The mechanism of attachment of bacteria to meat surfaces involves two consecutive stages. During the primary stage, bacterial attachment is probably due to physical forces, and the number of bacteria becoming attached is proportional to the number in the water film over the surface. The second stage is initially characterized by an increased strength of attachment due to polysaccharide formation, which is a time-dependent process. The dependence of attachment on various factors such as bacterial strain, type of meat surface, temperature, culturing method, etc. is discussed. Some potential consequences of attachment on slaughter hygiene, kitchen hygiene and methodology are described.
A rapid impedimetric determination for total, mesophilic and psychrotrophic counts in raw milk showed correlations (between impedance detection times and standard plate counts) of -0.96, -0.95, and 0.96, respectively. Mesophiles were most often seen as the predominant population, the impedimetric method allowed for these samples containing above 1.0 x 105 CFU/mI to be screened out within 4 hr. Psychrotrophic levels of 1 x 105 CFU/ml and above were screened within 21 hr, while total concentration of samples containing above 1 x lo5 CFU/ml were screened within 16 hr.
The mechanism of attachment of bacteria to meat skin is of great importance in slaughter hygiene and sampling methods. In this study teats of cows were chosen as the meat surface for attachment experiments. Both the attachment rate and strength of attachment were determined. Results show that bacteria attached themselves readily to the surface of the teat. After the initial attachment the strength of attachment increased. This increase appeared to be faster at higher storage temperatures, and an optimum was reached after 2 h at 20 C and after 3 h at 12 C. After longer periods of storage the strength of attachment decreased, probably due to formation of colonies.
The attachment of bacteria to chicken and beef meat with and without fascia was studied. It was found that bacteria attach readily to the meat surfaces. The kinetics of attachment depend on the bacterial strain, as well as on the meat surface. Of the bacteria tested, Pseudomonas EBT/2/143 attached most readily to all meat surfaces examined. Chicken breast with fascia was the best surface for attachment.
A study was also made of the effects of storage on the multiplication of the attached bacteria and the feasibility of removing them. A high level of Salmonella infantis was found in comparison to the other bacteria after 24 h of storage at 20°C.
More investigations are needed to find out whether other serotypes of salmonellae will multiply to similar levels on these surfaces.
After micro‐colonies began to form, the newly generated bacteria were easy to remove. The hygienic consequence of this phenomenon is discussed.
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