THERMAL-RESISTANCE OF BACILLUS-STEAROTHERMOPHILUS SPORES IN DIFFERENTHEATING-SYSTEMS CONTAINING SOME APPROVED FOOD-ADDITIVES

The effects of different heating systems on the heat resistance of Bac illus stearothermophilus spores (ATCC 7953, 12980, 15951 and 15952) we re investigated. Spores were heated in distilled water, Sorensen buffe r (0.18 mol l(-1)), McIlvaine buffer (0.0025-0.18 mol l(-1)), and seve ral solutions containing sodium chloride (0.06-12%), sodium nitrite (1 25 ppm), potassium sorbate (0.1%) and sodium benzoate (0.1%) over a wi de range of temperatures (115-140 degrees C). D-values obtained for Mc Ilvaine and Sorensen buffers, at the same molarities, were not signifi cantly different (P > 0.05), but decimal reduction times increased as phosphate concentrations in the solutions decreased. The concentration s, in which statistically significant differences (P < 0.05) were obta ined, varied among strains. Among the additives assayed, only sodium c hloride reduced heat resistance, being effective at concentrations as low as 0.06%. The z-values calculated in this study ranged from 6.99 t o 8.40 with a mean value of 7.60 +/- 0.45. Although z-values observed for salt and buffers (180 mol l(-1)) were slightly higher than those o btained in the other conditions assayed, the difference was not statis tically significant (P > 0.05).