Functional and Edible Uses of Soy Protein Products

Enzymatic hydrolysis and simultaneous saccharification and fermentation of soybean processing intermediates for the production of ethanol and concentration of protein and lipids

Carbohydrates in soybeans are generally undesirable due to their low digestibility and because they "dilute" more valuable components (proteins, lipids). To remove these carbohydrates and raise the titer of more valuable components, ethanol production was investigated. Commercial enzymes (Novozyme cellulase, β -glucosidase, and pectinase) were added to ground soybeans (SB), soybean meal (SBM), soybean hulls (SH), and soybean white flakes (WF) at a 10% solids loading rate to quantify hydrolyzed glucan. Saccharification resulted in glucan reductions of 28%, 45%, 76%, and 80% (SBM, SB, SH, WF, resp.). Simultaneous saccharification and fermentation (SSF) trials were conducted at 5%, 10%, 15%, and 20% solids loading with Saccharomyces cerevisiae NRRL Y-2034 and Scheffersomyces stipitis NRRL Y-7124, with protein, fiber, and lipids analyzed at SSF 10% solids and saccharification trials. S. cerevisiae and S. stipitis produced ~3-12.5 g/L ethanol and ~2.5-8.6 g/L ethanol, respectively, on SB, SBM, and WF over all solid loading rates. SH resulted in higher ethanol titers for both S. cerevisiae (~9-23 g/L) and S. stipitis (~9.5-14.5 g/L). Protein concentrations decreased by 2.5-10% for the SB, SBM, and WF, but increased by 53%-55% in SH. Oil concentrations increased by ~50% for SB; by ~500%-1300% for the others.

Antioxidant and antiinflammatory properties of germinated and hydrolysed Brazilian soybean flours

The effect of germination in combination with Alcalase hydrolysis of Brazilian soybean cultivar BRS 133 on the production of soybean flours with bioactive peptides as modulators of oxidative stress and markers of inflammation was monitored. The electrophoretic profile showed a weak protein breakdown during germination. However, a strong breakdown of the proteins can be observed after the first hour of hydrolysis with Alcalase. MALDI-TOF-MS analysis of the protein extracts showed differences in the intensity and profile of peptide mass fingerprint due to germination and hydrolysis. Germinated flour showed higher soluble protein concentration and antioxidant capacity. All soybean protein extracts and protein hydrolysates produced (G0, G18 and G72) showed a significant (p<0.05) inhibition on inflammatory markers such as nitric oxide (20.5-69.3%), iNOS (22.8-93.6%), PGE(2) (64.0-88.3%), COX-2 (36.2-76.7%), and TNF-α (93.9-99.5%) in LPS-induced RAW 264.7 macrophages. However, protein extracts of flours with 18 h of germination were more potent in inhibiting pro-inflammatory responses when compared to 72 h. It can be concluded that a combination of 72 h of soybean BRS 133 germination and 1h Alcalase hydrolysis resulted in the formation of bioactive compounds with more potent antioxidant activity, and improvement in the reduction of some of the markers of inflammation.

Protein hydrolysates from beta-conglycinin enriched soybean genotypes inhibit lipid accumulation and inflammation in vitro

Obesity is a worldwide health concern and a well recognized predictor of premature mortality associated with a state of chronic inflammation. The objective was to evaluate the effect of soy protein hydrolysates (SPH) produced from different soybean genotypes by alcalase (SAH) or simulated gastrointestinal digestion (SGIH) on lipid accumulation in 3T3-L1 adipocytes. The anti-inflammatory effect of SPH produced by alcalase on LPS-induced macrophage RAW 264.7 cell line was also investigated. SAH (100 microM) derived from soybean enriched in beta-conglycinin (BC) (up to 47% total protein) decreased lipid accumulation (33-37% inhibition) through downregulation of gene expression of lipoprotein lipase (LPL) and fatty acid synthase (FAS). SGIH (100 microM) inhibited lipid accumulation to a lesser extent (8-14% inhibition) through inhibition of LPL gene expression. SAH (5 microM) decreased the production of nitric oxide (NO) (18-35%) and prostaglandin E(2) (PGE(2)) (47-71%) and the expression of inducible nitric oxide synthase (iNOS) (31-53%) and cycloxygenase-2 (COX-2) (30-52%). This is the first investigation showing that soy hydrolysates inhibit LPS-induced iNOS/NO and COX-2/PGE(2 )pathways in macrophages. Soybeans enriched in BCs can provide hydrolysates that limit fat accumulation in fat cells and inflammatory pathways in vitro and therefore warrant further studies as a healthful food.

Purification, thermal stability, and antigenicity of the immunodominant soybean allergen P34 in soy cultivars, ingredients, and products

Protein P34 (Gly m Bd 30K) is the immunodominant allergen in soybean (Glycine max L.). The objectives of this study were (1) to study the effect of thermal treatment on P34 antigenicity and secondary structure after isolation and purification of P34 from soybean by chromatographic techniques; (2) to identify the variability of P34 allergen within 138 accessions from a diverse USDA soybean germplasm collection by ELISA; and (3) to quantify P34 immunoreactivity in various commercial soy ingredients and products. Thermal processing decreased P34 antigenicity. Soybean accessions with the highest P34 content were ancestral (12 mg/g defatted flour) followed by modern (10 mg/g defatted flour) and exotic (8 mg/g defatted flour). The cultivar that emerged as the lowest-expressing P34 accession was PI548657 (2.3 mg/g defatted flour). Among commercial soy ingredients, soy flour yielded the highest P34 antigenicity (32 mg/g extracted protein) followed by soy protein isolate (29 mg/g extracted protein) and soy protein concentrate (24 mg/g extracted protein). Among soy consumer products, soymilk presented the highest P34 antigenicity, ranging from 7 to 23 mg/g extracted protein, followed by tempeh (8 mg/g extracted protein), soy infant formula (3.4 mg/g extracted protein), soy powder (2 mg/g extracted protein), and soy cheese products (0.50 mg/g extracted protein). Korean miso, soy sauce, soy chili mix, soy nuts, soy cream cheese, soy meat patty, texturized soy protein, and soy cereal exhibited undetectable P34 antigenicity (detection limit = 0.45 ng). Selecting soybean varieties with low levels of this allergen, or via processing, could potentially make soybean products less antigenic.