules and the formation of new cross-links in the network.

Wu et al. (2010b) also reported rheological property of extruded and

enzyme treated flaxseed mucilage. The steady-shear tests indicated that the apparent

viscosity of flaxseed mucilage fitted well to Power law model and all samples showed a

shear-thinning behavior. The consistency index decreased and the flow behavior index

increased with an increasing temperature and a decreasing screw speed. The addition of

initial moisture content improved the degradation of flaxseed mucilage while further

increase affected the action negatively. The empirical equations describing relationships

between parameters of rheological models and extrusion factors were obtained. The

results showed that extrusion can damage the compact fiber structure which improved the

effect of enzyme treatment. The apparent viscosity decreased with the increase in

hydrolyzing time and enzyme loading amount.

Kassis et al. (2010) developed nutraceutical egg products enriched with

omega-3 rich oils by substituting cholesterol-containing yolk with ω -3 FAs-rich

flaxseed, menhaden, algae, or krill oil. Experimental egg products (egg whites, ω-3 oils,

and annatto), whole egg, and liquid egg product (Egg Beaters_) were microwave-cooked,

analyzed, and compared. Protein, fat, and moisture contents of experimental egg products


50

matched (P > 0.05) whole egg. Cholesterol was the highest (P < 0.05) in whole egg (1.35

g/100 g, dry weight basis); while it ranged 0.01e0.24 g/100 g (dry weight basis) in

experimental egg products. On a per egg basis, one whole egg contained 216 mg; while

experimental egg products ranged 1e38 mg. The total u-3 FAs content was the lowest (P

< 0.05) in whole egg (5.9% of total FAs) and the highest (P < 0.05) in experimental egg

products developed with krill oil (46.5%), followed by flax (43.1%), algae (DHASCO-

42.5% and DHAS-39.5%), and menhaden oil (27.6%). The essential amino acid (EAA)

content of experimental egg products was similar (P > 0.05) to whole egg except

methionine, phenylalanine, and valine were generally greater in experimental egg

products. Experimental egg products also had similar (P > 0.05) content of non-EAA to

whole egg except alanine and glutamic acid were higher (P<0.05); while arginine and

cysteine were generally lower and higher in experimental egg products, respectively.

Aliani et al. (2011) developed muffins and snack bars with incorporation

of flaxseed. They evaluated the flavor profile of different muffin and snack bar

formulations with and without milled flaxseed. Both the orange cranberry and apple spice

muffin formulations with flaxseed had significantly lower sweetness and vanilla aroma

and flavor intensities, and significantly higher grain/flax aroma and flavor, and bitter taste

compared to the non-flax muffin. Of the two flavorings apple spice appeared to have the

best potential, since the apple aroma and flavor were significantly higher for the flax

muffin compared to the non-flax muffin. The orange cranberry, gingerbread raisin and

cappuccino chocolate chip snack bar formulations with and without flaxseed showed no

significant differences in intensities for the grain/flax aroma and flavor. The gingerbread

raisin snack bar formulations showed no significant differences for any other attributes

except for higher spice aroma in the flax sample, which makes it a promising flavoring

option.

Ivanov et al. (2011) explored the flaxseed additive application in dairy

products production. They reported that microstructure of flaxseed additive is

multicomponent and structured system. It consists of uninterrupted phase of

polysaccharides solution and structural elements such as particles of flaxseed, globules

and areas with a cellular structure from polygonal cells. As a result the mechanism of

microstructure suspension formation was proposed. It has a few stages. They are the


51

formation of dispersion of globules, the aggregation of globules and formation of areas

with a cellular structure. Sensory evaluation has shown that butter with flaxseed additive

has pure creamy flavour and odor without flavour and odor of additive, yellow color and

good spreadability and plasticity. It was proven that addition of structured suspension of

flaxseed additive makes structure destruction decrease and plasticity increase. It was also

revealed that recovering ability of butter structure soars when flaxseed additive dose

increases. This fact indicates that butter with the flaxseed additive has coagulation-

crystallization structure with domination of the coagulation one. Decrease of structure

destruction and increase of recovering ability of butter structure apparently due to the

formation of additional intermolecular bonds between the components of flaxseed

additive and butter.

Pu et al. (2011) developed microencapsulated flaxseed oil containing

shrimp astaxanthin using a pilot scale spray drier. The antioxidant-rich natural

astaxanthin, dispersed in alpha-linolenic acid-rich flaxseed oil, may provide healthier

functional food options for consumers. The measured production rate of

microencapsulated flaxseed oil (MF) and flaxseed oil containing shrimp astaxanthin

(MSA) was lower than the estimated production rate. The astaxanthin concentration of

MSA was 16.08 mg g-1

powder. The lipid oxidation of MSA was lower than that of MF

at 5, 25, and 40 0C during 26 days storage. Degradation of astaxanthin in MSA, fitted

with first-order reaction kinetics model, showed that the degradation rate constant for

MSA increased with increased storage temperature, which indicated that astaxanthin

degraded faster at higher temperature than that at lower temperature.

