Not all fats are the same. This is immediately apparent to anyone who reads up on healthy nutrition.
This fact is related to the structure of fat. Fats are the esters of long-chain carboxylic acids. These carboxylic acids are esterified with glycerol (propane-1,2,3-triol, glycerol), a polyhydric alcohol.
Each of the three hydroxyl groups of the glycerol can react with another carboxylic acid, so that completely different fats are formed and exist.
Importance of fats
As unpleasant as an excess of fat in the body is for humans, fats are vital and of great importance for plants, animals and humans.
To build up the body’s own fats, humans and animals have to take in these substances with their food.
Plants form fats through the conversion of glucose, which is produced during photosynthesis.
Continuous fat building and fat decomposition takes place in the living beings. Enzymes trigger and control these processes.
Energy is released when fats are broken down. This energy is available to organisms for the running of life processes. Fats are energy stores in the cells.
Fats ingested with food are broken down into their smallest water-soluble components during digestion, enter the bloodstream and can serve as starting materials for the body’s own fats.
Fat that is not needed immediately is stored and serves as an energy reserve. A part coats the internal organs and is called building fat.
Many animals have a thick layer of endogenous fat to protect themselves from cold and moisture. A pronounced subcutaneous fat tissue, z. B. in seals and whales, is a good insulating layer.
The plumage of birds or the fur of mammals becomes water repellent through greasing.
However, fats are also of great importance in connection with a healthy diet: since vitamins A, D and E are insoluble in water but soluble in fat, the body can only absorb them in dissolved form in fatty foods.
Structure and properties of fats
Not all grease is the same. This is immediately obvious to anyone who reads up on healthy nutrition.
Fats have very different structures. Fats are esters of carboxylic acids.
The carboxylic acids are linked in the fat with glycerol (glycerol, propane-1,2,3-triol), a polyhydric alcohol.
Each of the three hydroxyl groups of glycerol can react with a different carboxylic acid, resulting in very different fats.
The carboxylic acids involved in the construction of fats are called fatty acids.
The fatty acids are long-chain carboxylic acids. An exception is butanoic acid, which has only four carbon atoms in the molecule.
In natural fats, the chains are always unbranched and composed of an even number of carbon atoms. These are either long-chain saturated (alkanoic acids) or unsaturated or. polyunsaturated compounds.
The unsaturated fatty acids contain double or triple bonds in the molecule.
That unsaturated carboxylic acids are contained in fats can be demonstrated by decolorizing bromine water (bromine in water).
Classification of the fires
According to the state of aggregation, solid fats, semi-solid and liquid fats can be distinguished.
Almost exclusively saturated fatty acids are involved in the formation of solid fats.
Solid fats are, with a few exceptions, z. B. Coconut fat, of animal origin.
Liquid fats contain unsaturated fatty acids in various proportions and are almost always of vegetable origin. They are very healthy, because the human body cannot produce these unsaturated fatty acids itself and therefore urgently needs them.
Fats that are liquid at room temperature are also called fatty oils.
Properties of fats
Since fats are not uniform substances but mixtures of substances, they do not have an exact melting temperature. They have a melting range.
All fats are insoluble in water. Their density is below 1 g/cm3. Therefore they float on water. Because of their insolubility in water, they can only be removed from tissues with special solvents.
By vigorous stirring or shaking fats can be mixed with water, an emulsion is formed, which contains smallest fat droplets, but is not stable for a long time.
Fat and water segregate. Emulsions are butter, margarine and milk.
Extraction of the fats
The extraction of fats from animals or plants can be done by melting, squeezing, extraction and refining.
During melting out, animal parts rich in depot fat are heated to the melting range of the fats they contain. Connective tissue components remain in the solid state and can be separated from the liquid fat.
Oily seeds are well broken down. Under pressure the oil is squeezed out. The residue, which still contains oil, is a nutrient- and energy-rich feedstuff.
During extraction, a solvent is sprayed over the crushed oil fruits (seeds). It dissolves the oil out of the seeds. The oil can be separated from the solvent by the distillation process.
The oil obtained by squeezing or extracting still contains free fatty acids as well as disturbing taste and odor substances. The process for their elimination is called refining.