Effects of Organic acids on Thermal Resistance of Clostridium Spores

Studies on Growth Inhibition of Food Spoilage Microorganisms for Low Salt Foods Part IX

Abstract

Effects of various organic acids on thermal resistance of spores of Clostridium botulinum 62 A and 213 B, Clostridium sporogenes PA 3679 and Clostridium perfringens JCM 01382 were investigated. Thermal resistance of all the tested Clostridium spores was maximum at pH7.0 and it decreased with increasing acidity or alkality. In particular, it was remarkable in acidic side. The addition of 0.2-0.5% adipic acid at pH 5.5-9.0 decreased thermal resistance of spores with increasing concentration of adipic acid. Decreases of thermal resistance of C. botulinum and C. perfringens spores by addition of adipic acid were almost not affected by pH. However, that of C. sporogenes spores increased as pH droped. The addition of 0.2% of acetic, adipic, lactic, maric, citric, fumaric, gluconic, tartaric, succinic, sorbic or propionic acid at pH7.0 and 9.0 decreased thermal resistance of C. botulinum 62 A spore by 35-65%. At pH5.5, the decreasing actions of most of the tested organic acids on thermal resistance of C. botulinum 62 A spores were significantly reduced or disappeared, although those of adipic and acetic acid were powerful.