Fofana et al. (2011) reported on the development of flaxseed bolls as

health food which have specific fatty acid profile. A comparative study was conducted

using two flax cultivars, AC McDuff and Linola, to evaluate fatty acid accumulation in

developing bolls at 12 different developmental stages and to determine stages having well

balanced omega-6/omega-3 FA ratio. The lipid hydroperoxide level in fresh bolls and

seeds, and the cyanogenic glucoside content in developing bolls were also measured in

AC McDuff following different heating treatments. The observed omega-6/omega-3 ratio

was below 4:1 from 0 to 8 days after arthesis developmental stages in both cultivars. The


52

findings indicated and suggested that the use of flax bolls as health promoting vegetable

can be considered if adequately processed and palatable food attributes are obtained.

Masoodi et al. (2012) assessed the effects of fortification of flaxseed at

different levels on the nutritional and sensory quality of biscuit. A novel fortified biscuit

was successfully produced and it was observed as the concentration of flaxseed increased

the moisture, fat, ash, protein showed gradual increase whereas dietary fibre showed a

rapid increase. However, carbohydrate content was decreased. The antioxidant activity,

phenolic concentration was linearly increased as the fortification was increased. Also the

dark color intensity was increased with the increase in fortification. On the basis of

nutritional and sensory quality, biscuit when fortified with blends of 10% flax seed

resulted in better quality and nutritious biscuits (carbohydrate content 69.76%, protein

content 10.59%, fat content 11.07%, ash content 2.48% and fibre content 7.77%).

Rajiv et al. (2012) reported on rheology, fatty acid profile and storage

characteristics of cookies as influenced by flax seed. Studies on the effect of substitution

of roasted and ground flaxseed (RGF) at 5, 10, 15 and 20% level on the wheat flour

dough properties showed that amylograph peak viscosity, farinograph dough stability,

extensograph resistance to extension and extensibility values decreased with the increase

in the substitution of RGF from 0–20%. The cookie baking test showed a marginal

decrease in spread ratio but beyond substitution of 15% RGF the texture and flavour of

the cookies was adversely affected. The data on storage characteristics of control and

cookies with 15% RGF showed no significant change with respect to acidity of extracted

fat and peroxide values due to storage of cookies up to 90 days in metallised polyester

pouches at ambient conditions. Fatty acid profile indicated that the control cookies

contained negligible linolenic acid and the flaxseed cookies contained 4.75 to 5.31% of

linolenic acid which showed a marginal decrease over storage. Hence, flaxseed could be

used as a source of omega–3–fatty acid.

Rao et al. (2013) studied on preparation and storage stability of flaxseed

chutney by mixing with other spices ingredients. The free fatty acid content of flaxseed

chutney powder (FSCP) increased from 0.38 to 1.03 after six months storage. The critical

moisture content for flaxseed powder and FSCP was 10.2 and 13.5%, which were

equilibrated at 82 and 68% RH respectively and the ERH studies indicated both the


53

powders are non hygroscopic in nature. Overall sensory quality of FSCP served with

cooked rice scored good (7.4) even after 6 months of storage.

Villeneuve et al. (2013) studied on the impact of flaxseed processing and

content on engineering properties of pasta after the extrusion, the drying and the cooking

process and they also characterized the fatty acids profile of flaxseed-enriched pasta

during the processing and after the in vitro digestion. Two processes were considered

prior to the incorporation of flaxseed into pasta at levels of 15% and 30% (dry basis):

(Process A) conditioning and milling of flaxseed; (Process B) conditioning of flaxseed,

oil pressing, milling of flaxseed cake and reformulation. Results showed that pressing oil

from flaxseed and then milling the flaxseed cake (Process B) allowed obtaining an

average particle size smaller than milling the whole flaxseed (Process A) which doubled

the flaxseed to semolina particles ratio. Flaxseed processing, prior to the incorporation

into pasta, and content had impacts on engineering properties after the extrusion, the

drying and the cooking process and, affected the protection and the release of free fatty

acids during in vitro digestion. While free fatty acids profiles remained relatively stable

through all steps of pasta processing, they were affected by the in vitro digestion.

