The primary contamination of the meat surface of healthy animals is decisively influenced by the abattoir environment and the condition of the animal.
Varying levels of both Gram-positive and Gram-negative bacteria constitute the initial microbial population.
Bacterial presence is limited almost exclusively to the exterior surface of carcasses unless the surface has been penetrated by utensils allowing transport of bacteria to interior muscle tissues.
The hides of cattle are loaded with bacteria. The intestinal tract of cattle is also loaded with bacteria. Bacteria from intestinal tract may come in contact with the carcass surface if the intestinal tract is rupture during evisceration.
Also, feces during slaughter and rumen contents spilled through the esophagus may additional sources of contamination.
The important spoilage bacteria of fresh meat include Pseudomonas, Acinetobacter/Moraxella, Aeromonas, Alteromonas putrefaciens, Lactobacillus and Brochothrix thermosphacta.
The major end products of metabolism of common meat spoilage organisms are sulfides, amines, acetic acid, lactic acid, isovaleric acid, isobutyric acid, esters and nitriles.
Bacterial contamination of beef meat
