POTENTIAL FOR USE OF BACTERIOCIN-PRODUCING LACTIC-ACID BACTERIA IN THE PRESERVATION OF MEATS

Bacterial spoilage and safety are major concerns in the marketing of r aw and processed meats. When meat is packaged under modified atmospher e with elevated levels of carbon dioxide (including vacuum packaging), the prevailing microflora of meat is changed from aerobic, putrefacti ve bacteria to lactic acid bacteria. Some ''new generation'' convenien ce foods rely almost entirely on refrigeration for assurance of safety against growth of pathogenic bacteria. With the emergence of cold-tol erant foodborne pathogens it is desirable to increase the ''hurdles'' to pathogen growth. Lactic acid bacteria preserve meats by competitive exclusion of other microorganisms but they also produce inhibitory su bstances, including lactic and acetic acids and bacteriocins. Bacterio cins are naturally produced peptides that are antagonistic to other cl osely related bacteria. Although bacteriocins are expected to have a n arrow range of antibacterial activity, nisin is a bacteriocin that is active against a relatively broad spectrum of gram-positive bacteria, including inhibition of the outgrowth of Clostridium botulinum spores. Nisin is not effective in meat systems; as a result, research on the lactic acid bacteria of meat is focused on the selection of lactic aci d bacteria that do not cause meat spoilage and that enhance product sa fety.