Effect of Curing Agents on the Heat Tolerance of Putrefactive Anaerobic Bacterial Spores

Abstract

Effects of curing agents contained in the heating and outgrowth medium on the heat tolerance of Clostridium subterminale spores were investigated. The quantities normally used of sodium chloride and sodium nitrate reduced D values (decimal reduction time in min) to nearly a half when mixed solution was added, but no reduction occurred when added individually. One hundredth per cent of sodium nitrite reduced D value to 31.2min from 59.0min at 105°C. The effect of mixed curing agents on reduction of D value was very obvious. D value was reduced to 3% at 105°C by a combination of 3.0% sodium chloride, 0.1% sodium nitrate and 0.01% sodium nitrite. The concentration of sodium nitrite added with other curing agents to the medium was a very critical factor in determining D values. D values were largely influenced by small differences in sodium nitrite concentration under 0.01%. Differences in D values, however, were scarcely observed at concentrations higher than 0.01%.