FATS

From Big Medical Encyclopedia

FATS — the organic compounds representing esters of triatomic alcohol — glycerin and the higher or average fatty acids; contain in all animals and vegetable fabrics, treat the main feedstuffs, are the main component of fatty tissue of animals and the person, and also the oils which are contained in seeds of plants. as impurity contain a nek-swarm quantity free fat to - t and insignificant amount of unsaponifiables., free from such impurity, are called neutral. Used in food of the person Zh. it is more correct to call fatty products since a small amount of zhiropodobny substances — lipoid enters into their structure, except actually fats (sterols, phospholipids and so forth). A structure of triglycerides of which consist., it can be expressed in a habit view by a formula:

where R1 and R2 — the remains various fat to - t.

Physical and chemical properties

All natural. represent mixes of various glycerides, not only symmetric, i.e. with three identical remains fat to - the t but also mixed which molecule contains two or three rests different fat to - t. Symmetric glycerides meet in the vegetable oils containing a large number of one fat to more often - you, napr, contains in sunflower-seed oil apprx. 60% linoleic to - you, and in linen — to 70% linoleic to - you. Majority of animals. differs in very various structure fat to - t. Modern methods of the analysis — a gas liquid chromatography and mass spectrometry established existence in animals. tens individual fat to - the t with a simple and branched chain and also containing oksi-and ketogroups. Names of mixed triglycerides are formed from being their part fat to - t, at the same time letters α and β indicate communication of the rest fat to - you with primary or secondary spirit group in a molecule of glycerin, napr, alpha oleo - beta palmitostearin. In a molecule of mixed triglycerides theoretically in beta situation it is possible availability of asymmetric S-atom, however still optical activity natural. it was not succeeded to find. Synthesis of symmetric glycerides is possible to carry out rather easily, receiving individual mixed. it is accompanied by considerable difficulties. Fatty acids (see), being a part of triglycerides, define them physical. - chemical properties. Along with palmitic, stearin, olein and linoleic to-tami, the most often being a part of natural., also presence at some of them of the glycerides containing fat to - you with a short and average carbon chain length is known. Such. tributyrin and glycerides are kapron, caprylic and capric to - t in milk fat, glycerides myristic to - you in coconut and muscat oils. At a dietotherapy of some diseases connected with disturbance of absorption. in a digestive tract, began to apply triglycerides with an average carbon chain length (10 — 14 S-atoms) which are a product of fractionation of natural. (piririma oil, etc.).

Specific weight of fats fluctuates from 0,910 to 0,996. Temperature of melting. depends on character being their part fat to - t:., the containing significant amounts saturated fat to - t (palmitic, stearin, etc.), have more than high melting temperature;., which part is a lot of mono - and polyunsaturated fat to - t, are liquid at a usual temperature and are called oils. marine animals are carried by the name of blubber; in medicine it is used. marine animals for external use (so-called medical fat): it contains 1000 ME vitamins A and 100 ME vitamins D in 1 g 2 . are well dissolved in organic solvents — benzene, chloroform, ether, carbon sulfur, petroleum ether, hot alcohol (in cold — it is more difficult), acetone and are water-insoluble. In the presence in water solutions Zh. surfactants (emulsifiers). are capable to form emulsions (see). Emulsifiers Zh. there can be proteins, phospholipids, soaps, salts bilious to - t, and also some specially synthesized substances (see. Emulsifiers food ).

Triglycerides are capable to enter all chemical reactions inherent to esters; reaction of saponification has the greatest value, as a result a cut are formed of triglyceride glycerin and fat to - you:

Saponification. can occur both at catalytic hydrolysis, and at effect of acids or alkalis. In the first case. are split in the autoclave at a temperature apprx. 170 ° and pressure of 6 — 8 atm, as the catalyst zinc oxide is applied. Acid hydrolysis is conducted in the presence of sulfuric to - you or some sulfonic acids. Alkaline cleavage. at effect of caustic soda or caustic heat the hl is carried out. obr. at industrial receiving soap. By means of enzymic hydrolysis with participation of lipases (e.g., lipases from seeds of a castor-bean tree) at a temperature apprx. 40 ° it is possible to achieve splitting of emulsified. on glycerin and fat to - you. In laboratory practice saponification is carried out boiling. in 0,5 N spirit solution caustic heat. It should be noted also that ester exchange is characteristic of triglycerides, a cut widely use for receiving methyl ethers fat to - the t used at gazokhromatografichesky identification of ratio of mixture fat to - t:

As catalysts in ester exchange both acids, and alkalis are used. Transesterification at temperature increase and in the presence of catalysts it is also possible to cause migration of acid residues and their redistribution between molecules of triglycerides. Thus receive reetherified., physical differing on. to properties from initial.

