Characterization of Amaranthus hypochondriacus seed protein fractions, and their antioxidant activity after hydrolysis with lactic acid bacteria

The objective of this work was to obtain and characterize five Amaranthus hypochondriacus seed protein fractions followed by the determination of antioxidant activities of hydrolysates produced with two Lactobacillus species. Molecular weights of polypeptides (SDS-PAGE) in fractions were 14-97 kDa and those identified by LC-MS/MS include agglutinin, trypsin inhibitor, and cystatin. Each fraction was hydrolyzed with Lactobacillus helveticus and Lactobacillus plantarum at their exponential (4 and 8 h) and stationary (14 and 24 h) growth phases. The free amino group content in hydrolysates produced with L. helveticus was up to 5.15% compared to 4.79% in those obtained with L. plantarum. In the antioxidant tests, higher ROO center dot scavenging activities were obtained for hydrolysates from albumins (1037 +/- 80 mu M TE/mL) and glutelins (1793 +/- 168 mu M TE/mL) fractions produced with L. helveticus and L. plantarum, respectively. Scavenging activities of center dot OH radicals were higher for 11S-G hydrolysates with both Lactobacillus at the stationary phase.