USE OF TIME-TEMPERATURE EVALUATIONS IN DETECTING THE RESPONSIBLE VEHICLE AND CONTRIBUTING FACTORS OF FOODBORNE DISEASE OUTBREAKS1

An investigation of an outbreak of Clostridium perfringens foodborne illness indicated that turkey or dressing prepared in a school kitchen was responsible. When turkey was again prepared in the kitchen, a bacteriological survey and a time-temperature evaluation were made of the thawing, cooking, chilling, and reheating to which the turkey, stock, or dressing were subjected. During thawing of 22-lb. turkeys in plastic wrappers and in paper bags at room temperature for 18 hr, neither internal nor surface temperatures reached a level at which C. perfringens could grow. Cooking the turkeys in a steamer or in a pot of boiling water raised internal temperatures to a level lethal to vegetative cells. The stock (in gallon jars and a large rectangular pan) and deboned meat (in similar pan) were stored overnight in a reach-in refrigerator. During storage the temperature of both were within a range so that C. perfringens spores could germinate and its vegetative cells multiply for 7–9 hr. The stock was later used in dressing, which when baked, reached internal temperatures known to destroy vegetative cells of C. perfringens. Meat and gravy, when reheated, did not reach such levels. Clostridium perfringens, Staphylocoocus aureus, and Salmonella were isolated from raw turkey; C. perfringens was isolated from cooked meat, stock, and kitchen equipment. Nine recommendations for heat destruction of vegetative cells, inhibition of bacterial growth during storage, and cleaning and sanitizing equipment are made. These recommendations will help prevent foodborne illness whenever turkey and dressing are prepared.