jfq_347 742..757

THE EFFECTS OF DIFFERENT DEBITTERING METHODS ONTHE PRODUCTION OF LUPIN BEAN SNACK FROM BITTER

LUPINUS ALBUS L. SEEDS

MUSTAFA ERBAS1

Department of Food Engineering, Faculty of EngineeringAkdeniz University

07070 Antalya, Turkey

Received for Publication January 21, 2009Accepted for Publication February 23, 2010

ABSTRACT

The aim of this study was to remove the alkaloids from bitter lupin(Lupinus albus L.) seeds by different debittering methods and to produce alupin bean snack. During production of the snack, the total alkaloid content ofseeds decreased significantly (P � 0.01) from 14.4 g/kg to a level that wasundetectable. A major alkaloid in lupin seeds was identified as lupanine. It waspresent at a concentration of 12.513 g/kg, which constituted 87% of the totalalkaloid content. The other alkaloids that were identified were sparteine,albine, a-isolupanine and multiflorine. The concentrations of the alkaloidsdecreased gradually during the debittering process. The values for dry matter,protein, lipid, starch and ash content of seeds changed in a statisticallysignificant manner (P � 0.05, P � 0.01) during production of the snack.Aqueous debittering at room temperature was found to be a more favorableprocess because it resulted in more acceptable sensorial properties thanalkaline and thermal debittering methods.

PRACTICAL APPLICATIONS

Bitter lupin seeds (Lupinus albus L.) cannot be consumed directlybecause they naturally contain high amounts of toxic alkaloids, which causebitterness, despite their high protein content. The aim of this study is to removebitterness from lupin seeds with different debittering methods and to producea lupin bean snack.

1 Corresponding author. TEL: +90-242-3106575; FAX: +90-242-2274564; EMAIL: erbas@akdeniz.edu.tr

Journal of Food Quality 33 (2010) 742–757.742 DOI: 10.1111/j.1745-4557.2010.00347.x

© 2010 Wiley Periodicals, Inc.

INTRODUCTION

The seeds of members of the genus in the family Fabaceae constitute animportant part of the diet of the human population. They provide approxi-mately 20% of the total protein that is consumed worldwide (ANZFA 2001;Jimenez-Martinez et al. 2001). The major cultivated species of Lupinus(lupins) genus belonging to Fabaceae are L. albus L. (white lupin), L. angus-tifolius L. (blue lupin), L. luteus L. (yellow lupin) and L. mutabilis (Andeanlupin or tarwi). The first three of these are commonly cultivated in Mediter-ranean countries and Australia, while L. mutabilis is cultivated in SouthAmerica (Allen 1998; Petterson 1998; Mulayim et al. 2002). L. albus seedshave a high protein content ranging from 33 to 47%, according to genotypeand location (Huyghe 1997). This protein is rich in essential amino acids,especially lysine. In addition, they can contain more than 150 g/kg of lipid anddietary fiber, but this value depends on genotype and location (Petterson 1998;Erbas et al. 2005; Sujak et al. 2006; Uzun et al. 2007). However, the usage ofbitter lupin seeds has been limited by the presence of toxic and bitter quino-lizidine alkaloids (ANZFA 2001; Jimenez-Martinez et al. 2001). The quino-lizidine alkaloids result in moderate acute toxicity and the LD50 level oflupanine, which is the most abundant of these alkaloids in lupin, is 0.41 g/kgfor oral intake in rats (ANZFA 2001; Sanchez et al. 2005).

Lupins can be divided into sweet lupins, which contain low levels ofalkaloids, and bitter lupins, which contain higher levels of alkaloids. Debitter-ing, which is an ancient procedure, involves the elimination of anti-nutritionalfactors to improve the nutritive value, and it is widely used to wash out thebitter components of seeds. Due to the fact that the alkaloids of lupin arewater-soluble, the alkaloid level in bitter lupins (0.05–4 g/kg) can be easilydecreased to levels that are safe for human consumption, by boiling the seedsand then soaking them in water (ANZFA 2001). However, this processing mayunfortunately remove a large proportion of the soluble proteins, minerals,flavonoids, monosaccharides and sucrose from the seeds, in addition to theundesirable bitter and toxic alkaloids and the flatulence-inducing oligosaccha-rides. The debittered lupin seeds can be also referred to as sweet lupin whenthe alkaloid content has been reduced to less than 0.2 g/kg, which is currentmaximum permitted concentration and adequate for safe consumption(ANZFA 2001). In addition, sweet lupins have been to grow sweet geneticvarieties with low alkaloid contents that range from 0.08 to 0.12 g/kg.However, this has ecological disadvantages because bitterness is a dominantgenetic characteristic (Allen 1998; Reinhard et al. 2006).

