Probiotic biological strategies to decontaminate aflatoxin M1 in a traditional Iranian fermented milk drink (Doogh)

Abstract

Aflatoxin M1 is an important mycotoxin mostly found in milk and dairy products. The main objective of this work was to study the effects of probiotic strains, a probiotic inoculated population, the physiology of probiotic bacteria and final fermentation pH at four consecutive stages on the reduction of 0.500 ppb of free aflatoxin M1 (AFM1) in Doogh (a traditional Iranian fermented milk drink). Samples’ biochemical, microbial and AFM1 binding characteristics were monitored during fermentation and storage (5 °C for 28 days). An immunoaffinity column was used to extract AFM1 and a high-performance liquid chromatograph with a fluorescence detector was used to measure it. Results showed that Lactobacillus acidophilus was probiotic strain that most reduced free AFM1. Inoculation of L. acidophilus at 9 log cfu/mL, despite the higher cost, revealed significantly higher free AFM1 binding capacity than 7 log cfu/mL. Heat-killed (dead) L. acidophilus bacteria reduced less free AFM1 at the end of storage than viable. Samples with a final fermentation pH of 4.5 bound more free AFM1 during fermentation and storage than those with a pH of 4.2. It is concluded that inoculation of 7 log cfu/mL L. acidophilus viable cells in Doogh with a final fermentation pH of 4.5 supplied a safety- and health-promoting and cost-effective drink.