Changes in the biochemical and functional properties of the extruded hard‐to‐cook cowpea (Vigna unguiculata L. Walp)

Changes in the biochemical and functional properties of the hard‐to‐cook cowpea bean after treatment by the extrusion process are reported. The extrusion was carried out at 150 °C, with a compression ratio screw of 3:1, a 5‐mm die, and a screw speed of 150 r.p.m. The extrusion caused the complete inactivation of the α‐amylase and lectin and it also reduced the trypsin inhibitor activity (38.2%) and phytic acid content (33.2%). The functional properties were also modified by the process, an increase of 2.5 times in the water absorption index and 3.1% in the water solubility were observed. The digestibility of the hard‐to‐cook flour of the cowpea bean was improved after the extrusion, with a 55.9% increase in protein digestibility and a 5.9% increase in starch digestibility.     

Effect of defatted almond flour on cooking,chemical and sensorial properties of gluten‐free fresh pasta

The aim of this work was to analyse the influence of defatted almond flour on soya bean‐based gluten‐free pasta. Optimal cooking time of pasta varied between 2.0 and 3.5 min, while cooking loss ranged 6.1% and 19.7%. The total protein content of samples varied from 30.4% to 41.0% (dry basis, db) in cooked pasta. The total phenols content of cooked samples varied between 1.66 and 2.99 mg ellagic acid equivalent/g, while the antioxidant activity (DPPH?) ranged between 19.1% and 41.9%. The sensory test showed no significant differences between the formulated pasta samples among brightness (3.20–3.27), surface appearance (1.14–1.20), hardness (2.14–2.36) and elasticity (1.56–1.71). Pasta developed is an innovative product that improves nutritional and functional properties of gluten‐free pasta compared to gluten‐free and traditional wheat flour pasta available on market.     

Combined effects of matrix and gene marker on the real‐time PCR detection of wheat

DNA‐based methods have been advanced as excellent alternatives for the detection and quantification of gluten‐containing cereals. In this study, it was intended to evaluate the effect of three distinct food matrices on the performance three TaqMan real‐time PCR approaches targeting α2‐gliadin, agglutinin isolectin (Tri a 18) and thioredoxin h(Tri a 25) genes of wheat. The results of wheat flour detection in soya bean, maize and rice model matrices evidenced that sensitivity was considerably affected by both the food matrix and the target gene. Rice matrix allowed the highest sensitivity, in opposition to soya bean. The α2‐gliadin method enabled the best sensitivity, especially when combined with rice matrix (5 mg kg^?1), followed by maize (10 mg kg^?1) and soya bean (50 mg kg^?1). These findings suggest that food matrix effects need to be carefully evaluated when developing real‐time PCR assays for wheat detection/quantification, but without compromising their great effectiveness as tools to monitor gluten‐containing cereals.     

Potentiality of Bacillus amyloliquefaciens KFCC11574P isolated from Korean traditional doenjang as a starter in the production of functional soya bean paste

Proteolytic activity, fibrinolytic activity and angiotensin converting enzyme (ACE)‐inhibitory activity, volatile compound profile, off‐flavour compound and sensory characteristics in soya bean paste made with Bacillus amyloliquefaciens KFCC11574P (KHG19) strain were compared with those in three different commercial soya bean paste samples. The KHG19 strain was isolated from doenjang, a traditional Korean soya bean paste, and the maximum dominance in soya bean paste prepared in this study was 68.8% after 2 months of ageing. Proteolytic and fibrinolytic activities in soya bean paste made with KHG19 strain (KHG19 soya bean paste) were higher than those in commercial soya bean pastes. The maximum proteolytic activity (2.47 cm²) was observed after 3 months of ageing, and the maximum relative fibrinolytic activity (236.98%) was appeared after 2 months of ageing. ACE‐inhibitory activity in KHG19 soya bean paste was similar to those in commercial samples. The volatile compound profile of KHG19 soya bean paste was closest to that of cheonggukjang according to the result from principal component analysis. The sensory score for off‐flavour character was significantly low in KHG19 soya bean paste (2.9) compare with the score (6.8) for Korean traditional doenjang. KHG19 strain can be used for the production of functional soya bean paste that would be affordable to global consumer.     