Decrease in the proportion of omega-3 fatty acid (C18:3) was more important for the

Process A compared to the Process B. Pasta with a higher level of whole flaxseed (30%)

maintained a larger proportion of omega-3 fatty acid after in vitro digestion compared to

those with a lower level (15%).


54

Table 2.7 Fortification of flaxseed and its fractions in food products and their

storage study

Sr.


1. Chen et al. 1994

After heating to 1780C for 1.5 h, α-linolenic acid

decreased from 55.1 to 51.3% in ground flaxseed,

and to 51.7% in lipid extracts, but it remained

unchanged in the whole flaxseed. At a baking

temperature of 1780C for 2 h, the α-linolenic acid

remained unchanged in muffin mixes.

2. Alpers and

Sawyer-Morse 1996

30% and 50% ground flaxseed muffins were rated

as more acceptable than the control muffin.

Panelists rated the 30% flaxseed cookies as slightly

more acceptable than the control cookies.

3. Ahmed 1999

Physico-chemical, structural and sensory quality of

corn-based flax-snack were reported. Expansion

ratio and water absorption decreased, bulk density

and breaking strength increased with increased

flaxseed content.

4. Manthey et al. 2000

Dough strength of sphagetti significantly decreased,

with small particles having the most detrimental

effect on dough strength as flaxseed content

increased. Fine particle size flaxseed gave

acceptable spaghetti quality. Flaxseed macaroni

was stable during processing and storage.

5. Hall and Schwarz 2002

Flaxseed oil replaced between 10% and 25% of the

milk fat in ice cream formulas has been

investigated. A trained sensory panel showed that

15% of the milk fat could be replaced in a vanilla


55

ice cream without being detected. Flaxseed oil

addition significantly improved the fatty acid

profile of frozen dessert.

6. Lee et al. 2003

Boiled macaroni and boiled-refrigerated-

microwave-heated macaroni with flaxseed

exhibited similar appearance attributes. Cooked

firmness values were highest with boiled macaroni,

intermediate with refrigerated macaroni, and lowest

with microwave-heated macaroni.

7. Ansorena and

Astiasaran 2004

P/S ratio increased from 0.4 in the control sausages

to 0.6 in the batch with 3.3% linseed oil and to 0.7

in the batch with linseed (3.3%) and antioxidants.

This improvement was particularly noticeable when

100 mg/kg of butylhydroxytoluene and 100 mg/kg

of butylhydroxyanisole were added.

8. Gambus et al. 2004

Bread with 10 and 13% addition of flaxseed meal

revealed elevated amounts of protein (1.1 and

1.4%, respectively) and fat (3 and 4.8%) in

comparison to standard bread. The fatty acid profile

exhibited 8-fold increase in α-linolenic acid and 5-

fold in dietary fiber. A 3% increase in linseed in the

recipe for flax hermit cookies and 5% rise in flax

muffins did not influence their sensory assessment

and improved their dietary and nutritional value.

The replacement of margarine and oat bran with

linseed in pastry recipes had beneficial effect on α –

linolenic acid content.

9. Sinha et al. 2004 Effects of various levels of flaxseed (0–20%) on

extrusion properties and cooking quality of fresh


56

pasta. Flaxseed flour decreased energy requirement

to extrude dough, by decreasing gluten strength.

10. Hall et al. 2005

Shelf life of flaxseed macaroni in terms of SDG

and lipid stability was reported. Samples did show

early signs of oxidation but no detectable off-aroma

was found by week 32.

11. Hussain et al. 2006

Cookies containing 20% and lower level of the full

fat flaxseed flour were acceptable in relation to

their overall acceptability. Color and crispiness of

the cookies showed a declining trend as compared

to flavour and texture of cookies. Addition of the

flaxseed flour restricted the spread of the cookies.

12. Montesano et al. 2006

Pizza and pizza crust made with whole wheat flour

and added flaxseed were evaluated. Mean scores

suggested that panelists preferred the pizza crust

made with only high gluten flour. However, results

are favorable towards the possibility of consumers

accepting a pizza crust made with flaxseed when

served with sauce and cheese.

13. Bashir et al. 2006

Supplementation of 10 to 20% of flaxseed flour

resulted in favorable baked products (cakes and

cookies) with respect to organoleptic properties.

14. Pohjanheimo et

al. 2006

The volatile compounds identified in flaxseed

breads, flaxseed grains and oil were mainly

aldehydes, ketones and alcohols. No clear off-

odours were found in the flaxseed bakery samples

after relatively short storage times. Rancidity tests

showed a high stability of flaxseed oil stored at


57

room temperature for eleven weeks.

15. Valencia et al. 2006

Different packaging conditions (aerobic, vacuum

and modified atmosphere) were studied with a

partial substitution of pork backfat by linseed oil

and antioxidants in dry fermented sausages.

