Physicochemical and functional properties of whole legume flour

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Physicochemical and functional properties of whole legume flour

Shuang-kui Du a,*, Hongxin Jiang b, Xiuzhu Yu a,*, Jay-lin Jane b

aCollege of Food Science and Engineering, Northwest A&F University, 28 Xinong Road, Yangling, Shaanxi 712100, ChinabDepartment of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, USA

a r t i c l e i n f o

Article history:Received 22 July 2012Received in revised form20 November 2012Accepted 3 June 2013

Keywords:Whole legume floursPhysicochemical characteristicsFunctional propertiesPasting properties

* Corresponding authors. Tel.: þ86 29 87092206; fE-mail addresses: [email protected]

hotmail.com (X. Yu).

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a b s t r a c t

The physicochemical, functional and pasting properties of whole flours from pinto bean, lima bean, redkidney bean, black bean, navy bean, small red bean, black eye bean, mung bean, lentil and chickpea wereinvestigated. Significant differences in physicochemical characteristics and functional properties wereobserved (P < 0.05). Bulk densities, water absorption indices, water solubility indices, oil absorptioncapacities, emulsion activities, and emulsion stabilities ranged from 0.543 g/mL to 0.816 g/mL, 4.09 g/g to6.13 g/g, 19.44 g/100 g to 29.14 g/100 g, 0.93 g/g to 1.38 g/g, 61.14%e92.20%, and 84.15%e96.90%,respectively. Phaseolus legume flour exhibited higher water absorption capacity, oil absorption capacity,emulsion activity, and emulsion stability compared with other kinds of legume flour. Pasting propertieswere significantly different (P < 0.05). Pasting temperatures and the peak, final, and setback viscosities ofthe flours ranged from 73.2 �C to 83.0 �C, 96.2 RVU to 216.8 RVU, 118.5 RVU to 243.8 RVU, and 28.3 RVU to103.2 RVU, respectively.

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1. Introduction

Legumes are dicotyledonous seeds of plants with approximately17,600 species in about 690 genera that belong to the family ofLeguminosae. Edible legumes include soybean, faba bean, pea,mung bean, small red bean, cowpea, kidney bean, hyacinth bean,and pigeon bean, among others. The annual production of legumesranks the fifth in the world after wheat, rice, maize, and barley(Hoover, Li, Hynes, & Senanayake, 1997). China is very rich inleguminous plants and statistical data indicates the cultivation ofmore than 20 types of legumes. These leguminous plants are wellknown in the planting history of China. More of them have a widerange of adaptabilities and thus, are planted nearly all over thecountry. Currently, faba bean, pea, mung bean, small red bean, andblack eye pea are the main leguminous plants grown in China.Mung bean is one of the main leguminous crops planted for food inAsia (Srinives &Yang, 1993, chap. 2).

Legumes are food resources that offer various health benefits.They are sources of complex carbohydrates, proteins, and dietaryfiber, as well as significant amounts of vitamins and minerals(Morrow, 1991; Tharanathan & Mahadevamma, 2003). The proteincontent of legume grains range from 17 g/100 g to 40 g/100 g, much

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higher than that in cereals (7e3 g/100 g) and approximately equalto the protein content of meat (18e25 g/100 g)(De Almeida Costa,Da Silva Queiroz-Monici, Pissini Machado Reis, & De Oliveira,2006). In developing countries, legumes are the second largestsources of human food after cereal, particularly for those low-income ones. They are used to enrich the diversity in humanfoods and provide a cheap source of protein in developing countries(Kaur, Singh, Sodhi, & Rana, 2009).

Health problems such as hypertension, gall-stone which arerelated to meat consumption have raised great social attentionrecently. Thus, leguminous has been found to play an importantrole in several favorable physiological responses, such as reducingheart and kidney diseases, lowering the sugar indices of diabeticpatients, increasing in satiety, and reducing the occurrence ofcancer (Mathres, 2002). In recent years, dried beans have regainedtheir previous roles as food sources in developed countries (Kauret al., 2009). Whole flour or the partial use of different legumeshas attracted increasing research interest. Studying their functionalproperties is important to efficiently utilize the flours producedfrom legumes and helps consumers easily accept them. Previousstudies have mainly focused on the functional properties of flourfrom legumes that are commonly planted in developed countries,and studies on legumes as food products have continued (Chau,Cheung, & Wong, 1997). The crude proteins and starch content of1696 germplasm accessions of nine Chinese legumes (i.e., fababean, pea, mung bean, adzuki bean, cowpea, kidney bean, rice bean,pigeon bean, and chickpea) average 25.93 g/100 g and 45.11 g/

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100 g, respectively; their starch contents are far lower than that ofsoybean and significantly higher than those of wheat, corn, barley,and millet (Zhu et al., 2005). Functional properties significantlyaffect the processing of legumes. Currently, legume flour has beenused as a food ingredient due to its functional properties for its highprotein content (Kaur, Sandhu, & Singh, 2007; Kaur et al., 2009).Damodaran (1990) suggested that the functionality of proteins isclosely related to their physical and chemical properties, such asmolecular weight, amino acid composition and sequence, structure,surface electrostatic charge, and effective hydrophobicity, andaffected by some food ingredients, including water, salts, proteins,sugars, and fats, as well as processing methods. Kaur and Singh(2005) investigated the functionality of chickpea and revealedthat in addition to proteins, the complex carbohydrates of legumes,such as starch, fibers, and other components (e.g., pectins andmucilages), contribute to their functionality.

