THERMAL DEATH TIME OF Clostridium botulinum TYPE E IN MEAT OF THE BLUE CRAB

Abstract

ABSTRACTThe thermal death time (TDT) of Clostridium botulinum type E spores in crabmeat between 165° and 185°F was determined to evaluate the safety of the pasteurization procedure. Samples (lg) of five strains of crabmeat, seeded with a known concentration of spores, were flamesealed in TDT tubes and dropped at regular intervals into a constant temperature water bath. Surviving spores were cultured and TDT curves were plotted from these data. The time of exposure at each temperature for the TDT curves was corrected by the graphic method. The TDT curves of the Beluga and Crab G21–5 strains both had slopes such that the temperature increment in °F for 1 log cycle (z) was approximately 15; the Alaska strain had a z of 13. In addition, the decimal reduction time (D) was calculated from the survival data for each temperature, and D curves were plotted for each strain. These curves had somewhat steeper slopes than those of the TDT curves. Differences in D values at the temperatures studied were small. However, the Beluga strain had somewhat higher D values, indicating a slightly greater heat resistance than the others. The Beluga strain had a D180 of 0.74; Alaska, 0.51; Crab G21–5, 0.63; Crab 25V–1, 0.62; and Crab 25V–2, 0.49.