Vacuum and MAP prevented 2,4-decadienal

formation. Nutritional benefits of linseed oil and

antioxidants containing products were maintained

after 5 months of storage.

16. Chen et al. 2007

Thermal properties, dynamic rheological properties,

texture and microstructure of salt-soluble meat

protein and flaxseed gum (SSMP-FG) mixtures

were investigated. Addition of 2% FG to SSMP

increased TSSMP1 and TSSMP2 by 90C and 14

0C.

These results indicated that addition of FG

increased thermal stability of SSMP, storage

modulus G0, gel strength and decreased syneresis,

and consequently changed the microstructure of

SSMP gels suggesting that an interaction between

FG and SSMP may have occurred.

17. Pelser et al. 2007

Dry fermented sausages were manufactured with a

substitution of 10%, 15% and 20% of pork backfat

by flaxseed oil and canola oil, pre-emulsified with

soy protein isolate The PUFA/SFA ratio increased

from 0.30 in the control to 0.42–0.48 with canola

oil and to 0.49–0.71 with flaxseed oil. Physical and

sensory analysis showed that the sausages with

encapsulated fish oil and flaxseed oil resembled the

control most.


58

18. Lu et al. 2008

The effects of no oil supplement (CON), 3%

soybean oil supplement (SO3), 3% linseed oil

(LO3) on the fatty acid compositions of the

longissimus and biceps brachii muscles and its

effects on cooked muscles flavour were studied.

Feeding LO3 did not deleteriously affect the flavor

of cooked longissimus muscle but cooked biceps

brachii muscle from LO3 had significantly lower

pork flavour and higher abnormal flavour than

CON and SO3.

19. Wang et al. 2008

The maximum in-vitro protein digestibility of

extruded flaxseed was obtained when the screw

speed, moisture content, temperature and feed rate

were 120 r/min, 10%, 120 0C and 91.4 kg/h,

respectively.

20. Strandas et al. 2008

Secoisolariciresinol diglucoside was the dominating

phenolic glucoside with an average relative content

of 62%, followed by p-coumaric acid glucoside

(20%) and ferulic acid glucoside (18%) in flaxseed

containing bread.

21. Bilek and Turhan 2009

The addition of 3%, 6%, 9%, 12% and 15%

flaxseed flour in beef patties were studied. The ω-6/

ω-3 ratio decreased from 5.76 in the control with

10% fat to 0.36 in the raw beef patties with 15%

flaxseed flour. The nutritional status of beef patties

was enhanced with minimal composition and

sensory changes with 3% or 6% flaxseed flour

addition.


59

22. Lipilina and

Ganji 2009

Breads containing 30% and muffins containing

50% flaxseed were rated better than their

counterparts regarding overall acceptability scores.

Flaxseed at 30–50% substitution for flour greatly

enhanced the nutritional qualities of some nutrients.

23. Chetana 2010

20% flaxseed incorporated groundnut chikki with

tertiarybutyl hydroquinone (TBHQ) at 200 ppm

level was developed and studied for 60 days of

storage. Addition of flaxseed increased α-linolenic

acid upto 9% compared to control. At the end of 60

days, rancidity developed in samples without

antioxidant.

24. Chetana et al. 2010

Flaxseed affected the pasting characteristics of the

wheat flour. Based on characteristics and sensory

parameters, muffins incorporated with 20% roasted

flaxseed powder had better overall acceptable

quality compared with 20% raw flaxseed addition,

there is no significant loss in the nutritional quality

characteristics in 20% roasted flaxseed muffins.

25. Wu et al. 2010a

Rheological properties of the extruded pastes

(dispersions of flaxseed-maize blend) at various

extrusion conditions by dynamic oscillation and

creep-recovery tests were studied. Starch

gelatinization of non-extruded pastes took place at

about 67 0C and no gelatinization was observed for

the extruded sample. The water holding capacity

results indicated that the viscoelastic properties of

pastes were depended on the swelled starch–protein

complex granules and the formation of new cross-


60

links in the network.

26. Wu et al. 2010b

Rheological property of extruded and enzyme

treated flaxseed mucilage was studied. The steady-

shear tests indicated that the apparent viscosity of

flaxseed mucilage fitted well to Power law model

and all samples showed a shear-thinning behavior.

Extrusion can damage the compact fiber structure

which improved the effect of enzyme treatment.

The apparent viscosity decreased with the increase

in hydrolyzing time and enzyme loading amount.

27. Kassis et al. 2010

Substitution of the cholesterol-containing egg yolk

with the ω-3 fatty acid rich oils (flaxseed,

menhaden, algae, or krill oil) resulted in the

development of nutritionally-enhanced cooked egg

products.

