The Tougher Quiz of D and Z values 


#1. Which of the following best describes the D-value in the context of microbial thermal death kinetics?

#2. If a bacterium has a D-value of 5 minutes at 121°C, how long will it take to achieve a 6-log reduction in the population at this temperature?

#3. The Z-value for a particular microorganism is 8°C. If the D-value at 100°C is 5 minutes, what is the D-value at 108°C?

#4. Given that the Z-value for a microorganism is 7°C, what would be the D-value at 93°C if the D-value at 100°C is 2 minutes?

#5. If a process requires a 12-log reduction of a specific microorganism with a D-value of 3 minutes at the processing temperature, how much total time is needed to achieve this reduction?

#6. A D-value of 4 minutes is observed at 115°C. What would be the D-value at 105°C if the Z-value is 10°C?

#7. What does the Z-value represent in microbial thermal death kinetics?

#8. For a bacterium with a Z-value of 12°C, how many degrees must the temperature be increased to reduce the D-value from 6 minutes to 0.6 minutes?

#9. If the initial population of a bacterium is 10(raised to the power 8) CFU and the D-value at the processing temperature is 2 minutes, how long would it take to reduce the population to 10 (raised to the power 2) CFU?

#10. A canning process is designed to achieve a 10-log reduction of Clostridium botulinum spores. If the D-value at 121°C is 2.5 minutes and the Z-value is 10°C, what would be the process time at 111°C?


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