The control of the botulism hazard in hot‐smoked trout and mackerel
ABSTRACT The growth and toxin production of Clostridium botulinum types B, C, E and F in hot-smoked trout and mackerel has been studied. Using whole trout which were naturally contaminated with Cl. botulinum type E it was established that salt was the major inhibiting factor; a minimum concentration of 2.5% salt-on-water phase prevented the production of toxin for 30 days when fish were stored at 10°C. When whole and minced fish were inoculated with spores of Cl. botulinum types, B, E and F at a concentration considerably higher than that found in nature (102g−1) a minimum salt concentration of 3% was required to achieve a similar effect. Further studies using trout which were inoculated with suspensions of a number of strains of Cl. botulinum containing both spores and vegetative cells (102g−1) showed that fish smoked to produce a minimal salt concentration of 3% had a safe shelf life of 30 days at 10°C and 1 day at 20°C.
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ABSTRACT: Studies were done to determine the effect of film oxygen transmission rate (OTR) on the time to toxicity in vacuum packaged cold and hot smoked rainbow trout fillets challenged with C. botulinum type E (102 spores/g) and stored at refrigerated conditions (4C), and under mild (8C) and moderate (12C) temperature abuse conditions. While no samples were toxic at 4C, toxin was detected within 28 days at 8C for cold smoked trout fillets vacuum packaged in films with high OTR. Toxin was also detected for most vacuum packaged hot smoked trout fillets within 14–28 days at 8C, with the exception of trout fillets packaged in films with an OTR > 10,000 cc/m2/day. In most cases at 8C, spoilage, based on odor/color scores, preceded or occurred simultaneously with toxigenesis. At 12C all cold and hot smoked trout were toxic after 14–21 days and samples packaged in films with an OTR <5000 cc/m2/day became toxic before, or at the same time as, samples became spoiled. This study has shown that vacuum packaging of trout fillets in low gas barrier films, ranging in OTR from approximately 3,000 to approximately 10,000 cc/m2/day at 24C and 0% relative humidity (RH), did not prevent the growth and toxin production by C. botulinum in vacuum packaged cold and hot smoked trout fillets at 12C. Additional barriers, other than the OTR of the packaging film, need to be considered to ensure the safety of vacuum packaged trout fillets, particularly at mild to moderate temperature abuse storage conditions.Journal of Food Safety 11/2000; 20(4):251-298. DOI:10.1111/j.1745-4565.2000.tb00303.x · 0.82 Impact Factor