28. Aliani et al. 2011

Flavor profile of different muffin and snack bar

formulations with and without milled flaxseed were

evaluated. The apple aroma and flavor were

significantly higher for the flax muffin. The

gingerbread raisin snack bar formulations showed

no significant differences for any other attributes

except for higher spice aroma in the flax sample,

which makes it a promising flavoring option.

29. Ivanov et al. 2011

Sensory evaluation has shown that butter with

flaxseed additive has pure creamy flavour and odor

without flavour and odor of additive, yellow color

and good spreadability and plasticity. Butter with

the flaxseed additive has coagulation-crystallization


61

structure with domination of the coagulation one.

30. Pu et al. 2011

Microencapsulated flaxseed oil containing shrimp

astaxanthin using a pilot scale spray drier was

developed. It may provide healthier functional food

options for consumers.

31. Fofana et al. 2011

Development of fresh flaxseed bolls as health food

which have specific fatty acid profile was reported.

The observed omega-6/omega-3 ratio was below

4:1 from 0 to 8 days after arthesis developmental

stages.

32. Masoodi et al. 2012

Biscuit when fortified with blends of 10% flax seed

resulted in better quality and nutritious biscuits

(carbohydrate content 69.76%, protein content

10.59%, fat content 11.07%, ash content 2.48% and

fibre content 7.77%).

33. Rajiv et al. 2012

Beyond substitution of 15% roasted ground

flaxseed the texture and flavour of the cookies was

adversely affected. The data on storage

characteristics of control and cookies with 15%

flaxseed cookies showed no significant change with

respect to acidity of extracted fat and peroxide

values due to storage of cookies up to 90 days in

metallised polyester pouches at ambient conditions.

Flaxseed cookies contained 4.75 to 5.31% of

linolenic acid which showed a marginal decrease

over storage.


62

34. Rao et al. 2013

The free fatty acid content of flaxseed chutney

powder (FSCP) increased from 0.38 to 1.03 and

overall sensory quality of FSCP served with cooked

rice scored good (7.4) even after 6 months of

storage.

35. Villeneuve et al. 2013

Flaxseed processing, prior to the incorporation into

pasta, and content had impacts on engineering

properties after the extrusion, the drying and the

cooking process and, affected the protection and the

release of free fatty acids during in vitro digestion.

Pasta with a higher level of whole flaxseed (30%)

maintained a larger proportion of omega-3 fatty

acid after in vitro digestion compared to those with

a lower level (15%).

Various food products were manufactured with fortification of flaxseed

and its fractions. Flaxseed desirable nutrients in food products were stable after

processing. Storage stability study of flaxseed fortified food products showed that

rancidity might be problem as unsaturated fatty acids are more prone to oxidation.

Addition of antioxidant and proper packaging of the products can be adopted to have

extended shelf life.

2.6 Application of response surface methodology (RSM) in extruded food product

development

Response surface methodology (RSM) is a statistical-mathematical

method which uses quantitative data in an experimental design to determine and

simultaneously solve multivariate equations to optimize and mathematical model

processes and products (Myers and Montgomery, 1995). The RSM produces a

mathematical model that can be used to predict a response. The model equation describes

the effect of the test variables on the responses, determine interrelationships among test


63

variables and represent the combined effect of all test variables in the response. Various

researchers adopted response surface methodology approach for the development of

extruded food products. The same is discussed as follows.

Jin et al. (1994) investigated the effects of soya fiber, sugar, salt and screw

speed on extrusion parameters and extrudates properties by using RSM. Increasing the

fiber content raised the product temeperature, extruder torque, die pressure and specific

energy. It also resulted in greater axial expansion but less radial expansion in extrudates.

The addition of sugar to corn meal had no appreciable effect on the lightness and redness

of the extrudates. The overall effect of adding fiber and sugar on the expansion was

dependent on the ratio of their additions. The colors of extrudates were mainly influenced

by the initial color of the fiber and screw speed, whereas the effects of salt were not

significant on the extrusion parameters.

Bhattacharya (1997) reported on twin screw extrusion of rice and green

gram blend by using central composite rotatable design. The linear (positive) effect of

temperature imparts more effect on ER followed by the negative linear effect of screw

speed. The effect of screw speed is mostly temperature dependent. Temperature has a

curvilinear effect on extrudate density and at high temperature, its quadratic effect

dominates. The torque during extrusion was highest at the highest temperature levels. The

specific mechanical energy linearly increased with screw speed. High barrel temperature

combined with a low screw speed is suitable for obtaining an expanded product.

