Question

Milk fat may be decomposed by various bacteria, yeasts, and molds, the changes that take place in the milk fat are:
A. Oxidation of the unsaturated fatty acids
B. Hydrolysis of the butterfat to fatty acids
C. Alkali production
D. Combined oxidation and hydrolysis to produce rancidity

• A. A, B and D only
• B. A, B and C only
• C. B, C and D only
• D. A, C and D only

Hint:

Remember the two main types of rancidity for fats: hydrolytic (lipolysis - requires water and lipase) and oxidative (autoxidation - requires oxygen and affects unsaturated fats). Both lead to spoilage.

Answer 1

The Correct Option is A

Step 1: Analyze the types of fat degradation mentioned. Milk fat (butterfat) degradation primarily involves two chemical processes:

Hydrolysis: Lipase enzymes (from microbes or native to milk) break down triglycerides into glycerol and free fatty acids. This is known as hydrolytic rancidity and is described in statement B.
Oxidation: Unsaturated fatty acids react with oxygen, leading to off-flavors. This is known as oxidative rancidity and is described in statement A. \end{itemize}
Step 2: Evaluate the given statements.

A. Oxidation of unsaturated fatty acids: This is a major pathway for fat decomposition.
B. Hydrolysis of the butterfat to fatty acids: This is another major pathway.
C. Alkali production: Fat decomposition produces fatty acids, which are acidic, not alkaline. So, this is incorrect.
D. Combined oxidation and hydrolysis to produce rancidity: Rancidity is the term for the off-flavors and odors resulting from these decomposition processes. Both processes contribute to it. This statement is correct. \end{itemize} Therefore, statements A, B, and D are correct.