Biogenic amines during ripening in 'Semicotto Caprino' cheese: role of enterococci

Semicotto Caprino is a traditional goats' cheese manufactured in the Basilicata region (Southern Italy). Four experimental lots of cheeses were produced from separate batches of milk. All the biogenic amines monitored increased during ripening, the most abundant at each ripening time being putrescine, followed by tryptamine and tyramine. Histamine was not detected at 15 days, but it reached 104 mg kg(-1) cheese at the end of ripening (60 days). A good correlation between free amino acids and total biogenic amines production was found. Strains of enterococci were isolated from all batches of goats' cheese and characterized for amine production and proteolytic activity. HPLC analysis showed that the isolates produced 2-phenylethylamine, tryptamine, cadaverine, spermidine and, sometimes, spermine. The high amine-positive strains were also highly proteolytic. In the growth medium with a mixture of amino acid precursors added, the tested isolates produced more amines, even if at different levels.