Guha et al. (1997) investigated the effect barrel temperature and screw

speed on extrusion and extrudate characteristics using twin screw extrusion without die

on rice flour. Temperature of barrel and screw speed were independent variables while

torque during extrusion, total SME, bulk density, water absorption index, water

solubility index, sediment volume, and in vitro starch digestibility were response

functions. A positive linear (correlation coefficient r = 0.78, significant at a probability

level (p < 0.01) relationship existed between and VIE and bulk density, indicating that

low-density extrudate is possible to obtain with low SME. Extrusion of rice flour without

a die appears to be an alternative approach to produce processed rice flours with high

water absorption index and in vitro starch digestibility.


64

Ilo et al. (1999) studied on extrusion cooking of rice flour amaranth blends

by using RSM. Increasing amaranth content in the blends increased die pressure, but

decreased torque and SME. Increasing amaranth content caused an enormous decrease in

the sectional expansion index (SEI) and increase in the breaking strength of extrudate.

Well expanded rice-amaranth products with acceptable soft texture were at amaranth

levels of 20-40 g/100 g. Optimal extrusion cooking conditions most likely to produce

rice-amaranth products suitable for a puffed snack food were at high barrel temperature,

low moisture, high screw speed, and feed rates in the range of 25-35 kg/h.

Gutkoski and El-Dash (1999) studied on the effect of extrusion process

variables on physical and chemical properties of extruded oat products by using RSM.

Initial moisture levels of extrusion feed and extrusion temperatures were considered as

independent variables while bulk density, water absorption and water solubility indexes,

viscosity, and color of extruded oat products were considered as responses. The water

absorption index of extrudates were relatively low (4.16–6.35 g gel/g sample) but

increased as the initial moisture of the raw material as well as the extrusion temperature

was elevated. Initial viscosity of the paste increased with the increase of raw material

moisture and extrusion temperature. Products with lower values of L (luminosity) and

greater values of a (red) and b (yellow) were obtained at high moisture rates and at a 120

0C extrusion temperature.

Nath and Chattopadhyay (2007) reported on the optimization oven

toasting for improving crispiness and other quality attributes of Ready to Eat Potato-Soy

Snack using RSM. Oven toasting experiments were conducted with varying temperature

(85.86–114.14 °C) and time (12.69–35.31 min) based on central composite rotatable

design. The final product was evaluated in terms of quality attributes such as crispness,

moisture content, ascorbic acid loss, colour (L and ΔE) values and overall acceptability.

The optimum product qualities in terms of crispness (38.7), moisture content (3.35%, db),

ascorbic acid loss (20.87%, db), L value (52.03), ΔE (8.60) and overall acceptability (7.8)

were obtained at temperature of 104.4 °C and time of 27.9 min.

Wu et al. (2006) studied the effects of flaxseed meal (0, 5, 10 and 15%) in

flaxseed meal/corn meal blend and processing variables, including moisture content (16,

18 and 20%), and screw speed (200, 300 and 400 rpm), on extrudates chemical property


65

(lignan residue) and physical properties (specific volume, hardness and color) were

studied. The lignan compounds in the flaxseed and corn meals were 2.27 and 0 mg/g,

respectively, before extrusion. A higher flaxseed meal level and a higher screw speed

favored the retention of lignan compounds, but higher feed moisture showed the opposite

effect. About 25–52% lignan compounds were lost after extrusion. Increasing flaxseed

meal level, increasing feed moisture or decreasing screw speed significantly reduced the

expansion and resulted in harder extrudate that was darker, more reddish and less yellow.

Yagci and Gogus (2008) investigated the effects of extrusion conditions

including moisture content (12–18%), temperature (150–1750C), screw speed (200–280

rpm), and change in feed composition, durum clear flour (8–20%), partially defatted

hazelnut flour (PDHF) (5–15%) and fruit waste (3–7%) contents on the physical and

functional characteristics of the extruded snack food based on rice grit in combination

with fruit waste, durum clear flour and PDHF. The product responses were mostly

dependent on PDHF content rather than fruit waste content. Increasing PDHF content

caused increase in bulk density and water solubility index, but decrease in porosity and

water absorption index of the extruded snacks. Changing process conditions affected the

physical and functional properties of produced snacks.

Chakraborty and Banerjee (2009) reported on development of extruded

product from green gram and rice by RSM. Temperature and moisture had significant

effect on expansion ratio, which decreased with increasing moisture content. Feed

moisture and die head temperature had negative effect on water holding capacity.

