Identification and characterization of a psychotrophic Clostridium sp. isolated from spoiled pasteurized crabmeat
Webster, Janet B.
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A number of crab processors in the Maryland and Virginia region experienced an abnormally high incidence of spoilage in their pasteurized product in the fall of 1989. The spoilage was only seen in cans that were processed either shortly before or after hurricane Hugo and the majority of spoilage occurred in machine picked meat only. All processors pasteurized the meat at least to an Fi~5 of 32 minutes, which is the minimum National Blue Crab Industry Association (NBCIA) recommendation. Spoiled pasteurized crabmeat, processed in 1989 and 1990, were analyzed for their microbial content. Several cans that had spoiled in 1972 were also analyzed for microbial content Isolated organisms were tested for heat tolerance, and those organisms able to survive an F11~5 of 32 minutes or longer were identified. Can seams were evaluated to determine if the spoilage was due to post processing contamination. Approximate D-values were determined for the heat tolerant organisms. A psychrotrophic Clostridium sp. was found in all cans tested from a Maryland processor, Processor B. This processor only had spoilage in machine picked meat pasteurized after hurricane Hugo. Spoilage was seen in cans which had received a F 16/185 of 80 to 100 minutes. Spores from this organism had an approximate D-value of 6.5 minutes at 85 C in brain heart infusion broth (BHI). Cans from Processor B did not show any seam defects, and it was concluded that spoilage was due to the survival of spores, during pasteurization, from the Clostridium sp. that were able to outgrow at the temperature at which crabmeat is stored commercially. A Bacillus sp., possibly Bacillus pasteuranii, was found in one can from Processor B. Spores from this organism have an approximate D-value of 26.5 minutes in BHI broth at 85 C. This organism is unable to grow at refrigeration temperatures and it is not felt to have caused spoilage in the crabmeat. The Clostridium sp. found in cans from Processor B, pasteurized in 1989 and 1990, was also found in a can of jumbo lump meat from Processor D, processed in 1989, and a can of claw meat from Processor E, pasteurized around 1972. Cans from Processor A, who saw small amounts of spoilage before hurricane Hugo and in some hand- picked meat as well as machine piced meat had can seam measurements which did not meet specifications. It was concluded that spoilage from this processor was due to post-processing contamination. Crab processors must be aware that spores, from organisms that are able to outgrow at refrigeration temperatures, are able to survive pasteurization. The Clostridium sp. isolated in this study is one example. Processors will need to make sure their product is receiving sufficient heat to kill all spores of these organisms, while still maintaining a product with good sensory characteristics. It appears, from this study, that crab processors may want to increase the F-value that a lot of crabmeat receives after major storms, since the Clostridium sp. seemed to show up after hurricanes. Finally, crab processors need to be stringent in their sanitation and cleanliness so as to minimize the numbers of these types of organisms in their product.
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