Further Studies on the Thermal Resistance of Streptococcus faecium and Streptococcus faecalis in Pasteurized Ham

Abstract

Strains of Streptococcus faecium and Streptococcus faecalis were inoculated into raw ham and subjected to heating conditions simulating the industrial processing of cured, pasteurized ham. Thermal resistance characteristics including survival curves, phantom thermal death time curves, D values and z values were determined. Streptococcus faecium P-1A was the most heat resistant organism tested, showing a D value of 29.04min at 66°C. Streptococcus faecium E-20 showed a D value of 13.69min at this temperature and Streptococcus faecalis P-2A was the least heat resistant organism with a D value of 1.69min at 66°C. It was demonstrated that these three organisms showed greater thermal resistance in the raw ham than in Sorenson's buffer or ham broth, as determined in a previous study. The derived z values for the raw ham suggest that the use of the z value in determining pasteurization process parameters be carefully reconsidered.