Question

Heating of unsaturated fats and oils, as in frying operations, can produce changes in the color, molecular weight, viscosity or refractive index due to

• A. Rancidity
• B. Hydrogenation
• C. Polymerization
• D. Termination

Hint:

When frying oil gets old, it becomes thick, gummy, and dark. This is primarily due to polymerization, where small fat molecules link up to form large, heavy polymers.

Answer 1

The Correct Option is C

Step 1: Understand deep frying's environment.Frying heats oil to high temperatures (typically 160-190\(^\circ\)C) for a prolonged time, exposing it to air and moisture from the food.
Step 2: Examine the chemical reactions happening under frying conditions.Unsaturated fatty acids in the oil are prone to reactions. While oxidation (causing rancidity) happens, polymerization is key at frying temperatures. Fatty acid molecules bond, creating larger polymer molecules. This increases molecular weight, significantly thickening the oil (increasing viscosity). These larger molecules also change the oil's color and refractive index. Hydrogenation, which needs a catalyst, isn't a main frying process. Termination is a chain reaction step, not the entire process itself.