Effect of storage on the level of aflatoxin M1 in milk and other dairy products sold at Tripoli province, Libya

Abstract

Milk and dairy products are one of the chief sources of nutrition for human beings particularly for infant and children. Aflatoxin M 1 (AFM 1 ) a hydroxylated metabolite of aflatoxin B1 found in milk and milk products causes serious health issues for human beings. The objective of this study was to evaluate the effect of storage on the level of aflatoxin M 1 in milk and other dairy products sold at retail stores of Tripoli Province, Libya. Selected samples (Skimmed and cream milk, infant milk formula, butter, cheese, Cheddar, spread and slice) were evaluated by using specialized RIDASCREEN AFM 1 competitive enzyme linked immune sorbent assay (ELISA) technique. Our investigation revealed that, the concentration of AFM1 increased with the duration of storage. Furthermore, we found that the newly manufactured samples had very low concentration of AFM 1 and within the permitted range. Moreover, AFM 1 concentration in skimmed and cream milk having 6 month shelf life had 5.00 ngkg -1 and 5.03 ngkg -1 respectively. Furthermore, both the expired skimmed and cream milk had AFM1 concentrations 121.8 ngkg -1 and 108.18 ngkg -1 , respectively. In addition to that, we found that the levels of AFM1 in different dairy products varies with different shelf lives (12 and 1 month), such as cheddar (5.0 and 72.79 ngkg -1 ), Spread (5.30 and 60.03 ngkg -1 ), Slice (5.50 and 61.18 ngkg-1). Additionally, infant milk formula with shelf life of 24 months and expired samples had AFM1 less than 5.00 ngkg -1 and 60.8 ngkg -1 , respectively. Based on our investigation, we found that the presence AFM1 in milk and milk products at high concentration may cause serious illness to consumers' health and the consequent economic losses.