The Influence of Incubation Temperature on Bacterial Counts in a Meat Production System

Samples for microbial evaluation were taken from various surfaces including those on carcasses, and equipment at an abattoir, a wholesaler, and 10 different supermarkets. Samples were also taken of minced meat in retail display cabinets. These surfaces were monitored by means of a modified agar sausage technique. A total aerobic plate count (30°C for 24 - 48 h), a psychrotrophic count (5°C for 7 d), and a total aerobic plate count (25°C for 2 to 3 d) were investigated. Counts obtained at 30°C, yielded higher numbers than those acquired at 25°C. The accuracy of predicting the psychrotrophic population by means of a 25°C count, depends on the habitat and environmental conditions. To predict the spoilage population, a count at 25°C for 2 to 3 d can be a time saving and fairly accurate tool, provided that some equation is used to account for inherent differences. The conditions regarding habitat, environmental temperatures, and vectors should also be accounted for in the interpretation of results. The present work proved that to study a specific population, the quantitative study should be conducted at the revelant temperature (30°C for the total population, 7°C for a psychrotrophic population, and 37°C for a mesophilic population). Hence, to study the cold tolerant spoilage population encountered in a certain habitat (e. g. meat), it is advisable to do the quantitative survey at 7°C and further studies on the isolates made at this incubation temperature, could be done at 20 to 25°C.