INHIBITORY EFFECT OF ORGANIC-ACIDS UPON MEAT SPOILAGE BACTERIA

The relative ability of acetic, benzoic, citric, lactic, propionic, an d sorbic acids to inhibit the growth of six common meat spoilage bacte ria (Brochothrix thermosphacta, Carnobacterium piscicola, Lactobacillu s curvatus, Lactobacillus sake, Pseudomonas fluorescens, and Serratia liquefaciens) was compared under otherwise optimum conditions (BHI or MRS broths; 20 degrees C). Because of their low solubility in the grow th media, benzoic and sorbic acids could only be used in low concentra tions (below 0.15% [wt/vol]) and did not efficiently inhibit bacterial growth. All other acids totally inhibited growth at concentrations ra nging from 0.1% to 1% (wt/vol). On a weight basis, acetic acid was fou nd to be the most inhibitory, followed by propionic, lactic, and citri c acid, while the order of efficiency was reversed (citric > lactic > propionic > acetic) when the acid concentrations were expressed on a m olar basis or when the acid effectiveness was evaluated relative to th e concentration of undissociated molecules. Overall, the lactobacilli were the bacteria most resistant to the action of organic acids, follo wed by P. fluorescens and S. liquefaciens, while B. thermosphacta and C. piscicola were considerably more sensitive.