Preparation and characterisation of glyceollin‐enriched soya bean protein using solid‐state fermentation

Glyceollins, stress‐induced phytoalexins from parent soya bean isoflavones, were elicited with Aspergillus oryzae. This solid‐state fermentation facilitated the conversion of isoflavone glycosides into aglycones and glyceollins, which could mainly enrich in soya bean protein isolate (SPI) during protein preparation due to protein–polyphenol interactions. Glyceollin‐enriched SPI exhibited less flavour volatiles, higher solubility, lower whiteness and higher antioxidant activity than unfermented SPI. Fermented SPI was more easily to be digested during in vitro pepsin–trypsin digestion. This may be attributed to partial degradation of protein, especially α′ and α subunits of β‐conglycinin and acidic subunit of glycinin. The antioxidant activity of digestive products derived from fermented SPI was obviously enhanced with increasing digestion time due to simultaneous release of antioxidant peptides and glyceollins involved in the interior of protein molecule. These results suggest an effective technique for producing a nutrient‐enhanced SPI as novel functional ingredients applied in food industry.     

混菌发酵豆豉中异黄酮含量及对小鼠肺癌细胞的抑制作用

选用高产蛋白酶菌株枯草芽孢杆菌D2和β-葡萄糖苷酶产生菌枯草芽孢杆菌U35进行单菌种、混合菌种发酵生产豆豉,测定大豆异黄酮含量及其抗肿瘤能力,分析异黄酮含量和抗肿瘤能力的关系。用HPLC法测定豆豉提取物异黄酮含量,采用MTT比色法检测异黄酮含量对细胞增殖的影响,并在荧光显微镜下观察小鼠肺癌(LLC)细胞形态变化。结果表明,D2U35混菌豆豉苷元型异黄酮含量分别比D2、U35单菌豆豉高101.95μg/mL(2.38倍)和35.48μg/mL(1.25倍),D2U35混菌豆豉对肿瘤细胞的抑制率分别比D2、U35单菌豆豉高15.79%和7.02%,说明混菌发酵不仅提高了苷元型异黄酮含量,还提高了豆豉提取物的抗肿瘤能力。对肿瘤抑制作用,苷元苷型异黄酮>总异黄酮>糖苷型异黄酮。     

Cereal bars functionalised with tempeh: nutritional composition,isoflavone content and consumer acceptance

The aim of this study was to produce cereal bars (CB) added with tempeh flour (TF) and evaluate the nutritional composition, fatty acids profile, isoflavone content and sensory acceptance. Tempeh was produced from organic soya beans cotyledons fermented by Rhizophus oligosporus followed by freeze-drying and milling in order to obtain the TF. The addition of 10%, 15% and 20% TF to CB resulted in both protein and lipid content increase and a higher polyunsaturated/saturated fatty acids ratio. The content of isoflavone aglycones, the forms considered to have higher biological activity, was higher in TF than in soya bean, which was also reflected in the CB chemical composition. An acceptance test showed that CB added with TF (up to 15%) were sensory accepted. Overall results suggest that the addition of TF as an ingredient in cereal bars allows improving the chemical and functional characteristics of this type of ready-to-eat foods.     

Effects of fermentation by Bifidobacterium bifidum on the rheology and physical properties of ice cream mixes made with cow and vegetable milks

Fermented and nonfermented probiotic ice creams were made by incubating Bifidobacterium bifidum (Bb‐12) culture in ice cream mixes with cow, soya, coconut and composite milks (combinations of coconut or cow milks with soya milk). The changes in ice cream‐eating qualities and physical properties (melting rate, apparent viscosity, hysteresis, fat globule size, zeta potential, microscopic structure and freezing behaviour) were evaluated. In general, fermentation decreased the melting rate and total acceptability of ice creams but increased the apparent viscosity, hysteresis, particle size and freezable water. For fermented ice creams containing composite milk, those containing cow milk showed a higher percentage change than those containing coconut milk in respect of hysteresis, particle size and freezable water; however, the apparent viscosity was not affected.     

