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The Use of Non-‐Wheat Derived Flours in Baked Goods. Food Science/Composition: FOS 4041 March 14, 2013 Matthew Thomas
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n recent years, there has been a rise in gluten intolerances as well as Celiac disease
patients which requires these individuals to exclude the gluten protein from their
diet. Gluten is a protein complex formed when wheat flour is exposed to water.1 (p339) Flour is
defined as the product from milling anytime of grain.1 (p392) Wheat is the most common grain for
milling because it is most favorable in baked products. When an alternative grain is milled into
flour, the lack of gluten often yields a liquid batter rather than dough. When this dough is baked
the product has a crumbling texture, odd color and other unfavorable baking quality
properties2. As a result, there has been extensive scientific research to create flours that mimic
the same favorable baking outcomes as wheat flour but using another grain that does not
contain the gluten protein complex. A common alternative grain that is milled into flour to be
used in baking are legumes. Legume flours consist of mug beans, soybeans, peas, lupins, lentils,
and chickpeas. In this paper, the scope of legume flours will include soybean and chickpea.3, 4
Soy flour is derived from soybean that is either ground whole or defatted. Soybeans have been
a staple crop in the Far East for centuries. Through agricultural advances, soybeans can be
processed into flour and can be partially substituted with wheat four in a variety of baked
goods. Soy flour is widely available and is a relatively inexpensive legume flour.5, 6 Chickpea
flour is the main ingredient for traditional fermented foods of some Mediterranean cultures.7
Rice flour is a common form of non-‐wheat derived that is composed of broken rice grains that
are milled or grounded into flour.8 A feature that makes rice flour unique is its hypoallergenic
properties, its mild indistinct taste, and its white color2. Rice flours are traditionally found in
baby foods, noodles and in many Asian cuisines.8 With a variety of alternatives grains being
milled into flour and incorporated into baked goods, the outcomes differ greatly due to their
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distinctive chemical and physical properties. In this paper, the chemical properties discussed
are carbohydrate, protein, lipid, and fiber content. Our sensory organs such as eyes, mouth,
and smell measure the physical properties of flours. In this paper, the physical properties
examined include volume, color, and crumbs1 (p71-‐82). All of these properties will be compared to
traditional wheat derived flour. The final portion of the paper will incorporate the findings of
the chemical and physical properties of non-‐wheat derived flours and apply it to the dietetics
practice. The purpose of writing this paper is to explain the effect of the physical and chemical
properties of baked goods when non-‐wheat derived flours are used.
1. Chemical Properties:
1.1 Carbohydrate Content
The macronutrient carbohydrate is the umbrella term for multiple types of carbohydrates
found in non-‐wheat flours. A common form of carbohydrate found in legume flours is the
polysaccharide: starch. A polysaccharide consists of thousands of glucose molecules forming
either amylose or amylopectin of which are polymers from glucose.1 (p129) The form of
polysaccharide found in legume flours is amylopectin.9 Amylopectin is composed of a linear
backbone of 10-‐25 glucose units then branch. The glucose unties are bonded together by 1-‐4-‐α
-‐glucosidic linkages and 1,6-‐ α-‐glucosidic linkages.1 (p133) Their composition allows for minimal
solubility which is has health promoting properties by lowering the glycemic index.3,4,7
According to Mohammed et.al whom conducted a study on the dough rheology and bread
quality of wheat-‐chickpea flour blends, starch is the primary macronutrient found in legume
flours consisting of 35-‐52% of the dry weight mass followed by fiber at 14.6-‐26.3% then protein
at 18.5-‐30%.10
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In comparison to legume fours, the amount of amylopectin found in rice flours is lower.11 In
a study directed by Hasjim et.al, they tested the impact milling had on the starch/flour
structure. There findings state that the starch structures may be related to the degradation of
starch crystalline structure caused by the milling processes of rice flour. As a result, the
disruption of the starch structure effects the gelatinization temperature which may act as a
physical barrier for heat transfer.8 The starch content can be detected by the level of gelling
due to the increased rate of gelatinization during baking2. Another macronutrient that
differentiates between wheat flour and legume flour is protein.
1.2 Protein Content
Protein is a macronutrient molecule composed of amino acids that are linked together
by peptide linkages. Amino acids are considered the building blocks of protein due to their
organic substances that containing a amino functional group, and a carboxyl amino group. The
various sequences of amino acids exist in foods.1 (p281) Legume flours are increasingly being used
in many countries because of its naturally good source of vegetable protein, have a low fat
content and most importantly, include all nine of the essential amino acids required by humans.
