GELATIN (fr. gelatine, from armor. gelare to stiffen; synonym: gelatin glue, glutin) — the product of partial hydrolysis of collagen finding broad application in the pharmaceutical, film photochemical, food, printing, textile industry by production of some grades of plastic, in medical laboratory and a wedge, practice. Receive. from bones, scraps of skins of animals, sinews, etc. Bones will demineralize previously (macerate) in diluted salt to - those. Rawhide (inner side) and the demineralized bones (ossein) subject to processing by alkali for removal of fat, mucins and other impurity. Then after neutralization and washing raw materials are heated in water at 60 — 100 ° therefore
characteristic property turns out Zh. Naiboley. — ability to gelatinize during the cooling of solutions, i.e. to give gels (see). Solutions Zh. filter and concentrate in vacuum devices to a condition of the gelatinous weight (galerta), to-ruyu cut on pieces and finally dry up in current of warm air. For conservation add to a galerta a nek-swarm quantity sulphurous to - you
. has an appearance of colourless or inodorous weak-yellow transparent plates and taste, contains 8 — 15% of moisture in an air-dry state. Ud. air-dry weight. the index of refraction — 1,5 is equal 1,37. On chemical structure. it is very close to to collagen (see), its molecule contains many remains of glycine, proline, oxyproline, alanine. In a cold water. it is not dissolved, but strongly absorbs water and bulks up. Bulked up. turns into solution during the heating higher than 30 ° and again gelatinizes during the cooling. Temperature of melting of 10 percent gel Zh. — apprx. 25 — 30 °, gelatinization temperature usually on 8 — 10 ° is lower than temperature of melting. Reduction of concentration., presence to - t, alkalis, salts monobasic to - t lower temperatures of melting and jellification, salt double-base to - t raise them. At repeated fusion and jellification, long boiling or short autoclaving at 140 °, and also at effect of some enzymes and bacteria solutions Zh. lose ability to gelatinize. Heating dry. higher than 120 ° reduces its ability to bulk up and be dissolved. The bulked-up gel Zh. during the heating it is dissolved in glycerin, diluted to-takh, alkalis, solutions of salts. The concentrated solutions of some substances, napr, acetic and ant to - t, urea, thioureas, Calcium chloratum, etc., dissolve. at the room temperature. In many organic solvents, including alcohol, ether, acetone, chloroform, gasoline, etc. it is not dissolved. From solution Zh. it is besieged at addition of equal volume of saturated solution of ammonium sulfate. In solutions Zh. floor and dispersn, average pier. the weight (weight) of its particles depends on pretreatment and is ranging from several tens of thousands to two hundred thousand. In vitro at short-term heating at 37 ° solutions of procollagens (soluble kollagen) the most high-molecular turns out. In an isoelectric point (at pH 4,4 — 4,7) minima of swelling, osmotic pressure, conductivity, ability to lower surface intention and, on the contrary, maxima of viscosity, a turbidity, ability are noted. to gelatinize and be besieged by alcohol. Jellification of solution Zh. at fall of temperature is followed by increase ud. optical rotations, at temperature increase ud. rotation decreases — the phenomenon so-called. mutarotations (see).
Use gelatin in medical and pharmaceutical practice
the Medical industry of the USSR is issued gelatin medical (Gelatina medicinalis) and solution of gelatin medical for injections of 10% (Solutio Gelatinae medicinalis of 10% pro injectionibus) representing colourless or poorly painted jellylike weight turning into liquid during the heating. Temperature of its melting is not lower 23 °, pH 6,0 — 7,2, relative viscosity not less than 6,0. In a wedge, the practician Zh. apply to increase in coagulability of blood and a stop gastric, intestinal and pulmonary bleedings (see), bleedings at hemophilias (see), at hemorrhagic diathesis (see), etc. Ability. to increase coagulability of blood, probably, it is partially caused by existence in its drugs of salts of calcium. Depending on indications. enter intravenously (0,1 — 1 ml of 10% of solution for 1 kg of body weight), subcutaneously (10 — 50 ml of 10% of solution) and per os (1 table. l. 5 — 10% of solution in 1 — 2 hour). Specially processed drug Zh., containing antiseptic agents, it is known as a sponge gelatinous and it is applied locally to a stop of capillary, parenchymatous and other bleedings. As plasma substituting drug Gelatinolum (Gelatinolum) — colloid 8% solution partially hydrolyzed food is applied. in isotonic solution of sodium chloride. In pharmaceutical practice. it is used also for production of capsules which are filled with pharmaceuticals with off-flavor or strongly painting properties. Gelatin capsules are used also for protection of cure for influence of a gastric juice, etc. In medical practice gelatin capsules with a lid (Capsulae gelatinosae operculatae), geloduratovy or glyutoidny capsules (Capsulae geloduratae, s. glutoidales), pearls, or pearls (Perlae gelatinosae) are applied. Glyutoidny capsules (as a result of processing by spirit solution of formalin or vapors of formaldehyde Zh. turns into the glutin steady against action salt to - you a gastric juice) break up in alkaline contents of intestines therefore they carry the name of «intestinal» capsules.
Use gelatin in the histologic equipment
Zhelatina in gistol. to the equipment it is used for production of injection masses, for gluing of cuts on glass, for filling gistol, the objects consisting of friable fabrics (in order to avoid their wrinkling and for cutting of blocks on the microtome), and also for the conclusion of cuts when it is necessary to avoid action on dyes of alcohols.
At the conclusion gistol, objects in. most often use S. Apathy and Gaskell's methods — Graffa (J. F. Gaskell, S. Graff).