Lupin seeds can be used as a source of supplementary protein and fiber inexisting or novel food products. Joray et al. (2007) have investigated thedevelopment of coated snacks from L. albus seeds. Debittered lupin seeds or

743SNACK FROM BITTER LUPINUS ALBUS L. SEEDS

flour can be used in baking, and in the production of pasta, emulsified meat anda variety of other food products to increase their nutritional value and toimprove aroma and texture. Also, lupin can be a good choice for vegetarians asregards protein abundance (Mohamed and Rayas-Duarte 1995; Lampart-Szczapa et al. 1997; Papavergou et al. 1999; Pollards et al. 2002; Chapleauand Lamballerie-Anton 2003; Johnson et al. 2003; Sanchez et al. 2005;Lampart-Szczapa et al. 2006; Martinez-Villaluenga et al. 2006). In addition,protein isolates can be produced from lupin seeds. The protein extracted fromlupin seeds has good nutritional and functional properties such as high emul-sifying, water-binding and foaming capacities (Mohamed and Rayas-Duarte1995; El-Adawy et al. 2001).

Lupin seeds have been used as a food source by the European, Mediter-ranean, Middle Eastern and Andean people since ancient times, especially insoups, stews, salads and snacks. In some European and Middle Eastern coun-tries, pickled lupin seeds, which are also known as “lupini beans,” are com-monly sold in brine, in a similar manner to olives, for human consumption(Petterson 1998; Papavergou et al. 1999; Pollards et al. 2002). This productcan be consumed as a snack with or without the husk. White lupin seeds thathave been boiled and soaked in water until they have been debittered and thensalted are known as “tirmis” or “termiye” in Turkey. They are similar to thelupini beans.

The objective of this study was to remove the bitter alkaloids from lupinseeds by the use of different debittering methods, and to introduce productionof a lupin bean snack.

MATERIALS AND METHODS

Raw Material

The lupin seeds (L. albus L.) were cultivated in the Gebiz village(37°08′N, 30°58′E), which is located in the province of Antalya, Turkey, in2005, and obtained from a local producer. The material was derived from thelandrace of the region.

Debittering of Lupin Seeds and Production of a Lupin Bean Snack

The production process for the lupin bean snack consisted of cleaning,boiling, debittering and salting stages. Extraneous material and immature anddamaged seeds were removed first. The cleaned seeds were boiled in water(1:3, seeds : water) for 75 min to destroy thermolabile anti-nutritional factors,such as trypsin inhibitors and to soften the seeds. The boiled lupin seeds werethen strained and divided into three portions, to which different debittering

744 M. ERBAS

methods were applied. The first group was debittered with water at roomtemperature (~25C), the second group was debittered with 0.5% NaHCO3

(sodium bicarbonate) solution at room temperature (~25C) and the third groupwas debittered with hot water (65C). The first, second and third groups werecoded as N (normal), A (alkaline) and T (thermal), respectively. The lupinseeds, during the debittering process, were covered fully with debitteringliquids and these steps were renewed subsequently in 12-h intervals for 144 h.After debittering, the seeds were washed gently with water (10 s) and trans-ferred to salt water (6%, NaCl) for 12 h. The brine was then removed to yieldthe lupin bean snack. Samples were taken for subsequent analysis at eachstage, and each time the debittering liquid was changed. The samples werestored at -18C for later analysis.

