Fatty acids

Synonym or subordinate term for monovalent, aliphatic carboxylic acids (monocarboxylic acids) which in nature are either ester-like bound to glycerol or to high molecular alcohols. Fatty acids are often designated by trivial names such as acetic acid, butyric acid, palmitic acid, which establish a relationship to their natural occurrence.

Fatty acids are organic compounds consisting of a hydrocarbon chain of varying length, usually unbranched, and a carboxyl group (-COOH). They occur in nature in great variety, for example in seed oils, fats and waxes. They are also involved in the formation of other natural substances such as phospholipids.

A distinction is made between saturated (no double formation) and unsaturated fatty acids (C=C), short- or long-chain fatty acids, branched (branched carboxylic acids are not always counted as fatty acids; they are found in some essential oils) or unbranched fatty acids.

Natural fatty acids: Many fatty acids occur naturally (natural fatty acids) in plant and animal organisms. Mostly not as free acids but as esters or salts. Natural fatty acids usually consist of an even number of carbon atoms and are unbranched. The carbon chain must be at least 4 C atoms long, making butyric acid the simplest natural fatty acid.

Unsaturated fatty acids: Fatty acids with double bonds are called unsaturated fatty acids. If there are several double bonds, they are usually separated by a CH2 group (-C=C-CH2-C=C-). Monounsaturated fatty acids are referred to as monoenoic acids, dienoic acids as double unsaturated fatty acids, triple unsaturated fatty acids as trienoic acids, polyunsaturated fatty acids as polyenoic acids.

Omega fatty acids: The classification of unsaturated fatty acids is based on the position of their double bonds. The carbon atom carrying the carboxylic group is called the omega carbon atom. All other atoms are numbered from here. E.g. Omega-3 fatty acids, omega-6 fatty acids, omega-9 fatty acids.

Essential fatty acids (vitamin F): Essential fatty acids are polyunsaturated fatty acids which the organism itself cannot synthesize. Of particular importance are the omega-6 fatty acids as components of vegetable oils. Furthermore, the omega-3 fatty acids found in cold-water fish (herring, salmon) and the fish oils produced from them.

Examples of saturated fatty acids and their natural occurrence:

• Formic acid (methanoic acid, HCOOH; widely used)
• Acetic acid (ethanoic acid, CH3COOH;vinegar (by oxidation of ethanol)
• Propionic acid (C2H5COOH, formed during methane fermentation)
• Butyric acid (C3H7COOH, milk fat, sweat)
• Valeric acid (pentanoic acid, C4H9COOH, valerian root, wood vinegar Valerian root, wood vinegar)
• Caproic acid (hexanoic acid, C5H11COOH, milk fat, formed during butyric acid fermentation)
• Caprylic acid (octanoic acid, C7H15COOH, milk and coconut fat)
• Pelargonic acid (nonanoic acid, C8H17COOH, essential oil of Pelargonium roseum, cheese, wine)
• Capric acid (decanoic acid, C9H19COOH; animal and vegetable fats)
• Lauric acid (dodecanoic acid, C11H23COOH; milk fat, vegetable fats)
• Myristic acid (tetradecanoic acid, C13H27COOH; milk fat, fish oil, animal and vegetable fats)
• Palmitic acid (hexadecanoic acid, C15H31COOH; palmitic acid and stearic acid, as glycerol esters, are the main components of all animal and vegetable fats. animal and vegetable fats)
• Margaric acid (heptadecanoic acid, C16H33COOH; animal and vegetable fats)
• Stearic acid (octadecanoic acid, C17H35COOH; frequently occurring animal and vegetable fats, is used as a food additive (E 570).
• Arachidic acid (eicosanoic acid, C19H39COOH; in small amounts in plant seeds and animal fats)
• Behenic acid (docosanoic acid, C21H43COOH, in small amounts in plant seeds and animal fats, pathologically occurring in the organism in Gaucher's disease)
• Lignoceric acid (tetracosanic acid, C23H47COOH, vegetable fats, component of sphingomyelin)
• Cerotic acid (hexacosanoic acid, C25H51COOH, beeswax, carnauba wax, montan wax)

Examples of monounsaturated fatty acids (1 double bond)

• Undecylenic acid (C10H19COOH)
• Palmitoleic acid (C15H29COOH, milk fat, depot fat of animals, fish oil, vegetable fat)
• Oleic acid (C17H33COOH, in almost all natural fats)
• Elaidic acid (C17H33COOH, in animal fats)
• Icosic acid (C19H37COOH, in rape oil)

Examples of polyunsaturated fatty acids

• Linoleic acid (C17H31COOH, vegetable oils, especially safflower oil)
• Linolenic acid (C17H29COOH, various vegetable oils, especially linseed oil; the linoleic acid isomer with the double bonds in positions 9, 12 and 15 is called alpha-linolenic acid, the isomer with the double bonds in positions 6, 9 and 12 is called gamma-linolenic acid)
• Arachidonic acid (C19H31COOH, animal fats, fish oil)
• Cervonic acid (C21H31COOH, fish oil)

In the food industry, fatty acids are mainly used as raw materials for various emulsifiers. Furthermore, fatty acids are used as carriers, separating agents or as coating agents. Fatty acids are generally approved in the EU as food additives under the collective designation E 570 without maximum quantity restriction (quantum satis) for foodstuffs.

Soaps: Soaps are sodium or potassium salts of higher fatty acids. They are used as surfactants.

1. Bährle-Rapp (2012) Springer Lexicon Cosmetics and Personal Care. 4th revised and extended edition. Springer Publishing House GmbH S 212-213
2. Burger A et al (1993) Hunnius Pharmaceutical Dictionary 7th Edition Walter de Gruyter Berlin-New York S 539-544