Question

Which of the following known as “Cold sterilization” is used to reduce the microbial load of dairy liquids?

• A. Tyndallization
• B. Thermization
• C. Microfiltration
• D. Stassanization

Hint:

Microfiltration is called "cold sterilization" because it physically filters out bacteria and spores without using heat, preserving the native state of milk proteins.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Thermal pasteurization can denature whey proteins and alter the sensory characteristics of milk.
Non-thermal technologies are used to reduce the microbial load while preserving the native structure of milk proteins.

Step 2: Detailed Explanation:
Microfiltration is a physical separation membrane process that uses pore sizes of approximately $4\,\mu\text{m}$.
These pores allow milk plasma components (whey proteins, lactose, and minerals) to pass through while retaining bacteria, bacterial endospores, and somatic cells.
Because this microbial reduction is achieved without heat, the process is referred to as "cold sterilization."
This technology produces extended shelf-life (ESL) milk with minimal thermal denaturation of immunoglobulins and lactoferrin.
In contrast:
Tyndallization is a thermal process involving three successive heating cycles to germinate and destroy bacterial spores.
Thermization is a mild heat treatment ($63^{\circ}\text{C}$ to $65^{\circ}\text{C}$ for 15 seconds) used to limit bacterial growth during raw milk storage.
Stassanization is an older thermal method where milk is pasteurized as a thin film between concentric tubes.

Step 3: Final Answer:
Therefore, microfiltration is the process known as cold sterilization in dairy processing.