What is the purpose of z-values in planning pasteurization?

• A. They measure pH stability.
• B. They help predict how changes in temperature affect the lethality against different organisms.
• C. They indicate fat content.
• D. They describe packaging durability.

Answer: (B)

Z-values quantify how temperature affects the microbial kill rate. They represent the temperature change required to change the time needed for a given level of kill by a tenfold factor. In pasteurization planning, you use the z-value together with the D-value at a reference temperature to predict how long you must hold at other temperatures to achieve the same lethality. This lets you design processes that reliably reach the target log reduction, compare how different organisms respond to heat, and adjust for temperature variations. It’s not about pH stability, fat content, or packaging durability.