Soy Protein

The influence of the conditions for isolation of soy protein on the content of genistein and its conjugated forms was studied. The major components of the genistein series isolated from soybean flour were malonyl genistin (54.3%), genistin (36.9%), and equal amounts (4.4%) of genistein and acetyl genistin. A modification in the conjugation profile of genistein between pH 4.5 and 8.0 and above pH 10 was attributed to the action of β-glucosidase and the saponification reaction, respectively. A decrease in the content of total genistein in the insoluble flour residue and in the soy protein isolate (SPI) with increasing extraction pH was detected, while in the whey, the total genistein content was not affected by pH. The effect of pH variation during acid precipitation on the content of genistein and its conjugated forms, at a constant extraction pH (8.0), was also studied. Under these conditions, the highest absolute content of total genistein in the SPI was obtained at pH 3.5 and the lowest was obtained at pH 5.6. The total genistein content in the whey followed an inverse trend compared with that of the protein yield. A temperature increase did not substantially affect the distribution of the different genistein forms or their total contents. The content of total genistein was higher in the glycinin than in the β-conglycinin protein fraction. The effect of the pH during the alcohol/water extraction of the isoflavones was also analyzed. The efficiency of the extraction was lower at pH values between 3.25 and 3.5 than at other pH values.

The protein content of ordinary white bread ranges from 8% to 9%. Specialty breads can be made with 13–16% protein by including soy protein. However, incorporating high levels of soy protein depresses loaf volume, gives poor crumb characteristics, and decreases acceptability. The objective of this study was to determine the influence of sodium stearoyl-2-lactylate (SSL), transglutaminase (TG), and xylanase (HE) on high-protein dough properties and bread quality and to improve dough handling and bread quality of soy–wheat bread by using an optimized additive combination. The influence of SSL, TG, and HE on soy–wheat dough and bread properties was modeled by response surface methodology. The negative effect of soy products on gluten network was confirmed. With regards to the additives tested and their combination, TG showed a major improving effect on dough rheological properties and crumb uniformity, whereas SSL and HE enhanced both dough and bread quality. The best formulation tested produced an increment of approximately 65% soy–wheat bread volume and a decrease of 79% and 71% crumb hardness and chewiness, respectively, compared with the standard formulation.

Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed.

Gluten is a major component of some cereals and is responsible for flour technological characteristics to make bakery products. However, gluten must be eliminated from the diet of celiac patients because its ingestion causes serious intestinal damage. The objectives of this study were to assess the effect of different flours and their mixtures on thermal and pasting properties of batters, and to study the quality parameters and staling rate of gluten-free breads. Starch gelatinization temperatures and enthalpies depended on batter composition. Soy flour addition had a higher effect on rice than on corn starch, indicating some differential interaction between starch and proteins. Inactive soy flour incorporation improved all bread quality parameters in both corn- and rice-based breads. Higher batter firmness of formulations with soy addition (extrusion force was doubled in rice/soy and rice/corn/soy batters with regard to rice and rice/corn batters) partially explained higher specific volume (rice breads: 1.98 cm3/g; rice/soy 90:10 2.51 cm3/g, corn/soy 90:10: 2.05 cm3/g, whereas corn/soy 80:20: 2.12 cm3/g), as these batters retained more air during proofing. The staling rate was decreased by soy flour incorporation on rice (staling rate of rice breads with 10% soy diminished 52%, and with 20% of soy addition, 77%, both regarding to 100% rice breads) and corn formulation (the staling rate of corn/soy 80:20 breads was 5.9% lower than corn/soy 90:10) because of the high water-holding capacity of soy proteins and the interactions established with amylopectin that could retard the retrogradation process. Breads made with rice, corn, and soy flours showed the best quality attributes: high volume, good crumb appearance, soft texture, and low staling rate.

Encapsulation is a promising technological process enabling the protection of bioactive compounds against harsh storage, processing, and gastrointestinal tract (GIT) conditions. Legume proteins (LPs) are unique carriers that can efficiently encapsulate these unstable and highly reactive ingredients. Stable LPs-based

The effect of dietary soy protein and flaxseed meal on metabolic parameters was studied in two animal models, F344 rats with normal lipid levels and obese SHR/N-cp rats with elevated levels of cholesterol and triglyceride. The rats were fed AIN 93 diet differing only in the source of ...

This study aimed to determine the effect of pretreating defatted soy flakes with ultrasound on soy protein isolate (SPI) yield and functionality. Defatted soy flakes dispersed into water (16%, w/w) were sonicated for 30, 60 and 120 s at ultrasonic amplitudes of 21 and 84 µmpp (peak to peak amplitude in µm), representing low and high power, respectively. The power densities were 0.30 and 2.56 W mL−1, respectively. The SPI yield increased by 13 and 34%, after sonication for 120 s at low and high power, respectively. The sonication of defatted soy flakes for 120 s at the higher power level improved the SPI solubility by 34% at pH 7.0, while decreasing emulsification and foaming capacities by 12 and 26%, respectively, when compared to control SPI. Rheological behavior of the SPI was also modified with significant loss in consistency coefficient due to sonication. Some of these results could be explained by the loss of the protein native state with increased sonication time and power.

Restructuring the current fermentation and recovery practices employed for the production of polyhydroxyalkanoates is essential for the commercialisation of environmentally benign and cost competitive biodegradable plastics. This study presents the potential of a wheat-based biorefinery for the production of poly (3-hydroxybutyrate)(PHB). Fed-batch bioconversions using Wautersia eutropha growing on wheat-derived media led to the production of 162.8 g/l PHB. A high PHB to total dry weight (TDW) yield of 93%(w/w) was achieved due to ...

Background: There has been an increase in demand for soy and its products, with soy protein having a huge market in particular. Several reports have established how soy protein hydrolysates (SPHs) yield better physiological properties and play essential functional roles than the crude soy protein.

Objective: To investigate the immunomodulatory and acute toxicity of soy protein hydrolysate (SPH) produced with pepsin protease in mice and rats.

Methods: Soy protein hydrolysate was enzymatically produced using pepsin, with E/S (enzyme to substrate ratio) of 0.5% (250 u/mg) and hydrolysis time of 4h. Afterwards, the SPH effects on murine spleen lymphocyte proliferation, and peritoneal macrophage phagocytosis were investigated in vitro. Confirmation studies were explored in rats’ sera IgG and IgA, and the acute toxic effect of SPH was observed in mice subjects.

Results: The hydrolysate increased the levels of splenocytes (stimulative index of 10.141 – 10.811) and peritoneal macrophages (phagocytic index of 1.285 – 1.721). Furthermore, the concentrations of sera IgG and IgA obtained from SPH-fed rats ranged from 0.198 – 0.345 mg/ml and 0.0184 – 0.0194 mg/ml, respectively in comparison with the soy protein isolate (SPI) -fed rats
(0.208 – 0.322 mg/ml and 0.0188 – 0.0189 mg/ml, respectively). Additionally, 10 mg dose of SPH stably elicited serum IgG in contrast to other doses, while there was a general decrease in the amounts of IgA obtained in the rat subjects. Moreover, there was no acute toxic effect recorded in the mice subjects.

Conclusion: In light of the results, it is possible that SPH prepared with pepsin has the potential of improving the immune system, and may therefore be used as immunomodulatory or functional food product.

Keywords: Soy protein hydrolysates, splenocyte proliferation, immunomodulatory, phagocytosis and pepsin