Physical Analysis of Seeds

The weight and volume of 1000 seeds were determined by measuringscale and filled with water cylinder. The water activity of the seeds wasmeasured with a water activity meter (Testo 650, Lenzkirch, Germany). Thehardness test was performed by pressing horizontally on a seed, using a textureanalysis device (TA TX Plus; Stable Micro Systems, Surrey, UK) that wasequipped with an SMS5 cylinder probe, until the first crack formed. Seed color(L*, a* and b* values) was analyzed by the CIELAB system using a CR-400chromameter (Konica Minolta, Osaka, Japan) that was equipped with a mea-suring head and DP-400 data processor. The L* value represents the light–darkspectrum with a range of 0 (black) to 100 (white), the a* value represents thegreen–red spectrum with a range of -60 (green) to +60 (red) and the b* valuerepresents the blue–yellow spectrum with a range of -60 (blue) to +60(yellow). The chromameter was calibrated using a white ceramic calibrationtile. Ten independent samples were analyzed and two readings from eachsample were recorded. The color differences between the raw lupin seeds andthe lupin bean snack were calculated using the following equation:DE = (Da2 + Db2 + DL2)0.5, where DL, Da and Db are the differences in colorvalues between the raw and processed seeds (Ozdemir and Devres 2000).

Proximate Analysis of Seeds

The amount of lost dry matter during the debittering process was calcu-lated from the weight difference between 100 dried seeds that were sampledbefore and after snack production. Prior to the chemical analyses, the seedswere dried and milled into a fine powder. The amount of dry matter wasdetermined by drying the samples at 105C to a constant weight (44–01 AACC2000). The nitrogen content was determined by the Kjeldahl method andmultiplied by a factor of 6.25 (Lampart-Szczapa et al. 2003) to determine the

745SNACK FROM BITTER LUPINUS ALBUS L. SEEDS

crude protein content (46–12 AACC 2000). The ash content was determinedby incineration of the sample at 925 °C to constant weight (08–01 AACC2000). The lipid content was determined by the Soxhlet method (30–25 AACC2000). The crude fiber content of the samples was determined, after the lipidhad been removed, by acid–base digestion to remove the starches and proteins(32–10 AACC 2000). The starch content was determined by the polarimetricmethod (TSE 2000). The pH values were measured using a pH meter (WTW537, Weilheim, Germany) in 5 g samples, after homogenization of the seeds in45 mL distilled water. The titratable acidity was determined by titration with0.1 M NaOH up to Ph 8.1, and expressed in terms of sulfuric acid. All themeasurements were expressed as a function of dry weight.

Measurement of Alkaloids

The dried and milled seeds (0.5 g) were weighed in a tube (PPCO,Nalgene, Rochester, NY), and homogenized in 10 mL petroleum ether for1 min at 3,000 rpm using an Ultra-Turrax T-25 homogenizer (IKA Labortech-nik, Staufen, Germany). They were then incubated at 40C for 30 min, centri-fuged in a 3K30 centrifuge (Sigma Laborzentrifugen, Harz, Germany) at4,500 ¥ g for 5 min, and the supernatant was removed. This process wasrepeated twice, with the exception of the incubation at 40C, to remove thelipids. The defatted and dried samples were homogenized in 5 mL trichloro-acetic acid solution (0.3 M) using an Ultra-Turrax T-25 homogenizer, centri-fuged at 4,500 ¥ g for 15 min and the supernatant collected in a beaker. Thisprocess was also repeated twice to extract the alkaloids from the solid phase.The supernatants that had been collected in the beaker were made alkaline byadding 1 mL 10 M NaOH, followed by gentle agitation and resting. Thealkaloids were extracted from the alkalized supernatant with 5 mL dichlo-romethane four times. The combined 20 mL of dichloromethane extract wasevaporated in a tube at 40C, and the resulting alkaloids were dissolved in 1 mLmethanol. The volume of 1 mL of each sample was injected in parallel into aFisons HRGC Mega 2 Series gas chromatograph (Milan, Italy) that wasequipped with a capillary column (HP-1, 19091Z-212, Agilent, Santa Clara,CA; 25 m length, 0.32 mm i.d., 1.05 mm film thickness). The injector blockand flame ionization detector (FID) were maintained at 250C and 300C,respectively. The oven temperature was increased gradually from 150C to235C at 5C/min (Muzquiz et al. 1994; Muzquiz 2000; Sanchez et al. 2005).The pressure of the carrier gas (helium) was 150 kPa, and the pressures of thehydrogen and dry air that were used in the FID were 50 and 90 kPa, respec-tively. The peaks were identified using sparteine as a standard (MP Biomedi-cals, Solon, OH), and retention times were compared. To measure the degreeof recovery, sparteine was added into some samples and extracted using the

746 M. ERBAS

same method. The recovery was higher than 95%. The standard calibrationcurve was prepared using sparteine in methanol. The response was linear overthe range 0.0000091–0.091 g/L and the regression coefficient was 0.99. Theresults were calculated as a function of dry weight.

