ULTRA‐HIGH TEMPERATURE EFFECT ON B. STEAROTHERMOPHILUS DURING PUFFING OF RICE1

ABSTRACT Destruction, damage and activation of thermophilic bacterial spores of Bacillus stearothermophilus at ultra‐high heating temperatures (170°C to 210°C) were studied using a rice cake machine as a model system. Activation of spores at ultra‐high temperatures was observed after 99.9% of the original spores were killed (P < 0.05). Significant difference (P < 0.01) in spore counts was found when a rich protein medium and a minimal nutritious medium were used simultaneously to recover spores after heating. This indicated that heat damage did occur and that amino acids were required to repair the damage.