Specific mechanical energy for extrusion and pressure developed at die head increased

with increasing proportion of green gram in rice-green gram blend. With increase in

barrel screw speed, viscosity of rice green gram dough decreased resulting lesser power

consumption and developed pressure at die head. Rapid rise in starch viscosity is also a

function of temperature so that higher range of extrusion temperature and extrudates

slurry viscosity caused high pressure drop, which caused greater expansion of green gram

extrudates.

Altan et al. (2009) reported on effect of screw configuration and raw

material on some properties of barley extrudates by using RSM. Twin-screw extrusion

was performed to evaluate the potential use of barley grits and barley flour for expanded


66

snack foods. The 2 x 2 factorial design had two levels of raw material (barley grits and

barley flour) and two levels of screw configuration severity (medium and severe). The

experimental responses were the following extrudate properties: specific mechanical

energy (SME), expansion (SEI), bulk density, water absorption index (WAI), hardness,

breaking strength and color. Means of the responses were significantly different for all

responses except bulk density and WAI with respect to screw configuration. For raw

material, the means of the responses were significantly different for all responses except

SEI and WAI. Barley flour extrudates produced by severe screw configuration had

significantly lower SME than barley grits extrudates. Severe screw configuration

produced more expanded product with low bulk density than that of medium screw

configuration. Correlations were found between product responses.

Meng et al. (2010) studied on the effect of extrusion conditions on system

parameters and physical properties of a chickpea flour-based snack by using RSM.

Second-order polynomials were used to model the extruder responses and product

properties as a function of process variables. Product temperature and die pressure were

affected by all three process variables, while motor torque and SME were only influenced

by screw speed and barrel temperature. All three variables affected product responses

significantly. Desirable products, characterized by high expansion ratio and low bulk

density and hardness were obtained at low feed moisture, high screw speed and medium

to high barrel temperature. It was demonstrated that chickpeas can be used to produce

nutritious snacks with desirable expansion and texture properties.

Oluwole and Olapade (2011) reported on effect of thermo-extrusion

processing of white yam (Dioscorea rotundata) and bambara nut (Vigna subterranean) on

some selected extrudate parameters of residence time, throughput and moisture content

by using RSM. The study revealed that the extrusion time varied between 13.1 and 29.7

sec, throughput varied from 13.3 to 34.4 kg/h and product moisture ranged from 11.1 to

16.8% dry basis. All investigated extrudate parameters were significantly affected (p <

0.05) by the process variables of screw speed, barrel temperature and feed moisture

content, and their interactions. The results were indicative that the second order poly-

nomial was adequate to model the dependence of the extrudate parameters of residence


67

time, throughput and moisture content on extrusion variables of barrel temperature, feed

moisture content and screw speed.

Choudhury et al. (2011) reported on optimization of rice flour and lali

(shrimp variety) extrusion by RSM. Response (dependent) variables were: expansion

ratio, density, shearing strength and sensory texture acceptability. Independent variables

were processing temperature and feed moisture. All other process variables (screw speed,

feed speed and die diameter) were kept constant (475 rpm, 28 g/min and 3 mm

respectively). The maximum expansion ratio obtained at 15% moisture and 150ºC

process temperature coincided with the minimum shearing force of the product, and

maximum sensory texture acceptance indicating a correlation between extrusion response

variables. Response surface study indicated the desired texture and sensory property

could be obtained by controlling cooking temperature and moisture condition.

Seth and Rajamanickam (2012) developed extruded snacks using soya,

sorghum, millet and rice by using RSM. The independent variables were different levels

of ragi (40–50%), sorghum (10–20%) and soy (5–15%). Response variables were bulk

density (BD), expansion ratio (ER), water absorption index (WAI) and water solubility

index (WSI) of the extruded snacks. The coefficients of determination, R2, of all the

response variables were higher than 0.90. Based on the given criteria for optimisation, the

basic formulation for production of millet-based extruded snack with desired sensory

quality was obtained by incorporating with 42.03% ragi, 14.95% sorghum, 12.97% soy

and 30% rice.

Table 2.8 Application of RSM in extruded food product development

Sr.

No. Author/s Year Important Findings

1. Jin et al. 1994

Increasing the fiber content raised the product

temeperature, extruder torque, die pressure and

specific energy. It also resulted in greater axial

expansion but less radial expansion in extrudates.

The addition of sugar to corn meal had no


68

appreciable effect on the lightness and redness of

the extrudates. The colors of extrudates were mainly

influenced by the initial color of the fiber and screw

speed, whereas the effects of salt were not

significant on the extrusion parameters.

