Formation of biogenic amines by proteolytic enterococci during cheese ripening

Six strains of Enterococcus faecalis and three strains of E faecium were investigated for their proteolytic activity and ability to decarboxylate the amino acids lysine, histidine, tyrosine, ornithine and phenylalanine. All strains tested displayed cell wall‐associated proteolytic activities, and three E faecalis strains displayed additionally extracellular proteolysis. None of the strains tested was able to form putrescine, histamine or cadaverine. Eight strains decarboxylated tyrosine, and two strains of E faecalis and one strain of E faecium formed phenylethylamine. Gouda cheese was produced from milk supplemented with two strains of E faecalis (10⁷ cfu ml⁻¹). Both strains were proteolytic and potent tyramine formers. Final viable counts of 10⁹ cfu g⁻¹ and tyramine concentrations of 477 mg kg⁻¹ were detected after a 12 week ripening period. © 1999 Society of Chemical Industry