Morphology, proliferation, and ribonucleic acid and fractional protein syntheses in the small intestinal mucosa of young goats fed soy protein-based diets with or without amino acid supplementation

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects jejunal protein synthesis and whether effects may be ameliorated by supplementation of those AA known to be at lower concentrations in soy protein isolate than in CN. Goat kids (14 d) were fed comparable milk protein diets, in which 50% of the crude protein was CN (CAS), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43 d (n = 8 per group). On d 42, plasma concentrations of protein, urea, and AA were measured before and after morning feeding. In the morning of d 43, [¹⁵N]RNA from yeast [13 mg/kg of body weight (BW)] was given with the diet to measure the reutilization of dietary RNA precursors for mucosal RNA biosynthesis. Four hours later, an oral dose of l-[1-¹³C]leucine (180 mg/kg of BW) was administered and blood samples were collected between −15 and +45 min relative to tracer administration for analysis of plasma ¹³C α-ketoisocaproic acid and ¹³C recovery in blood CO₂. Kids were killed 60 min after the tracer application, and jejunal tissue was collected to determine mucosal morphology, cell proliferation, enzyme activities, RNA synthesis, and fractional protein synthesis rate. Plasma protein concentrations were higher in CAS than in SPI and SPIA. Plasma concentrations of Thr were higher in CAS than in SPI and SPIA, and those of Met were lower in SPI than in CAS and SPIA. In mid-jejunum, villus circumferences were higher in CAS than in SPI and SPIA, and villus height and villus height:crypt depth ratio were higher in CAS than in SPI. In mid-jejunum, mucosal protein concentrations were higher in CAS than in SPI and SPIA and mucosal activities of aminopeptidase N tended to be higher in CAS than in SPI, whereas activities of dipeptidyl peptidase IV tended to be lower in SPI than in SPIA. Activities of 5′ nucleotidase and xanthine oxidase were lower in CAS than in SPI. The ¹³C recovery in blood CO₂ tended to be higher in SPI than in CAS. In mid-jejunum, ¹⁵N enrichment of RNA tended to be higher in CAS than in SPI, and ¹³C enrichment of protein-bound Leu was higher in SPI than in CAS. In mid-jejunum, the fractional protein synthesis rate tended to be higher in SPI than in CAS. Our results revealed changes in intestinal growth after soy protein feeding that were associated with effects on intestinal RNA and protein synthesis but that were not ameliorated by AA supplementation.     

Physicochemical properties of soya bean protein gel prepared by microbial transglutaminase in the presence of okara

The influences of okara on the gelling and secondary protein structure of soya protein isolate (SPI) were investigated. Okara was ultra‐refined by high‐pressure homogenisation. The resulting particle sizes and microscopic morphologies were determined using a laser particle size analyser and a confocal laser scanning microscope, respectively. After okara homogenisation, surface area average particle size (D₃₂) decreased from 49.68 to 23.29 μm and volume average particle size (D₄₃) decreased from 118.94 to 55.08 μm. Dynamic rheological measurements showed that the storage (G′) and loss (G′′) moduli of SPI gelled in the presence of okara were mostly higher than those of SPI gels alone and were increased as the okara amounts increased. Linear law analysis revealed that SPI–okara gels were weak gels and frequency independent. Fourier transform infrared spectroscopy showed that okara and transglutaminase influenced the prevalence of α‐helices, β‐turns, β‐sheet and random coils.     