Sensory Evaluation

The lupin bean snacks that had been produced by the different debitteringmethods were subjected to sensory analysis. The snacks were placed on whiteplastic plates. They were coded and served to panelists at random on a white,light bench at 3:00 p.m. The snacks were evaluated by six trained panelists(three female, three male; 24–33 years old) who were familiar with the char-acteristics of this type of snack, and were studying as research assistants at theDepartment of Food Engineering of Akdeniz University, Turkey. The panelistsparticipated in a group discussion to establish terms that described the char-acteristics of the lupin bean snack. The descriptive terms those were selectedas appearance, color, smell, texture, taste, bitterness and overall. The accept-ability of the lupin snack was scored by the panelists on a 5-point scale(1 = disliked extremely, 5 = liked extremely). Sensory scores obtained fromthe six trained panelists were averaged and analyzed by analysis of variance(ANOVA) with respect to debittering methods.

Statistical Analysis

The physical and chemical analyses were performed on samples from thefour stages of production of the lupin bean snack, which corresponded to raw,boiled, debittered seeds and the final product (snack). However, analysis of thealkaloids was performed for each stage, as well as for each change of thedebittering liquid because alkaloids have restricted effects in the consumptionof lupin. In the research, production of the lupin bean snack were realized intwo replicates, and analyses were duplicated. The data were analyzed byANOVA using the SAS statistical software package (v.7.00, SAS Institute Inc.,Cary, NC) to compare the means with respect to debittering time and method.The Duncan’s multiple range test was used to determine significant differencesat the 5% level. Results are given as the mean � standard deviation.

RESULTS AND DISCUSSION

Changes in Properties of Seeds during Processing of Lupin Bean Snack

The weights of 1,000 raw and 1,000 processed seeds were 319 and 702 g,respectively. The increases in the weight and volume of the seeds during the

747SNACK FROM BITTER LUPINUS ALBUS L. SEEDS

production of the snack were 120 and 60%, respectively. These increases weredue to the high hydration capacity of the lupin proteins (Chapleau andLamballerie-Anton 2003; Lampart-Szczapa et al. 2006). The gains in theweight and volume of the seeds showed a similar trend for all the debitteringmethods. It has been reported that the seeds absorb an amount of water that isapproximately equal to twice their original weight during the debitteringprocess (Jimenez-Martinez et al. 2001). Solomon (2007) has reported similarfindings with respect to the weight gain of lupin seeds that had been soaked inwater at different temperatures.

The loss of dry matter from the seeds during the process was ~260 g/kg.This loss was a result of the loss of fiber (~60 g/kg), which occurred becauseof separation of the softened husks and soluble material (~200 g/kg) during thedebittering process. The detached husks could be observed as small particles inall the changes of extraction liquid during debittering. In addition, the extrac-tion liquids became yellowish in color because of the presence of pigments.Jimenez-Martinez et al. (2001) have reported that during the process of deb-ittering, 120–270 g/kg of solids were lost, which depended on the specifictreatment that was used. The other changes in the physical and chemicalproperties of the seeds, which depended on the processing stage and time, areshown in Table 1. All the physical and chemical properties of the seeds wereaffected significantly (P � 0.05, P � 0.01) by the processing stage and time.The greatest changes in the properties of the seeds occurred during the debit-tering stage. Dry matter was decreased by the introduction of water into theseeds and the loss of soluble components and detached husks. Therefore, thewater activity of the seeds increased, whereas the hardness decreased. Duringthe debittering process, the components of the seeds were modified at differentrates. The protein and starch contents of seeds increased by 67 and 18 g/kg,respectively. These increases may have been caused by the fact that oligosac-charides, minerals, alkaloids, flavonoids and fiber were removed when thedebittering liquid was changed. The crude fiber content decreased by ~60 g/kgduring the debittering process because of the loss of the husks. The ash contentof the seeds decreased as a result of the decrease in crude fiber content and theremoval of minerals by the extraction process. The acidity of the seedsdecreased because of the loss of soluble material. The lipid content increasedby ~10 g/kg in the boiled seeds as compared to the raw seeds. This wasproportional the result of the loss of water-soluble solids during boiling. Thecommon decrease in lipid content that was observed during the snack produc-tion may have been caused by removal of the lipid-rich embryo together withthe detached husk.