For efficient utilization and consumer acceptance of legume seedflours, a study of their functional properties is necessary (Adebowale& Lawal, 2004). The successful performance of legume flour as afood ingredient depends on the functional characteristics, such asfoaming, emulsification, gelation, water and oil absorption capac-ities, and viscosity that they contribute to the end product(Adebowale & Lawal, 2004). Several investigators have studied thefunctional properties of lima bean, mung bean, chickpea, and fieldpea flours (Chel-Guerrero, Pérez-Flores, Betancur-Ancona, & Dávila-Ortiz, 2002; Kaur & Singh, 2005; Singh, Kaur, Rana, & Sharma, 2010).Adebowale and Lawal (2004) reported a comparative study on thefunctional properties of bambarra groundnut, jack bean, andmucuna bean flour (Adebowale & Lawal, 2004). Onimawo andAsugo (2004) studied the nutrient content and functional proper-

WSI ðg=100 gÞ ¼ Weight of dissolved solids in supernatant � 100Weight of flour sample

ties of pigeon pea flour. In these reports, the tested legume flour wasusually prepared after removing kernel skin and lipids. There wereno reports on the properties of whole legume flour up to now. Moreimportant, great diversity has been found in the functional prop-erties of legume flours derived from different varieties. Diversitywas supposed to be in the properties of different whole legumeflours. However, few studies have focused on the comparison ofproperties among different kinds of whole legume flour.

Therefore, the present study is aimed to investigate andcompare the physicochemical, functional, and pasting properties ofwhole flours derived from ten different legume varieties and thusprovides useful information on the effective utilization of theselegume varieties in food processing.

2. Materials and methods

2.1. Materials

Ten commercial legume seeds, pinto bean (Phaseolus vulgaris L.),lima bean (Phaseolus vulgaris L.), red kidney bean (Phaseolus vul-garis L.), black bean (Phaseolus vulgaris L.), navy bean (Phaseolusvulgaris L.), small red bean (Vigna umbellata L.), black eye bean(Vigna sinensis S.), mung bean (Vigna radiate L.), lentil (Lens culinarisM.) and chickpea (Cicer arietinum L.), were purchased from a localsupermarket. All of the seeds were air dried at 25 �C and groundinto small size that can pass through sieve no. 72 (British SieveStandards).

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2.2. Proximate composition of legume flour

Flour samples from different legume cultivars were estimatedfor their moisture, ash, fat, and protein (N � 6.25) contents byemploying the standard methods of analysis (AOAC, 2003). Totalstarch contents were determined using the Total Starch Kit (Meg-azyme Co., Wicklow, Ireland).

2.3. Physicochemical properties

2.3.1. Water absorption index and water solubility indexThe water absorption index (WAI) and water solubility index

(WSI) of the legume flours were determined by referring to themethod reported by Kaur and Singh (2005) with slight modifica-tion. A legume flour sample (2.5 g) was dissolved in 30 mL distilledwater and cooked in water bath at 70 �C for 30 min. Then thecooked paste was cooled to room temperature, transferred to pre-weighed centrifuge tubes, and centrifuged at 3000 g for 20 min.The supernatant was decanted into a pre-weighed evaporating dishto determine its solid content and the sediment was weighed. Theweight of dry solids was recovered by evaporating the supernatantovernight at 105 �C. WAI and WSI were calculated using thefollowing equations:

WAI ðg=gÞ ¼ Weight of sedimentWeight of flour sample

2.3.2. Bulk densityFlour samples were gently transferred into 10 mL graduated

cylinders that were previously weighed. The bottom of the cylinderwas gently tapped on a laboratory bench several times until nofurther diminution of the sample level was observed after it wasfilled up to the 10 mL mark. Bulk density is defined as the weight ofthe sample per unit volume of the sample (g/mL). Measurementswere made in triplicate.

