The iodine value (IV), also known as iodine number or iodine absorption value, is a measure of the degree of unsaturation in a substance, most commonly used for fats, oils, and waxes. It's expressed as the grams of iodine absorbed by 100 grams of the substance.
Here's the key concept:
Unsaturation: Fats and oils with double bonds between carbon atoms in their fatty acid chains are considered unsaturated. Iodine is a reactive element, and these double bonds readily react with it.
Higher Iodine Value: The more double bonds (more unsaturation) present, the more iodine a substance can absorb, resulting in a higher iodine value.
Saturated Fats: Conversely, saturated fats lack double bonds and have only single bonds between carbon atoms. Since iodine cannot react with these single bonds, saturated fats have an iodine value of zero.
Therefore, the iodine value essentially tells you how much unsaturation is present in a fat, oil, or wax.