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

Abstract 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 log 10  cfu/100 cm 2 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.