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albumen
Значение термина albumen в knolik
albumen - albumen
albumen - albumen, an organic nutritive principle, is a constituent of all animal fluids and solids. The white of eggs contains 12 per cent, of albumen, and the fluid portion of blood [serum] 7 per cent. It occurs also in the flesh, in the brain, and more or less in all serous fluids. Fibrin also may be regarded as coagulated albumen. It occurs in the vegetable kingdom, in the sap or juice of many plants, such as the potato, turnip, carrot, cabbage, in the green stem of peas, in the seeds of the cereal grasses, and in many nuts.
There are two modifications of albumen, soluble and insoluble. The former occurs in the animal body, but the insoluble modification may readily be prepared from it by the action of heat. This property of becoming in soluble, or "coagulating," as it is termed, by the action of heat, is especially characteristic of this substance, and constitutes its chief value for technical applications.
Albumen contains carbon, hydrogen, oxygen, and nitrogen, together with traces of sulphur and phosphorus. Its chemical composition is:
| Chemical composition | Per cent |
| Carbon | 53.3 |
| Hydrogen | 7.1 |
| Oxygen | 22.1 |
| Nitrogen | 15.7 |
| Sulphur | 1.8 |
| Phosphorus | trace |
| total | 100.0 |
Animal albumen is always associated with certain inorganic salts and free soda. It exists in the animal body in solution, in the form of an alkaline albuminate. If the white of eggs, or the serum of blood, or any animal liquid containing albumen, be incinerated, the residue is chiefly carbonate of soda. This alkali may readily be removed, and the albumen rendered insoluble, or coagulated, by the action of heat. Exposed to a gentle heat, soluble albumen gives off a peculiar, characteristic odour. It can be dried at 104° F. (40° C.) without being rendered insoluble, and in this form is usually met with in commerce. On raising the heat to 130° F. (54° C.), white fibres of insoluble albumen begin toappear; at 160° F. (70° C.) it becomes a solid, jelly-like mass; and at 212° F. (100° C.) it dries up, turning yellow and brittle, like horn. When in this condition, 5 times its weight of water will redissolve it, bringing it once more to its original consistence. The only change which the albumen undergoes during the process of coagulation is the removal, by the hot water, of the alkali and soluble salts. Its chemical composition remains the same throughout.
Albumen of good quality is recognized by its transparency when in flakes, by its flavour not being disagreeable, and by having no odour of putrefaction. Constantly stirred in cold water, it should dissolve entirely. For practical purposes, it is best dissolved in warm water, at a maximum temperature of 113° to 122° F. (45° to 50° C.). The albumen should be added gradually, and the liquid constantly stirred. The water should on no account be added to the albumen. The liquid, after straining through a fine silk sieve, is usually mixed with a small proportion of ammonia, turpentine-oil, etc., in order to prevent frothing, and make it work smoothly. Turpentine also tends to prevent putrefaction, but an addition of about 1 per cent, of arsenious oxide is said to be the best preservative. Commercial albumen is very liable to adulteration (especially the dearer egg-albumen) with gum-arabic, dextrine, flour, sugar, etc.
Blood-albumen
Blood-albumen occurs in commerce in various forms. The lowest quality is packed in casks in the liquid state, and consists merely of blood which has been defibrinated by whipping. The purer forms of blood-albumen are prepared from the blood of slaughtered animals, which after coagulation, is filtered: 5 oxen or 20 sheep, or 34 calves are said to yield the same quantity of dry albumen - viz. 2 lb. In producing blood-albumen for commerce, the objects borne in mind are the attainment of a substance whose solution is free from colour, possesses perfect coagulation, and which is cheap. The superior price of egg-albumen has led to various attempts to prepare a blood-albumen of a similar whiteness and quality. In these attempts, animal charcoal, incipient coagulation, air rendered ozonic by means of electric induction, have severally been employed, but none proved capable of producing an albumen at all comparable in value to egg-albumen.The manufacture of blood-albumen is largely carried on in this country of recent years, and is the subject of some interesting remarks from Dr. Ballard, especially with regard to the noxious effluvia arising from it. The trade consists in the separation of the serum from the blood-clot, and the drying of the former into transparent flakes of a reddish-yellow colour, but varying in depth of colour according to the quality of the serum from which they are made. Blood-clot is absolutely worthless for the purposes of this trade if it be not fresh. The more recently the blood has coagulated, the more valuable it is for albumen making. Hence the blood-albumen makers effect arrangements for the speedy collection of blood from butchers and town abattoirs, and it is dealt with immediately on its arrival at the works. Sometimes the first process, that of separation of the serum from the clot, is carried on in some part of a public abattoir. The serum is, in such cases, sent away in casks to the establishments, where it is dried.
