Thermal tolerance of Lactobacillus viridescens in ham

Lactobacillus viridescens is a ubiquitous organism in meat plants causing a green discoloration of cured meat products, resulting in serious financial losses. Using a method similar to that of Niven et al. (1954) the thermal tolerances of strains isolated from core greening and surface greening were established. It was found that the thermal tolerance of the surface greening strain could be doubled by successive heat shocks. Time-temperature studies of the processing of ham showed that the normal process could not be relied upon to destroy all the organisms present. So, if L. viridescens can adapt itself in industry, as in the laboratory, to be able to withstand the thermal processing, it is possible for the organism to survive heat processing and cause outbreaks of green discolorations in cured meats. Studies showed that the D(65) values for the organism are higher in ham broth and slices than in laboratory media. Thus, ham appears to act as a heat protective agent for L. viridescens.