THE EFFECT OF LACTIC-ACID DECONTAMINATION ON THE MICROFLORA ON MEAT

Meat acquires a characteristic microflora after slaughter and butcheri ng. This normal microflora may be beneficial in that it occupies a nic he that would otherwise permit unimpeded growth of potential pathogens . Lactic acid decontamination (LAD) is intended to eliminate pathogens but also affects the normal microflora. The immediate effect was stud ied by means of an in-vitro model. Experiments using this model achiev ed a reduction in the mesophilic Enterobacteriaceae on meat by 1 to 3 log10 colony forming units and shifted the predominant microflora in t he direction of Gram-positive bacteria and yeasts. Colony counts were an unreliable indicator of LAD-induced reductions in Gram-negative foo dborne pathogens. Their reduction depended on the ratio of the more la ctic acid resistant Gram-positive bacteria to the more sensitive Gram- negative bacteria. The rank order of lactic acid-resistance of nonpath ogens present on meat was yeasts = lactobacilli > psychrotrophic Gram- positive bacteria > mesophilic Enterobacteriaceae. Psychrotrophic Gram -negative bacteria were the most sensitive.