No abstract

Functional properties of the soy protein need to improve to have better applications in food industry. Alkali extracted and acid precipitated soy protein isolate (SPI) was glycosylated using D-glucose (G) and Xanthan gum (X) via Maillard reaction to improve solubility. The effects of SPI to G and SPI to X ratios (SPI:G = 2:1, 1:1, and 1:2; SPI:X = 100:1 and 10:1) and incubation time (0, 6, 12, and 24 h) on the solubility and functional properties of glycosylated SPI were evaluated. The SPI:G ratio of 1:2 yielded a maximum degree of glycosylation of 71.1 %. The solubility of SPI after glycosylation significantly increased (P<0.05) at pH 4.0-8.0 compared to SPI alone. Although the emulsion stability of glycosylated SPIs has not significantly increased (P>0.05), the emulsifying activity improved significantly (P<0.05). Glycosylation with SPI-X at a ratio of 10: 1 showed maximum emulsifying activity of 191.6 m 2 /g (SPI alone: 66.3 m 2 /g). Moreover, the SPI:X (ratio of 100:1) showed the maximum foaming activity (205 mL) compared to SPI alone (155 mL). The foaming stability of SPI (2.6 %) increased to 5.5 and 8.2 % when using xanthan gum at the ratio of 100:1 and 10:1, respectively. Glycosylated SPI with enhanced emulsifying and foaming properties has potential to improve the functional quality of the food products.

Several organic acid based antimicrobials are reported to reduce bacterial populations but studies showing inhibition of autoinducer-2 (AI-2) activity or quorum sensing are limited. The effect of lactic and malic acids on autoinducer activity of selected strains of E. coli O157:H7 and Salmonella Typhimurium is tested in this study. The strains were screened for AI-2 like activity on spinach and cantaloupe homogenates using autoinducer sensing V. harveyi biosensor strains. The ED 14 strain of E. coli O157:H7 and the SD 10 strain of Salmonella showed highest AI-2 like activity of 55 and 53 Relative Light Units respectively. These two strains were used to evaluate the AI-2 inhibitory activities of lactic and malic acids at 1 to 4% concentrations (alone or in combinations). Lactic acid at 4.0% had the highest inhibition of 80% on ED 14 E. coli strain while the combination treatment of lactic acid + malic acid at 4.0% each had the highest inhibition of 80% on SD 10 Salmonella strain. Results from the study indicate that the quorum sensing ability of the E. coli O157:H7 and Salmonella Typhimurium strains can be effectively inhibited by antimicrobial organic acids.

promote the use of high oleic acid soybeans as a source of protein and peptides with functional activities.Abstract Soybeans are cultivated in the United States chiefly for cooking oil, while the residue after oil extraction (soybean meal) is mostly used in animal feed formulations. High protein content in the defatted soybean meals led to the extraction of pure protein and its application in food products. We selected 44 soybean lines to determine their moisture and protein contents, and their amino acid composition was investigated. Soybean lines with high protein content, one high yielding (R95-1705), and two high oleic acid (N98-4445A, S03-543CR), were selected for protein isolate preparation, hydrolysis using alcalase and gastrointestinal (GI) resistance. Furthermore, the GI resistant hydrolysates were fractionated and tested for angiotensin-I-converting enzyme (ACE-I) inhibition activity. The amino acid analysis showed high methionine in the high protein and fatty acid lines (R05-4494 and R05-5491), and high cysteine content in one of the high oleic acid soybean line CRR05-188 in comparison to the check lines (UA-4805 and 5601-T). The protein isolate with the highest purity (90-93 %) was derived from the selected lines N98-4445A and S03-543CR, and hydrolyzed using alcalase enzyme. The protein hydrolysates (500 µg/mL) showed inhibition of the ACE-I by 49 %. The results from this study will

potential use as protein rich nutraceutical for developing many non-genetically modified food product applications.