Influence of peptides-phenolics interaction on the antioxidant profile of protein hydrolysates from Brassica napus

The role of the peptides-phenolic compounds (PC) interaction on the antioxidant capacity profile (ACP) of protein hydrolysates from rapeseed (Brassica napus) was studied in 36 hydrolysates obtained from a PC-rich and PC-reduced protein substrate. The latent profile analysis (LPA), with data of seven in vitro methods and one assay for cellular antioxidant activity (CAA), allowed identifying five distinctive groups of hydrolysates, each one with distinctive ACP. The interaction of peptides with naturally present PC diminished in vitro antioxidant activity in comparison with their PC-reduced counterparts. However, CAA increased when peptides-PC interaction occurred. The profile with the highest average CAA (62.41±1.48%), shown by hydrolysates obtained by using alcalase, shared typical values of Cu2+-catalysed β-carotene oxidation (62.41±0.43%), β-carotene bleaching inhibition (91.75±0.22%) and Cu2+-chelating activity (74.53±0.58%). The possibilities for a sample to exhibit ACP with higher CAA increased with each unit of positively charged amino acids, according to multinomial logistic regression analysis.