Fatty and oil are one of the groups included in the class of lipids, namely organic compounds found in nature and not soluble in water, but soluble in non-polar organic solvent such as diethyl ether (C2H5OC2H5), Chloroform (CHCl3), benzene and hydrocarbons other, fat and oil are soluble in the solvents mentioned above because the fats and oils have the same polarity with the solvent.
In daily life oil used as an intermediate heat as in frying, beside oil in condition solid (fatty) is used in food processing. In the process of production of fatty and oil generally are done with the extraction and refining. In some types of fatty or oil susceptible to rancidity. Rancidity is the process damage cooking oil that causes taste and unpleasant smell. This is a result of process decomposition oil due to seepage water (hydrolysis) and damage to oil because of presence oxygen (oxidation).
Oxidative and hydrolytic rancidity will cause the formation of new compounds that are not molecule of oil (tiasilgliserol), thus providing a distorted taste and unpleasant smell. process of Hydrolytic rancidity will cause the disintegration of the oil molecules (triasilgliserol) into fatty acids and glycerol. Hydrolytic rancidity is usually due to presence of water and high temperatures (in the frying process wet food products) and on butter or margarine products. To inhibit process rancidity, often added a few compounds. Among other things, carotene (pro-vitamin A).
To prevent rancidity on production of fatty oil by adding antioxidants, which aims to prevent rancidity is caused by oxidative activity.