Lactic acid decontamination of fresh pork carcasses: a pilot plant study

Abstract

Lactic acid decontamination (LAD) was carried out in an abattoir on pork carcasses, artificially contaminated with Salmonella typhimurium in faeces suspensions. The surface contamination with S. typhimurium ranged from 1–2 log 10 cfu cm 2 . Before cold and hot LAD was undertaken, the inoculum was allowed to adhere to the meat surface for 20 min. Cold LAD consisted of treatment for 60 s with 2% (pH 2.3) or 5% (pH 1.9) lactic acid (LA); for hot LAD the exposure times were 30, 60, 90 and 120 s. The spray nozzle temperatures were 11 °C and 55 °C, and that of the treated meat surface 16–18 °C and 36–38 °C, respectively. Treatment with cold 2% and 5% LA for 60 s eliminated S. typhimurium from pork carcasses inoculated with ca. 1 log 10 cfu cm 2 , but not from those inoculated at ca. 2 log 10 cfu cm 2 . However, this could be achieved by hot 2% and 5% LA sprayed for 60–120 s. Also exposures of at least 30 s using these hot LA solutions eliminated S. typhimurium consistently from carcasses inoculated with ca. 1 log 10 cfu cm 2 . Rinsing-off contributed only marginally to contamination reduction. Application of 2% or 5% LA for 120 s led to an unacceptable deterioration of the organoleptic qualities of the meat. Addition of nicotinic and ascorbic acid as colour stabilisers to the spraying solutions reduced these changes to just acceptable levels when 2% LA was used.