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Bio-detoxification of aflatoxin M1 in kefir using Lactobacillus casei

A.Mohammadi Sani, Z.Marhamati, M.H.Marhamatizade

Kefir is a fermented dairy product, manufactured by starter culture and nowadays consumed widely around the world. It may become contaminated with aflatoxin M1 (AFM1) which even in small quantities, have harmful effects on consumers health. Therefore‚ a practical and effective method is needed for detoxification ofAFM 1 contaminated milk or decreasing its toxicity‚ such as using different cultures and probiotic agents. Specific lactic acid bacteria strains have been reported in removing AFM 1 fromliquid media by physical binding. The aimof this studywas to detect the effect of kefir starter and Lactobacillus casei to bind AFM1 in kefirmade frommilk spikedwith 500pgAFM1mL-1.Accordingly, five levels of kefir starter (2%‚ 4%‚ 6%‚ 8%‚ 10%) and five levels of Lb. casei (0.1%‚ 0.3%‚ 0.5%‚ 0.7% and 0.9%) with constant amount of kefir starter (4%) were used‚ separately. After 48h, the AFM1 content of kefir samples was measured by competitive ELISA technique. Statistical analyses showed that the sample containing 6% kefir starter had the most reduction in AFM1 concentration (88.17%) which was significant (p<0.05).Although there were no significant differences (p<0.05) betweenAFM1 concentration of samples containing 0.5‚ 0.7 and 0.9% levels of Lb.casei‚ but the sample containing 0.9% Lb.casei and 4% kefir starter, had more AFM1 binding (82.12%). Generally‚ the effect of kefir starter (alone) was more than Lb. casei inAFM1 binding and the combination of these strains had synergistic effect inAFM1 reduction. These findings affirmed that particular bacteria and yeast used in this study can offer decontaminating AFM1 kefir.