Question

Which among the following will not contribute to the iodine value of ghee?

• A. Palmitoleic acid
• B. Linoleic acid
• C. Palmitic acid
• D. Arachidonic acid

Hint:

Only unsaturated fatty acids containing double bonds (\(\text{C}=\text{C}\)) undergo addition reactions with iodine and contribute to the measured iodine value of a fat sample.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The Iodine Value is a chemical index used to measure the degree of unsaturation in fats and oils.
It is defined as the number of grams of iodine absorbed by \(100\,\text{g}\) of the fat sample.
Iodine reacts quantitatively via an addition reaction across carbon-carbon double bonds (\(\text{C}=\text{C}\)).

Step 2: Detailed Explanation:
The iodine absorption reaction depends on the molecular structure of the constituent fatty acids:
Palmitoleic acid is a monounsaturated 16-carbon fatty acid (\(16:1\)) containing one double bond, which reacts with iodine.
Linoleic acid is a polyunsaturated 18-carbon fatty acid (\(18:2\)) containing two double bonds, which react with iodine.
Arachidonic acid is a polyunsaturated 20-carbon fatty acid (\(20:4\)) containing four double bonds, which react with iodine.
Palmitic acid is a saturated 16-carbon fatty acid (\(16:0\)) containing only single carbon-carbon bonds.
Saturated fatty acids do not undergo addition reactions with halogens under standard test conditions and do not absorb iodine.
Therefore, palmitic acid does not contribute to the iodine value of ghee.

Step 3: Final Answer:
Thus, palmitic acid does not contribute to the iodine value of ghee.