2.4. Functional properties

2.4.1. Water and oil absorptionWater absorption of legume flours was measured by the

centrifugation method reported by Kaur and Singh (2005). Forwater absorption, samples (3.0 g) were dissolved in 25 mL ofdistilled water and placed in 50 mL pre-weighed centrifuge tubes.The mixtures were stirred at 5 min intervals and held for 30 min,followed by centrifugation for 30 min at 3000 g. The supernatantwas decanted, the excess moisture was removed by draining for25 min at 50 �C, and the sample was reweighed. For oil absorption,the method of Kaur and Singh (2005) was used. Samples (2.5 g)were mixed with 30 mL peanut oil in pre-weighed centrifuge tubesand stirred for 1 min. After a holding period of 30 min, the tubeswere centrifuged at 3000 g for 30 min. The oil was then removedwith a pipette when it formed a separate layer; the tubes wereinverted for 25 min to drain the oil prior to reweighing. Triplicatedeterminations were carried out and the water and oil absorption


S.-k. Du et al. / LWT - Food Science and Technology xxx (2013) 1e6 3

capacities were expressed as grammes of water or oil bound pergramme of the sample on a dry basis.

2.4.2. Emulsion activity and stabilityEmulsifying properties were determined according to the

method reported by Kaur and Singh (2005). Flour samples (3.5 g)were mixed with 50 mL distilled water and homogenized at10,000 rpm using a high-speed scattering machine (XHF-D,China), for 30 s. Peanut oil (25 mL) was added and the mixturewas homogenized again for 30 s. Then, another 25 mL peanut oilwas added and the mixture was homogenized for 90 s. Theemulsion was divided evenly into two 50 mL centrifuge tubesand centrifuged at 1,100 g for 5 min. Emulsifying activity wascalculated by dividing the volume of the emulsified layer by thevolume of emulsion before centrifugation � 100. The emulsionstability was determined using the samples prepared for mea-surement of emulsifying activity. They were heated for 15 min at85 �C, cooled, and centrifuged at 1100g for 5 min. The emulsionstability was expressed as the % of emulsifying activity remainingafter heating.

2.4.3. Foaming capacity and foaming stabilityThemethod of Kaur and Singh (2005) was used to determine the

foaming capacity (FC) and the foam stability (FS). Flour samplemixtures (50 mL of 3 g/100 mL w/v) in distilled water were ho-mogenized using a high-speed scattering machine (XHF-D, China),at 10,000 rpm for 2e3min. The blend is immediately transferred toa graduated cylinder and the homogenizer cup was rinsed with10 mL distilled water, which was then added to the graduatedcylinder. The volume was recorded before and after whipping andmeasured as the percent of volume increase due to whipping. Thefoaming activity was expressed as the % of volume increase.Changes in foamvolume in the graduated cylinder were recorded atintervals of 20, 40, 60, and 120 min of storage. To study the effect ofconcentration on foam foamability, 2, 5, 7, and 10 g/100 mL (w/v)aqueous suspensions of the legume flours were whipped identi-cally as described above, and the final volume in the graduatedcylinder was noted in each case.

The foaming capacity and foaming stability of each legume floursuspension were calculated using the following formula:

FC ¼ V2 � V1

V1� 100%; FS ¼ V3

V2 � V1� 100%

where FC is the foaming capacity, FS is the foaming stability, V1 isthe volume of the suspension (mL) before stirring, V2 is the volumeof the suspension (mL) after stirring, and V3 is the volume of thestirred suspension (mL) after it was allowed to stand.

Table 1Chemical compositions of legume flour.a

Legume flour Moisture (g/100 g) Starch (g/100 g, db)

Pinto bean 10.0 � 0.0bc 42.86 � 0.11eLima bean 10.2 � 0.1cd 44.55 � 2.41deSmall red bean 9.8 � 0.0b 44.19 � 1.80eRed kidney bean 9.2 � 0.2c 44.19 � 0.40eBlack bean 9.4 � 0.0a 44.02 � 0.40eNavy bean 9.7 � 0.2cd 42.92 � 0.23eBlack eye bean 9.7 � 0.1f 52.5 � 0.72abMung bean 9.5 � 0.1ef 54.58 � 2.80aLentil 9.9 � 0.1cd 50.52 � 0.53bcChickpea 11.2 � 0.1de 47.85 � 1.42cd

a All data represent the mean of triplicates. Values followed by the same alphabets inb Total nitrogen � 6.25.


2.5. Pasting properties

Pasting properties of the legume flours were analyzed by using arapid visco analyzer (Newport Scientific Pty Ltd., Sydney, Australia).Each legume flour suspension (12 g/100 g, db, w/w; 28 g totalweight) was equilibrated at 50 �C for 1 min, heated at a rate of 6 �C/min to 95 �C, and then kept at 95 �C for 5 min. Then, the suspen-sions were cooled to 50 �C at a rate of 6 �C/min. The rotating speedof the paddle was set at 160 rpm during the measurements exceptof 960 rpm at the first 10 s.

2.6. Statistical analysis

The data reported in all of the tables are the averages of tripli-cate observations. Statistical analysis of the results was done withSAS 8.1 (Institute Inc., USA) and Microsoft Excel 2003 (MicrosoftInc., USA).

