Page:A Practical Treatise on Brewing (4th ed.).djvu/225

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DIASTASE.
209

the inferiority of the materials used. Having thus endeavoured to put an end to all mystery on this most important subject, we here insert our article on Diastase from the First Edition.

The researches of the French chemists last summer (1834), will shed a new light on the nature and properties of malt, and the mode of extracting. Starch is described as consisting of minute particles, like granules, each of them included in a skin or cuticle, a thick, slimy, gum-like body, and therefore resembling somewhat the structure of seeds. To the internal contents of these granules, M. Biot gave the name dextrin; it might also be called starch-gum, because in its properties it is quite analogous with the latter. The skinned integument, including the dextrin, prevents the starch from coming forth; for starch is not soluble in cold water. But by breaking the cuticle this is accomplished, and gum produced from starch, or rather gum contained in starch, is made free.

For attaining this, the following means are at present known.—1. Boiling. The more such particles are torn by the heat, the more of the gum is dissolved; and the more particles of starch are preserved in the fluid, the more paste-like remains the latter.—2. Roasting. In both cases, the heat partly tears and partly annihilates the cuticles. This case sometimes occurs in kiln-drying.—3. Treating it with some acid fluid.—4. Treating it