The production process caused a difference in color (DE) of 16 unitswhen the raw and processed seeds were compared. The color values (L*, a*and b*) of the seeds changed from cream (71.3, 5.9 and 17.1; raw seeds) to

748 M. ERBAS

golden yellow (63.2, 8.6 and 32.9; processed seeds) during snack production,when water at room temperature was used. Lupin seeds contain high levels ofcarotenoids and zeaxanthin, which give the cotyledon its bright yellow color(El-Difrawi and Hudson 1979). The color changes may be a result of theMaillard reaction, in addition to the loss of flavonoid pigments, which havebeen shown to be present in lupin (Allen 1998).

In the raw seeds, the total concentration of alkaloids was 14.4 g/kg, andthis was reduced to below the detection limit (0.0000091 g/L) by the debitter-ing process. It has been reported that the total alkaloid content of Turkish bitterlandraces of L. albus is 19.1 g/kg (Muzquiz et al. 1994). The changes in thelevels of seed components that occurred during debittering in this study weresimilar to those that were described by other researchers (Jimenez-Martinezet al. 2001; Torres et al. 2005). The protein content of the debittered lupinseeds was determined to be 480 g/kg, and it was similar to other lupin speciespoint of view protein abundant. Furthermore, the crude fiber and lipid contentswere similar to those found in the seeds of other lupin species (Jimenez-Martinez et al. 2001). Sujak et al. (2006) have reported that the protein, lipid,crude fiber and ash contents of L. albus seeds are 363, 115, 144 and 34 g/kg,

TABLE 1.THE PHYSICAL AND CHEMICAL PROPERTIES OF THE LUPIN SEEDS CHANGES DURING

THE DIFFERENT STAGES OF PRODUCTION OF THE LUPIN BEAN SNACK†

Properties Processing stage and time (h) Sign.

Raw (0) Boiled (1) Debittered (144) Snack (156)

Dry matter 896a � 2.4 411b � 4.5 291d � 6.9 311c � 7.9 **Protein 413d � 1.2 451c � 4.5 516a � 9.8 480b � 10.0 **Crude fiber 146a � 1.9 138a � 2.1 93.0b � 12.5 87.7b � 11.8 **Lipid 98.7b � 0.2 109a � 0.2 87.2c � 4.2 79.4d � 1.7 **Starch 27.7b � 1.3 48.0a � 0.2 47.9a � 0.9 46.1a � 0.7 **Ash 25.7b � 0.6 22.3c � 0.0 23.3c � 1.5 31.3a � 0.5 **Total alkaloids 14.4a � 0.2 6.2b � 0.2 0.01c � 0.0 LOQ **Acidity (as H2SO4) 10.9a � 0.2 8.8b � 0.2 2.0c � 0.7 2.3c � 0.4 **pH 5.40b � 0.01 5.52b � 0.02 6.47a � 0.23 6.29a � 0.14 **Water activity 0.57c � 0.01 0.92b � 0.00 0.96a � 0.02 0.94ab � 0.01 **Hardness (kg) �60a � 0.00 3.69b � 0.01 2.93c � 0.34 3.21c � 0.27 **Color difference, DE – 12.5b � 0.64 14.8ab � 2.15 16.0a � 1.64 *

† Properties are given as the mean � standard deviation. The means are represent average for threetreatments (N, A and T). Chemical properties are expressed as a function of dry weight (g/kg). LOQrepresents the limit of quantitation.

Sign: Statistical significance: * P � 0.05, ** P � 0.01, n = 6 (two replicates for each of three debit-tering methods).Superscript letters beside the mean values denote values in the same line that are significantly differentby the Duncan’s multiple range test (P < 0.05).

749SNACK FROM BITTER LUPINUS ALBUS L. SEEDS

respectively. Lupin seeds are low in starch (23 g/kg), whereas the seeds ofother common legumes have high starch content (Cerning-Beroad and Filiatre1976). Therefore, the debittered and defatted lupin seeds may be a potentialsource of material for the production of dietetic foods because they have a highprotein and dietary fiber content and low starch content as compared with otherlegumes and cereals. Also, lupin seeds could be used to enrich different typesof food products with respect to protein and dietary fiber.

