Subtopic: Kinetics of microbial death – pasteurization and sterilization of milk and other liquid foods
Question Statement:
The decimal reduction time of a heat-resistant microorganism is $D_1 = 10.0\text{ minutes}$ at $110^\circ\text{C}$. The thermal resistance constant ($z$-value) is $10^\circ\text{C}$. Calculate the $D$-value of the organism at $120^\circ\text{C}$ in $\text{minutes}$.
Answer Key:
1
Step-by-Step Solution & Explanation
The relationship between $D$-value and temperature is:
$\log_{10}\left(\frac{D_1}{D_2}\right) = \frac{T_2 - T_1}{z}$
$\log_{10}\left(\frac{10}{D_2}\right) = \frac{120 - 110}{10} = \frac{10}{10} = 1$
$\frac{10}{D_2} = 10^1 = 10 \implies D_2 = 1.0\text{ minute}$