微生物与生化技术杂志

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Quantifying the Levels of the Mutagenic, Carcinogenic Hydroxylated Aflatoxins (AFM1 and AFM2) in Artisanal Oaxaca-Type Cheeses from the City of Veracruz, Mexico

Estela Hernández-Camarillo, Magda Carvajal-Moreno, Víctor J Robles-Olvera, Manuel A Vargas-Ortiz, Marco A Salgado-Cervantes, Alain C Roudot and Guadalupe Rodríguez-Jimenes

Aflatoxins (AF) are fungal secondary toxic metabolites that have mutagenic and carcinogenic effects in humans. Aflatoxin B1 (AFB1), the most toxic Aflatoxin, contaminates cattle feed and can be metabolized and excreted as the hydroxylate Aflatoxin M1 (AFM1). Aflatoxin B2 (AFB2) is excreted as Aflatoxin M2 (AFM2) in milk, and dairy products such as cheese can concentrate these carcinogens. Artisanal Oaxaca-type cheeses were sampled in Veracruz City, Mexico in 2005 and 2006, and three different extraction methods which were representative of many other reported methods- were selected for testing and validation. The R-Biopharm method was chosen and used to analyze the 30 samples that were derivatized and quantified by HPLC. The validation methods gave limits of detection (LODs) of 0.01 ng g-1 for AFM1 and 0.05 ng g-1 for AFM2; the limits of quantification (LOQs) for each Aflatoxin were four times the respective LOD. The recovery percentages were 95% for AFM1 and 93% for AFM2. The retention times were in the range of 8.514 to11.849 min for AFM1 and 20.208 to 22.447 min for AFM2. The extraction method, derivatization, and quantification (which were achieved using an HPLC-fluorescence detector) showed that 16 of the 30 samples (53%) were contaminated with AFM1, at concentrations ranging from 0.01 to 44 μg kg-1, whereas AFM2 contamination was less frequent. AFM2 contamination was found in only 3 of the 30 samples and was below the LOD, and concentrations ranged from 0.67 to 3.43 μg kg-1. These two ranges of AF contamination surpassed the tolerance limits stated by NAFTA (0.5 μg kg-1) and by Codex Alimentarius and the European Union (0.05 μg kg-1).