Combined Effect of Heat Treatment and Protamine on the Growth and Heat Resistance of Bacillus Spores

Abstract

Combined effects of heat treatment and clupeine sulfate on the growth from the spores of Bacillus subtilis and Bacillus licheniformis were studied. The effectiveness of protamine in pre-venting the growth from the spores was considerably influenced by heat treatment at 95°C. In general, increasing the length of heating time at 95°C, decreased the required protamine level in the prevention of growth from the spores or the presence of higher level of protamine decreased the heating time. In nutritionally rich media with higher concentration of organic substances, higher level of protamine and longer heating time was necessary for the prevention of growth. D value for the thermal death of B. subtilis heated at 90°C were 17 and 14.5 min for control and with 200μg pratamine/ml respectively. This meant a 15% decrease in the D value of the spores when heated along with protamine.