Inactivation of soya bean trypsin inhibitors by thiols

Systematic studies of factors that inactivate soya bean trypsin inhibitors showed that thiols facilitate heat inactivation, as illustrated by the following examples. Heating soya flour in an aqueous medium in a water-bath from 25 to 93°C for 1 h showed that heat alone does not begin to inactivate the inhibitor until about 55°C (around 10% inactivation). The corresponding value at 85 °C is 60%. In contrast, inactivation in the presence of N-acetylcysteine proceeds more rapidly, as shown by 70% inactivation at 55 °C and 94% at 85 °C. These results, and additional data, illustrate the complementary co-operative effect of heat and thiols in inactivating soya bean trypsin inhibitors in commercial soya flour. The thiol treatment also strikingly enhances the in-vitro digestibility of soya proteins by trypsin. The results are discussed with reference to the role of disulphide bonds in the mechanism of enzyme inhibition.     

Effect of hydrothermal treatment of runner bean (Phaseolus coccineus) seeds and starch isolation on starch digestibility

The study investigated the effect of traditional soaking and cooking, storage after cooking and freezing (? 18 °C, 21 days) and autoclaving of two varieties of runner bean on starch digestibility. Results achieved were compared with digestibility of isolated starch subjected to similar treatments. The digestibility of native starch from Nata var. seeds was lower after isolation than in raw flour. This starch was characterized by a higher content of fat and lower values of swelling power (SP) and amylose leaching (AML). After the thermal treatment, a significantly higher content of rapidly digestible starch (RDS) was observed both in seeds and starch. It was accompanied by reduced contents of resistant starch (RS) and slowly digestible starch (SDS). In flours from cooked seeds, the content of RDS was observed to be higher than in flours from autoclaved seeds, despite similar changes in contents of other constituents (ash and protein). It was probably due to better starch gelatinization owing to the long-lasting soaking of seeds. This resulted in a greater decrease of amylose content of starch compared to the other flours. Differences in SP, AML and thermal properties between starches isolated from two bean varieties had no influence on their digestibility after cooking. The storage of starch pastes at a temperature of ? 18 °C, unlike that of seeds, resulted in a significant increase in RS content, which shows the importance of other flour components in the process of starch retrogradation.     

Wet Fractionation of Hard-to-Cook Bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.) Seeds and Characterization of Protein,Starch and Fibre Fractions

A 2³ factorial design with four replicates of the central trial was used to evaluate wet-fractionation conditions for complete use of hard-to-cook (Phaseolus vulgaris L.) seeds. Tested variables were flour/water ratio (1:5, 1:7.5 and 1:10 w/v), pH (8, 9.5 and 11) and a soaking time (1, 2 and 3 h). The optimum conditions (1:10 w/v flour/water ratio; pH 8; and 1 h soaking time) were determined by the percentages of protein and starch recovery. Three fractions were obtained by the process: a protein isolate, starch fraction and fibrous residue. Isolate crude protein content was 73.03%; its in vitro digestibility was 76.7%, and its amino acids concentrations, except for methionine and cysteine, met essential amino acids requirements for preschool children and adults. Total starch content was 71.41% with an amylose content of 21.46% and an amylopectin content of 78.54%. Total dietary fibre in the fibrous residue was 42.12%, with 81.10% insoluble fibre and 18.91% soluble fibre. The protein isolate’s high protein content, the purity of the starch fraction and high proportion of insoluble fibre in the fibrous residues show wet fractionated hard-to-cook bean to be a promising source of functional ingredients with possible food industry applications.     

A Raman spectroscopic study of meat protein/lipid interactions at protein/oil or protein/fat interfaces

Structural changes in proteins of meat, FC (fat cream layers) and OC (soya bean oil cream layers) were studied by Raman spectroscopy. Results revealed that adsorption of proteins to the cream layers resulted in a maximum scattering change from 1657 to 1661 cm^?1, the intensity of amide I was significantly increased (P < 0.05), the percentages of secondary structures of proteins in the raw meat and meat cream layers were significantly different (P < 0.05), the bands near 540 and 475 cm^?1 were significantly (P < 0.05) higher in intensities in the soya bean oil cream layer samples compared to raw meat alone, the normalised intensity of the tryptophan band near 758 cm^?1, from 0.52 in the raw meat to 1.11 (fat cream layer) or 0.72 (soya bean oil cream layer). These results indicated that disulphide bonds, hydrophobic interactions and hydrogen bonding were of the main interactions observed in proteins and lipids at the emulsion interface.     

