Control of nonproteolytic Clostridium botulinum types B and E in crab analogs by combinations of heat pasteurization and water phase salt

Water phase sodium chloride (WPS) levels of 1.8 to 3.0% in combination with heat pasteurization for 15 min at temperatures of 75, 80, 85, and 90 degrees C were evaluated as methods for the inactivation or inhibition of nonproteolytic, psychrotrophic Clostridium botulinum types B and E in crab analogs (imitation crab legs) subsequently stored at 10 and 25 degrees C. Samples inoculated with 10(2) type B or E spores per g prior to pasteurization remained nontoxic for 120 days at 10 degrees C and for 15 days at 25 degrees C. With 10(4) type E spores per g and 80 degrees C pasteurization, > or = 2.4 and 2.7% WPS was required for inhibition at 10 and 25 degrees C storage, respectively. Pasteurization at 85 degrees C decreased the inhibitory level of WPS to 2.1% at 10 degrees C and to 2.4% at 25 degrees C. When the inoculum was 10(4) type B spores per g, samples with 2.7% WPS were toxic after 80 days of storage at 10 degrees C. Samples inoculated with 10(3) type B spores per g and processed at 85 degrees C remained nontoxic for 15 days at 25 degrees C with a WPS of > or = 2.4%. When pasteurization was carried out before inoculation and packaging, 1.8% WPS prevented toxin production by 10(2) and 10(4) type E spores per g for 30 days at 10 degrees C, and this time period increased as the WPS concentrations increased. Three percent WPS prevented toxin production by 10(4) type E spores per g in vacuum-packaged analogs stored 110 days at 10 degrees C. Pasteurization processes used in these experiments, however, do not inactivate the heat-resistant proteolytic types of Clostridium botulinum. Therefore, the most important factor controlling the growth of this bacterium is continuous refrigeration below 3.0 degrees C or frozen storage of the finished product.