APPLICATION OF THE INOCULATED PACK TEST METHOD FOR THE DETERMINATION OF THE HEAT-RESISTANCE OF CLOSTRIDIUM-SPOROGENES PA3679 SPORES IN ACIDIFIED MUSHROOMS

The effect of pH in the range 5.2-6.7 on the thermal destruction of Clostridium sporogenes PA3679 spores suspended in mushrooms in brine acidified with citric acid was examined by the 'inoculated pack test' method. The results indicated that increasing acidity is accompanied by decreasing decimal reduction times at 121.1 degrees C: D-121.1 at pH 6.0 and 5.2 was, respectively, 64% and 17.5% of that at pH 6.7, the pH of natural mushrooms (D-121.1 = 2.22 min). A linear model (r = 0.988, alpha = 0.05) was developed where the D-121.1 value was a function of the pH over the range studied. The inoculated pack test seems to be the only method to evaluate the actual microbial heat resistance, whether of spore or of vegetative forms, in order to estimate within reasonably close limits a suitable process time required to eliminate health hazards and to prevent spoilage losses in a given food product.