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Food Science and Technology QUESTION #6000
Question 1
The \(Z\)-value in thermal processing refers to:
  • The decimal reduction time at a given temperature
  • The temperature change required to produce a \(10\)-fold (\(1\) log cycle) change in \(D\)-value✔️
  • The total number of logs of microbial reduction achieved
  • The activation energy of the spoilage reaction
Correct Answer Explanation
\(Z\)-value is the temperature increase (\(^{\circ}\text{C}\) or \(^{\circ}\text{F}\)) required to reduce the \(D\)-value by a factor of \(10\) (1 log cycle). For \(C.\;botulinum\) spores, \(z = 10^{\circ}\text{C}\) (\(18^{\circ}\text{F}\)). \(Z\)-value is used to calculate equivalent thermal processes: \(F_T = D_T \times \log\left(\frac{N_0}{N}\right)\).