Rimozione della aflatossina M1 e potenziali applicativi di una laccasi da Pleurotus eryngii per la sicurezza del latte

Aflatoxin M1 removal and potential applications of a laccase enzyme from Pleurotus eryngii for milk
safety - Aflatoxin M1 (AFM1), is the main catabolite deriving from the hydroxylation of aflatoxin B1 (AFB1), found in the milk of animals fed with AFB1 contaminated feeds. The International Agency for the Research on Cancer (IARC) has classified it in group 2B, thus possibly carcinogenic for humans. Their maximum limit in raw milk, heat-treated milk and milk for the manufacture of milk-based products, has been set by the Regulation (EC) 1881 of 2006 to 50ng/kg. AFM1 resists to the most common treatments of food industry and persists in processed product. Its occurrence has been registered throughout the whole dairy supply chain, including yogurts and cheeses, and it represents a serious risk for humans and animals. The development of mild, green and efficient methods for AFM1 degradation is an actual and crucial topic. Aflatoxins degradation is difficult to achieve since they must not affect the organoleptic and nutritional qualities of food. In this work we evaluated the activity of a fungal laccase from Pleurotus eryngii for the degradation of AFM1 in buffer solution and in skimmed UHT milk. We also analyzed the effects on the protein pattern of milk in order to evaluate its application for the improvement of the safety of milk based products. AFM1 degradation in sodium acetate buffer (pH 6.5 1mM at 25°C) was nearly 50% after one hour and complete after 72h. The same trend was registered in skimmed UHT milk, although with a lower rate of degradation, at least during the first three hours of treatment. The analysis of the protein pattern revealed that the intensity of α e β caseins, β-lactoglobulin and bovin sieroalbumin electrophoretic bands significantly decreased, while the appereance of protein aggregates of molecular weight higher than 200kDa was detected. These results highlight several potential applications of this laccase for the development of green detoxification methods towards AFM1 in milk, and also for the improvement