Attachment of Bacteria to Beef from Steam-Pasteurized Carcasses

Abstract

The extent to which a bacterial cocktail containing equal numbers of Pseudomonas fragi NCTC 10689, Listeria monocytogenes BL5/2, Salmonella Typhimurium LT2, and Escherichia coli JM 109 attached to loin surface cuts (7 by 5 cm) derived from steam-pasteurized beef carcasses has been evaluated. The extent of attachment was categorized as loosely attached (removed by rinsing), firmly attached (released by stomaching), and irreversibly bound. No significant difference (P > 0.10) in the attachment of bacteria to steam-pasteurized carcasses was found compared with control loin samples that had received no treatment. No significant difference (P > 0.05) was also found in the attachment strength between the different bacterial species tested. Most bacteria inoculated onto the loin cuts were reversibly bound, since they had been removed by rinsing and stomaching. The irreversible attachment of bacteria to loin cuts was found to vary significantly (P < 0.01) among the different carcass sets used but was independent of whether the carcass had undergone steam pasteurization treatment. Use of a bioluminescent strain of E. coli showed that cells bound preferentially to cut edges and convoluted areas on the loin surface and could not be removed by rinsing. The possible mechanisms of bacterial attachment and the suitability of steam pasteurization to remove contamination incurred during slaughter are discussed.

Bioluminescence lights the way to food safety

“…It was shown that retention of the pathogen after water rinses was significantly higher on lean tissue than on adipose tissue. In other work (59), it was demonstrated that irreversible attachment of E. coli to loin cuts was independent of whether the carcass had undergone a steam pasterization treatment. Use of bioluminescent E. coli showed that cells bound preferentially to cut edges and convoluted areas on the loin surface, and could not be removed by rinsing.…”

Technical specifications on harmonised epidemiological indicators for biological hazards to be covered by meat inspection of bovine animals

“…However, there may also be methodology difficulties with recovery of bacteria from chilled carcases as the bacteria may be sublethally injured by the combination of chilling and reduced water activity rendering them non-cultivable. During chilling, some bacteria may become firmly attached to the meat or embedded into the meat tissue and thus not be readily recoverable by swabbing (Warriner et al, 2001). The microbial levels found at this point in the process reflect the VTEC contamination level entering the food chain from the slaughterhouse.…”

The anti-microbial effect of a dairy extract (LactiSAL®) on Salmonella enterica Typhimurium and Escherichia coli O157:H7 on different beef carcass surfaces

“…This was performed in a laminar flow cabinet and yielded approximately 6 log 10 cfu cm À2 . The meat pieces were then left at room temperature for 30 min to allow for bacterial attachment (Warriner et al, 2001). Following attachment, each excised sample in the treatment tray was sprayed with the dairy extract (LactiSAL Ò ) as follows.…”