3. Results and discussion

3.1. Chemical composition

The legume flours significantly differed in chemical compo-sition. The starch, protein, crude fat, and ash contents of differentkinds of legume flours ranged from 42.86 g/100 g to 54.58 g/100 g, 22.37 g/100 g to 28.05 g/100 g, 1.14 g/100 g to 6.63 g/100 g,and 2.91 g/100 g to 4.30 g/100 g, respectively (Table 1). Theprotein contents of the legume flours were higher than those ofcereal crops (7.5e12 g/100 g), poultry (15e20 g/100 g), eggs(12.8 g/100 g), and meat (10e20 g/100 g). The fat contents werelower than those of soybean (18.0 g/100 g), corn (4.0 g/100 g),and millet (4.0 g/100 g); conversely, the fat contents were equalto those of rice and wheat (1e2 g/100 g). The ash contents wereslightly higher than those of animal meat and cereals (Wu, 2005,chap. 4). The starch content was highest in mung bean flour(54.58 g/100 g) and lowest in pinto bean flour (42.86 g/100 g).Lentil flour had the highest protein (28.05 g/100 g) and thelowest fat (1.14 g/100 g) contents. The fat content (6.63 g/100 g)of chickpea flour was significantly higher than those of ten kindsof wild legumes (1.16e1.85 g/100 g), while the fat contents ofother kinds of legume flour were similarly reported (Viano et al.,1995). Seena and Sridhar (2005) reported that the ash, protein,and fat contents of legume flour were 3.3 g/100 g, 32 g/100 g, and1.9 g/100 g, respectively. The variation in chemical compositionamong the different kinds of legume flours can be attributed tothe differences in their genetics, varieties, and growth environ-ments (e.g., geographical location and growing season) (Kauret al., 2007).

Proteinb (g/100 g, db) Oil (g/100 g, db) Ash (g/100 g, db)

22.80 � 0.14e 1.51 � 0.01d 4.14 � 0.13ab23.92 � 0.35d 1.15 � 0.08f 4.30 � 0.11a25.68 � 0.19c 1.58 � 0.04d 4.25 � 0.16ab25.60 � 0.20c 1.56 � 0.05d 3.54 � 0.11c25.37 � 0.39c 1.90 � 0.04b 4.04 � 0.08b25.73 � 0.48c 1.77 � 0.01c 4.10 � 0.03ab24.58 � 0.13d 1.56 � 0.03d 3.73 � 0.08c27.10 � 0.21b 1.28 � 0.04e 2.91 � 0.05e28.05 � 0.01a 1.14 � 0.01f 3.01 � 0.08de22.37 � 0.49e 6.63 � 0.03a 3.16 � 0.05d

each column are not significantly different (P > 0.05) by Duncan test.


Table 3Functional properties of legume flour.a

Legumeflour

Waterabsorptioncapacityb (g/g)

Oil absorptioncapacityc (g/g)

Emulsionactivity (%)

Emulsionstability (%)

Pinto bean 1.87 � 0.01a 1.03 � 0.01d 88.94 � 2.00b 84.15 � 1.89bLima bean 1.17 � 0.01d 0.97 � 0.01e 63.77 � 0.04fg 91.75 � 1.80aSmall red

bean1.89 � 0.03a 1.05 � 0.02cd 92.20 � 0.95a 92.06 � 0.00a

Red kidneybean

1.67 � 0.05b 1.20 � 0.02b 82.46 � 0.47c 86.54 � 2.54b

Black bean 1.61 � 0.11b 1.38 � 0.00a 67.82 � 2.85d 95.07 � 1.19aNavy bean 1.39 � 0.03c 1.15 � 0.02b 66.94 � 1.79de 96.90 � 1.50aBlack eye

bean1.12 � 0.00d 0.97 � 0.02e 67.02 � 0.26de 93.18 � 0.00a

Mung bean 1.22 � 0.04d 1.05 � 0.06cd 64.14 � 0.86efg 94.59 � 1.37aLentil 1.33 � 0.02c 0.93 � 0.00e 65.75 � 0.11def 91.99 � 4.75aChickpea 1.19 � 0.01d 1.10 � 0.02c 61.14 � 0.61g 94.19 � 1.64a

a All data represent the mean of triplicates. Values followed by the same alpha-bets in each column are not significantly different (P > 0.05) by Duncan test.

b Amount of water absorbed divided by the initial weight of flour.c Amount of oil absorbed divided by the initial weight of flour.


3.2. Physical and chemical properties

3.2.1. Bulk densitiesSignificant differences were observed among the bulk densities

of the flours from different legumes (Table 2). The bulk density forlegume flours varied from 0.543 g/mL to 0.816 g/mL, where thehighest and the lowest values were obtained from lentil flour andblack bean flour, respectively. The higher bulk density of lentil floursuggests that it is denser than the other legume flours. Kaur andSingh (2005) reported that the bulk densities of differentchickpea varieties range from 0.536 g/mL to 0.571 g/mL, which arecomparable to the results in this study. The bulk density of legumeflour plays an important role in weanling food formulation, that is,reducing the bulk density of the flour is probably helpful to theformulation of weanling foods (Milán-Carrillo, Reyes-Moreno,Armienta-Rodelo, CaráH bez-Trejo, & Mora-Escobedo, 2000).