The essential amino acid content in soybean exceeds the amino acid requirements of children
and adults, which confirms the protein quality. An amino acid found in legume flours and
absent in wheat flours is the essential amino acid lysine.3,5,6,7,10,12 The legume flour that has the
highest protein content is soybean.12 In a study conducted by Doxastakis et al., the aim of their
study is to measure soybean, lupin and wheat flours and there effect on rheological properties.
They discovered that soybean flour contain high amounts of the following amino acids: lysine,
leucine, aspartic acid, glutamic acid and arginine which provide a balanced essential amino acid
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profiles when consumed with cereals and other foods rich in sulphur-‐containing amino acids
and tryptophan The amino acid profiles of legume flours are complementary to wheat flours
when they are incorporated together. For example the legume flour lupin flour contains high
amounts of lysine and low amounts of methionine whereas wheat flour has poor in lysine
content and rather higher levels of sulphur-‐containing amino acids. Therefore integrating
legume flours into wheat flour creates a blend that improves the nutritional value of bread.4,5
Coda et al. measured the concentration of free amino acid and amino acid derivatives (mg/kg)
of wheat flour (WFB), non-‐conventional flour (NCB) and non-‐conventional flour sourdough
(NCSB) breads in his study regarding the use of sourdough fermentation, pseudo-‐cereals and
leguminous flours for the making of functional breads. There results showed that the amino
acid lysine content in NCSB breads was 10 times higher than in WFB breads.7 However, only a
fractioned amount of legume flours can be incorporated into wheat flours to prevent
undesirable changes in the physical properties of the baked good including the color, texture,
moisture, and volume.4 Some other non-‐wheat derived flours that contain the amino acid lysine
are rice and buckwheat flour.2
In a study conducted by Chillo et.al, the aim was to determine the effects of incorporating
25% chickpea flour into semolina spaghetti measuring its cooking quality and glycemic impact.
Due to the higher protein content in chickpea flours, the spaghetti sample containing a blend of
chickpea flour was more firm than the control even though the cooking time for both samples
were closely similar. This study show how chickpea flour can be incorporated into the
traditional semolina wheat flour and promote healthy properties while not dramatically
including sensory properties nor cooking time.3 In regards to using legume flours in baked
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goods, the higher protein content results in a greater increase in water absorption versus baked
goods solely containing wheat flours. This increase in water absorption leads to weakening the
gluten network. 10 According to Mohammad et al. whom studied about dough rheology and the
bread quality of wheat and chickpea flour blends. In this study, there were four samples to test
the dough rheology and bread quality of wheat and chickpea flour blends. The first sample was
the control containing 100% wheat flour, the second sample consisted of 90% wheat flour and
10% chickpea flour. The next sample comprised of 80% wheat flour and 20% chickpea flour. The
final sample had only 70% wheat flour and 30% chickpea flour as illustrated in figure 1 below.
This figure shows that an increase amount of chickpea flour in dough yields more stickiness
hence making the dough tougher to handle. The stickiness of the dough is due to the greater
gluten protein: glutenin found in legume flours. Notice that the addition of chickpea flour lead
to a weakening of the gluten network even with the elevated glutenin. This confirms that the
both gliadin and glutenin are equally critical for optimal gluten network development.10 In
comparison to wheat flour, rice flour contains a greater amount of protein but not as much as
legume flours. The correlation of protein content and water absorption still applies when
baking with wheat flour.2
Figure 1: Dough surface characteristics containing different levels of chickpea flour (CF). (1) 100% WF; (2) 90% WF and 10% CF; (3) 80% WF and 20% CF; and (4) 70% WF and 30% CF.
Mohammed I, Ahmed AR, Senge B. Dough rheology and bread quality of wheat–chickpea flour blends. Industrial Crops and Products. 2012;36(1):196-‐202. http://dx.doi.org/10.1016/j.indcrop.2011.09.006 Assessed March 13, 2013.