Changes in Alkaloid Content of Seeds during Production of LupinBean Snack

The alkaloid content of the seeds showed significant differences(P � 0.01) between the different stages of production of the snack. Thechanges are shown in Table 2. Five components were identified during gaschromatography that, together, exceeded 95% of the total alkaloid content. Themajor alkaloid in the lupin seeds was identified as lupanine with a concentra-tion of 12.513 g/kg, which constituted 87% of the total alkaloid content.Sparteine, albine, a-isolupanine and multiflorine were the other alkaloids thatwere identified in this study. The alkaloid content decreased gradually duringthe debittering process; sparteine was eliminated first, after 12 h in boilingwater, and lupanine was eliminated last, after 120 h. However, the debitteredseeds were soaked in water for an additional 24 h in order to ensure that theywere safe to consume. The amount of a-isolupanine did not show a steadydecrease; rather, its level also increased at certain stages during the productionprocess, which could have been caused by isomer transformations among thealkaloids. Cuadra et al. (1994) reported that alkaloids underwent isomeriza-tion. In lupin seeds, lupanine is the precursor of the other alkaloids (Sanchezet al. 2005).

The results of this study with respect to the alkaloids are in agreementwith the findings of previous studies (Cuadra et al. 1994; Sanchez et al. 2005).Muzquiz et al. (1994) examined 29 bitter ecotypes of L. albus, and reportedthat lupanine was the main alkaloid (0.5–18.8 g/kg), and albine and multiflo-rine were the other major alkaloids. Albine, a-isolupanine, lupanine, multiflo-rine and 13-hydroxylupanine were found in all ecotypes, and their levels in theTurkish ecotype were 0.2, 0.1, 11.2, 0.9 and 0.6 g/kg, respectively. Sanchezet al. (2005) reported that the lupanine level in L. albus was 13.6 g/kg.Sparteine has been found in some ecotypes of L. albus that are cultivated inEurope (Petterson 1998).

Comparison of Different Debittering Methods

Some physical and chemical properties of the seeds are shown in Table 3to allow comparison of the debittering methods. The values for protein, crude

750 M. ERBAS

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751SNACK FROM BITTER LUPINUS ALBUS L. SEEDS

fiber and lipid content, acidity, pH, and color differences of the seeds did showsignificant differences (P � 0.01, P � 0.05), whereas between the differentdebittering methods, the values for dry matter, starch, ash, water activity andhardness did not differ significantly (P � 0.05). There were no significant(P � 0.05) differences between the total alkaloids content of the lupin seedsproduced by different debittering treatments.

The acidity and pH values were different in the A group because of thealkaline treatments, and the color difference was different in the T groupbecause of the high temperature treatments at 65C. The color of seeds in the Tgroup was darker than the others. This darkness might be resourced thatMaillard reaction, non-enzymatic browning reaction between reducing sugarand free amino groups, was encouraged by high temperature. The proteincontent was low in the T group, it is possible that this differences resourcedfrom loss water-soluble nitrogen contain compounds due to increase the solu-bility and cellular permeability in high temperature. The crude fiber contentswere the lowest in the A group that is treated with sodium bicarbonate becauseof the alkali effect. The lowness might be due to fact that alkaline effect

TABLE 3.SOME PHYSICAL AND CHEMICAL PROPERTIES OF THE LUPIN SEEDS TREATED BY

THE DIFFERENT DEBITTERING METHODS†

Properties Debittering methods Sign.

N A T

Dry matter 354a � 27.5 353a � 27.6 358a � 27.4 –Protein 469a � 15.4 475a � 18.2 451b � 10.5 *Crude fiber 112b � 11.1 102c � 15.5 134a � 5.8 **Lipid 96.6a � 4.4 91.2b � 5.0 92.9b � 4.4 *Starch 42.8a � 3.4 41.7a � 3.2 42.7a � 3.3 –Ash 25.5a � 1.5 26.2a � 1.5 25.2a � 1.3 –Total alkaloid 2.5a � 1.0 2.8a � 1.1 2.4a � 1.0 –Acidity (as H2SO4) 6.7a � 1.2 5.9ab � 1.5 5.4b � 1.7 *pH 5.69b � 0.11 6.08a � 0.26 5.98a � 0.21 *Water activity 0.84a � 0.06 0.84a � 0.06 0.85a � 0.06 –Hardness (kg) 17.4a � 9.30 17.1a � 9.35 17.8a � 9.20 –Color difference, DE 15.9a � 1.25 16.8a � 1.50 10.6b � 0.90 **