Biochemical,textural and microstructural changes in whole‐soya bean cotyledon sufu during fermentation

This study aims to investigate the nutritional value of sufu and reduce environmental problems caused by okara, which results from the traditional processing method of sufu. The feasibility of the whole‐soya bean cotyledon sufu (WSCS) processing method, which does not produce okara, was investigated. WSCS was prepared by ripening okara‐containing tofu through various hydrolytic enzymes secreted by Actinomucor elegans for 70 days. After fermentation, total nitrogen, amino nitrogen and lipid contents were found to be lower in WSCS than in traditional sufu (TS), whereas contents of reducing sugar, dietary fibre, isoflavone aglycone and soya bean polysaccharide were higher in WSCS than in TS. The hardness, springiness and adhesiveness of WSCS were 249.703 ± 0.500 g, 0.606 ± 0.008 and 8.393 ± 0.032 J, respectively. The corresponding values for TS were 264.863 ± 0.572 g, 0.615 ± 0.007 and 7.516 ± 0.031 J, respectively. In addition, microstructural changes in WSCS and TS during fermentation were observed through scanning electron microscopy. The results from this study may provide a basis for industrial production of WSCS.     

Physicochemical and sensory characteristics of soya protein isolate hydrolysates with added substrate‐like amino acids

Soya protein isolate (SPI) with or without added substrate‐like amino acid was subject to enzymatic hydrolysis catalysed by commercial proteases (Alcalase 2.4 L, flavourzyme and pancreatin). Addition of a small amount of amino acids (amino acid: SPI = 1: 2500, mol g^?1) during hydrolysis would cause a significantly (P < 0.05) reduced protein recovery, increased degree of hydrolysis, and altered amino acid composition and antioxidant activities of SPI hydrolysates. The SPI hydrolysates prepared with added Asp, Arg or Lys exhibited a higher antioxidant activity than the control. The bitterness of SPI hydrolysates was largely reduced upon addition of Met, Asp or Glu during hydrolysis, whilst the umami taste and mouthfeel‐liking were remarkably increased. Therefore, adding amino acid during hydrolysis is a feasible and beneficial approach to improve both the functional and sensory properties of SPI hydrolysate.     

Soya-yoghurt starter culture development from fermented tropical vegetables

The development of soya-yoghurt starter culture from fermented tropical vegetables was initiated. Soya milk fortified with 10 g litre^?1 sucrose was sterilised (121°C for 15 min) and inoculated with the exudate of fermented tropical vegetables. Acid production in the soya milk medium during incubation at 42°C for 5 h was evaluated and compared with cows' milk based cultures. Aroma of the soya milk based and cows' milk based cultures was also compared. Cultures derived from fermented cassava and corn separately reduced soya milk pH from 6′8 to 43 and 45, and significantly greater culture activity was observed in soya milk than in cows' milk. The culture from corn produced the most acceptable yoghurt-like aroma in soya milk while that from African oil bean seed produced the least acceptable aroma. The consumer-acceptable mild buttermilk-like aroma of yoghurt was not produced in soya milk or cows' milk by the cultures evaluated.     

Properties of soya milk and tofu prepared with γ-irradiated soya beans

Soya beans (Glycine max) ‘hwang keum’ were γ-irradiated at dose levels of 0, 2.5, 5, 10 and 20 kGy and the effects of the irradiated soya beans on soya milk and tofu properties were studied. An irradiation dose of 5 kGy caused an increase in yield of soya milk and tofu while having very little effect on their quality. The properties of tofu prepared with the soya beans irradiated at 2.5–5 kGy showed no significant difference from the non-irradiated control. However, at higher doses (10–20 kGy), decreases in yield, water holding capacity and sag value of tofu were observed. Compared with the non-irradiated control, hardness and fracturability in the texture of tofu were both significantly increased when the soya bean had been irradiated at 10–20 kGy, while cohesiveness and adhesiveness decreased. The changes in color values of soya milk and tofu were pronounced at 20 kGy.     

