Microbiology Z-value of an organism: A The time required to kill 90% of cells at a particular temperature B The time required to kill all cells at a particular temperature C Is the temperature change required for the D-value to change by a factor of ten D Is the temperature change required for the D-value to change by a factor of five 💡 Explanation Z-value of an organism: ✓ Correct Answer: C. Is the temperature change required for the D-value to change by a factor of ten