The fates of microbial populations on pig carcasses during slaughtering process, on retail cuts after slaughter, and intervention efficiency of lactic acid spraying.

This study was conducted to detect and identify microbial populations on pig carcasses at different slaughtering stages and on retail pork cuts at 24 h after slaughter as well as to evaluate the intervention efficiency of sprays containing different concentrations (2% and 4%) of lactic acid. The sprays were applied to the carcass surfaces at the end of the slaughter line. Microbial samples were collected from carcass surfaces after bleeding and after eviscerating, and from retail cuts at 24 h after chilling/spraying. The detected microorganisms were identified through using a Microflex identification instrument and 16S rRNA gene sequencing. The diversity of the bacterial genera; Staphylococcus, Salmonella, Shigella, Enterococci, Escherichia, Acinetobacter and Corynebacterium spp. showed counts ranging from 2.70 to 4.91 log10 cfu/100 cm2 on the carcasses during slaughter. Most of these genera were also detected on the carcasses after 24 h of chilling. Three species (Staphylococcus hyicus, Acinetobacter albensis, and Corynebacterium xerosis) were also found on the retail cuts of non-sprayed carcasses but not on those of the sprayed groups. Significantly greater reductions in all bacterial species were observed on the carcasses and retail cuts that were sprayed with lactic acid, particularly at the 4% level. Thus, spraying with 4% lactic acid may be an effective intervention for controlling bacterial contamination on pig carcasses to improve the microbiological safety of pork meat.

The effects of pre-and post-slaughter spray application with organic acids on microbial population reductions on beef carcasses.

As an attempt to control bacterial cross-contamination of beef carcasses, in the present investigation acetic acid and lactic acid (3% v/v) were used for bacterial decontamination. For the decontamination, cows were sprayed with each above acid at two different stages; (i) on live animal's hides, (ii) on carcass surfaces immediately after slaughter. Microbiological samples were taken on different hide areas of animals before spraying and on carcass surfaces at 24h after spraying. Meat quality traits were also analyzed on the sprayed animals. The detected microorganisms were identified using 16SrRNA gene sequencing. A diversity of bacterial species such as Staphylococcus, Shigella, Bacillus, Escherichia and Salmonella etc. were found on both external hide and carcass surface samples. The decontamination sprays significantly reduced the numbers (2-5 log unit) of all aforementioned bacterial species on carcass surfaces as compared with non-sprayed control. Thus, the two times-spray applications with the acid could be an effective tool for reducing bacterial cross-contaminations of beef carcass without adverse effect on meat quality.