Fatty acids are monobasic carboxylic acids of the aliphatic series with a hydrocarbon chain of at least four carbon atoms, a component of the lipids of animals and plants, predominantly with an even number of carbon atoms (C14 – C24). They are present in all organisms in the form of esters (i.e., with glycerol and cholesterol) and serve as structural elements of fats and membrane lipids. Fats are organic compounds of animal, plant or microbial origin, consisting mainly (up to 98%) of triglycerides (acylglycerols), full esters of glycerol and fatty acids. The iodine number represents the content of double bonds and determines the overall unsaturation of fats. The higher the iodine number, the more iodine can attach, the more unsaturated acids are contained in the fat. For example, the iodine number of plant oils is higher than iodine number of animal fats due to the difference in the number of unsaturated bonds.