The vegetable oils containing a large number fat to - t with two or three double bonds (linen, hempy, poppy, tung), are known under the name of drying oils since under the influence of oxygen of air they will be polymerized and harden. These oils are applied by production of varnishes and drying oils., containing unsaturated fat to - you, can be hydrogenated, i.e. are subjected to saturation by hydrogen in the place of double and acetylene bonds. The technology of this process was developed for the first time by the Russian scientist S. A. Fokin (1909). The hydrogenation is applied to receiving from vegetable oils Zh. firmer consistence, margarine which are used as a fatty basis. At a hydrogenation. there is not only a saturation of double or acetylene bonds hydrogen, but also formation of trans-isomers unsaturated to - t which have more than high melting temperature, than cis-isomers. Changing conditions of process (temperature, partial pressure of hydrogen, the catalyst), it is possible to receive hydrogenated. with various set physical. characteristics

. at storage, especially on light and at free access of air, undergo certain changes, develop off-flavor, turn rancid. It is established that in rancidification. the major role is played by processes of oxidation unsaturated fat to - t oxygen of air. The peroxides which are formed at the same time decay then with release of aldehydes. Existence of «aldehydic» rancidification can be established on reaction with phloroglucinol in the presence of salt to - you, followed by emergence of red coloring. There is also an oxidation unsaturated fat to - t in r - ketonic acids which as a result decarboxylations (see) turn into methylketones.

«Ketonic» rancidification is found reaction with salicylic aldehyde, specific to methylketones.

For establishment of the nature and the characteristic of this or that. along with definition its physical. properties the results of definition of some of its chemical properties expressed as conditional numbers are of great importance. The most important of them are acid number, saponification ratio, an oxirane value and peroxide value. Availability of peroxides fat to - t is established by definition of the peroxide value (PV) titration of the free iodine which is emitted at addition of KI to.; PCh express in weight percents of iodine. The Acid Number (AN) serves for quantitative assessment fat to - the t which are contained in. in a stand-at-ease; it is in number equal to the number of milligrams caustic heat, spent for neutralization of one gram. Saponification ratio (40) represents the number of milligrams caustic heat, spent for neutralization of all fat to - the t (both the free, and present at a look ethers of glycerin) which are contained in one gram.; it serves for assessment of total quantity fat to - t in investigated. Size 40 at the main animal fats (beef, mutton, pork) is almost identical — 191 — 206. The Iodine Number (IN) is equal to amount of the iodine joining in certain conditions the 100th weight. h substance; it serves for definition of total quantity of attendees in. unsaturated compounds. YCh of beef fat is equal 32 — 47, mutton fat 35 — 46, and pork fat 46 — 66.

The impurity which are contained in., are defined in not saponifiable fraction by hromatografichesky and chemical methods.

., marked radioisotopes, most often a radioiodine, are used as diagnostic drugs in clinic, napr, at differential diagnosis of diseases went. - kish. path. Serve as such diagnostic drugs 131 I-glitserintrioleat ( 131 I-triolein) and 131 I-olein to - that, and also 131 I-vegetable oils (sunflower, corn and olive). Branding. make by accession to olein to - those or to its remains (or to the remains of another unsaturated fat to - you) on double bonds of a molecule of the iodine chloride containing 131 I. Drugs represent the transparent oily liquids of yellow or ocherous color containing radioactivity in concentration 0,1 — 5,0 mkyuri/ml and which are characterized by radio chemical purity not less than 98%. Impurity of free 131 I does not exceed 2%. Are issued packaged in penicillinic bottles.

Radioactive. ( 131 I-luccu oil) for studying of absorbability. in went. - kish. a path were for the first time used in a wedge, practice in 1949 by U. Stanley and S. Thannhauser. Differential diagnosis of disturbance of processes of digestion and absorption. by means of radioactive. it is based that neutral. ( 131 I-triolein) before absorption in intestines is exposed to splitting under the influence of steapsin whereas fat to - you are soaked up directly. Therefore at diseases of a pancreas absorption is broken 131 I-trioleina at normal absorption 131 I-olein to - you. At damage of intestines absorption and a trioleina and free olein to - you decreases.

