Question

Given below are two statements
Statement I: Homogenisation increases susceptibility of milk to lipolytic rancidity
Statement II: Homogenisation decreases susceptibility of milk to autoxidative changes
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are correct
• B. Both Statement I and Statement II are incorrect
• C. Statement I is correct but Statement II is incorrect
• D. Statement I is incorrect but Statement II is correct

Hint:

Homogenization increases both lipolytic rancidity (by increasing fat surface area for lipase action) and autoxidative rancidity (by disrupting the protective native membrane).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Homogenization is a mechanical process that reduces the size of milk fat globules to less than 1 to 2 micrometers.
This process stabilizes the emulsion against creaming but alters the chemical and physical susceptibility of the fat to rancidity.

Step 2: Detailed Explanation:
Let us evaluate both statements:
- Statement I: Homogenization reduces fat globule size, increasing the total surface area of the fat-water interface by up to ten-fold.
This disruption strips away the native milk fat globule membrane (MFGM), which is replaced by caseins and whey proteins.
This newly formed interface exposes the core lipids (triacylglycerols) to the active, indigenous lipoprotein lipase present in the skim milk phase.
If the milk is not immediately pasteurized to inactivate this enzyme, rapid lipolysis occurs, causing hydrolytic (lipolytic) rancidity. Thus, Statement I is correct.
- Statement II: Homogenization actually increases the susceptibility of milk to light-induced and copper-induced autoxidative changes.
The physical disruption of the native MFGM spreads pro-oxidative transition metals (such as copper and iron) and phospholipids over a larger surface area, accelerating free radical chain reactions.
Homogenized milk also allows deeper light penetration, which accelerates photo-oxidation. Thus, Statement II is incorrect.
Consequently, Statement I is correct but Statement II is incorrect.

Step 3: Final Answer
The correct option is (C).