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1.3 Lipid Content
Lipids are organic compounds composed of a glycerol backbone and a varying fatty acid
chain.1 (p237) The lipid content of legume flours (with the exception of mug bread and lentil flour)
is greater than wheat flour.3,12 The lipid content of flour controls the gelatinization rate as well
as the peak viscosity of a baked product. In legume flours, the increased lipid content lower the
maximum peak as well as lowering the gelatinization rate which. In baking, the high lipid
content along with the low starch content of legume flours lowers gelatinization rate. The
decrease in peak viscosity is due to lipids forming a complex with amylose that results in
lowering peak viscosity.3 On the other hand, rice flours, whom composition is higher in
carbohydrate contains higher maximum peak torques and gelatinization rates than other
flours.12
1.4 Fiber Content
Fiber, most commonly found in plant foods, is the combination of materials in foods that
cannot be freely digested. Fiber is classified into two categories, soluble and insoluble. Soluble
fibers are capable of being partially digested thus providing some energy. Insoluble fibers are
non-‐digestible fibers that are excreted from the body it is full form.1 (p223) Both types of fiber
have been shown to have multiple health benefits thus needs to be increasingly integrated into
the Western diet. Dietary fiber content in legume and rice flours is greater than wheat flour.10
In a study directed by Veluppillai et al. shows that malted rice flour bread contained more
soluble fiber, insoluble fiber, and total fiber than wheat flour bread. Even though there are
many beneficial health properties to fiber, the presence of fiber in flours may inhibit
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carbohydrate absorption.11 The chemical properties of legume and rice flours do not only
impact the nutritive properties of backed goods but the physical properties are also influenced
as well.
2. Physical Properties
2.1 Volume
According to research team of Miñarro et al. “the loaf specific volume is considered as
one of the most important gauges in evaluating bread quality since it provides quantitative
measurements of baking properties.”13 The volume of foods is established by seed
displacement.1 (p71) When legume flours are integrated or substituted with wheat flour, the
volume of the baked good decreases.4, 5,6,7,10,13 A study orchestrated by Gómez et al. measured
the cake quality made of wheat/chickpea flours showed that the cake volume condenses as the
chickpea flour percentage rises in both layer and sponge cakes tested.4 In the study regarding
the dough rheology and bread quality of wheat/chickpea flour blends carried out by
Mohammad et al. also found that the volume of the control bread sample was significantly
higher than the samples containing chickpea flour. As the level of chickpea supplementation
increased, the loaf volume of the breads gradually decreased as illustrated in figure 2 below.10
The reduced volume of baked goods is a result of starch gelatinization occurring at low
temperatures as well as the increased fiber, and protein content found in legume flour.4
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Figure 2: Loaf volume, crust color and crumb structure of breads containing different levels of chickpea flour (CF) (1) 100% WF; (2) 90% WF and 10% CF; (3) 80% WF and 20% CF; and (4) 70% WF and 30% CF.
Mohammed I, Ahmed AR, Senge B. Dough rheology and bread quality of wheat–chickpea flour blends. Industrial Crops and Products. 2012;36(1):196-‐202. http://dx.doi.org/10.1016/j.indcrop.2011.09.006 Assessed March 13, 2013.
Given the chemical properties of legume flour yielding a lower volume product. Studies
have been implemented to view possible solutions of increasing the volume of a baked good
without compromising the amount of legume flour. Shogren et al. states in their study that a
possible solution to increase the loaf volume of breads containing soy flour is to treat the dough
by adding gluen, oxidants such as bromate, ascorbic acid, and surfactants such as sodium
steroyl lactylate.6 Another solution to increase volume is to increase water levels in the dough.
A study conducted by Doxastakis et al. concluded that, the supplying more water would lead to
greater water absorbed yielding in a greater bread volume. However, this increased water
amount in dough cannot be applicable because of the workability of the dough becomes
impaired thus making the dough non-‐manageable.5, 10 Interesting enough, the increased water
absorption chickpea flours require does not alter the product weight. This information was
determined in a study specifically focusing on baked cakes.4 Another alternative to lessen the
effect of chickpea flour on the volume of baked goods is the type of chickpea flour used.
According to Gómez et al., the volume changes are minimized if white chickpea flours are used
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instead of whole chickpea flours. Although legume flours in baked goods yield a lower volume
baked product, chickpea flour has the highest specific volume of the popular legume flours
shown in figure 3 below. The chickpea protein flour offerings a higher foam expansion and
stability values compared to the other popular legume flours proteins like pea and soybean
protein.4, 13
Figure 3: Digital images of legume flour gluten-‐free breads.
Miñarro B, Albanell E, Aguilar N, Guamis B, Capellas M. Effect of legume flours on baking characteristics of gluten-‐free bread. J Cereal Sci. 2012;56(2):476-‐481. http://dx.doi.org/10.1016/j.jcs.2012.04.012 Assessed March 13, 2013.