Amino acid composition and biological value of pastries with protein-rich additives

The authors studied amino acid composition of confectionery (bisquits) enriched with dry fat-free milk, dried buttermilk, dry whey and soya bean flour. The biological value of the products was estimated by the sum of essential amino acids, by the ratio of essential amino acids and total nitrogen, by the chemical score and the variation coefficient of the amino acid score. It has been established that confectionery enriched with dry fat-free milk and dried buttermilk contain more lysine than those enriched with soya bean flour. The balance of amino acids is improved in the products enriched with dry fat-free milk and dried buttermilk. To improve the amino acid balance and increase protein content in food products it iz recommended that by-products of milk manufacturing be mildly used.     

Higher bioavailability of isoflavones after a single ingestion of aglycone-rich fermented soybeans compared with glucoside-rich non-fermented soybeans in Japanese postmenopausal women

BACKGROUND: There have been conflicting study results concerning how the food matrix affects the bioavailability of isoflavone aglycone and glucoside. In this study the bioavailability of isoflavones after a single ingestion of aglycone‐rich fermented soybeans (Fsoy) and glucoside‐rich non‐fermented soybeans (Soy) was compared. Eleven healthy postmenopausal Japanese women were recruited for a randomised, double‐blind, crossover trial and consumed Fsoy or Soy powder dissolved in hot water. Blood samples were collected 0, 1, 2, 3, 4, 6, 8, 12 and 24 h and urine samples from 0 to 48 h after ingestion of the powders. The Fsoy and Soy powders ingested had the same total isoflavone content (95 µmol), but the former was rich in aglycone (90.6 µmol) while the latter was rich in glucoside (81.9 µmol). RESULTS: Serum concentrations of total isoflavones after 1–4 h were significantly higher in the Fsoy group than in the Soy group. The Fsoy group showed significantly higher maximum concentration (Cmax: 2.79 ± 0.13 vs 1.74 ± 0.13 µmol L^?1) and area under the curve (AUC_{0–24 h}: 23.78 ± 2.41 vs 19.95 ± 2.03 µmol day L^?1) and lower maximum concentration time (Tmax: 1.00 ± 0.00 vs 5.00 ± 0.67 h) compared with the Soy group. The cumulative urinary excretion of total isoflavones after 2 h was significantly higher in the Fsoy group than in the Soy group. Individual isoflavones (daidzein, genistein and glycitein) showed similar trends to total isoflavones. Equol (a metabolite from daidzein) did not differ between the two groups. CONCLUSION: The results of this study demonstrated that the isoflavones of aglycone‐rich Fsoy were absorbed faster and in greater amounts than those of glucoside‐rich Soy in postmenopausal Japanese women. Copyright © 2010 Society of Chemical Industry     

Protein nutrition of dairy cows receiving grass silage diets. Effects on silage intake and milk production of postruminal supplements of casein or soya-protein isolate and the effects of intravenous infusions of a mixture of methionine,phenylalanine and tryptophan

Milk production responses to protein supplementation of grass silage diets were investigated in two experiments with dairy cows. In Experiment 1. four cows received a basal diet of grass silage ad libitum plus a barley/soya supplement at 5 kg day^?1. The cows received the following treatments in a 4 × 4 Latin square design with 10-day periods: (1) basal diet, (2) basal diet plus 230 g casein day^?1 infused into the abomasum; (3) basal diet plus 225 g soya protein isolate (SPI) day^?1 into the abomasum; and (4) basal diet plus a dietary addition of 1.2 kg fishmeal-based product (AP) day^?1. All three supplements increased (P < 0.05) the yield of milk and milk protein relative to the basal diet, the values being 16.9. 535:18.8. 610; 19.5, 625; and 18.5 kg day^?1 and 582 g day^?1 for the basal. AP, casein and SPI treatments respectively. Responses to casein were greater (P < 0.05) than to SPI. Changes in the concentrations of amino acids in blood plasma suggested that methionine, tryptophan and phenylalanine were in shortest supply relative to demand, and their potential role as limiting amino acids was investigated in a second experiment. In Experiment 2, four dairy cows were used in a 4 × 4 Latin square design with 10-day periods. The four treatments were (1) a diet of grass silage ad libitum plus 5 kg day^?1 of a barley/soya supplement containing 176 g CP kg^?1 DM (LP); (2) LP plus an intravenous infusion of 5.0 g methionine, 9.1 g phenylalanine and 2.2 g tryptophan day^?1; (3) grass silage ad libitum plus 5 kg day^?1 of a barley/soya supplement containing 334 g CP kg^?1 DM (HP); and (4) HP plus the intravenous infusion of methionine, phenylalanine and tryptophan. The HP treatment produced a higher yield (P < 0.05) of milk protein than the LP treatment (722 vs. 667 g day^?1) but the amino acid infusion had no effect with either treatment. The elimination of methionine, phenylalanine and tryptophan (and, in previous experiments, methionine and lysine) as candidates for limiting amino acids on diets of grass silage plus soya-based supplements questions whether the differences in responses to casein and SPI can be explained in terms of their amino acid compositions. The role of factors such as peplides, producing during digestion, some of which may be biologically active, deserves investigation.     

