Rancidification is the decomposition of fats and other lipids by hydrolysis and/or oxidation. Hydrolysis will split fatty acid chains away from the glycerol backbone in glycerides. These free fatty acids can then undergo further auto-oxidation. Oxidation primarily occurs with unsaturated fats by a free radical-mediated process. These chemical processes can generate highly reactive molecules in rancid foods and oils, which are responsible for producing unpleasant and obnoxious odors and flavors. These chemical processes may also destroy nutrients in food. Under some conditions, rancidity, and the destruction of vitamins, occurs very quickly. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... A polyunsaturated triglyceride. ... Hydrolysis is a chemical reaction or process in which a chemical compound reacts with water. ... The most fundamental reactions in chemistry are the redox processes. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... Glycerol is a chemical compound with the formula HOCH2CH(OH)CH2OH. This colorless, odorless, viscous liquid is widely used in pharmaceutical formulations. ... Glycerides are esters of glycerol and fatty acids. ... In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. ... An unsaturated fat is a fat or fatty acid in which there are one or more double bonds in the fatty acid chain. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ... A nutrient is either a chemical element or compound used in an organisms metabolism or physiology. ... Retinol (Vitamin A) For the record label, see Vitamin Records A vitamin is an organic compound required in tiny amounts for essential metabolic reactions in a living organism. ...

Antioxidants are often added to fat-containing foods in order to retard the development of rancidity due to oxidation. Natural anti-oxidants include flavonoids, polyphenols, ascorbic acid (vitamin C) and tocopherols (vitamin E). Synthetic antioxidants include butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and ethoxyquin. The natural antioxidants tend to be short-lived, so synthetic antioxidants are used when a longer shelf-life is preferred. The effectiveness of water-soluble antioxidants is limited in preventing direct oxidation within fats, but is valuable in intercepting free-radicals that travel through the watery parts of foods. A combination of water-soluble and fat-soluble antioxidants is ideal, usually in the ratio of fat to water. Space-filling model of the antioxidant metabolite glutathione. ... Molecular structure of flavone The term flavonoid refers to a class of plant secondary metabolites based around a phenylbenzopyrone structure. ... Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. ... This article deals with the molecular aspects of ascorbic acid. ... Tocopherol, or Vitamin E, is a fat-soluble vitamin in eight forms that is an important antioxidant. ... Butylated hydroxyanisole (BHA) is a mixture of two isomeric organic compounds, 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. ... Butylated hydroxytoluene (BHT) is a fat-soluble organic compound primarily used as an antioxidant food additive (E number E321). ... Ethoxyquin is a quinoline-based antioxidant used as a food preservative. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ...

Additionally, rancidification can be decreased, but not completely eliminated, by storing fats and oils in a place with little exposure to oxygen or free radicals, low temperature, and away from light, since light and heat accelerate the rate of reaction of fats with oxygen.

See also

• Food preservation
• Preservative
• Putrefaction
• Fermentation