Chemical,biological and sensory evaluation of pasta products supplemented with α‐galactoside‐free lupin flours

α‐Galactoside‐free lupin flour has been used to supplement durum wheat semolina flour in order to increase the nutritive value of pasta products. Supplemented pasta products had a shorter cooking time, higher cooking water absorption, cooking loss and protein loss in water than control pasta prepared with only semolina. Sensory evaluation of cooked pastas showed that products supplemented with 80 g kg^?1 of α‐galactoside‐free Lupinus angustifolius var. Emir flour or with 100 g kg^?1 of α‐galactoside‐free Lupinus angustifolius var. Troll flour showed the same acceptability by panellists as the semolina pasta. These levels of supplementation were selected for further studies. The cooked α‐galactoside‐free lupin/semolina pastas showed higher amounts of protein, dietary fibre, calcium, phosphorus, magnesium, zinc and antioxidant capacity than control pasta and a reasonable level of vitamin B₁, vitamin B₂ and vitamin E. Biological assessment of cooked pastas indicated that the true protein digestibility did not change after the fortification of semolina but protein efficiency ratio increased sharply in the pasta supplemented with α‐galactoside‐free lupin flours (2.07 and 1.92 for Emir and Troll lupin varieties, respectively) in comparison with the control pasta (1.11). It is concluded that the α‐galactoside‐free lupin flours are an adequate ingredient to improve the nutritional quality of pasta products without adding flatulent oligosaccharides. Copyright © 2006 Society of Chemical Industry     

In vitro digestibility of protein and amino acids in protein mixtures

Six protein sources, casein, field peas, peanut meal, wheat flour, rapeseed and soya bean concentrate and their blends (ratio 1:1) were subjected to in vitro enzymic digestion. Wheat flour had the lowest in vitro digestibility (30% in 6 h) while the other sources had similar digestibilities (40%). Basic and aromatic amino acids were the most readily liberated from these protein sources. Some protein combinations, such as a rapeseed/field pea blend, gave in vitro digestibilities higher than calculated from individual proteins. The type of response observed could not be predicted from either nitrogen digestibility or amino acid composition of the individual sources. The digestibility of some amino acids was modified and this could be due to varying affinity of digestive enzymes for the protein.     

Physico- Chemical Characteristics and Functional Properties of Starch and Dietary Fibre in Grass Pea Seeds

Physico-chemical and functional properties of starch and fibre in raw and processed grass pea seeds were evaluated. Whole grass pea seeds were found to contain 41 % starch and 17% total dietary fibre (2% soluble and 15% insoluble) on dry matter basis. Examination by using scanning electron microscopy revealed oval shaped starch granules with an average width of 17 μm and length of 25 μm. Raw sample had a gelatinization onset temperature of 62°C and two endothermic transition peaks at about 73°C and 94°C, in addition the starch isolated from grass pea flour was shown to have a transition enthalpy (ΔH) of 10 Jg⁻¹. The viscosity of the raw sample (using a Brabender amylograph) reached peak maximum at 80–95°C, decreasing during the 30 min holding time (at 95°C) followed by an increase during cooling to 50°C. Raw whole seed flour was shown to have a water absorption and water solubility index (WSI) of 3 and 16%, respectively. Samples that had been cooked for 60 min had a lower WSI than those cooked for 30 min; this was further reduced in the samples cooked after soaking. The carbohydrate extracted from raw flour was found to be mainly high Mwt carbohydrate (55%), eluted at Kav < 0.2.     

Ingredient composition and pasta:water cooking ratio affect cooking properties of nontraditional spaghetti

An experiment was conducted to determine the effect of different pasta:water ratios and nontraditional ingredients on the cooking properties of spaghetti. Spaghetti was made using semolina and semolina containing 20% (w/w) nontraditional (NT) ingredients (corn, flaxseed, lentil, oat, pinto bean and soybean flours). Pasta:water ratios evaluated were 13 g:400 mL, 27 g:400 mL and 48 g:400 mL. Addition of pasta caused a decline in cooking water temperature. The water temperature drop and recovery time to boiling (100 °C) varied with pasta:water ratio and with nontraditional ingredient in the spaghetti. These results were attributed to the calculated specific heat capacity of the ingredients incorporated in the spaghetti. Cooking time was reduced for all NT spaghetti with respect to the control sample and was longest when 48 g of pasta was cooked. Pasta:water ratio affected cooking loss but not cooked weight or cooked firmness. Cooking losses were greater with 13 g:400 mL compared to 48 g:400 mL.     

