What are short-chain fatty acids? Everything about propionic acid and its sisters
The building blocks of life consist of a large number of different carbon compounds. This is due to the special ability of carbon to form complex long-chain and branched molecules. In interaction with other elements - mainly hydrogen, oxygen, sulphur, nitrogen and phosphorus - the huge number of compounds that determine life on earth are created. It starts with methane, which consists of just one carbon and four hydrogen atoms, and extends to the huge molecules of DNA, which consist of hundreds of thousands of atoms. Fatty acids and their subgroup, the short-chain fatty acids, are also part of this cosmos of carbon-based compounds. Thanks to their ability to store energy, they protect us and give us - life.
What are fatty acids in general?
To understand fatty acids, we need to understand their chemistry: fatty acids are carbon chains of varying lengths, which are determined by their functional group. This refers to the part of the chemical compound that determines its individual chemical behavior. For this reason, this part of the molecular chain is also called the "characteristic group." The functional group of fatty acids is called the carboxy group. This is why fatty acids are also referred to as carboxylic acids. In nature, medium and long-chain fatty acids - those with more than six carbon atoms - are often found in combination with glycerin. In glycerin, they form the natural fats and oils found in seeds, nuts and - undesirably - on hips. The longer the fatty acid, the firmer the fat. And the firmer the fat, the more energy is stored in it. At the same time, however, it is also more difficult for the body to process the fat and use the energy in it.
To clarify: Why do we need long-chain fatty acids?
For our body, fat is primarily an ideal energy store. The body can convert excess energy from sugar into fat and thus store it for later use. Fats not only play a role as an energy store, but are also of great importance for many metabolic processes. For example, they are needed for vital conversion processes of vitamins or hormones. The Omega 6 fatty acid linoleic acid and linolenic acid, which belongs to the Omega 3 fatty acids, are also essential, meaning that the human body cannot produce them itself.
What does short-chain fatty acids mean?
Short-chain fatty acids are fatty acids that consist of a chain of a maximum of six carbon atoms. Due to their low mass, short-chain fatty acids are liquid at room temperature, very volatile and give off an intense smell. Let's be honest: they often smell pretty bad. In nature, they do not normally occur in their pure form, but only in combination with other molecules. While medium and long-chain fatty acids can be ingested with food, short-chain fatty acids are mainly formed by intestinal bacteria. There are six different types of short-chain fatty acids, which we would like to introduce to you below:
- formic acid
- acetic acid
- propionic acid
- butyric acid
- valeric acid
- caproic acid
formic acid
It is the shortest of the short-chain fatty acids because it consists of just one carbon atom, more precisely the carboxyl group (COOH) and a hydrogen particle (H), in the molecular formula HCOOH. Analogous to methane, molecular formula CH 4 , it is also called methanoic acid. Formic acid is widespread in nature. It is found in almost all organisms, particularly in the venom glands of ants. Other plants and animals also use formic acid for their defense mechanism, such as some species of jellyfish or stinging nettles. In the human body, formic acid is produced as a metabolic product during the breakdown of methanol. Formic acid is used in a wide variety of industrial processes, from rubber production to de-icing aircraft. In medicine, formic acid is used as an anti-rheumatic and for the external treatment of warts.
acetic acid
In acetic acid, two carbon atoms have already joined together, resulting in the molecular formula CH 3 COOH. Chemists call it ethanoic acid. Acetic acid is colorless and typically smells pungently of vinegar. Household vinegar is a five to six percent acetic acid solution. In the world of plants, acetic acid is found as a component of essential oils, among other things. Widespread bacteria also produce acetic acid as a metabolic product. Otherwise, natural acetic acid is created by the oxidation of alcohol. All you need to do is leave a bottle of beer or wine open for a few days. Acetic acid is of great importance as a food, whether as a seasoning or for making cheese products. Its industrial uses range from cleaning agents to the production of plastics and solvents. The painkiller acetylsalicylic acid, better known as aspirin, is a compound of acetic acid and salicylic acid. Its versatile uses make acetic acid one of the most industrially important organic acids.
propionic acid
Propionic acid is the common name for propanoic acid. It consists of a real chain of three carbon atoms in the molecular formula CH 3 CH 2 COOH. Propionic acid has a pungent smell and tastes slightly unpleasant. In nature it occurs as an essential oil and is also produced by some bacteria. This is particularly important in the production of Emmental cheese, because it is responsible for the typical holes and, in the form of its salt propionate, also for the taste of the cheese. In the human large intestine, propionic acid is produced by bacteria that break down previously undigested carbohydrates, i.e. fiber. Propionic acid is used industrially as a preservative for food, although due to its volatility and taste it is used in the form of its salts sodium propionate, calcium propionate or potassium propionate.
butyric acid
Butyric acid, formally butanoic acid and formally CH 3 (CH 2 ) 2 COOH, consists of four carbon atoms. It is considered the first real fatty acid because it actually occurs in fat, namely milk fat. Butyric acid does not smell good. It is responsible for the smell of rancid butter. It is also not blameless for bad breath and the smell of sweaty feet. Butyric acid is formed by bacteria that are also involved in fermentation processes. As a result, butyric acid is contained in all foods that are produced by fermentation, such as sauerkraut, cheese or beer. The esters of butyric acid are responsible for the aroma of a wide variety of fruits. Esters are compounds of acids and alcohol, such as methanol, ethanol or propanol. The food industry takes advantage of this effect and also uses the various butyric acid esters as flavorings. In the chemical industry, butyric acid is used to produce plastics. A diet rich in fiber promotes the formation of butyric acid.
valeric acid
Valeric acid is a fatty acid with five carbon atoms, hence its systematic name is pentanoic acid (from the ancient Greek word for five: pénte). Strictly speaking, pentanoic acid is a group of acids that all have the molecular formula C 4 H 9 COOH in common, but have different structures and properties. These are then referred to as isomers. They are a component of the essential oils of valerian, tea, cocoa and apples. The esters of pentanoic acids are particularly important as flavorings for the food industry.
caproic acid
With six carbon atoms, caproic acid is the longest of the short-chain fatty acids. Its molecular formula is C 5 H 11 COOH and its chemical name is hexanoic acid. Its unpleasant smell is reminiscent of goat, hence the common name goat acid. It is found in small amounts in milk fat and is also a component of various essential oils, for example pine needle oil, lavender oil or raspberries. Caproic acid is also used to produce flavorings for the food industry.
Conclusion: What can short-chain fatty acids do?
Due to their special chemical properties, short-chain fatty acids can be found in a wide variety of areas of life - and they do amazing things there. Although they often smell bad in their pure form, a wide variety of scents and flavors are made from them. They are used to make plastic or nail polish remover. But also far beyond that: short-chain fatty acids are an essential component in the building blocks of life.
