Subtopic: Kinetics of microbial death – pasteurization and sterilization of milk and other liquid foods
Question Statement:
The Arrhenius activation energy ($E_a$) for thermal destruction of bacterial endospores ($E_a \approx 250\text{--}350\text{ kJ/mol}$) compared to the activation energy for quality degradation reactions like vitamin loss ($E_a \approx 80\text{--}120\text{ kJ/mol}$) is:
Options:
(A) Significantly higher, meaning spore death is far more temperature-sensitive than nutrient destruction
(B) Identical, meaning temperature changes affect both at equal rates
(C) Significantly lower, meaning nutrient loss accelerates much faster with temperature
(D) Negative under all conditions
Answer Key:
A
Step-by-Step Solution & Explanation
Because bacterial spores possess a substantially higher activation energy ($250-350\text{ kJ/mol}$ vs $80-120\text{ kJ/mol}$), increasing the processing temperature accelerates sterilization lethality exponentially faster than chemical nutrient loss, underpinning the High-Temperature Short-Time (HTST/UHT) philosophy.