The blood arrives in the shallow iron vessels in which it is caught from slaughtered animals, or in casks. The clot is immediately taken out and carefully sliced (when it arrives in shallow vessels it is sliced before removal from them), and the slices are arranged upon iron strainers, each with a pan beneath, to receive the serum which flows out as the clot continues to contract spontaneously. The season of the year governs the time during which this draining is prolonged. In summer it is continued for about 12 hours, but in winter for 18 or 24 hours. The strainers, each with its pan beneath, are arranged on racks in a building which is so constructed as to be kept as cool as possible. It is also important that the building should be in such a locality as to be free from vibration caused by the passage of heavy vehicles or railway trains. From the pans, the serum is, in the best works, transferred into a settling tank, where it remains about 2 days until all the red colouring matters, etc., which may be in suspension have been deposited. At some works, where an inferior article is made, the highly-coloured serum which comes with the clot in the casks is dried, and after the clot has been drained, it is put into a cask (from which the head has been taken out) to separate the bulk still further, and the dark serum which exudes is run off for use.
About 25 to 30 per cent, of serum is thus obtained from ox-blood, and this raw material can be manufactured into either the so-called "natural" albumen, without gloss, or the " patent " glossy albumen.
In making natural albumen, ¼ lb. of oil of turpentine is added to 100 lb. of serum, and the whole is whipped for an hour with apparatus similar to the dasher of an old-fashioned churn. The turpentine not only bleaches the serum and extracts the grease, but also helps to preserve it. It is allowed 24 to 36 hours to settle, when the clear serum is drawn off from the sediment, The drying is done in japanned iron dishes 1 ft. long, 6 in. wide, and ¾ in. deep. The temperature is at first about 122°F., and is raised to nearly 135° F. (57° C.) for 2 hours, after which it is allowed to fall to 118° or 120° F. (48° to 49° C.). The drying occupies |about 36 hours.
The manufacture of "patent" albumen differs from the above in the use of acids. To 100 lb. of serum are added 7 dr. sulphuric acid, mixed with 6¼ oz. concentrated acetic acid, and 6 lb. water; ¼ lb. oil of turpentine is next mixed with it, and the compound is whipped for an hour. After settling for a day or more, the clear liquid is poured off, neutralised with ammonia, and dried as before. About 10 lb. of serum will yield 1 lb. of dried blood-albumen.
Both these preparations are called " primary " products, as distinguished from the "secondary" and "tertiary" products obtained from the residues left in the dishes after the drawing off of the pure serum and from the clot on the sieves. The albumen from the last-named source is, of course, of very inferior quality, but is largely used in sugar refining.