3.2.2. Water absorption index and water soluble indexThe WAI determines the volume occupied by the starch after it

swells in excess water and indicates the integrity of starch inaqueous dispersions. The WAI of different kinds of legume floursranged from 4.09 g/g to 6.13 g/g, where the highest value was ob-tained from chickpea flour and the lowest value was determinedfrom black eye bean flour (Table 2). WAI is related to the hydro-philicity and gelation capacity of biomacromolecules, such as starchand protein, in flour (Kaur & Singh, 2005). The amorphous region ofchickpea starch can greatly swell by absorbing water, causing thestarch to have a high WAI. However, the components of differentkinds of legume flours are diverse, which may induce differentinteractions with water. Thus, the WAI of legume flours may notcompletely depend on the water absorption and swelling of thestarches.

The WSI, which indicates the solubility of molecules, differedsignificantly among the legume flours. TheWSI varied from 19.44 g/100 g to 29.14 g/100 g, where the highest value was obtained fromlima bean flour and the lowest value was determined from pintobean flour. Amylose-lipid and protein-starch complexes formed inthe process of heating could affect the WSI (Sathe, Deshpande, &Salunkhe, 1982).

3.3. Functional properties of the legume flours

3.3.1. Water absorbing capacities and oil absorbing capacitiesTheWAC of flour plays an important role in the food preparation

process because it influences other functional and sensory prop-erties. TheWACs of the legume flours ranged from1.12 g/g to 1.89 g/g, where the WAC of small red bean flour was the highest and thatof black eye bean flour was the lowest (Table 3). The WACs of the

Table 2Physicochemical properties of legume flour.a

Legume flour Bulk density (g/mL) WAI (g/g)b WSI (g/100 g)c

Pinto bean 0.680 � 0.00ef 4.27 � 0.08fg 19.44 � 0.79eLima bean 0.782 � 0.00c 4.82 � 0.13c 29.14 � 0.67aSmall red bean 0.683 � 0.00ef 4.79 � 0.13cd 22.15 � 1.85cdRed kidney bean 0.679 � 0.00f 4.57 � 0.15de 21.69 � 0.12dBlack bean 0.543 � 0.01h 4.40 � 0.06ef 20.97 � 0.00deNavy bean 0.690 � 0.01e 4.31 � 0.13efg 25.92 � 1.26bBlack eye bean 0.764 � 0.01d 4.09 � 0.00g 25.04 � 0.63bMung bean 0.798 � 0.01b 5.64 � 0.12b 20.76 � 0.64deLentil 0.816 � 0.01a 4.76 � 0.03cd 26.15 � 0.59bChickpea 0.573 � 0.00g 6.13 � 0.02a 24.08 � 0.92bc

a All data represent the mean of triplicates. Values followed by the same alpha-bets in each column are not significantly different (P > 0.05) by Duncan test.

b Water absorption index.c Water solubility index.


legume flours are directly correlated with their cooking propertiesand affect their food processing properties. The water absorption oflegume flours greatly influences the type of foodmade from cereal-legume mixed flours; addition of some types of legume flour tocereal flour could help maintain the soft texture of the resultingfood product (Wall, 1979). Kaur and Singh (2005) reported thatlegume flour containing several water-loving components, such aspolysaccharides, generally have high WAC. The protein quality oflegume flours also affects their WAC.

The OAC of legume flour is very important for improving themouth texture and maintaining the flavor of food products. TheOACs of the legume flours ranged from 0.93 g/g to 1.38 g/g andsignificantly differed (Table 3). The OAC of black bean flour wassignificantly higher than those of the other legume flours. The OACsof flours from lentil, lima bean, and black eye bean did not differsignificantly from each other; however, they were lower than thoseof the other legumes. The oil absorbing mechanism involvescapillarity interaction, which allows the absorbed oil to be retained.Hydrophobic proteins play the main role in oil absorption. TheOACs of different legume flours are influenced by particle sizes,starch and protein contents, protein types (Sathe et al., 1982), andnon-polar amino acid side chain ratios on the protein moleculesurface (Chau et al., 1997). According to Kinsella (1976), more hy-drophobic proteins show superior binding of lipids, indicating thatnon-polar amino acid side chains bind the paraffin chains of fats.Based on this suggestion, legume flour that shows higher OAC likelycontains a higher amount of available non-polar side chains in itsprotein molecules.

