Which of the following is NOT an intrinsic factor affecting microbial survival in foods?

• A. pH
• B. Water availability
• C. Nutrient availability
• D. Temperature

Answer: (B)

Understanding intrinsic versus extrinsic factors is essential for predicting microbial survival in foods. Intrinsic factors are properties of the food itself, such as pH, water activity (water availability), and nutrient content, along with the food’s physical structure and redox potential. These characteristics are inherent to the product and don’t depend on how the food is stored or handled.

Extrinsic factors are environmental conditions surrounding the food, like storage temperature, humidity, and the atmospheric conditions in which the food is kept. Temperature is a classic extrinsic factor because it comes from the storage environment rather than from the food’s own properties.

So, among the options, pH, water availability, and nutrient availability are intrinsic factors, while temperature is not. The factor not intrinsic is temperature.