Biogenic amines in Manchego cheese: a statistical PDO-wide evaluation of milk treatment, ripening, seasonal, and geographical factors

Biogenic amines (BA) are bioactive nitrogenous compounds that accumulate in ripened cheeses due to microbial activity, representing both quality indicators and potential food safety concerns. Despite the economic and cultural relevance of Manchego cheese, a Protected Designation of Origin (PDO), representative data on BA occurrence in commercial cheeses remain scarce. In this work, a comprehensive study on the BA content was conducted across all cheese factories within the PDO Manchego cheese, comprising 55 cheeses made from raw milk and 60 from pasteurized milk. Seven BAs were quantified by RP-HPLC, and the individual effects of milk treatment, ripening time, season of manufacture, and geographical origin were evaluated using univariate and non-parametric statistical analyses. Histamine and tyramine were the predominant BAs, reaching concentrations of 835 and 598 mg/kg, respectively, whereas the other amines were detected at low concentrations or were absent. With some exceptions, raw milk cheeses showed significantly higher concentrations of BAs than pasteurized milk cheeses (p<0.05), with median concentrations of 981 and 350 mg/kg, respectively. Both ripening time and season significantly influenced BA formation in both types of cheeses, while geographical origin also significantly affected most BAs in pasteurized milk cheeses, highlighting the importance of post-pasteurization factors. Estimated dietary exposure to BAs from Manchego cheese intake would be well below the available toxicity thresholds. This study provides the first comprehensive and representative survey of BA occurrence in commercial Manchego PDO cheeses, demonstrating that milk treatment is an important determinant of BA accumulation, while ripening, season, and geographical origin also contribute to BA variability.