Question

Subjecting fats to high temperature in the presence of oxygen such that fats deteriorate is called ...........

• A. Hydrolytic rancidity
• B. Auto‐oxidation
• C. Thermal decomposition
• D. Lipolysis

Hint:

To prevent auto-oxidation, food scientists add antioxidants (like BHA/BHT or Vitamin E) which act as radical scavengers, interrupting the propagation stage of the chain reaction.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the term describing the chemical degradation of fats when exposed to heat and oxygen. This process leads to the formation of off-flavors and off-odors, commonly known as rancidity.

Step 2: Detailed Explanation:

• Auto-oxidation: This is the primary mechanism for oxidative rancidity. It is a free-radical chain reaction involving three main stages:
- Initiation: Heat, light, or metal catalysts cause the formation of a fatty acid radical ($R \cdot$) by the removal of a hydrogen atom.
- Propagation: The radical reacts with atmospheric oxygen to form a peroxy radical ($ROO \cdot$), which then reacts with another fat molecule to produce a hydroperoxide ($ROOH$) and a new radical.
- Termination: Radicals react with each other to form stable, non-radical products.

• Role of Temperature: High temperatures act as a catalyst, significantly accelerating the initiation phase. The resulting hydroperoxides are unstable and break down into secondary products like aldehydes, ketones, and alcohols, which cause the characteristic rancid smell.

• Hydrolytic Rancidity (A) Lipolysis (D): This involves the cleavage of triglycerides into free fatty acids and glycerol by the action of water (hydrolysis) and enzymes (lipases). It does not necessarily require oxygen or high temperatures.

• Thermal Decomposition (C): While related to high heat, it usually refers to the deeper breakdown of molecules (like polymerization or cracking) at extreme temperatures beyond simple oxidation.

Step 3: Final Answer:
The process of fat deterioration in the presence of oxygen and heat is Auto-oxidation.