Sensitivity of an Enrichment Culture Procedure for Detection of Clostridium botulinum Type E in Raw and Smoked Whitefish Chubs

Interrelationship of Heat and Relative Humidity in the Destruction of Clostridium botulinum Type E Spores on Whitefish Chubs

“…Spore concentrations were based on the number surviving mild heat treatment (60 C for 15 min). In the case of type E spores, heat-treated suspensions repeatedly yielded viable counts ranging from 40 to 60% less than nonheated suspensions, as previously reported (15). Viable counts of type B spores, in similarly heated suspensions, were increased by a factor of 20 to 50% over counts of nonheated suspensions.…”

“…The effectiveness of heat in destroying or reducing types B and E C. botulinum spores on fish is directly related to the RH at which they are processed. Refrigeration of the finished product and shelf life limitation are feasible, enforceable, and necessary additional safety factors to protect the consumer (14,15). An alternative to compliance with these processing requirements is the abandonment of smoked whitefish chubs as a food source.…”

“…Each of the 16 cultures was capped with sterile Vaspar and incubated at 28 C for 7 days. Toxin testing and neutralization tests in mice, and upon occasion reisolation procedures, were performed as previously described (15). MPN values were taken from a published table (1).…”

“…The former was isolated from commercially smoked whitefish chubs and the latter, a nonproteolytic type B, from commercially brined whitefish chubs (13,14). Stock spore suspensions were prepared and assayed by a procedure described previously (15). These were employed in qualitative tests of C. botulinum survival in and on fish exposed to controlled temperatures and RH.…”