Effects of probiotic strains and inoculated population, physiology of probiotic bacteria and fermentation final pH on free aflatoxin M1 binding in Doogh

study، the effects of probiotic strains (L. acidophilus، L. rhamnosus، L. casei and B. bifidum)، inoculated probiotic population (7 and 9 log cfu/ml)، physiology of probiotic bacteria and fermentation final pH (4. 2 and 4. 5) at four stages (respectively) on the reduction in 0. 500 ppb of free aflatoxin M1 in Doogh during fermentation and refrigerated storage (5°C) were studied. Doogh milk with 4% of dry matter was made by reconstitution of skim milk powder. The mixture also contained 0. 7% of sodium chloride and 0. 500 ppb of aflatoxin M1. After heat treatment، treatments with different starter culture inoculations were prepared. The treatments were incubated until the determined final pH was reached. Immunoaffinity column and HPLC with fluorescence detector were used for extraction and measurement of free aflatoxin M1، respectively. Data were analyzed by SPSS software. Treatment with L. acidophilus (AY-7-A-4. 2) compared to other probiotic strains had highest reduction in free aflatoxin M1 during fermentation and refrigerated storage. L. acidophilus with inoculation of 9 log cfu/ml (AY-9-A-4. 2) compared to 7 log cfu/ml (AY-7-A-4. 2)، had significantly more free aflatoxin M1 binding capacity.. However، AY-9-A-4. 2 was not suitable treatment because of the strongly higher cost. Treatment containing 7 log cfu/ml dead (heat-killed) L. acidophilus (AY-7-D-4. 2) significantly binded more free aflatoxin M1 than AY-7-A-4. 2 treatment at the first day of storage. However، the live probiotics in AY-7-A-4. 2 treatment were more effective in the reduction of free aflatoxin M1 at day 14 and 28 of storage. Treatment with higher fermentation final pH (AY-7-A-4. 5) was more effective on free aflatoxin M1 binding than AY-7-A-4. 2 at day 14 and 28 of storage. Live cells of L. acidophilus with inoculation of 7 log cfu/ml and final fermentation pH of 4. 5 showed the highest free aflatoxin M1 binding capacity during refrigerated storage; meanwhile، it was the best treatment from health and economic points of view.