Effect of pre-heating was examined on the resistance of bacterial spores to growth-inhibitory action of food preservatives including furylfuramide, sorbic acid, and tylosin. The spore resistance was estimated by the number of colonies of the heated spoers outgrown on the agar medium to which each of the preservatives has been incorporated.
The bacterial spores used in this study were those of Bacillus firmus and Bacillus pulvifaciens isolated at authors' laboratory from spoiled fish sausages and the strains were confirmed of their unsusceptibility to the preservatives examined. The spores from three days' cultures at 37°C were collected and suspended in phosphate buffer of pH 5.5-7.0 and heated at temperatures ranging from 75 to 95°C for 50 minutes. As shown in Fig. 1 to 8, heat treatment did not show any significant effect on the lowering of the spore resistance to growth inhibitory action of the preservatives, suggesting the difficulty of coupled action between heat treatment and preservatives to a certain food processing.