Production of beta-glucosidase and hydrolysis of isoflavone phytoestrogens by Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus casei in soymilk

ABSTRACT:  The study determined β-glucosidase activity of commercial probiotic organisms for hydrolysis of isoflavone to aglycones in fermenting soymilk. Soymilk made with soy protein isolate (SPI) was fermented with Lactobacillus acidophilus LAFTI^® L10, Bifidobacterium lactis LAFTI^® B94, and Lactobacillus casei LAFTI^® L26 at 37 °C for 48 h and the fermented soymilk was stored for 28 d at 4 °C. β-Glucosidase activity of organisms was determined using ρ-nitrophenyl β-D-glucopyranoside as a substrate and the hydrolysis of isoflavone glycosides to aglycones by these organisms was carried out. The highest level of growth occurred at 12 h for L. casei L26, 24 h for B. lactis B94, and 36 h for L. acidophilus L10 during fermentation in soymilk. Survival after storage at 4 °C for 28 d was 20%, 15%, and 11% greater ( P < 0.05) than initial cell counts, respectively. All the bacteria produced β-glucosidase, which hydrolyzed isoflavone β-glycosides to isoflavone aglycones. The decrease in the concentration of β-glycosides and the increase in the concentration of aglycones were significant ( P < 0.05) in the fermented soymilk. Increased isoflavone aglycone content in fermented soymilk is likely to improve the biological functionality of soymilk.     

Stability of isoflavone phytoestrogens in fermented soymilk with Bifidobacterium animalis Bb12 during storage at different temperatures

Soy isoflavones in fermented soymilk with Bifidobacterium animalis Bb12 were stored at various temperatures (?80, 4, 24.8 and 37 °C) for 8 weeks and the concentration of isoflavones determined weekly using reverse‐phase high‐performance liquid chromatography (RP‐HPLC). The first‐order kinetic model was used to assess the degradation of each isomer at each storage temperature. Soymilk predominantly possesses high concentrations of isoflavone glucosides and very low concentration of bioactive aglycone component. During storage at various temperatures, concentrations of individual isoflavone isomers appeared to be significantly stable (P < 0.01). Interestingly, aglycones showed much smaller degradation constants compared with glucosides at all the storage temperatures studied. Genistein and daidzein were much more stable than glycitein and had almost similar degradation patterns, despite differences in their concentrations in the fermented soymilk. It was, however, observed that 4 °C was the most suitable storage temperature for the product in order to guarantee minimal degradation of bioactive isoflavone aglycones.     

