Subtopic: Kinetics of microbial death – pasteurization and sterilization of milk and other liquid foods
Question Statement:
Bacterial population in milk increases 200 times in 18 hours of storage at 20 °C. The increase in population in 3 hours of storage at the same temperature is
Options:
(A) 1.34 times
(B) 2.42 times
(C) 7.02 times
(D) 14.14 times
Official Answer Key:
B
Step-by-Step Solution & Explanation
Exponential growth: N/N₀ = 2^(t/g), where g = generation time. 200 = 2^(18/g) ⟹ g = 18/log₂(200) = 18/7.644 = 2.355 h. In 3 h: N/N₀ = 2^(3/2.355) = 2^1.274 = ≈2.42 times. (D) results from using 18/3=6 doublings incorrectly instead of solving for g.
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