The well-known faint odour of blood always pervades an establishment of this kind, and is especially marked in the drying chamber; but it does not. pass beyond it in any such way as to cause a nuisance, unless the manufactory be very badly conducted. The two ordinary sources of nuisance from blood-albumen works consist: (1) In the effluvia of putrid blood arising from the exhausted clots retained on the premises prior to removal. (2) In the general disagreeable faint smell proceeding from the yard premises, especially when due cleanliness is not observed. (3) In effluvia from other and further processes, such as blood-boiling or blood-manure making, carried on upon the premises. As to the remedies for nuisances, Dr. Ballard observes: (1) It is a practice in some works to throw the exhausted clot into a clot-bin, where it is left until removal. But now, in the best works, the clots are at once put into moderately sized casks, through a sufficiently large opening at one end, which, when the cask is full, is closely fastened down with a cover secured by screws. (2) Such works as these require to be conducted in a very cleanly manner. The yard should be well paved with stone, set so that no water may lodge upon it, and so that any offensive liquids that may reach it may not form pools, but flow readily away to the drain inlet. It should be kept at all times well swept up, and should be daily washed down with water. The separation room and the room in which the clots are sliced, when very near inhabited houses, should be closed in on all sides, and ventilated at the roof, as recommended for slaughter-houses, and they should be well and evenly paved. The best kind of pavement for such a room is one of cement. Flagstones are apt to crack or loosen, and the pavement to become uneven, and thus liable to retain pools of liquid matters, or to the insinuation of these liquids between and beneath the stones. Nothing can be more objectionable than a wooden floor. The floors should be frequently. scrubbed and cleaned, all the vessels and implements used ought to be regularly cleansed, and the whole interior of the buildings periodically lime-whited. The vapours from the drying chambers should be discharged at an elevation greater than that of adjoining houses.
A. H. Allen states that the qualities of blood-albumen as made by the leading firms are "refined," "prime," "No. 1," "No. 2," and "black." " Refined " is made from highly rectified serum, and is of a dirty-yellow colour; like "prime," it is employed as a mordant for printing delicate colours. " No. 1 " is darker-coloured and of less value, though suitable for all ordinary printing purposes. " No. 2 " is made from the second drainings of the serum, which, after the clear top serum has been siphoned off, is more or less tinged with red, and consequently only fit for printing dark colours; as a rule it also contains some insoluble matter, which is objectionable. "Black albumen" or dried blood is obtained from the last portions of serum, and is almost black in colour. It is not used in calico printing, but finds applications in sugar refining, and Turkey red dyeing.
C. T. Kingzett has patented a process of bleaching blood-albumen, and at the same time preserving it from putrefaction, by aerial oxidation of certain hydro-carbons in the presence of the albuminous solution to be bleached at a temperature below the coagulable point. Thus, if turpentine be employed, peroxide of hydrogen is formed on the one hand (and this bleaches the albumen), while other substances are simultaneously produced in sufficient quantity to preserve the mass from putrefactive decomposition. This process has been worked on serum and dark-coloured scales, producing solutions containing 2 to 4 lb. of albumen per gallon. The existence of the salts present in serum does not interfere with its photographic applications.
Egg-albumen
Albumen may be prepared in a pure state from white of eggs, by the following method: The white of eggs is beaten up well with water and filtered. To the filtrate is added a small quantity of sub-acetate of lead, in order to remove the mineral substances. The whole of the albumen is now precipitated as albuminate of lead. This is stirred up with water, and carbonic acid gas is passed through, by which the albuminate of lead is decomposed; carbonate of lead is precipitated, and the albumen remains in solution. The carbonate of lead is now filtered off through paper which has been washed with dilute acid. Traces of lead still remain, and to remove these the filtrate is treated with a few drops of aqueous sulphuretted hydrogen, and gently heated. The first flocks of albumen which appear, retain the whole of the lead as sulphide. This is filtered off, and the filtrate evaporated gently in a basin, the residue consisting of pure soluble albumen.The yolks of the eggs are mostly used in the preparation of glove-leather, sometimes under the name of "egg-oil."
In preparing egg-albumen there is considerable difficulty in completely separating the white from the yolk. Campe recommends that the whites should be refined by whipping up with oil of turpentine and a trace of acetic acid, and allowing the whole to stand for 25 to 36 hours, when the oil floats on the surface, and carries impurities with it. From a pecuniary point of view, this process does not appear to be advantageous, at least not in Moravia, Silesia, and Saxony.
An important condition in the production of albumen from eggs is the possibility of easily disposing of the yolk. Since this cannot always be done in the neighbourhood of albumen factories, and as transporting the material to a distance is apt to produce decomposition, it is necessary to add to it some antiseptic substance. Campe finds a solution of soda arsenate in glycerine, to which some salt is added, best suited for the purpose. Carbolic acid, soda hyposulphite, etc., have been more or less successfully tried, but found objectionable on the part of tanners and glovers, who are the chief consumers of yolk of egg. The former imparts to the leather its penetrating smell, the latter produces stains.