2. Bhattacharya 1997

The linear (positive) effect of temperature imparts

more effect on ER followed by the negative linear

effect of screw speed. . Temperature has a

curvilinear effect on extrudate density and at high

temperature, its quadratic effect dominates. The

torque during extrusion was highest at the highest

temperature levels. The specific mechanical energy

linearly increased with screw speed. High barrel

temperature combined with a low screw speed is

suitable for obtaining an expanded product.

3. Guha et al. 1997

Extrusion of rice flour without a die appears to be an

alternative approach to produce processed rice

flours with high water absorption index and in vitro

starch digestibility.

4. Ilo et al. 1999

Well expanded rice-amaranth products with

acceptable soft texture were at amaranth levels of

20-40 g/100 g. Optimal extrusion cooking

conditions most likely to produce rice-amaranth

products suitable for a puffed snack food were at

high barrel temperature, low moisture, high screw

speed, and feed rates in the range of 25-35 kg/h.

5. Gutkoski and

El-Dash 1999

The water absorption index of oat extrudates were

relatively low (4.16–6.35 g gel/g sample) but

increased as the initial moisture of the raw material


69

as well as the extrusion temperature was elevated.

Initial viscosity of the paste increased with the

increase of raw material moisture and extrusion

temperature. Products with lower values of L

(luminosity) and greater values of a (red) and b

(yellow) were obtained at high moisture rates and at

a 120 0C extrusion temperature.

6. Wu et al. 2006

Effects of flaxseed meal incorporation on corn meal

extrudates lignan residue and physical properties

were studied. A higher flaxseed meal level and a

higher screw speed favored the retention of lignan

compounds, but higher feed moisture showed the

opposite effect. Increasing flaxseed meal level,

increasing feed moisture or decreasing screw speed

significantly reduced the expansion and resulted in

harder extrudate that was darker, more reddish and

less yellow

7. Nath and

Chattopadhyay 2007

The optimum Potato-Soy Snack qualities in terms of

crispness (38.7), moisture content (3.35%, db),

ascorbic acid loss (20.87%, db), L value (52.03),

ΔE (8.60) and overall acceptability (7.8) were

obtained at temperature of 104.4 °C and time of

27.9 min

8. Yagci and

Gogus 2008

The product responses were mostly dependent on

partially defatted hazelnut flour content rather than

fruit waste content. Increasing PDHF content caused

increase in bulk density and water solubility index,

but decrease in porosity and water absorption index

of the extruded snacks. Changing process conditions


70

affected the physical and functional properties of

produced snacks.

9. Chakraborty

and Banerjee 2009

Temperature and moisture had significant effect on

expansion ratio, which decreased with increasing

moisture content. Feed moisture and die head

temperature had negative effect on water holding

capacity. Specific mechanical energy for extrusion

and pressure developed at die head increased with

increasing proportion of green gram in rice-green

gram blend. With increase in barrel screw speed,

viscosity of rice green gram dough decreased

resulting lesser power consumption and developed

pressure at die head.

10. Altan et al. 2009

Barley flour extrudates produced by severe screw

configuration had significantly lower SME than

barley grits extrudates. Severe screw configuration

produced more expanded product with low bulk

density than that of medium screw configuration.

11. Meng et al. 2010

Desirable products, characterized by high expansion

ratio and low bulk density and hardness were

obtained at low feed moisture, high screw speed and

medium to high barrel temperature. It was

demonstrated that chickpeas can be used to produce

nutritious snacks with desirable expansion and

texture properties.

11. Oluwole and

Olapade 2011

Second order polynomial was adequate to model the

dependence of the extrudate parameters of residence

time, throughput and moisture content on extrusion

variables of barrel temperature, feed moisture


71

content and screw speed in extrusion processing of

white yam.

12. Choudhury et

al. 2011

Optimization of rice flour and lali (shrimp variety)

extruded product was carried out.

13. Seth and

Rajamanickam 2012

Formulation for production of millet-based extruded

snack with desired sensory quality was obtained by

incorporating with 42.03% ragi, 14.95% sorghum,

12.97% soy and 30% rice.

RSM is a useful tool to minimise the numbers of trials and provide

multiple regression approach to achieve optimization. The effectiveness of response

surface methodology (RSM) in optimisation of ingredient levels, formulations and

processing conditions in snack food has been documented by different researchers.

Extrusion is one of the most versatile operations available to the food industry for

transforming ingredients into intermediate or finished products. Extrusion has been used

to produce a wide variety of foods such as snack, ready-to-eat cereals, textured vegetable

protein, confectioneries and pet foods. Applications of extrusion cooking technology to

different cereals, millet and pulses have promise for preparation of diversified and value

added food products.

Documents

CHAPTER 2 Review of Literature - Shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/37191/10/10_chapter2.pdf · use of response surface methodology in development and optimization