Action of Acetic Acid on Food Spoilage Microörganisms

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Abstract
Acetic acid in nutrient broth inhibited the growth of various organisms related to food spoilage. The bacteria used did not grow in broth adjusted with acetic acid to pH 4.9. Saccharomyces cerevisiae did not grow at pH 3.9 and Aspergillus niger was inhibited at pH 4.1. An increase in the H-ions resulted in a decrease of the thermal death points of the bacteria studied. The reduction in lethal temp. was more marked in the case of Bacillus mesentericus and B. cere us than with the non-spore forming organisms. Thermal death points of the yeast and the mold were unaltered by the addition of small amts. of acetic acid. Acetic acid was more toxic than either lactic acid or HC1 to Salmonella aertrycke, Saccharomyces cerevisiae, and Aspergillus niger. These organisms were inhibited or destroyed at a higher pH value with acetic acid than with lactic acid or HC1. The mold utilized large amts. of lactic acid to develop a growth heavier than that obtained from the acetic acid or the HC1 series. Because of lethal activity at high pH values, the toxicity of acetic acid to various organisms is not due to the H-ion alone, but also seems to be a function of the undissociated acetic acid molecule.