Biogenic amines content in Fiore Sardo cheese in relation to free amino acids and physicochemical characteristics

Fiore Sardo is a Protected Designation of Origin (PDO) cheese produced in Sardinia (Italy) from raw sheep's milk, presenting risk factors due to an accumulation of Biogenic Amines (BA). A total of 37 Fiore Sardo cheese samples produced in 19 dairy farms were collected from local retail stores to evaluate BA content and its relationship with free amino acids (FAA) and composition. The following were determined for each sample: pH, water activity, composition (moisture, dry matter, NaCl, protein and fat content). FAA and BA, after extraction, were determined by HPLC-FL. The total BA content in Fiore Sardo PDO cheese samples was 127±87 mg 100 g-¹, ranging between 6 and 366 mg 100 g-¹. Tyramine showed the highest concentration (82±51 mg 100 g-¹), followed by putrescine (21±26 mg 100 g-¹). Moreover, cadaverine, histamine, β-phenylethylamine and tryptamine were detected at concentrations lower than 10 mg 100 g-¹. Overall 54% of the samples analysed exceeded the threshold of 90 mg 100 g^-1 for total BA content, posing a potential risk for consumers. BA, total FAA (2233±764 mg 100 g-¹) and pH were positively correlated (P≤0.01) between themselves, whereas BA content was not correlated with a_w, humidity and percentage of NaCl. The hierarchical cluster analysis results, considering 37 samples and 6 variables, detected four different groups. Samples with BA ≥200 mg 100 g-¹ were distributed in two groups characterized by a higher proteolysis indicator levels (FAA, pH) but significantly different for a_w, humidity and NaCl concentration. The results showed that high levels of BA were detectable in some samples of Fiore Sardo PDO cheese, suggesting that effective technological conditions at production should be adopted.