Analysis of aflatoxin M1 contamination in milk and cheese produced in Mexico: a review

Due to the carcinogenic character of aflatoxins when present in foods, these compounds are considered a risk to human health. This systematic review aimed at compiling the available research data on detection and quantification of aflatoxin M1 (AFM1) in milk and common types of cheese produced in Mexico in the past two decades. A limited number of studies were found that matched the purpose of our review. Only ten research works focused on the evaluation of AFM1 content in milk while three studies analysed the occurrence of this mycotoxin in oaxaca and panela cheeses. HPLC-FD and ELISA were the methods of choice utilised to detect AFM1. Concentrations higher than 0.5 μg AFM1/kg, a maximum limit set in current food regulation in Mexico, were found in major dairy brands consumed in Mexico. Analysis of raw milk produced during the rainy season in the states of Jalisco (2007) and Chiapas (2013) showed mycotoxin levels within the regulation limits while milk samples obtained during the dry season in the Mexico City and the State of Mexico (2008) exceeded that threshold. For cheeses, 33% of the artisanal produced oaxaca type samples from Veracruz (2016) and 55% of those acquired in Mexico City (2019) were found above the limit set for milk. In contrast, the panela cheese samples obtained in Baja California and Guanajuato (2009) complied with the AFM1 regulation. Additionally, the presence of AFB1 and its hydroxylated metabolites other than AFM1 were determined in the major milk brands at concentrations that could be of high risk for human health. Similar results were reported for both artisan and industrially produced oaxaca cheese. Finally, mycotoxins enter human food chain through animals fed with contaminated fodder. Our systematic review demonstrated the urgent need to amend the existing food regulation in Mexico to include mycotoxins as potent contaminants in cheese.