Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2002
Publication Date: 6/20/2002
Citation: Juneja, V.K. 2002. Increased thermotolerance of Clostridium perfringens spores following sublethal heat shock. (Abstract). International Association Food Protection. P05-P221.
Technical Abstract: Beef gravy samples inoculated with Clostridium perfringens spores were heat shocked at 75C for 20 min, and then thermotolerance at 100C was assessed using a submerged-coil heating apparatus. Survivors were enumerated on Shahidi-Ferguson perfringens agar. An association of heat resistance with the origin of the C. perfringens strains could not be established due to significant variations in the heat resistance among strains. Interestingly, deviations from classical logarithmic linear declines in the log numbers with time were not observed in either control or heat-shocked samples. D-values at 100C for C. perfringens spores ranged from 15.5 to 21.4 min. Heat shocked spores of 9 of 10 strains had significantly higher (p < 0.05) D-values at 100C than unstressed spores. Proteins with epitopic and size similarity to Escherichia coli GroEL and Bacillus subtilis small acid-soluble protein, SspC, were present in the spores. However, heat- shock treated spores did not appear to significantly increase expression o these proteins. Acquired thermotolerance is of substantial practical importance to food processors and should provide useful information for designing thermal treatments to eliminate C. perfringens spores in ready- to-eat foods.