Antioxidative activity of lactic acid bacteria in yogurt

The antioxidative effect of intact cells and cell-free extract of Lactobacillus casei subsp. casei SY13 and Lactobacillus delbrueckii subsp. bulgaricus LJJ, isolated from the traditional yogurt, was evaluated by various antioxidant assays. The results showed that two Lactobacillus strains had good antioxidant capacity, inhibiting the peroxidation of linoleic acid by 62.95% and 66.16%. The cell-free extract showed excellent scavenging superoxide anion and hydroxyl radicals activity. The intact cells on 1,1-Diphenyl-2-Picrylhydrazyl (DPPH) radical scavenging ability and chelating ferrous ion capacity were superior to cell-free extract. The highest reducing activity was equivalent to 305 and 294 mu M L-cysteine. This study suggests that two strains are high antioxidative bacterial strains. Antioxidative property of lactobacilli would be useful in the dairy manufacturing industry. They could beneficially affect the consumer by providing dietary source of antioxidants.