Antioxidant activity of camel and bovine milk fermented by lactic acid bacteria isolated from traditional fermented camel milk (Chal)

Chal is a traditional fermented product produced from spontaneously fermented camel milk which contains several bacterial species with potential usage in producing traditional dairy products and functional foods. The aims of this study were to isolate and identify predominant lactic acid bacteria (LAB) from Chal and investigate antioxidant activity of camel and bovine milk fermented by these isolates. Chal samples were collected from Turkman Sahra, Golestan Province, Iran. The protein hydrolysis was determined by o-phthaldialdehyde (OPA) method, and antioxidant activities of whey fractions were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals scavenging methods. Nine catalase-negative bacteria including Lactobacillus (L.) plantarum, L. paraplantarum, L. kefiri, L. gasseri, L. paracasei, Leuconostoc (Leu.) lactis, Weissella (W.) cibaria, and Enterococcus (E.) faecium were isolated and identified by conventional and molecular methods. Both camel and bovine milk were fermented by the strains for 24 h. Fermented camel milk showed significantly (P < 0.05) higher antioxidant activity than bovine milk. Camel milk fermented by Leu. lactis showed significantly (P < 0.05) higher DPPH (57.90 +/- 4.59 mu M) and ABTS (1484.35 +/- 128.20 mu M; P < 0.05) radical scavenging activity compared to samples fermented by other strains. According to sensory evaluation of fermented camel and bovine milks, camel milk fermented by Leu. lactis SM10 had the highest overall acceptance values. Our findings suggest that camel and bovine milk fermented by LAB isolated from Chal could potentially be used for producing novel functional foods.