In vitro digestibility of processed and fermented soya bean,cowpea and maize

Tropical legumes, ie soya bean and cowpea, were pre‐treated and subsequently fermented using pure cultures of Rhizopus spp. Impact of soaking, cooking and fermentation of the legumes on their digestibility was determined using an in vitro digestion method. Processing of white maize included, amongst others, natural lactic acid fermentation, cooking and saccharification using barley malt. An in vitro method was standardised to carry out comparative determinations of the dry matter digestibility of cereal and legume food samples as a function of processing conditions, without attempting to exactly mimic gastrointestinal digestion. Using this method based on upper digestive tract digestion, it was observed that digestibility of the legumes increased during cooking and fermentation. Cooking improved the total digestibility of both soya bean and cowpea from 36.5 to 44.8% and from 15.4 to 40.9% respectively. Subsequent fungal fermentation increased total digestibility only by about 3% for both soya bean and cowpea. Digestibility was also influenced by fungal strain and fermentation time. Cooking and subsequent saccharification using malt almost tripled total digestibility of white maize from 25.5 to 63.6%, whereas lactic fermentation of maize had no effect on in vitro dry matter digestibility. Although total digestibility of cooked legumes was only slightly improved by mould fermentation (3% for both soya bean and cowpea), the level of water‐soluble dry matter of food samples increased during fermentation with Rhizopus oryzae from 7.0 up to 27.3% for soya bean and from 4.3 up to 24.1% for cowpea. These fermented products could therefore play a role as sources of easily available nutrients for individuals suffering from digestive disorders. © 2000 Society of Chemical Industry     

Growth and thermal inactivation of Listeria monocytogenes and Escherichia coli O157:H7 in four kinds of traditionally non-fermented soya bean products

This study evaluated growth and thermal inactivation of Listeria monocytogenes and Escherichia coli O157:H7 inoculated in tofu, dougan, qianzhang and doupi which were stored at 4, 25 and 37 °C and heated at 55, 60, 65 and 70 °C. Growth of the two pathogens in four soya bean products increased with temperature or A_w of soya bean products increasing. At the same temperature, lag time (LT) values of L. monocytogenes (16.32–0.94 h) and E. coli O157:H7 (2.66–0.98 h) in tofu which has the highest A_w were the lowest. When inoculated soya bean products were stored at 4 °C, L. monocytogenes grew slowly, while E. coli O157:H7 did not grow but survived for 14 days. With temperature increasing, δ-values of L. monocytogenes and E. coli O157:H7 in the four soya bean products were decreased. With A_w of soya bean products increasing, thermal resistance of L. monocytogenes decreased, while that of E. coli O157:H7 increased. This study could assist retail soya bean products processors and food industry to enhance safety of soya bean products and design thermal processing regimes.     

High pressure treatments largely avoid/revert decrease of cooked sorghum protein digestibility when applied before/after cooking

The results obtained in this work showed that high pressure treatments avoid/revert, to a large extent, cooking deleterious effects that decrease sorghum proteins digestibility, when pressure is applied before/after cooking. The best results were obtained when pressure is applied before the cooking process. Digestibility of cooked sorghum proteins increased from 16.1% to 35.3/25.4% when pressure at the level of 300 MPa was applied during 15 min before/after cooking, respectively (the value for uncooked sorghum was 42.1%). When 300 MPa were applied for 5 min before cooking, similar results were obtained for digestibility (36.0%).Analysis of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of sorghum prolamins, revealed that high molecular weight aggregates and a 45 kDa dimer, which usually increase with cooking and are related to protein digestibility decrease, did not significantly change when high pressure is applied.A relationship between Infra-red (IR) spectra and protein digestibility by means of a Partial Least Square (PLS1) regression was assessed, showing changes in proteins and also on lipids and starch.It can be concluded that pressurization of sorghum flour, before or after cooking, particularly the former, is a suitable process to greatly improve cooked sorghum protein digestibility.     

Sensory evaluation and in vitro protein digestibility of mung bean as affected by cooking time

Heat treatment is particularly important in the preparation of mung bean for consumption, from the point of view not only of acceptability but also of improvement on protein digestibility. Sensory evaluation of cooked mung bean in terms of taste, colour, aroma and texture has an organoleptic panel indicated that there was no significant difference (P < 0.05) between mung bean cooked for 25, 30, 35, 40 and 45 min. An in vitro protein digestibility assay was used to examine the effect of cooking time on protein digestibility. The applied non-linear mathematical model indicated a high correlation coefficient between experimental and predicted data (R² ≥ 0.999). A maximum improvement in in vitro protein digestibility (IVPD) of 4.83% was obtained by cooking for 38.6 min. No remarkable changes in most amino acids were found between raw and cooked samples except that tryptophan was decreased by 4.69% and a 10.29% loss of threonine occurred with the optimum cooking time. © 1999 Society of Chemical Industry     

