Animal Fat with Highest Iodine Number, Refractive Index and Linoleic Acid

Iodine number, refractive index & linoleic acid content are highest in:

Correct Answer: Horse Fat

Horse fat has the highest iodine number, refractive index, and linoleic acid content among all common animal fats.

What is Iodine Number (Iodine Value)?

• Iodine number measures the degree of unsaturation of a fat — the number of grams of iodine absorbed per 100g of fat.
• Higher iodine number = more unsaturated fat = more double bonds = lower melting point = softer/liquid at room temperature.

Why Horse Fat Has Highest Iodine Number?

• Horse fat is rich in polyunsaturated fatty acids (PUFAs), particularly linoleic acid (C18:2, omega-6).
• High PUFA → high iodine number (75–80 for horse fat).

Fat Properties by Species

• Horse fat: Iodine no. = 75–80; most unsaturated; highest linoleic acid
• Pig fat (lard): Iodine no. = 55–70; moderately unsaturated
• Cow fat (tallow): Iodine no. = 35–46; more saturated
• Sheep fat (suet): Iodine no. = 35–40; most saturated among common fats

Practical Implication

High iodine number fats are more susceptible to oxidative rancidity — pork fat is more susceptible than beef fat for this reason.