What is the composition and general formula of fats? To begin with, lipids play an important role in human nutrition. In addition to the energy function, they also enter all the tissues of our body. Let us analyze the features of this class of organic substances.
Definition
The general molecular formula of fats is O = CH 2 O - C - R 1 O - CHO - C - R 2 O - CH 2 O - C - R3
From a chemical point of view, this class of organic substances can be represented as a derivative of the trihydric alcohol glycerol and fatty carboxylic acids.
Depending on which alcohol and acid are part of lipids, there are three types of lipids:
- derivatives of lower alcohols and carboxylic acids (fruit);
- compounds of higher acids and alcohols (waxes);
- derivatives of glycerol and carboxylic acids (fats).
The general formula of the fat molecule confirms that these compounds belong to organic substances.
Connection Features
The molecules of these compounds contain a significant amount of hydrophobic groups and radicals; therefore, they are characterized by hydrophobicity, minimal solubility in water, and also in various organic substances.
Esters formed by alcohols and acids are volatile liquids with a pleasant fruity odor. The general formula of esters and fats is similar to the presence of carbonyl groups in the molecules.
Value for the body
Fats are found in foods much more often and in larger quantities than other representatives of the lipid class. In the general formula of complex fats, depending on which acids they form specifically, the radicals differ from each other. It is fats that are the source of the necessary energy in a living organism, in addition, they take an active part in plastic processes. It is in them that many biologically active compounds dissolve: vitamins A, D, E, K, sterols, phospholipids.
The general structural formula of fats indicates that the nature of the acid in their molecules affects the properties of these compounds.
Fats contain polyunsaturated fatty acids that cannot be synthesized in the human body: arachidonic, linolenic, linoleic.
Classification
Despite the fact that there is a general formula for fats, there is a division of these compounds by origin: into animal and plant species.
Vegetable fats are called oils. The general formula of the compounds of this group is characterized by the presence of glycerol and residues of unsaturated higher carboxylic acids.
Oils are divided into liquid and solid. Among the representatives of solid fats, palm and coconut oils are distinguished.
The general formula of fats of this group as radicals includes polyunsaturated essential acids, as a result of which these compounds have special nutritional value.
Depending on the properties, liquid fats are divided into groups:
- non-drying (almond, olive oil);
- semi-drying (cotton, sunflower oil);
- drying out (poppy, hemp, linseed oil).
Despite the differences in physical and chemical properties, the general formula of fats looks the same.
In vegetable drying oils there are glycerides of carboxylic acids with several unsaturated (double) bonds, and during their oxidation transparent films form.
Animal fats are obtained from mammalian adipose tissue, as well as from milk. There is a division of fats into solid and liquid compounds. Solid animal fats include mutton, beef, pork fat, butter (cow) oil. These substances are contained in the connective tissues of fish and animals, the amount of fat in living organisms depends on gender, age, season.
Features of the chemical composition of fats
We already know what the general formula of fats looks like. Chemistry is a science due to which it is possible to find out the structure of substances. A qualitative analysis found that plant and animal lipids contain vitamins, aromatic compounds, proteins, phosphatides, pigments, styrenes, which have a significant effect on the properties of fats.
Aldehydes, ketones, which are formed during their long-term storage, wag the taste and smell of these compounds.
Any fats enter the human body along with food. Each person has his own need for these compounds, taking into account age, working conditions, climatic factors. On average, an adult should consume about 80-100 grams of fat: seventy percent of animal origin, thirty percent of plant type.
In nature, there are about seventy different fatty carboxylic acids, but only five of them are considered the most common:
- palmitic;
- stearic;
- oleic;
- linoleic;
- linolenic.
Features of the physical properties of lipids
Depending on which acid is part of the fat, the melting point may have different meanings. At room temperature, lipids are presented in a liquid, ointment, solid state. Pork fat has a higher quantitative content of polyunsaturated fatty acids in comparison with beef.
The fats of various fish and plant lipids are high in unsaturated carboxylic acids.
Many vegetable fats rich in such organic acids retain a liquid state of aggregation even at temperatures of 0 ° C and below.
In fish oil, the percentage of unsaturated fatty acids is in the range of 62 to 82 percent; as a result, it is a liquid at room temperature.
When cooled, liquid fats thicken. With increasing temperature, solid fats turn into liquids, since they contain various triglycerides. Unsaturated fatty acids have the lowest melting point, since their molecules have double (unsaturated) bonds.
With an increase in the molecular weight of fatty saturated acids, an increase in their melting point is observed, and the digestibility of compounds decreases.
Body Assimilation Classification
According to the degree of digestibility, all fats are divided into three groups:
- Melting point less than 37 ° C, the percentage of digestibility 97-98%. This group includes vegetable liquid fats, melted pork and goose fat, cow's milk, fat of fish and birds.
- Lipids with temperatures above 37 ° C, which are absorbed up to 90 percent. Among the representatives of this group we single out the fat of cattle.
- Compounds with a melting point of 50-60 ° C, with little assimilation by the body.
Fat solutions have an acidic reaction. These compounds are practically insoluble in water, but in the presence of protein substances in it are able to form stable emulsions.
It is this property that allows you to get mayonnaise, margarine, ointments and creams on the basis of fats.
Fats dissolve well in organic compounds: petroleum and sulfuric ethers, carbon disulfide, chloroform, gasoline.
Chemical indicators
Fats are able to undergo various changes, for example, during prolonged storage, oxidative and hydrolytic damage to lipids is observed. Hydrolytic cleavage is observed in the manufacture and storage of fat-containing products. Under certain conditions, fats interact with water (hydrolysis), resulting in the formation of fatty carboxylic acids
The degree of hydrolysis is determined by the percentage of free fatty acids that degrade the smell and taste of the product. The process proceeds in three stages:
- First, one fatty acid is cleaved from the starting molecule of the triglyceride, and diglyceride is obtained.
- At the second stage, another fatty acid molecule is cleaved off, and the monoglyceride acts as the product.
- At the final stage of hydrolysis, the last molecule of fatty acid leaves, the product of the interaction is glycerin.
Glycerides formed in the first two stages act as catalysts (accelerators) of this process.
The non-enzymatic variant of fat hydrolysis is associated with the amount of water, which is an active participant in the reaction.
Enzymatic hydrolysis is carried out using lipases. The process accelerates significantly with increasing temperature. In bacon, smoked sausages, bacon, deep hydrolysis occurs, so long-term storage of these foods is not recommended.
Conclusion
Lipids are necessary for the full functioning of the body. Depending on age, gender, climatic characteristics, the amount of fat consumed varies significantly. Among the common options for spoiling foods containing fats, we highlight their oxidation. There is auto-oxidation and an enzymatic process. As a result of these transformations, the taste qualities of the products change, their nutritional value for the body decreases.
In order to avoid such problems, manufacturers of products containing vegetable and animal fats indicate the recommended shelf life. The general chemical formula of lipids indicates that these organic compounds may contain limiting and unsaturated higher carboxylic acids, which significantly affects the importance of fats for the body. Liquid fats do much more good for the human body than solid types.