Sign: Statistical significance: * P � 0.05, ** P � 0.01, –: P � 0.05, n = 8 (two replicates for each ofthe four processing stages (raw, boiled, debittered seeds and snack).† Properties are given as the mean � standard deviation. Chemical properties are expressed as a

function of dry weight (g/kg).Superscript letters beside the mean values denote values in the same line that are significantly differentby the Duncan’s multiple range test (P < 0.05).N: Normal aqueous debittering at room temperature. A: Alkaline (0.06 M NaHCO3) debittering at roomtemperature. T: Thermal aqueous debittering at 65C.

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detached husk of lupin seed. Saxena et al. (1990) has reported sodium bicar-bonate solutions have been used for dehulling of pulses. The lipid contents inthe A and T treatments were determined lower than the N. The decrease in lipidcontent in the A could be a result of the removal of the lipid-rich embryotogether with the detached husk. This decrease in T could be arose from thetemperature’s lipid-melting effect. All of the lost components mentionedearlier were eliminated during the changing of debittering water.

Sensory Evaluation of Lupin Snacks

All of the sensorial properties of the lupin snack were affected signifi-cantly (P � 0.01, P � 0.05) by the debittering methods (Table 4). The snackthat was produced by debittering with water at room temperature (N) showedthe highest degree of preference because it had a golden yellow color, and agood taste and texture, although it is same statistic group with the A that wasproduced alkaline debittering. The panelists found the snack that was preparedby thermal treatment (T) to be unacceptable. All of the sensorial properties ofthe T snack were worse than those of the others (N and A). This may be a result

TABLE 4.SENSORIAL PROPERTIES OF LUPIN BEAN SNACKS

HAVE BEEN PRODUCED BY THE DIFFERENTDEBITTERING METHODS†

Properties Debittering methods Sign.

N A T

Appearance 4.6a � 0.4 3.9a � 0.1 1.8b � 0.4 *Color 4.2a � 0.2 4.4a � 0.2 1.4b � 0.2 **Smell 4.3a � 0.3 4.1a � 0.3 2.6b � 0.6 *Texture 4.5a � 0.4 4.3a � 0.6 2.3b � 0.1 *Taste 4.6a � 0.1 4.0a � 0.3 2.0b � 0.4 **Bitterness 4.3a � 0.0 4.0a � 0.4 2.7b � 0.5 *Overall 4.6a � 0.3 3.9a � 0.2 2.1b � 0.6 *Acceptance yes yes no

Sign: Statistical significance: * P � 0.05, ** P � 0.01, n = 2 (tworeplicates, snack).† Properties are given as the mean � standard deviation in a range

from 1 to 5.Superscript letters beside the mean values denote the values in thesame line that are significantly different by the Duncan’s multiplerange test (P < 0.05).N: Normal aqueous debittering at room temperature. A: Alkaline(0.06 M NaHCO3) debittering at room temperature. T: Thermalaqueous debittering at 65C.

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of the browning reaction, auto-oxidation and thermal degradation of the seedcomponents, which occur during debittering at high temperature. The T snackhad an unpleasant smell and taste, and was dark in color. The color of food isone of the most important attributes for its acceptance. Therefore, the color ofthe lupin bean snack was a useful and practical attribute for the comparison ofthe debittering methods and snack quality. None of the panelists stated anybitterness in the snacks, although T got a lower bitterness score. It might havesourced that bitterness all of snacks have acceptable level.

CONCLUSIONS

In conclusion, the debittering methods that were used in this studyenabled the successful removal of alkaloids from lupin seeds. The normalaqueous debittering method, which used water at room temperature, was foundto be the superior process because it was more straightforward to perform andresulted in more acceptable sensorial properties than the other two methods.This method could be used to produce a commercial lupin bean snack. Theabsence of a bitter taste and the presence of a golden yellow color (L*, a* andb*; 63.2, 8.6 and 32.9, respectively) were considered to be important qualitycriteria. The lupin bean snack provides a suitable and safe means of consump-tion of lupin seeds and a valuable nutritional source, especially as a dieteticfood, because of its high protein and dietary fiber content and its low starchcontent.

ACKNOWLEDGMENTS

This research was supported financially by the Akdeniz UniversityResearch Fund (Project Number 2004.01.0104.005).

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