Studying of absorption of marked. is a simple and reliable method of identification of a steatorrhea; it allows to distinguish a steatorrhea of a pankreatogenny origin from disturbance of absorption fat to - t at diseases of a small bowel. The procedure of a research is that after purpose of marked. inside on an empty stomach count the radioactivity which appeared in blood, and also radioactivity of urine and a calla.

At disturbance of lipidic exchange (see. Lipometabolism ), accompanying a number of diseases (e.g., obesity and atherosclerosis), essential value gets definition in blood of quantity and qualitative structure lipids (see), including triglycerides or neutral. Maintenance of neutral. in blood significantly fluctuates depending on terms of acceptance of food, especially fat. In blood of the healthy person after fatty loadings the hyperlipemia comes 2 — 3 hours later, reaches a maximum in 4 — 6 hours, contents. is returned to initial sizes in 8 — 9 hour. Therefore the maintenance of the general lipids should be defined on an empty stomach.

The increased maintenance of neutral. in blood serum confirms suppression of mechanisms of utilization. from blood. The Giperlipemichesky syndrome is observed at obesity, hepatitises, atherosclerosis, nefroza, diabetes and the phenomena of blockade of reticuloendothelial system. Gipertriglitseridemiya is adverse biochemical, a symptom since promotes decrease in synthesis fat to - to t and partial transfer of ways of utilization of cellular funds atsetil-KOA in the direction of biosynthesis of cholesterol. The triglycerides rich saturated fat are especially adverse in this respect to-tami.

Normal blood serum contains about 200 mg of % neutral. (triglycerides). The majority of lipids is found in blood not in a stand-at-ease, and in the form of proteinaceous and lipidic complexes. Normal these complexes contain 13 — 16% alpha lipoiroteidov and 13 — 16% of beta lipoproteids.

Neutral. (triglycerides) in clinic determine by Carlson and Ignatovskaya on change of amount of the glycerin released as a result of hydrolysis of triglycerides.

== Fats in food ==. treat the main feedstuffs and are an obligatory component of the balanced diet of the person. are an important energy source, they can be considered as the natural food concentrate of great energy value capable in small volume to provide an organism with a significant amount of energy. Balance. in food is defined by amount of proteins, fats and carbohydrates in diets concerning 1:1:4. Requirement in. depends on age, the nature of work and climatic conditions. At advanced age, and also at small physical. to loading and employment brainwork requirement in. decreases. In a frigid climate requirement in. at the person raises. On average requirement in. it is defined in number of 80 — 100 g a day.

Value Zh. as feedstuff it is very diverse. are an important energy source. In comparison with proteins and carbohydrates Zh. have bigger caloric power: 1 g. at oxidation in an organism gives 9,3 kcal whereas 1 g of protein or carbohydrates gives 4,1 kcal. are solvents of A, D, E vitamins (tokoferol) in this connection security of an organism with these polyneuramins of considerable degree depends on receipt. as a part of food. S Zh. the complex of biologically active agents (phosphatides, sterols, etc.) playing an important role in normalization is entered into an organism lipometabolism (see).

. have significant effect on tastes of food, impacting it at culinary processing palatability and aroma.

Full value. is defined by existence in their composition of vitamins A and D, tokoferol, polyunsaturated fat to - t (linoleic, linolenic, arachidonic), phosphatides (lecithin, sphingomyelin), sterols (beta sitosterol), etc., and also ease of absorption in went. - kish. path and tastes. Practically any of., used in food, is not biologically full in every respect. Biol, full value. it can be provided only with a combination in food of various. animal and plant origin. Optimum in biol, the relation of a combination are created at inclusion in a daily diet of 70 — 80% of an animal (including as a part of foodstuff, napr, meat) and 20 — 30% of vegetable.

Insufficiency. in food or constant disturbance of their optimum ratio leads to various disbolism and energy and serves as the reason of a number of diseases (see. Starvation ).

