Discussion
Thermal death time (TDT) of Clostridium botulinum at 121 °C is 2.78 min with a z-value of 10 °C. The TDT of the microorganism at 116 °C (in min) is
Answer: B
The TDT at 116°C is about 8.791 min.
The z-value is the temperature change that alters the thermal death time tenfold. A drop of 5°C is half of z, so the time rises by a factor of \(10^{0.5}\):
\[ \begin{aligned} TDT_{116} &= TDT_{121} \times 10^{(121 - 116)/z} \\ &= 2.78 \times 10^{0.5} = 2.78 \times 3.162 = 8.791\ \text{min} \end{aligned} \]
A lower temperature needs a longer time, so the options smaller than 2.78 min (1.390 and 0.712) have the direction wrong. 5.270 does not follow from the 100.5 factor.
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