The effects of hot water pasteurizing treatments on the appearances and microbiological conditions of beef carcass sides

Abstract

Beef carcasses from a commercial carcass dressing process were selected at random. One side of each selected carcass was deluged with water at 85°C, with 10, 25 and 25 sides being treated for 20, 15 and 10 s, respectively. After cooling, the treated and untreated sides of each carcass were assessed for the appearances of the fat, membrane-covered, cut bone and cut muscle surfaces and for the overall appearance of each side. For all treatments, the differences between the mean scores, on a seven-point scale, for treated and untreated sides were greatest for the appearances of cut muscle surfaces, the differences for that tissue being 1·04, 0·85 and 0·56 assessment units less for treated than for untreated sides from the 20, 15 and 10 s treatments, respectively. Microbiological samples were collected by swabbing both sides of each of the carcasses used in the 15 and 10 s treatments, both after the treatments and after cooling of the sides. Both treatments reduced the log total numbers of the total aerobic counts recovered from 25 sides by about 1·5 and the log total numbers of coliforms and Escherichia coli recovered from 25 sides by about 2. Cooling of the sides resulted in small reductions in the numbers of all three of those groups of bacteria on untreated sides, but similar reductions in only the numbers of coliforms and E. coli on treated sides. One side from each of 25 carcasses which had been heavily contaminated with visible filth during dressing was treated for 10 s. Microbiological samples were collected from both sides of each carcass before and after treatment. The numbers of bacteria recovered from untreated sides were similar to the numbers recovered from the untreated sides from carcasses selected at random, but the treatment reduced the log total numbers of total aerobic counts, coliforms and E. coli recovered from 25 carcasses by only 1, 1·5 and 1·5, respectively. The data indicate that treatment of beef carcass sides with water of 85°C for 10 s will substantially reduce the numbers of bacteria on the meat without unacceptable damage to the appearance of the product.