Evaluation of Aflatoxin M1 Enrichment Factor in Semihard Cow's Milk Cheese and Correlation with Cheese Yield

Abstract

The fate of aflatoxin M1 (AFM1) in cow's milk cheese produced from naturally contaminated raw milk was evaluated. Cow's milk, naturally contaminated by AFM1 at levels ranging from 0.020 to 0.148 μg/kg, was used to manufacture a semihard, ripened Caciotta cheese. The cheeses, produced in eight cheesemaking trials, were ripened for 45 days. The enrichment factor (EF) of cheese did not change during maturation from day 7 to day 45 of ripening. The EF of the aflatoxin was established to evaluate the maximum level of contaminants in cheese, according to Commission Regulation (EC) No. 1881/2006. The EF factor in cheese at 45 days of ripening was between 4.68 and 5.78, with a mean value of 5.16. Moreover, this factor was not affected by the AFM1 level in milk. Pearson's correlation analysis showed a significant negative correlation between EF and cheese yield (r = −0.811). The regression analysis confirmed that the cheese yield and, subsequently, the milk composition, had a marked impact on EF (P < 0.0003). Cheese yield was identified as potentially influencing the presence and concentration of the toxin in cheese, demonstrating that this aspect, along with the cheese hardness category, contributes significantly to an exact definition of the EF. HIGHLIGHTS

Evaluation of Aflatoxin M1 enrichment factor in different cow milk cheese hardness category

“…Milk samples were collected from cattle farms located in the Umbria Region (Central Italy) during 2016; samples were subsequently analyzed for AFM 1 determination by the Istituto Zooprofilattico Sperimentale of Umbria and Marche regions (IZSUM), as reported by Pecorelli et al (2019). Among all milk samples analyzed, contaminated samples were chosen for the production of Primosale and Fior di Latte cheese.…”

“…Milk and cheese samples were assessed for AFM 1 content, using the validated methods described by Pecorelli et al (2018Pecorelli et al ( , 2019. Briefly, 50 g of milk were centrifuged to remove fat and applied to the Immunoaffinity column (IAC).…”

“…Aflatoxins (AFs) are secondary metabolites, toxic to superior animals including humans, produced mainly by genus Aspergillus fungi, in particular A. flavus and A. parasiticus. These harmful molecules can be present in forages and feedstuff as well as in food such as nuts, dried fruit, spices and cereals as a consequence of fungal contamination occurred before and after harvest (Campagnollo et al, 2016;Pecorelli et al, 2018Pecorelli et al, , 2019. Human exposure to such contaminants through food consumption must be as limited as possible because of their proven genotoxic and carcinogenic activities.…”

“…Due to the phenomenon referred to as carry-over, aflatoxin M 1 (AFM 1 ), an hydroxylated metabolite of AFB 1 , is usually found in the milk of lactating animals fed with contaminated feed. The International Agency for Research on Cancer has recently reassessed the toxicity of AFM 1 upgrading it from Group 2B (possible carcinogens for humans) to Group 1, therefore classifying it as a certain carcinogen for humans, as has already been established for AFB 1 (Pecorelli et al, 2019). Owing to its toxicity and in order to minimize the risk for consumers, the European Commission (EC) established a maximum level for AFM 1 in raw milk, heattreated milk, and milk for the manufacture of dairy products at 0.050 μg/kg (Regulation EC No.…”

“…Later the Italian Ministry of Health specified in a note (Italian Ministry of Health 2017 DGISAN note I.4) that the "hard cheese" group to which EF 5.5 is applied, includes the semi-hard, hard, and very hard cheese categories, while the soft cheese group, characterized by an EF of 3.0, includes the hardness categories of soft and semi-soft cheeses. Data collected from numerous studies in the literature, concerning the definition of specific EFs during different cheese productions (Cattaneo et al, 2008;Fernandes et al, 2012;Cavallarin et al, 2014;Pietri et al, 2016;Pecorelli et al, 2018Pecorelli et al, , 2019, suggest that the division of cheeses into the abovementioned two wide categories based on MFFB and the consequent attribution of the suggested EF, may not be very accurate due to experimental evidences showing that cheeses belonging to the same hardness category are characterized by different EFs.…”