The analysis and adulteration of foods / by James Bell.

  • Bell, James, 1824-1908.
Date:
1881-1883
Catalogue details

Licence: Public Domain Mark

Credit: The analysis and adulteration of foods / by James Bell. Source: Wellcome Collection.

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    in a form in which it can be removed by treatment with cold water. Vegetable albumin closely resembles, in appearance and in its behaviour with acids and alkalis, the albumin obtained from the white of egg and the serum of blood. It forms when moist a white elastic mass which, on drying, acquires a yellow colour and horny appearance. In contact with water, the dried substance again absorbs several times its weight of that liquid, and assumes much of its original character. A solution of albumin is readily precipitated by nitric or hydrochloric acid, but such acids as acetic or tartaric have no effect upon dilute solutions. Tartaric acid by the aid of heat, and dilute alkalis in the cold, dissolve coagulated albumin, whilst concentrated alkalis convert it into the form of a jelly. Gliadin, or Glutin.—It is to this substance that bread made from wheaten flour owes its well-known porous and spongy character, and its deficiency in the other cereals unfits them generally for bread-making. In the hydrated condition it is of a soft and pasty character and can be drawn out into threads. When dried in air or in the water-bath, it, resembles gelatin, but when dehydrated by alcohol and ether, and dried in vacuo, it forms a hard mass easily reducible to powder. When gliadin is left in contact with water for some time, it decomposes and gradually passes into solution, in which state it acts upon starch in a way very similar to that of the soluble albuminoids. Gliadin is insoluble in cold water and only slightly soluble in hot water, but readily soluble in the fixed alkalis and in alcohol of 70 per cent. Mucin.—This is a body having much the same properties as gliadin. It dissolves in hot alcohol along with the latter, but is slowly deposited in a flocculent condition as the spirit cools. In its several characteristics it appears to come between gliadin and vegetable fibrin.