Apati's method apply during the studying of connecting fabric and others gistol, objects which heating to 60 ° and conducting in alcohol does not influence. Previously prepare mix Zh.: 50 g. in heated mix of 175 g a dist, waters and 25 g of glycerin filter in the thermostat and condense over CaCl2. The received weight is cut on cubes and stored in the closed vessel. Gistol, the objects condensed in 96% alcohol carry out several times through mix of glycerin and water (4 parts of glycerin and 5 parts of water), add the equal volume of solution Zh to the last portion. (3 parts Zh. dissolve in 7 parts of water) and an object is maintained in this last portion by 24 hours at 40 °, then transfer to the thermostat (45 — 60 °) before evaporation of a half of weight and allow to harden at the room temperature. The hardened block is cut on smaller parts and out through absolute alcohol within 5 — 6 days, the same time is kept in terpineol then drugs can be cut on the microtome.
Gaskell's method — Graffa it is used when it is necessary to avoid action on the studied objects of alcohol and high temperature. Prepare two solutions Zh. — liquid and dense. For preparation of the last take 1 part Zh. also dissolve in the closed vessel at 37 ° in 3 parts 1% of water solution of phenol (carbolic water). Liquid solution Zh. prepare, diluting 1 part of dense solution Zh. 1 part of carbolic water. The fixed pieces of fabric are not thicker than 3 mm washed from the fixer, postpone to 6 — 24 hours in liquid solution Zh., and then for the same term in dense solution Zh. at 37 °. Further objects place in the refrigerator for 30 min. then they are dried at the room temperature on air and condense in solution of formalin (1:4). The received blocks wash out water and cut on the freezing microtome.
For the conclusion of cuts use also mix glycerin — gelatin, prepared as follows: 7 g. dissolve in 42 ml of water, add to solution 50 g of glycerin and 0,5 g of phenol (carbolic to - you), heat on the water bath and filter through glass wool. On gistol, drug put one drop of the warmed-up environment and cover with cover glass.
== Gelatin as a medium in microbiology ==. in microbiology it is used for production of dense mediums (see); it is entered into bacterial, practice by R. Koch. Usually Wednesdays with. are used only for definite special purposes since gelatinous gel melts at 25 — 30 ° that below the optimum temperature of an incubation of pathogenic microorganisms (37 °). Besides. it is split by bacterial proteases. This its property is used for establishment at microorganisms of proteolytic activity that is a certain indicator at identifications of microbes (see).
For preparation of a medium with. add 10 — 15% to a beef-extract broth solution Zh., dissolve, heating during the stirring to 40 — 50 °, lead up pH to 7,0 — 7,1; on 0,5 l of the environment add one ovalbumin, shake up and warm up fluid steam within 1 hour; Wednesday is filtered via the paper filter, spilled on test tubes and sterilized fluid steam 3 times 20 min. within 4 days. After sterilization Wednesday is cooled with immersion in a cold water. Microbes sow with a prick in a column and incubate at 20 — 22 °.
The microorganisms having proteolytic activity liquefy a column. in the place of seeding. Wednesdays with. use also for department of mobile microorganisms. To a beef-extract agar add 10% to 0,4% solution Zh. After sterilization Wednesday is cooled to 60e, spilled on cups and incubate after crops at 37 °. Crops is carried out on one party of a cup. In soft melted. there is possible a distribution of mobile microorganisms from the place of seeding. After decrease in temperature to 20 ° gelatin hardens, the movement of microorganisms stops and their mobile options are fixed on those places to which they managed to promote. is also a part of the special mediums used during the drying of microorganisms. Addition Zh. in number of 0,01% in the salt solutions applied to cultivation of bacteria and viruses warns them an inactivation during the stirring.
Gelatin in food
On the amino-acid structure. treats incomplete proteins since consists preferential of replaceable amino acids, contains a lot of glycine, proline, oxyproline, alanine and there is not enough tryptophane which is irreplaceable amino acid (only 6 mg of %).
Property Zh. to bulk up in water, to be dissolved during the heating higher than 30 ° and to stiffen in gelatinous weight during the cooling it is used for preparation of jellylike and gelatinous dishes. Ability. to stimulate a blood coagulation serves as the reason of inclusion of such dishes in a diet of patients with gastric, intestinal, pulmonary and other bleedings. Property Zh. to increase coagulability of blood is a contraindication to the frequent use of such dishes by the people having the cardiovascular diseases which are followed by the increased coagulability of blood
. is oksalogeny and it is not recommended at oksalurichesky diathesis.
Released by the industry. (sheet and crushed) has no taste and a smell, it is colourless or weak-yellow color, with humidity of 8 — 15% and ud. weighing 1,37.
At sanitary examination of samples food. organoleptic properties, physical are defined. - chemical and bacterial indicators (the general obsemenennost, quantity of zhelatinorazzhizhayushchy bacteria etc.). Existence of pathogenic microflora is not allowed.
Bibliography: Weiss A. Macro-molecular chemistry of gelatin, the lane with English, M. 1971; Kozlov Yu. A. Mediums in medical microbiology, M., 1950, bibliogr.; Meynell Dzh. and Meynell E. Experimental microbiology, the lane with English, M., 1967, bibliogr.; Pearce E. A histochemistry, the lane’ with English, M., 1962.
V. O. Shpikiter; S. S. Belokrysenko (mikrobiol.), Yu. K. Eletsky (gist.), V. A. Kudasheva (pitas.), V. V. Parin (pharm.).