Degradation of Aflatoxin M1 by Lipase and Protease in Buffer Solution and Yoghurt

Abstract

Objective: This study aimed to examine the effectiveness of lipase and protease obtained from bacteria in the degradation of aflatoxin M1 (AFM1) in phosphate-buffered saline (PBS) and during the production of yoghurt. Methods: In this study, two strains, Levilactobacillus brevis and Lactobacillus plantarum, were used to produce protease and lipase, respectively. We then investigated the ability of protease and lipase to degrade AFM1 at four concentrations (50, 100, 150, and 200 U/ml for each enzyme) in vitro and during the preparation of yoghurt. Results: The results revealed that the highest activity was recorded at pH 7 and 7.5 for protease and lipase, respectively. As well, the optimum activity was observed at temperatures of 50 °C and 30 °C for protease and lipase, respectively. In vitro, the lipase enzyme at 200 U/ml degraded the AFM1 to 31.8, 37.4, and 56.7%, after incubating the PBS for 6, 12, and 18 h, respectively. Concerning protease, the means of degradation for AFM1 were 35.03, 43.7, and 72.9%, under the same conditions in yoghurt made from samples contaminated with 10 μg/L of AFM1, which was treated by both lipase and protease enzymes at 0.3, 0.6, and 0.9%, respectively. In yoghurt made from contaminated milk at 10 μg/L for AFM1, which was treated by 0.3, 0.6, and 0.9% of both lipase and protease, after two days of storage, the means of degradation of AFM1 were 23.4, 37.8, and 65.9%, respectively, which increased after five days to 27.3, 52.6, and 78.5%, respectively. Conclusion: Degradation of AFM1 was examined during the manufacturing of yoghurt using both bacterial lipase and protease without significantly affecting the sensory qualities of the finished product. Because of this, these enzymes could be a useful option in the biotech and dairy industries.