Distribution of aflatoxin M1 during production of sheep and goat cheeses

The occurrence of Aflatoxin M1 (AFM1) in milk results from ingestion of contaminated feed with Aflatoxin B1 by dairy animals, its conversion into AFM1, and secretion in milk. The objective of this work was to investigate AFM1 fate along goat and sheep cheese production. Cheese production was carried out using spiked milk (levels between 0.08 and 0.10 μg/L). Samples were collected throughout the production and analyzed by immunoaffinity cleanup and chromatography. Higher concentration of AFM1 was always observed in curd rather than in whey; with a mean enrichment factor of 1.8. A strong and positive correlation was established between casein content and AFM1 percentage in curd. Throughout production, a significant increase in AFM1 concentration on a wet basis was observed. In turn, on a dry basis, there was no statistically significant reduction during ripening. These observations are justified by the loss of cheese moisture and the absence of AFM1 degradation. Practical applications: The distribution of aflatoxin M1 during the production of two different cheeses was studied, where the amount of the toxin was monitored on a wet and a dry basis. On the wet basis, there was a continuous increase in concentration; which has already been reported by different authors, without clarifying whether this increase is due exclusively to the loss of moisture during milk processing. The same study on a dry basis allowed us to conclude that under the tested conditions, there is no degradation of the toxin, and the concentration increase observed previously was in fact due to the loss of humidity.CIMO, Grant/Award Number: UID/AGR/00690/2019; European Regional Development Fund (FEDER), Grant/Award Number: PT2020; Portuguese Foundation for Science and Technology (FCT), Grant/ Award Number: UIDB/04469/2020