Microbial Decontamination of Porcine Liver with Lactic Acid and Hot Water

Because current hygienic practices did not appear to result in bacteriologically fully acceptable porcine livers, the combined effects of decontamination and vacuum packaging on their bacteriological condition were investigated. Livers were taken from freshly slaughtered carcasses, immersed either in a 0.20% (v/v) lactic acid solution for 5 min or in hot water at 65°C for 15 s and subsequently vacuum packed and stored at 3 ± 1°C for 1 or 5 d. As compared with controls, both treatments resulted in significant reductions of total colony counts (TCC at 32°C), Enterobacteriaceae CFU-counts (EC at 37°C) and Lactobacillaceae CFU-counts (LC at 30°C) both after 1 d and, with the exception of LC in the hot water group, after 5 d of cold storage. Treatment with lactic acid was significantly more effective in reducing TCC and LC on liver surfaces than treatment with hot water. Moreover, lactic acid, but not hot water, improved the bacteriological condition of the inner parts of liver, resulting, after 5 d of storage at 3 ± 1°C, in a significant decrease of TCC and EC; a similar tendency was found for LC. Decontamination resulted in a reduction of the number of genera of Enterobacteriaceae as compared with controls. The genus Escherichia was isolated most frequently both in control and in treated groups. Slight discoloration of the liver surface was effected by both treatments. It disappeared, however, within 2 h after opening of vacuum packs.