Principles of Biochemistry

6.4.5.3 Iodine number

It is defined as the amount in grams of iodine absorbed by 100 g of fat. The triglycerides of unsaturated fatty acids react with a definite amount of iodine, which adds across the double bond. In commercial practice it usual to measure the degree of unsaturation in oil which is reported as the iodine number. It is often used to classify an unknown oil or fat into a particular class by determining the degree of unsaturation. e.g. cod liver oil has an iodine value between 155 and 170.