Question Bank • QB_SUB_DFE_STE_002 NAT • 2 Marks

Section 7: Dairy and Food Engineering

Thermal Sterilization, Retort Processing & 12D Concept

Subtopic: Lethal rate calculation Bigelow method

Question Statement:

For Clostridium botulinum spores with reference temperature $T_{\text{ref}} = 121.1^\circ\text{C}$ and $z = 10^\circ\text{C}$, the lethal rate $L$ at a retort temperature of $124.1^\circ\text{C}$ is:

Answer Key:

2.0

Step-by-Step Solution & Explanation

Lethal rate formula: $L = 10^{(T - T_{\text{ref}})/z} = 10^{(124.1 - 121.1)/10} = 10^{3.0/10} = 10^{0.30103} = 2.00$
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