Question

The D121 and Z- value for a thermophilic spore in whole milk were experimentally determined as 30 s and 10.5oC respectively. Calculate D150 (min) for the spore.

Answer 1

Here given decimal reduction time D at 121 ^oC(D₁₂₁) and the value z for a thermophilic spore =30 s and 10.5^oC.

we know that

$log(\frac{D_1}{D_2})=\frac{T_1 -T_2}{z}$

$log(\frac{30}{D})=\frac{121 -150}{10.5}$

$\frac{ 30}{D}=$ antilog(-2.7619)

D=0.00087 min