EXTRACTIVES

From Big Medical Encyclopedia

EXTRACTIVES (lat. extractum something taken, from extrahero) — the low-molecular organic matters received at extraction by water of animal and vegetable objects.

At the highest animals are most studied by E. century of skeletal muscles (see. Muscular tissue). Intensive research E. began after widespread introduction of the way of industrial receiving extract from meat (the aqueous extract from muscles exempted from proteins by boiling) offered by Yu. Libikh in 1847 century. As a part of such extract nitrogenous (nonprotein) and nitrogen-free extractives were found.

To nitrogenous E. century of muscles of the person and mammals belong adenosinephosphoric acids (see) ATP, ADF and AMF, concentration to-rykh in skeletal muscles of a rabbit, e.g., by data of I. I. Ivanov (1969), makes respectively 4,43; 0,81 and 0,93 µmol on 1 g of crude weight of fabric. Quantity of nucleotides (see. Nucleic acids) a neadeninovy row (tuanilovy, cytidine, uridilovy) in muscular tissue is not enough in comparison with quantity of adenylic nucleotides. (See) and kreatinfos the veil (phosphocreatinine) — the nitrogenous compounds participating in the chemical processes connected with muscular contraction is the share of a share of creatine to 60% of nonprotein nitrogen of muscles. To number of the major nitrogenous E. century of muscles possess imidazolsoderzhashchy dipeptides carnosine (see) and anserine (see), or anzerin — connections, specific, characteristic of skeletal muscles. According to S. B. Severin, these dipeptides do not influence directly the sokratitelny device of a muscle, but, keeping structure of membranes of muscle cells, increase overall performance of ionic pumps (see Transport of ions) in muscular tissue. Others important nitrogenous E. century of muscles are the carrying-out transfer of the remains of fatty acids (see) a carnitine, the phospholipids (phosphatides) which are a part of membranes of muscle cells, e.g. phosphatidylsincaline, phosphatidylethanolamine, phosphatidylserine, coenzymes (see), including nikotinamidny (NAD and NADF) both flavin, and other physiologically active agents. To number nitrogenous E. century of muscles belong and formed in the course of disintegration and updating of myoproteoses of amino acid, always present at a muscle in small amounts. It is highest concentration of glutamic acid (see) — to 1,2 g/kg, and also its amide of a glutamine (see) — 0,5 — 1 g/kg. Others nitrogenous E. century, meeting in muscular tissue in small amounts, as a rule, are intermediate or end products of a nitrogen metabolism (see). Methyl guanidine, adenine, guanine, xanthine (see), hypoxanthine (see), taurine (see), sincaline (see), etc. concern to them urea (see), uric acid (see).

The major nitrogen-free E. century carbohydrates are (see). Muscles of the person and mammals contain a significant amount (0,3 — 3% and more) a glycogen (see), traces of glucose (see) and geksozofosfat. Products of metabolism of carbohydrates — pyruvate (see. Pyruvic acid), a lactate (see. Lactic acid), intermediate products of glycolysis (see), and also a cycle of tricarboxylic acids — di - and tricarboxylic to - you (see. Tricarboxylic acids a cycle) also are nitrogen-free E. century. In structure nitrogen-free E. century neutral fats (see Triglycerides) and nek-ry other lipids, including cholesterol enter (see). The various inorganic salts which are contained in muscular extracts usually do not carry to extractives.

In a crust. time the term «extractives» substantially lost scientific value.

Value of extractives in food is defined by their ability to improve organoleptic qualities of food, to excite c. N of page to increase appetite, to stimulate secretion of digestive glands. AA. century in different quantities contain in many foodstuff. Practical value in a balanced diet has their presence at products of an animal and plant origin. Contents nitrogenous E. century in meat (see) depends on a look and age of page - x. animals: the largest content nitrogenous E. century pork — mutton differs in the smallest. Meat of mature animals is richer with extractives in comparison with meat of young growth.

Abundance of nitrogen-free extractives in meat makes apprx. 1%. On the nutritional value they considerably concede nitrogenous E. century. Quantitative ratio nek-ry nitrogen-free E. century in meat changes at various stages of its «maturing». So, in the first hour after slaughter of animals of a glycogen in muscular tissue several times it is more, than milk to - you, and in a day their ratio becomes the return.

AA. century during the cooking of foodstuff pass into broth. So, during the cooking of meat passes into broth from 1/3 to 2/3 contained in it E. century depending on duration of cooking, reduction ratio of meat etc. It is less extractives in muscular tissue of fishes, than in muscular tissue of hematothermal animals, but they pass into broth more stoutly and therefore possess rather expressed action. Also vegetable juice and vegetables decoctions, mushroom broths belong to strong activators of secretion of a gastric juice (see).

Properties E. defined their differentiated use in clinical nutrition century (see clinical nutrition): boiled products apply in chemically sparing diets whereas meat and fish in a fried look, broths from them, vegetable juice and snack use as means, orexigenic and stimulating secretion of a gastric juice.

Bibliography: Berezov T. T. and Korovkin B. F. Biological chemistry, M., 1982; Hygiene of food, under the editorship of B. S. Petrovsky, t. 1, M., 1971; The Study guide of food and health of the population, under the editorship of A. A. Pokrovsky, M. 1964; The Reference book on dietology, under the editorship of A. A. Pokrovsky and M. A. Samsonov, M., 1981.

N. V. Gulyaeva (biochemical), V. A. Kudasheva (tsit.).

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