3.3.2. Emulsion activity and emulsion stabilityThe emulsion activity reflects the ability and capacity of a

protein to aid in the formation of an emulsion and is related to theprotein’s ability to absorb to the interfacial area of oil and water inan emulsion. The emulsion stability normally reflects the ability ofthe proteins to impart strength to an emulsion for resistance tostress and changes and is therefore related to the consistency ofthe interfacial area over a defined time period (Singh et al., 2010).The emulsion activity of the legume flours differed (Table 3), withsmall red bean flour exhibiting the highest value (92.20%) andchickpea flour yielding the lowest value (61.14%). The emulsionstabilities of the legume flours ranged from 84.15% to 96.9%; pintobean flour showed the lowest value (84.15%) and navy bean flourshowed the highest (96.9%). The differences among the emulsionactivities and emulsion stabilities are related to the protein


10

20

30

40

50

60

70

80

90

1 3 5 7 9 11

Concentration (g/100mL)

Foa

min

g ca

paci

ties

(%)

Pinto bean Black eye bean Lima bean Lentil

Chick pea Small red bean Red kidney bean Black bean

Navy bean Mung bean

Fig. 1. Effect of flour concentration on foaming ability of legume flours. Three repli-cates were taken for data analysis.

S.-k. Du et al. / LWT - Food Science and Technology xxx (2013) 1e6 5

contents (soluble and insoluble) and other components, such asstarch, fat, and sterol contents, of the legume flours. Protein-waterinteractions occur in the polar amino acid regions of proteinmolecules, and most proteins contain several polar side chainswith peptides on the parent chains, making them hydrophobicand thus affecting their solubility and emulsification properties(James & Norman 1979). The protein content of chickpea flour islower than the other kinds of legume flour; thus, indicating rela-tively poor emulsion activity. In contrast, the protein content oflentil flour was the highest among the legume flours but itsemulsion activity was poor, such variation may be related to theother components in the flours (Table 1).

3.3.3. Foaming capacities and foam stabilitiesFoaming capacity and stability generally depend on the interfa-

cial film formed by proteins, which maintains the air bubbles insuspension and slows down the rate of coalescence. Foamingproperties are dependent on the proteins and some other

(

(

)

)

Fig. 2. Foam stability of the legume flours at 3 g/100 mL solid concentration. Threereplicates were taken for data analysis.


components, such as carbohydrates, that are present in the flours(Sreerama, Sashikala, Pratape, & Singh, 2012). The foaming capac-ities and foam stabilities of different legume flours differed fromeachother (Figs.1 and2). The concentrations of theflours in solutionexhibited significant effects on foaming. When the concentrationswere lower than 5 g/100mL, the foaming capacities of legumefloursincreased significantly as the concentrations increased, which isconsistent with the previous results (Adebowale & Lawal, 2003;Seena & Sridhar, 2005).

Adebowale and Lawal (2004) found that when protein concen-trations increase to a certain point, the foaming capacity reaches toits maximum value, which agrees with the result of the study. At5 g/100 mL concentration, the foaming capacities of pinto bean,chickpea, navy bean, lentil, black bean, and mung bean flours reachto peak-value (Fig. 1). Seena and Sridhar (2005) found that theconcentrations of two wild sword beans differ (6 g/100 mL and 8 g/100 mL, respectively), at which point their foaming capacitiesattain their peak-values. When their concentrations ranged from5 g/100 mL to 10 g/100 mL, the foaming capacities of flours fromblack eye bean, red kidney bean, and small red bean initiallydeclined and subsequently increased, which is probably due to theinteraction of several proteins with starch and the squeezing outand dissolution of fats. Aremu, Olaofa, and Akintayo (2007)discovered a similar phenomenon. Diversity of the foaming ca-pacities of the legume flours among different legume flours mightbe caused by the physical differences of the main proteins.

The legume flours, except red kidney bean flour and chickpeaflour, exhibited excellent foam stabilities. Black eye bean flour andblack bean flour were able to maintain their foam stabilities (Fig. 2),allowing them to be used as substitutes of foam food proteins.Chickpea flour had the highest protein and the lowest fat contents,as well as the lowest foaming capacity and foam stability; thesefindings indicate that the protein content and protein-fat complexformation of legumes can affect their foaming capacities and foamstabilities. Black eye bean flour and black bean flour had good foamstabilities, which is probably related to the high surface activities ofsoluble proteins in their continuous water phases (Kaur & Singh,2005).

3.4. Pasting properties

Significant differences were observed among the pasting char-acteristics of the legumes flours (Table 4). The pasting temperaturesof flours from different legumes ranged from 73.2 �C to 83.0 �C. Thehighest pasting temperature was determined from lima bean flourand the lowest was determined from mung bean flour. The highpasting temperature of lima bean flour indicates that its starch ishighly resistant to swelling and rupture. The peak viscosities ofdifferent kinds of legume flour varied from 96.2 RVU to 216.8 RVU,where the highest value was obtained from black eye bean flourand the lowest value was obtained from chickpea flour.