Fish-albumen
Fish-albumen is not unknown in the market, and may be recognised by its fishy odour. Hilman's process for preparing it is as follows: The crushed spawn is macerated in sufficient water to dissolve out the albumen. The albuminous water is separated by filter press, and evaporated in a vacuum-pan nearly to dryness. The thickened mass is then dried on drying floors, salicylic acid, in the proportion of 1 to 20, being added as a preservative. There are difficulties in the way of freeing fish-albumen from accompanying substances, which reduce its value.Vegetable-albumenM
Vegetable-albumen is most easily prepared from potatoes, by cutting them into slices, covering them with very dilute sulphuric acid (2 per cent.), leaving them 24 hours, then adding fresh potatoes and repeating the operation once more, afterwards neutralising with potash and boiling. A considerable quantity of albumen is then deposited in thick white flocks. It can also be made from wheat-flour and from oleaginous seeds. Kingzett's and Portheim's processes, briefly alluded to under "Blood-albumen," are equally applicable to gluten, the protein of worts, etc. The latter inventor takes 100 lb. of the albuminous matter, ground up and washed with water, and dissolves it in 200 to 250 lb. of water, in which has been previously dissolved 4 lb. of caustic soda or potash at 194° to 212° F. (90° to 100° C.). To the solution thus prepared he adds 4 per cent, of a solution containing 40 per cent, of glycero-sulphate or glycero-phosphate of calcium, or 4 per cent, of a mixture of calcic chloride and an alkaline salt of citric, tartaric, or meta-phosphoric acid. The mixtures are "scaled " in the usual way.Albumen in powder
If blood serum, or white of egg, is exposed in thin layers, and a current of dry air passed over it, it will become a solid transparent substance like horn. It will keep well in this state, or it may be reduced to powder and stored in bottles.For use in photography, 3 teaspoon-fuls of cold water added to every ½ teaspoonful of powder represent the normal consistence of egg albumen.
Preserving Albumen
It is often required to keep fresh white of egg for a considerable time ready for use. Oil of cloves or salicylic acid will do this for a moderate time, but for proper preservation a poisonous substance must be resorted to, and of these carbolic acid is best.According to Berg's process for preserving egg-albumen for photographers, the whites, separated from the yolks, are evaporated to dryness in zinc or porcelain basins, at a temperature of 113° F. (45° C.), the operation being conducted in vacua, to hasten the evaporation. The solid albumen thus obtained is reduced to powder, which, if kept -perfectly dry, may be preserved for a long time without alteration, and is applicable to all ordinary purposes.
Restoring Insoluble Albumen
According to Wagner and Witz, albumen which has been coagulated (rendered insoluble) may be restored to the soluble (coagulable) state by means of treatment with pepsin. By Wagner's plan 12 to 13 oz. of insoluble albumen are placed in contact with 1 oz. of calf's stomach, cut into little pieces, and distributed through 1¾ pints of water, previously treated with ⅓ oz. concentrated hydrochloric acid, and having a temperature of 100°F. (37½°C.). After 24 to 36 hours' standing, the whole is passed through a fine sieve, and the filtrate neutralised with ammonia.Witz uses sheep's stomach, and over 4 oz. of dry insoluble albumen to 1¾ pints of acidified water, digesting for 40 hours at a temperature of 95° to 104° F. (35° to 40° C.), whereby about half the albumen goes into solution. This portion is removed by nitration, and the insoluble residue is again treated in the same manner to yield a second portion of soluble albumen. Pigs' stomachs are even more active than sheep's. The solution of albumen obtained by Witz is odourless and colourless, and, after the neutralisation with ammonia, coagulable either by heat or alcohol. More, it does not gelatinise, even after long standing. The addition of the hydrochloric acid is essential to success with the pepsin processes. Indeed, dilute hydrochloric acid (1 part of 1.169 sp. gr. in 100 water) alone, at a temperature of 100° F. (38° C.), after some days effects the solution of insoluble albumen, affording a solution which will coagulate on boiling.
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