Response surface analysis and extrusion process optimisation of maize–mungbean‐based instant weaning food

This study was conducted to produce high‐quality weaning food from easily available and low‐cost raw materials by extrusion technology. Weaning mix was developed using extrudates of maize (Zea mays) and mungbean (Vigna radiata) flour with a twin‐screw extruder. Experiments were designed using three independent variables [feed moisture (12.6 – 19.4%), screw speed (349 – 601 rpm) and barrel temperature (108 – 192 °C)] and five dependent variables (specific mechanical energy, bulk density, water absorption index, water solubility index and degree of gelatinisation) at five levels of central composite rotatable design (CCRD). Optimisation results indicated that feed moisture of 14.33%, screw speed of 524 rpm and barrel temperature of 174 °C would produce maize–mungbean extrudates of preferable functional properties. The optimised weaning mix contained maize–mungbean extrudates 40%, skim milk powder 35% and sugar 25% (w/w). The nutrient content of the weaning mix was in accordance with the standards specified by PFA, (2004) with high protein and starch digestibility.     

Feeding differently processed soya bean Part 1. Effect on performance,protein utilization,relative organ weights,carcass traits and economics of producing broiler-chickens

The comparative utilization of differently processed (roasted, cooked and oil cake) soya bean base diets and groundnut cake diet were evaluated in a feeding trial using 100 day-old Anak broiler-chicks. The response criteria included performance, protein utilization, relative organ weights, carcass traits and economy of production. At the end of the feeding trial, the average weight gains of chicks fed processed soya bean diets were significantly (P < 0.05) higher than those fed groundnut cake and raw soya bean diets. Both feed consumption and efficiency were significantly (P < 0.05) enhanced by processing. For example, feed consumption was highest in the chicks fed soya bean oil cake and least in those fed raw bean. Feed efficiency was best in chicks fed roasted soya bean. The relative weights [g/100g body wt.] of the liver, kidneys, lungs, heart, gizzard and bursa were not significantly affected by the differently processed soya bean while the raw bean (unprocessed) significantly (P < 0.01) increased pancreas weight. The dressed weight [%], eviscerated weight [%] and the relative weight of the thigh, drumsticks, chest, back and head were not significantly influenced by the dietary treatments. However, the relative weights of the shank and belly fat were significantly (P < 0.05) affected. Cost-benefit analysis showed that the processed soya bean gave higher profit than groundnut cake diet. Among the soya bean diets, profit was in the order: roasted > cooked > oil cake > raw bean.     

Preparation and characterisation of soya milk enriched with isoflavone aglycone fermented by lactic acid bacteria combined with hydrothermal cooking pretreatment

A fermented soya milk (FSM) enriched with isoflavone aglycone (FSM‐SPIA) was prepared from heated soya protein isolate (SPI)‐isoflavone complex. After 48 h of fermentation, FSM‐SPIA contained higher contents of living bacteria, free amino acids and aglycone compared with the FSM of SPI (FSM‐SPI) and the FSM of SPI‐isoflavone complex (FSM‐Mix). In the in‐vitro digestion experiment, FSM‐SPIA showed higher antioxidant capacity and isoflavones (ISO) bioavailability than FSM‐SPI and FSM‐Mix. This was likely due to the soya milk containing a higher level of amino acid, peptides and the presence of soya bean isoflavone. The improved protein digestibility, the interaction and binding ability between proteins and ISO may affect the properties of the protein and the fermented products. The FSM enriched with isoflavone aglycone can be used as a functional fermented drink, as well as an auxiliary food for menopausal women during a specific pathological period.     

Mixing properties and rheological characteristics of dough used to make potato‐cereal soft wraps

We have studied mixing, rheology and stability of potato‐cereal flour doughs. These were prepared using samples of two varieties of cooked and cold‐stored potatoes. Dependent on variety a minimum duration of 24–48 h cold‐storage was required. Dough mixing torque plateau was inversely related to potato water content. This should be <79 g/100 g. It was also necessary to have a stable dough mixing torque plateau of >2 Nm at a specific total mechanical energy input of 18–22 kJ kg^?1. The resting temperature of the dough was also inversely related to its strength (plateau elastic modulus at time zero). Target dough strength should be about 25 kPa in a bob‐cup. Above 15 °C it decreased as a function of time and within 1 h it became too sticky for commercial processing. At 4 °C the dough remained stable. Sufficient potato starch retrogradation is a pre‐requisite to make optimal potato‐cereal flour dough for commercial processing.