Ripening temperature affects the content and distribution of isoflavones in sufu,a fermented soybean curd

Sufu, a fermented soybean curd, was prepared by ripening the salted tofu cubes in the Aspergillus oryzae‐fermented rice–soybean koji mash at 25, 35 or 45 °C for a period of 16 days. It showed that the 16‐day ripened sufu contains less total isoflavone content (629.29–739.68 μg g^?1 dried matter) than the salted tofu before ripening (942.59 μg g^?1 dried matter). Regardless of ripening temperature, ripening causes a major reduction in the content of β‐glucoside and malonylglucoside isoflavones along with a significant increase of aglycone isoflavone content. These changes were enhanced as the ripening period extended. Among the various treatments examined, sufu ripened at 45 °C showed the greatest increase in aglycone content coupled with the greatest decrease in malonylglucosides. The distribution of malonylglucosides decreased from an initial 40.32% in the tofu cube to 9.78% after 16 days of ripening at 45 °C. Meanwhile, the distribution of aglycone increased from 13.17% to 39.88%.     

The nutritional quality of two types of fish silage for broiler chickens

Fish waste was ensiled either by acidification with formic acid or by fermentation with a bacterial starter culture and molasses. The resulting liquids were mixed with wheat bran (85:15 w/w liquid: bran) and dried (70°C) to produce acid silage meal (ASM) and fermented silage meal (FSM). ASM and FSM were incorporated into wheat-based diets at 25, 50 and 100 g kg^?1 at the expense of soya bean meal. There were two control diets, one which contained soya bean meal as the predominant protein supplement and a second in which fish meal (50 g kg^?1) was added at the expense of some of the soya bean meal. Starter diets (13.25 MJ ME kg^?1, 12 g kg^?1 lysine) were fed from 1-day-old to 21-days-old and finisher diets (13.25 MJ ME kg^?1, 9.5 g kg^?1 lysine) were fed from 22 to 42-days-old to six replicates each of five birds. Birds were reared in raised-wire cages, and feed intake, liveweight and mortality were recorded. There were no significant effects of dietary inclusion of either ASM and FSM on the performance of broiler chickens relative to those fed on control diets. FSM contained less crude protein and amino acids than ASM. The recovery of amino acids relative to the total crude protein content from FSM was only 78.7%, presumably as a result of formation of Maillard reaction products during drying.     

响应面法优化贝莱斯芽孢杆菌发酵水豆豉的工艺条件

发酵产品的质量与微生物的产酶能力和发酵条件息息相关。为提高水豆豉的发酵品质,采用单因素法结合响应面法对一株高产豆豉纤溶酶的贝莱斯芽孢杆菌发酵水豆豉的条件进行优化,以获取最佳的发酵条件。首先利用单因素法缩小发酵时间、温度和接种量的范围,然后通过响应面法以水豆豉中的氨基酸态氮含量和豆豉纤溶酶活性为指标,确定最优发酵条件为:时间5d,温度35℃,接种量0.01%。最终发酵的水豆豉氨基酸态氮含量为8.95g/kg,豆豉纤溶酶活性为420.05IU/g,与市售相比,豆豉纤溶酶活性升高约400倍。该研究为贝莱斯芽孢杆菌发酵水豆豉提供了理论依据。     

Thermal treatments affect the polyphenol profile and increase antioxidant capacity in five varieties of edible bean milks

We investigated the influence of two thermal treatments, steaming and boiling, on polyphenol profile and antioxidant capacity in milks from five edible bean varieties, including green mung bean milk, yellow and black soya bean milk, rice bean milk and white cow gram milk. The two thermal treatments had different influences on polyphenol profile and antioxidant capacity with steaming better than boiling in increasing total phenolic content (TPC) and antioxidant capacity in edible bean milks. In particular, steaming substantially increased soya bean isoflavone glucosides in the two soya bean milks. Bioconversion between polyphenols, the release of bound polyphenols and the induction of Maillard reaction products could contribute to the increase in TPC and antioxidant capacity in some edible bean milks. Therefore, it is recommended to steam edible bean milk for consumption, and edible bean milk containing antioxidant polyphenols can be developed into functional drinks with potential health benefits.