Rice flour in baked goods decreases the product volume due to hydrocolloid content. In
rice flour, hydrocolloids improve the dough development and gas retention leading to the
increase in dough stickiness, hence producing breads with higher specific volume.9 According to
Lazaridou et al., the volume of breads made with rice flour increased with addition of
hydrocolloids at 1% supplementation level (except xanthan gum and pectin) versus the control
100% wheat flour sample. However, when the hydrocolloid concentration increased from 1% to
2%, bread volume was reduced occurred (excluding pectin). 2 A possible loophole in avoiding
the decreased volume of breads without changing the rice flour content is to supplement 2g of
margarine per 100g of flour. According to Veluppillai et al., the specific volume increased only
up a threshold fat level of 20 g/kg of flour, beyond that threshold the specific volume decreased
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and the bread's texture was sticky. Therefore, including more fat will raise the fat threshold
level that will allow the bread to continue to rise.11 Manipulating the amount and type of
hydrocolloid has shown to increase bread volume as well. According to Sciarini et al., the
addition of carrageenan made with 75% water incorporation resulted in the highest specific
bread volume among tested hydrocolloid samples. Carboxymethylcellulose (CMC), xanthan
gum, and algin fortification showed the same specific bread volume as the 100% wheat flour
control bread.9
2.2 Color
Color is a physical property that food manufactures place a heavy emphasis on because
it is the one property that people are able to evaluate before purchasing/consuming. In baked
goods the incorporation of legume flour yield in a rich, more concentrated colors resulting from
the Maillard reaction and sugar caramelization occurring while baking.4,7,10 The Maillard
reaction is a type of chemical reaction in which non-‐enzymatic browning occurs when a protein
and sugar are heated or stored together for some time 1 p145. As a result of the increased
protein (and amino acids) content found in legume flours is responsible for this chemical
reaction to occur. Sugar caramelization is another chemical reaction which monosaccharaides
are fragmented into a variety of compounds including organic acids, aldehydes, and ketones
resulting from the use of intense heat1 p144. Sugar caramelization occurs in all baked goods
despite the flours used but baked goods containing legume flours will have both of these
chemical reactions occurring. 4,7,10 The amount and type of legume flours applied also
determines the color intensity in baked goods. According to Chillo et al., the incorporation of
10% of legume flours did not significantly alter the product color compared with the 100%
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wheat flour control.3 Breads made with soybean flour received the highest approval rating
versus the other legume flours show in figure 3 on page 10.13
2.3 Crumbs
The incorporation of chickpea flour alters the crumb color of the baked good. The
substitution of chickpea in baked goods produces a redder and more yellow crumb color. As the
amount of chickpea flour in a baked good increase, the greater deeper red/yellow crumb color
appears after baking. The absence of gluten network as well as the increased protein content is
responsible for the heavier and tougher crumb found in baked goods make with legume and/or
rice flours.10 An possible way to avoid this unfavorable crumb composition is enhancing the
dough with hydrocolloids. The fusion of hydrocolloids and legume flour dough allows the
hydrocolloids to reduce the moisture loss during storage that delays staling thus making the
crumbs hard and lose moisture.9
3. Other Types of Non-‐Wheat Derived Flour
Similar to legume and rice flours, buckwheat flour has greater protein content and a
different array of amino acids versus wheat flour. The amino acid lysine is also present in
buckwheat flour in greater amounts versus rice flour, but lesser amounts then legume flour.14
Buckwheat flour also follows the same trend as the previously mention flours regarding a
higher protein and fiber content. The increase amounts of fiber (cellulose) in buckwheat flour
leads to a longer water absorbing time hence requires longer dough development time the
rhenological, textural and sensory properties of gluten free bread formation using rice and
buckwheat flour blend was studied by Torbica et al. In this study, they tested both husked and
un-‐husked buckwheat flour blended with rice flour in bread making. The focus of this paper was
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to prepare a gluten-‐free product that contained rice and buckwheat flour that is known as
nutritionally improved flour blend. The increase the buckwheat flours content lead to greater
weakening of protein network. This is due to the decrease in protein quality in both husked
and un-‐husked buckwheat flours. Some benefits of utilizing buckwheat flour and rice flour are
the end product of an optimal rheological profile. Buckwheat flour has lower lipid and protein
content is associated with a higher peak viscosity that leads to higher starch swelling. This study
concluded that the increase in the ratio of buckwheat flour to rice flour did not significantly
affect the textural properties of the bread. Therefore, gluten-‐free bread containing higher
amount of nutritionally valuable buckwheat flour could be produced without affecting the
textural properties of the product.15 It is still important to note than when working with
buckwheat flour that the protein quality decreases as the buckwheat flour amount increases.
The decease in protein quality is evident when cracked surfaces appear on the upper crust of
gluten-‐free products2.
