Antioxidant Capacity of Lactic Acid Bacteria and Yeasts from Xinjiang Traditional Fermented Dairy Products

Abstract

(1) Background: The objective of this study was to screen strains with antioxidant potential from lactic acid bacteria (LAB) and yeasts isolated from traditional Xinjiang fermentation products. (2) Methods: Twenty-three strains of LAB and twelve strains of yeast isolated from traditional fermented dairy products from different regions of Xinjiang were selected, and the strains with antioxidant ability were initially screened by measuring the hydroxyl radical scavenging, superoxide anion scavenging, DPPH radical scavenging, ABTS+ radical scavenging, anti-lipid peroxidation, and ferrous ion chelating abilities of their bacterial bodies, cell-free extracts, and fermentation broth. They were further screened by measuring their superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) activities to identify strains with more powerful oxidative abilities. (3) Results: The results show that Lacticaseibacillus paracasei NM-12, Enterococcus faecium UM-12 and NM-11, and Pichia fermentans QY-4 had effective antioxidant enzyme activities. The SOD activity of these strains reached 4.846 ± 0.21 U/mL, 9.105 ± 0.428 U/mL, 8.724 ± 0.365 U/mL, and 6.518 ± 0.223 U/mL; the GPX activity reached 0.1396 ± 0.009 U/mL, 0.1123 ± 0.006 U/mL, 0.014 ± 0.007 U/m, and 0.0919 ± 0.006 U/mL; and the CAT activity reached 19.934 ± 3.072 U/mL, 3.749 ± 0.926 U/mL, 92.095 ± 1.017 U/mL, and 97.289 ± 0.535 U/mL, respectively (p < 0.05). (4) Conclusions: Lacticaseibacillus paracasei (NM-11), Enterococcus faecium (UM-12, NM-11), and Pichia fermentans (QY-4), isolated from traditional fermented dairy products, are probiotics with high antioxidant activity and potential applications in the food and fermentation industries.