Abstract: In this study, the antioxidant activity of the fermentation supernatants and intracellular extracts of four species of lactic acid bacteria including Lactobacillus fermentium, Lactococcus lactis, Lactobacillus acidophilus and Lactobacillus helveticus was comparatively studied by anti-lipid peroxidation assay, reducing power assay, and DPPH and superoxide anion and hydroxyl free radical scavenging assays. The results indicated that different lactic acid bacteria had different antioxidant activity. Lactobacillus helveticus had higher hydroxyl radical scavenging activity, DPPH radical scavenging activity and reducing power, while Lactococcus lactis and Lactobacillus acidophilus had notable superoxide anion radical scavenging activity. In addition, Lactobacillus fermentium had the highest lipid peroxidation-inhibitory activity. Further, the antioxidant mechanism of lactic acid bacteria may be related to the presence of SOD and GSH-Px activities.

Key words: lactic acid bacteria, fermentation supernatant, intracellular extract, antioxidant activity