All of the flour samples showed a gradual increase in viscosity asthe temperature increased. Final viscosities and setbacks in thelegume flours ranged from 118.5 RVU to 243.8 RVU and 28.3 RVU to103.2 RVU, respectively. The breakdown of flour from various le-gumes ranged from 0.2 RVU to 79.0 RVU. The variation in viscosityof the starches during the test (within 50 �Ce90 �C) correspondedto their WACs and swelling capacities. The breakdown of small redbean flour was the lowest, indicating that this flour exhibits goodpaste stability and strong shearing resistance. Chickpea flour had alow pasting temperature (73.6 �C) and breakdown (6.0 RVU),lowest peak viscosity (96.2 RVU), trough (90.1 RVU), final viscosity(118.5 RVU), and setback (28.3 RVU). These results indicate thatchickpea flour can easily be used as a paste, is poorly resistant toshearing, and difficult to retrograde; these characteristics are


Table 4Pasting properties of legume flours.a

Legume flour Pasting temperature (�C) Peak viscosity (RVU) Trough viscosity (RVU) Breakdown (RVU) Final viscosity (RVU) Setback (RVU)

Pinto bean 77.8 � 0.9b 156.7 � 1.5cd 140.6 � 6.7a 16.0 � 5.1d 243.8 � 2.0a 103.2 � 4.7aLima bean 83.0 � 0.2a 160.6 � 2.9c 129.9 � 1.2b 30.7 � 1.7c 215.5 � 4.1d 85.6 � 2.9cSmall red bean 78.3 � 0.0b 103.3 � 2.7g 103.1 � 2.1c 0.2 � 0.6f 181.5 � 3.1e 78.4 � 1.0dRed kidney bean 77.9 � 1.7b 155.5 � 0.7d 140.6 � 1.8a 14.9 � 2.5d 233.8 � 0.4bc 93.2 � 2.1bBlack bean 79.5 � 0.0b 109.8 � 0.6f 108.2 � 0.6c 1.6 � 0.1f 166.8 � 0.4g 58.6 � 1.0fNavy bean 78.3 � 1.1b 113.8 � 2.1f 104.4 � 0.4c 9.5 � 1.7de 173.8 � 2.1f 69.5 � 1.7eBlack eye bean 78.3 � 0.0b 216.8 � 1.3a 137.8 � 5.7ab 79.0 � 4.4a 239.3 � 1.5ab 101.5 � 4.2aMung bean 73.2 � 1.1c 177.3 � 5.2b 105.4 � 0.9c 71.9 � 4.3b 180.1 � 2.6e 74.7 � 1.7deLentil 75.0 � 0.3c 136.4 � 2.3e 130.0 � 6.7b 6.3 � 4.4ef 228.4 � 5.1c 98.4 � 1.6abChick pea 73.6 � 0.7c 96.2 � 1.8h 90.1 � 2.2d 6.0 � 0.4ef 118.5 � 2.1h 28.3 � 0.1g

a All data represent the mean of triplicates. Values followed by the same alphabets in each column are not significantly different (P > 0.05) by Duncan test.


related to its high fat content (Table 1). High fat content restrictsstarch from swelling as it absorbs water and inhibits interactionsamong starch molecules, as well as between starch and its stirringpaddles, thereby affecting pasting viscosity. High fat content canalso inhibit the directional arrangement of dispersed molecularchains of starch, which induces the difficulty to retrograde. Thelower tendency to retrograde is an advantage in food products suchas soups and sauces, which undergo loss of viscosity and precipi-tation as a result of retrogradation (Adebowale & Lawal, 2003).

4. Conclusion

The functional properties of different types of legume floursignificantly differed within the group. The variation in functionalproperties among the legume flours can be associated with thevarying ratios of protein to starch and other constituents in theflours. The flour from Phaseolus legumes exhibited high WACs,OACs, emulsion activities, and emulsion stabilities. Significant dif-ferences were observed in the pasting properties of the differentflours, and pasting properties were greatly related to starchswelling and water absorption. These properties can influence theproperties of legume food processing.

Acknowledgments

The authors would like to thank the Young Support Funda-mental Research Funds of Northwest A&F University (QN2009072)and Shaanxi Province Agriculture Research Project (2008K01-02and 2012K02-14) for the support on this research.

References

Adebowale, K. O., & Lawal, O. S. (2003). Foaming, gelation and electrophoreticcharacteristics of mucuna bean (Mucuna pruriens) protein concentrates. FoodChemistry, 83, 237e246.

Adebowale, K. O., & Lawal, O. S. (2004). Comparative study of the functionalproperties of bambarra groundnut (Voandzeia subterranean), jack bean (Cana-valia ensiformis) and mucuna bean (Mucuna pruriens) flours. Food ResearchInternational, 37, 355e365.

AOAC. (2003). Official methods of analysis (1st ed.). Gaithersburg, Maryland: Asso-ciation of Official Analytical Chemists.

Aremu, M. O., Olaofa, O., & Akintayo, E. T. (2007). Functional properties of somenigerian varieties of legume seedflours andflour concentration effect on foamingand gelation properties. Journal of Food Science and Technology, 5, 109e115.

