Characterization of Enterobacteriaceae strains isolated from spoiled dry-cured hams

Microbiological and physicochemical aspects of spoiled specimens of dry-cur ed hams affected by deep putrefaction were studied. Total aerobe (10(3)-10( 4) Cfu g(-1)), Micrococcaceae(10(4) cfu g(-1)) and lactic acid bacteria (< 10(2) cfu g(-1)) were present at the same levels as in unspoiled control ha ms. The overall hygienic qualify of the hams was good, even when spoiled. O nly Enterobacteriaceae counts (10(2)-10(3) Cfu g(-1)) were higher in spoile d dry-cured hams. pH (5.85-6.09) and A(w) (0.888-0.909) were similar in spo iled and unspoiled hams. Thirty strains of the family Enterobacteriaceae we re isolated and characterized. The strains were identified as Serratia liqu efaciens and Proteus vulgaris. The strains of S. liquefaciens were slightly lipolytic, proteolytic, and psychrotrophic. Only two strains of this speci es were able to grow at an A(w) level of 0.949. The strains of P. vulgaris were not lipolytic, were strongly proteolytic and only slightly psychrotrop hic, and were able to grow at an A(w) level of 0.949. None of them were abl e to grow at an A(w) level of 0.929. The results indicate that the isolated strains could have caused deep putrefaction of dry-cured hams, growing dur ing the first non-refrigerated steps of the curing process before the decre ase of A(w). Enterobacteriaceae ought therefore to be considered a microbia l quality-related hazard in the development of HACCP systems for dry-cured ham. (C) 2000 Academic Press.