Development of antioxidant rich peptides from milk protein by microbial proteases and analysis of their effects on lipid peroxidation in cooked beef

Antioxidant capacity of alcalase hydrolysates and protein profiles of two conventional and seven low glycinin soybean cultivars

Soy protein hydrolysates are considered a potential dietary source of natural antioxidants with important biological activities. This study was conducted to compare the effect of two conventional and seven low glycinin soybean cultivars on the antioxidant capacity (AC) of soy hydrolysates. Nine cultivars were grown in Bloomington, IL, Findlay, OH and Huxley, IA. The hydrolysates were produced enzymatically using alcalase and analyzed for AC using oxygen radical absorbance capacity (ORAC) assay and soluble protein. Statistical differences were observed in the protein profiles and AC among the different cultivars tested (P < 0.05). The hydrolysate from low glycinin cultivar 3 enriched in β-conglycinin, grown in Bloomington, exhibited the highest AC, compared to the other cultivars across all locations. On average, soy cultivars rich in BC and purified BC hydrolysates (36.2 and 31.8 μM Trolox equivalents (TE)/μg soluble protein, respectively) (P > 0.05) had higher AC than purified glycinin (GL) hydrolysate (28.5 μM TE/μg soluble protein) (P < 0.05). It was possible to select a soybean cultivar that produced a higher antioxidant capacity upon alcalase hydrolysis.

Chromatographic separation and tandem MS identification of active peptides in potato protein hydrolysate that inhibit autoxidation of soybean oil-in-water emulsions

A previously developed antioxidative potato protein hydrolysate was fractionated using gel filtration. The efficacy of different fractions for inhibiting lipid oxidation in soybean oil-in-water emulsions, neutralizing 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+*)) radicals, and chelating prooxidative metal ions was investigated. Low-molecular-weight fraction Peak 3 (709 Da) exhibited the strongest antioxidant activity and radical scavenging activity. Active peptides based on the ABTS(+*) scavenging assay were isolated by RP-HPLC and purified by UPLC. The amino acid sequence determination by MS/MS identified eight prominent peptides in the antioxidative Peak 3 fraction, of which Thr-Tyr, Tyr-Phe-Glu, Tyr-Ser-Thr-Ala, and Asn-Tyr-Lys-Gln-Met matched the sequence of papatin.