Chau, C.-F., Cheung, P. C. K., & Wong, Y.-S. (1997). Functional properties of proteinconcentrates from three Chinese indigenous legume seeds. Journal of Agricul-tural and Food Chemistry, 45, 2500e2503.

Chel-Guerrero, L., Pérez-Flores, V., Betancur-Ancona, D., & Dávila-Ortiz, G. (2002).Functional properties of flours and protein isolates from Phaseolus lunatus


and Canavalia ensiformis seeds. Journal of Agricultural and Food Chemistry, 50,584e591.

Damodaran, S. (1990). Interfaces, protein films and foams. Advance Food NutritionResearch, 34, 1e79.

De Almeida Costa, G. E., Da Silva Queiroz-Monici, K., Pissini Machado Reis, S. M., &De Oliveira, A. C. (2006). Chemical composition, dietary fibre and resistantstarch contents of raw and cooked pea, common bean, chickpea and lentil le-gumes. Food Chemistry, 94, 327e330.

Hoover, R., Li, Y. X., Hynes, G., & Senanayake, N. (1997). Physicochemical charac-terization of mung bean starch. Food Hydrocolloids, 11, 401e408.

James, C. O., & Norman, N. P. (1979). Physico-chemical and functional properties ofcowpea powders processed to reduce beany flavor. Journal of Food Science, 44,1235e1240.

Kaur, M., Sandhu, K. S., & Singh, N. (2007). Comparative study of the functional,thermal and pasting properties of flours from different field pea (Pisum sativumL.) and pigeon pea (Cajanus cajan L.) cultivars. Food Chemistry, 104, 259e267.

Kaur, M., & Singh, N. (2005). Studies on functional, thermal and pasting propertiesof flours from different chickpea (Cicer arietinum L.) cultivars. Food Chemistry,91, 403e411.

Kaur, S., Singh, N., Sodhi, N. S., & Rana, J. C. (2009). Diversity in properties of seedand flour of kidney bean germplasm. Food Chemistry, 117, 282e289.

Kinsella, J. E. (1976). Functional properties of proteins in foods: a survey. CriticalReviews in Food Science and Nutrition, 7, 219e232.

Mathres, J. C. (2002). Pulses and carcinogenesis: potential for the prevention ofcolon, breast and other cancers. British Journal of Nutrition, 88, S273eS279.

Milán-Carrillo, J., Reyes-Moreno, C., Armienta-Rodelo, E., CaráH bez-Trejo, A., &Mora-Escobedo, R. (2000). Physicochemical and nutritional characteristics ofextruded flours from fresh and hardened chickpeas (Cicer arietinum L). Leb-ensmittel-Wissenschaft und-Technologie, 33, 117e123.

Morrow, B. (1991). The rebirth of legumes: legume production, consumption andexport are increasing as more people become aware of legumes nutritionalbenefits. Food Technology, 9, 96e121.

Onimawo, I. A., & Asugo, S. (2004). Effects of germination on the nutrient contentand functional properties of pigeon pea flour. Journal of Food Science andTechnology-Mysore, 41, 170e174.

Sathe, S. K., Deshpande, S. S., & Salunkhe, D. K. (1982). Functional properties ofwinged bean (Psophocarpus tetragonolobus, L.) proteins. Journal of Food Science,47, 503e508.

Seena, S., & Sridhar, K. R. (2005). Physicochemical, functional and cooking proper-ties of under explored legumes, Canavalia of the southwest coast of India. FoodResearch International, 38, 803e814.

Singh, N., Kaur, N., Rana, J. C., & Sharma, S. K. (2010). Diversity in seed and flourproperties infield pea (Pisum sativum) germplasm. Food Chemistry,122, 518e525.

Sreerama, Y. N., Sashikala, V. B., Pratape, V. M., & Singh, V. (2012). Nutrients andantinutrients in cowpea and horse gram flours in comparison to chickpea flour:evaluation of their flour functionality. Food Chemistry, 131, 462e468.

Srinives, P., & Yang, C. Y. (1993). Mung bean production in Asia. Beijing: ChinaAgriculture Press.

Tharanathan, R. N., & Mahadevamma, S. (2003). Grain legumes e a boon to humannutrition. Trends in Food and Science Technology, 14, 507e518.

Viano, J., Masotti, V., Gaydou, E. M., Bourreil, P. J. L., Ghiglione, C., & Giraud, M.(1995). Compositional characteristics of 10 wild plant legumes from Mediter-ranean French pastures. Journal of Agriculture and Food Chemistry, 43, 680e683.

Wall, J. S. (1979). Properties of protein contributing to functionality of cereal foods.Cereal Food World, 24, 288e292.

Wu, K. (2005). Nutrition and food hygiene (5th ed.). Beijing: People’s Medical Press.Zhu, Z. H., Li, W. X., Zhang, X. F., Liu, F., Li, Y., & Liu, S. C. (2005). Evaluation of protein

and starch content in food legumes germplasm. Journal of Plant Genetic Re-sources, 6, 427e430.


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