Heat resistance of Bacillus subtilis and Bacillus coagulans: Effect of sporulation temperature in foods with various acidulants

Abstract

The influence of the sporulation temperature (35 and 52°C) on the effect of different acidulants on the heat resistance of Bacillus subtilis and Bacillus coagulans in homogenized tomato and asparagus at pH 4 was investigated. Several acidulants (hydrochloric, citric, acetic, lactic, and malic acids and glucono-δ-lactone) currently used by the canning industry to lower the pH of some vegetables before processing were studied. The sporulation temperature determined the response of these microorganisms to the type of acidulant. While the heat resistance of spores sporulated at 35°C was the same at all heating temperatures tried, regardless the type of acidulant, that of spores sporulated at 52°C was two to fivefold lower when lactic or acetic acids were used. This decrease in heat resistance was the same at every temperature over the whole range of heating temperatures tested. The z values obtained with each microorganism were the same for a given heating menstruum, regardless the type of acidulant used.