The aerobic psychotrophic populations on meat and meat contact surfaces in a meat production system and on meat stored at chill temperatures.

At a city abattoir, a wholesaler and 10 different supermarkets, surface microbiological samples were taken of carcasses, hands and apron fronts of members of staff and equipment (mincers and saws). In addition, minced meat, packaged and displayed in chilled cabinets, was also sampled. Carcasses, personnel surfaces and equipment were monitored by a modified agar sausage technique. From each of the highest dilution psychotrophic plate counts, five colonies were selected randomly, isolated and identified (1265 in total). Microbes developing on chilled meat were also isolated from other surfaces in the production chain. On chilled meat (51%) and at the abattoir (36%) pseudomonads were the predominant organisms followed by the Gram-positive cocci on chilled meat and by Acinetobacter, Moraxella and Alcaligenes spp. at the abattoir. At the wholesaler Gram-positive cocci (32%) predominated, followed by Alcaligenes, Moraxella and Alcaligenes spp. Pseudomonas, Alcaligenes, Neisseriaceae and related genera, Gram-positive cocci, species from the coryneform groups of bacteria and yeasts were identified from all the surfaces monitored. Identification with the API NE20 was unsatisfactory. Enterbacteriaceae, lactobacilli and endospore-forming bacteria were identified occasionally, but their significance as contaminating organisms seems low. No Salmonella spp. were identified.

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.

A Quantitative Survey of a Meat Production Chain to Determine the Microbial Profile of the Final Product.

Samples from carcasses, personnel surfaces, equipment, and minced meat, packaged and displayed in cabinets were taken at a city abattoir, a wholesaler, and 10 different supermarkets. Bacteria enumerated were 1) psychrotrophs; 2) Enterobacteriaceae ; 3) enterococci; 4) micrococci; 5) Pseudomonas spp; and 6) Brochothrix thermosphacta . The non integrated production system of abattoirs, wholesalers, and retailers yielded psychrotrophic and enterococci counts at retail which compared fairly well with those reported in literature, while the Enterobacteriaceae and micrococci counts were higher. Besides the psychrotrophs the pseudomonads were the most numerous group in the final product. Different surfaces were not sanitized with the same efficacy, while a general tendency towards lower counts at one supermarket group was monitored. The counts described 96% of the variation in the psychrotrophic count at the abattoir, while the success in using these counts in estimating the psychrotrophic count at the wholesaler and retailers was not as significant. At the abattoir the Enterobacteriaceae and psuedomonads were the biggest contributors to the psychrotrophic count, at the wholesaler the Enterobacteriaceae and micrococci counts, and at the retailers the micrococci and pseudomonads respectively. This indicates that Enterobacteriaceae might be common psychrotrophs in the meat production chain, maybe originating from the abattoir and wholesale environments.