Figure 4: Upper surface crust appearance and breadcrumb structure of the final gluten-‐free products. KEY: Husked Buckwheat Flour (HBF) Un-‐husked Buckwheat Flour (UBF)
Torbica A, Hadnađev M, Dapčević T. Rheological, textural and sensory properties of gluten-‐free bread formulations based on rice and buckwheat flour. Food Hydrocoll [serial online]. 2010;24(6–7):626-‐632. Available at: http://linksource.ebsco.com/FullText.aspx?linkout=https%3a%2f%2flogin.dax.lib.unf.edu%2flogin%3furl%3dhttp%3a%2f%2fdx.doi.org%2f10.1016%2fj.foodhyd.2010.03.004 Accessed March 13, 2013.
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4. Application to Practice
In the field of nutrition and dietetics, acquiring a fundamental education about gluten
and its function in foods, health and how the absence of gluten in foods alters its baking
properties it critical. The role of replacing gluten presents a major challenge due to its functions
as a structure-‐building protein, contributing to the volume, color and crumb structure of many
baked products. The gluten complex in baked goods dictates the important rheological
characteristics of dough, such as the elasticity, extensibility, resistance to stretch, mixing
tolerance, and gas-‐holding ability.2 It is also imperative that dietitians know the chemical and
physical properties of the common substitutes for wheat flour in baked goods. According to
Hadnađev, et al., wheat is considered one of the most common grains use for bread making
however Bread prepared from wheat flour is considered to be nutritionally poor.12
With the growing number of research and non-‐wheat derived flours such as legume, rice
and buckwheat flours, dietitians are able to enhance the nutrient content of baked goods by
creating blends of wheat and non-‐wheat flours to achieve the expected physical properties as
well as including some additional nutrition. Torbica et al. says rice flour is becoming increasingly
popular wheat flour alternative for the preparation of foods for wheat-‐intolerant, celiac
patients or wheat allergen patience. They suggest that rice flour is the most practical cereal
grain flour alternative for the preparation of foods due to its indistinguishable taste, white
color, and hypoallergenic properties.15 Legume is another wheat alternative flour that has
additional health promoting characteristics including low glycemic index, providing additional
energy, dietary fiber, proteins, minerals, and vitamins when compared to wheat flour.3 For
example, if a client is looking to improve there protein and/or is lacking in sufficient amino acid
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intake, incorporating legume flours into wheat flours to create a blend to yield a product that
will look and taste as the clients envisions as well as containing a greater protein and lysine
content in the baked good.12 In union of rice flours and wheat flours as a blend provide a low
the glycemic index of a baked good which is a pertinent health promoting property.11
5. Conclusion
In conclusion, the gluten protein complex found in wheat flour is the backbone in
the yield of a good quality baked goods. However due to the rise in gluten intolerant, celiac
and wheat allergen patents, further research is continually being conducted to study non-‐
wheat flour alternatives that will successfully achieve the functions of gluten while
resulting in a products that looks, feel and taste like a food product made with traditional
wheat flour. This paper analyzed the chemical and physical properties of common non-‐
wheat flour alternatives including legume flours, rice flour and buckwheat flours. The
analyzed results were compared to wheat flour. The chemical properties of flour examined
were carbohydrate, protein, lipids and fiber. Legume and rice fours primary macronutrient
is carbohydrate. The carbohydrate found was mostly in the form of amylose that is effective
in reducing the glycemic index, a property not found in wheat-‐derived flours. The protein
content of legume and rice flours are also higher in comparison to wheat derived flours and
include the full essential amino acid profile. Too much of these protein-‐rich flours will lead
to undesirable outcomes in baked goods. The augment amounts of lipids in both the non-‐
wheat derived flours lower the gelatinization rate and the peak viscosity of baked goods.
This is an unfavorable property in food preparation. Higher amounts of fiber are found in
these non-‐wheat derived flours that is beneficial for digestive health but is not ideal in food
preparation because fiber inhibits carbohydrate absorption. All of these chemical
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properties influence the physical properties of flours that include volume, color and
crumbs. In baked goods, as the substitution rate of legume and rice flour increases, the
volume of the end product decreases due to the increase in protein and hydrocolloid
content. Research is being performed to find alternative additives to dampen this effect.
The color tones of baked goods made with legume and rice flours are darken due to the
Maillard and sugar caramelization chemical reactions occurring during baking. The crumb
composition of gluten free baked goods is often harder as a result of the accelerated stalling
rate versus wheat-‐derived baked goods. The chemical and physical properties of non-‐
wheat derived flours falls within the scope of the dietetic practice. Knowing the chemical,
physical, and health properties of wheat-‐derived fours containing gluten and the common
non-‐wheat derived flours including legume, rice and buckwheat flours is critical when
working with client based on their health needs and recommendations.
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