Inactivation of Clostridium botulinum nonproteolytic type B spores by high pressure processing at moderate to elevated high temperatures

Abstract

The effect of high pressure and high temperature treatments at various process times on the inactivation of spores of Clostridium botulinum nonproteolytic type B strains, 2-B, 17-B, KAP8-B, and KAP9-B, suspended in phosphate buffer (0.067 M, pH 7.0) and a crabmeat blend was investigated. Spores of KAP8-B were less resistant to high pressure treatment than the spores of 2-B, 17-B, and KAP9-B in both phosphate buffer and crabmeat blend. No survivors of initial counts (> 4.3 log units) of KAP8-B spores were detected in these menstura after processing at 827 MPa and 60 °C for 10 min. The amount of inactivation of spores of 2-B, 17-B, and KAP9-B in phosphate buffer or crabmeat blend increased with the increase in processing time from 10 to 30 min at 827 MPa and 75 °C. Similar inactivation patterns were observed for these spores in both phosphate buffer and crabmeat blend. A reduction of > 6-log units of 2-B, 17-B, and KAP9-B spores in phosphate buffer and crabmeat blend was observed at 827 MPa and 75 °C for a processing time of between 20 and 30 min. Crabmeat blend as a suspension menstrum provided no protection against inactivation of spores of 2-B, 17-B, and KAP9-B by high pressure processing. High temperature (> 95 °C) and lower pressure (620 MPa) treatments for up to 10 min were also found to inactivate 17-B spores in phosphate buffer. Spores of nonproteolytic type B strains, 2-B, 17-B, KAP8-B, and KAP9-B in phosphate buffer and crabmeat blend can be inactivated by a combination of high pressure and temperature treatments. Spores of nonproteolytic type B strains of Clostridium botulinum are of primary concern because they have been involved in the foodborne botulism outbreaks associated with marine products. Foodborne botulism results from consumption of these foods in which C. botulinum has grown and produced neurotoxin. Recently, high pressure processing (HPP) received a great deal of interest because of its ability to destroy vegetative pathogens, viruses, and certain bacterial spores and results in a product with natural sensory, quality, and nutritional attributes. Currently, HPP is being evaluated at the National Center for Food Safety and Technology as an alternative to other traditional thermal processes for its ability to inactivate C. botulinum spores. In this study, the effects of high pressure in conjunction with moderate to elevated high temperatures on inactivation of C. botulinum nonproteolytic type B spores were investigated. Based on limited number of strains tested, HPP showed a potential of destroying spores of nonproteolytic type B strains of C. botulinum when process temperature is above 75 °C.