EFFECT OF LIVE OR HEAT-KILLED L. ACIDOPHILUS ON FREE AFLATOXIN M1 IN DOOGH

Background and Aim:Aflatoxin is one of the most important contaminants in milk and dairy products. Therefore, more efforts must be performed due to reduce or remove the Aflatoxin in dairy products. In this study, the effects of live or dead L.acidophilus on the reduction in 0.500 ppb of free aflatoxin M1 in Doogh during fermentation and refrigerated storage were studied.Methods:Immunoaffinity column and HPLC with fluorescence detector were used for extraction and measurement of free AFM1, respectively.Results:Treatment containing dead (heat-killed) L.acidophilus significantly binded more AFM1 than live L.acidophilus treatment. However, the live probiotics were more effective in the reduction of AFM1 at day 14 and 28 of storage (p<0.05).Conclusion:Although the mechanism of probiotics action on aflatoxin has not been clarified yet, it has been suggested to be a physical adhesion to the bacterial cell-wall components, rather than covalent binding or degradation by bacteria metabolism. Both polysaccharides and peptidoglycans are expected to be greatly affected by heat treatment, which can cause denaturation of proteins, in turn increasing hydrophobic nature of surface or forming products of a Maillard reaction. Such disturbances allow aflatoxins to bind to the bacterial cell wall and plasmatic membrane components,which are unavailable when the cell wall is intact. In contrast, at days 14 and 28, AFM1 reduction was significantly increased in treatment with live probiotics. Viable inoculated probiotics exhibit reproduction activity during fermentation and refrigerated storage; this could be responsible for increases in both live and dead cell populations in Doogh, resulting in higher AFM1 removal comparing to dead probiotics treatment.

کلیدواژه ها:

Aflatoxin ، Reduction ، Milk ، Dairy products