By origin food. are divided on animal, vegetable and artificial. To animals. belong beef, mutton and pork., received by melting from a fatty and bone tissue. Animals. are characterized by high content saturated (limit) fat to - t (to 50% and more) and high melting temperature. Animals. shall meet requirements of state standard specification. According to the standard in animals. the premium no more than 0,2% are allowed moisture, and KCh shall not exceed 1,2; in. the first grade according to moisture there have to be no more than 0,3%, and KCh shall be equal to 2,2. There are data on the promoting role of excess consumption of animals. in development of atherosclerosis.

Vegetable. (oils) receive from seeds of oily plants, napr, from sunflower, cotton, flax, soy (see. Vegetable oils ) by extraction. or pressing. On extent of cleaning vegetable oils are divided on crude, not refined and refined. The oils subjected only to filtering carry the name of crude. As a result of refinement transparency of oil and lack in it of a sediment, smell and taste is provided. In biol, the relation refined oil is less valuable owing to loss of phosphatides and partial decrease in content of sterols and tokoferol. The oils subjected to partial cleaning — to upholding, filtering, hydration and neutralization belong to not refined. The biologically fullest is crude vegetable oil, in Krom phosphatides, sterols and other valuable components completely remain.

To artificial. belong table and culinary margarine (see) and all others., having in the basis salomas. Salomas represents the hydrogenated (hydrogenated) liquid. (vegetable oil or. marine animals). During the receiving a salomas basic process is saturation nonlimiting fat to - t hydrogen and transfer liquid., containing these to - you, in strong aggregate state. In hydrogenation process. lose polyunsaturated fat to - you, and vitamins A and D, being their part, are inactivated. Low-melting salomasa shall have temperature of melting 30 — 32 °, temperature of a full enlightenment 34 — 35 ° and the hardness of 120 — 150 g / see. Artificial. — compound lard represents a type of culinary., to-rogo 65 — 74% of a vegetable salomas, 15 — 20% of pork are a part., 10 — 14% of vegetable oil and some other substances. To artificial. belongs also margaguselin, consisting of mix of a vegetable and whale salomas (to 25%), pork. (to 20%), vegetable oil (10 — 20%), etc. The feature of a margaguselin distinguishing it from other compound lards is existence in its composition of the onions extract impacting to a margaguselin specific relish and aroma. Culinary. shall contain. not less than 99,7%, moisture no more than 0,3% to have temperature of melting 28 — 36 °. Sometimes artificial. vitaminize with addition of vitamin A at the rate of 15 mg of vitamin on 1 kg of fat.

Reason of damage. the changes connected with their oxidation are. At the first stage of oxidation. there is an education of highly active peroxide radicals and hydroperoxides. Further low-molecular products of decomposition are formed. — aldehydes, ketones, free fat to - you that organoleptic is perceived as rancidification. (off-flavor and taste). For the prevention of damage and rancidification. it is necessary to watch that. were stored at a low temperature in the container making impossible access to them of light and oxygen of air. For the prevention of oxidation. use antioxidants — buthylhydroxytoluene, ionol, etc.

In the course of long thermal treatment. also can decay with formation of a number of the irritating, harmful substances — hydroperoxides, epoxides and other aggressive cleavage products. Overheating. reduces their food and biol, value.

See also Fatty products .


Bibliography: Hygiene of food, under the editorship of. K. S. Petrovsky, t. 2, page 182, M., 1971; Grishina V. I., etc. Isotope method of definition of digestion of fat, Vopr, medical chemistry, No. 2, page 214, 1962; 3 and N about in-e in A. A. Himiya of fats, M., 1952, bibliogr.; P. E Kalmyks. and Logat-k and M. N N. Modern ideas of a role of components of food, page 105, L., 1974, bibliogr.; Kozin N. I. Merchandizing of food fats, M., 1958; Medical use of the diets enriched with fat, under. edition of A. A. Pokrovsky, Kiev, 1976, bibliogr.; Petrovsky K. S. Gigiyena of food, M., 1975; With t of An to about V. I. and Bulychev E. Yu. Receiving radioactive drugs, Isotopenpraxis, t. 7, No. 3, page 91, 1971; Tyutyunnikovb. N. Himiya of fats, M., 1974, bibliogr.; The role of fats in human nutrition, ed. by A. J. Yergroesen, L., 1975.

A. A. Pokrovsky; K. S. Petrovsky (pitas.), H. F. Tarasov (I am glad.).

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