Antioxidant activity of lactic acid bacteria (LAB) fermented skim milk as determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferrous chelating activity (FCA)

Bioactive peptides can be generated from milk protein by fermentation with lactic acid bacteria. In this study, lactic acid bacteria (LAB) were isolated from different food samples. Isolates that showed clear zone on modified de Man, Rogosa and Sharpe (MRS) - CaCO3 agar, catalase negative and Gram positive were considered as LAB and used for this study. Seven isolates that showed proteolytic activity on skim milk agar produced whey that have free radical scavenging activity ranging from 14.7 to 50.8% (v/v) after 24 to 72 h fermentation, respectively as determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Ferrous chelating activity (FCA) of the whey showed similar values for EDTA after 24 h fermentation but decreased after 72 h for all LAB isolates with values between 41.8 to 97.6% (v/v) for 24 to 72 h, respectively. This study highlights that local LAB isolates have the potential to be used to generate peptides in whey with antioxidative activity from skim milk.