Question

Which of the following statements are true regarding transfat?
A. Deep frying leads to conversion of cis fatty acids to trans fatty acids
B. Cis fatty acids have straight carbon chain while trans fatty acids have bent carbon chain
C. Trans fatty acids have straight carbon chain while cis fatty acids have bent carbon chain
D. Deep freezing leads to conversion of cis fatty acids to trans fatty acids

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

Hint:

Trans double bonds result in straight, linear fatty acid chains that mimic saturated fats, while cis double bonds insert a distinct bend (kink) in the chain.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Unsaturated fatty acids contain one or more double bonds in either a cis or trans geometrical configuration.
These configurations differ in the spatial arrangement of hydrogen atoms around the carbon-carbon double bond, which determines their physical and chemical properties.

Step 2: Detailed Explanation:
Let us analyze the provided statements regarding trans fatty acids:
- Statement A: During deep frying, oil is subjected to high temperatures (above 180$^\circ$C) and thermal stress in the presence of oxygen and water.
This thermal stress induces isomerization, converting some of the natural cis double bonds of unsaturated fatty acids into the thermodynamically more stable trans configuration. Thus, Statement A is true.
- Statement B and C: In a cis configuration, the hydrogen atoms are on the same side of the double bond, creating a steric repulsion that introduces a rigid bend or "kink" in the hydrocarbon chain.
In a trans configuration, the hydrogen atoms are on opposite sides of the double bond, allowing the carbon chain to remain relatively straight and linear, similar to saturated fatty acids.
This linear structure allows trans fatty acids to pack tightly, raising their melting point. Thus, Statement C is true and Statement B is false.
- Statement D: Deep freezing preserves chemical structures and does not provide the activation energy required to isomerize cis double bonds into trans double bonds. Thus, Statement D is false.
Consequently, statements A and C are correct.

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