Page:A Practical Treatise on Brewing (4th ed.).djvu/229

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DIASTASE.
213

quantities so small as to be but very rarely seen, and such a substance is now hardly known, nor is it to be obtained at the present time even in Paris, where the discovery is said to have been made. I have been favoured with the following opinion of diastase by a scientific friend who has made some experiments on the subject.

"The gluten of all grain is known to be particularly prone to spoil or undergo decomposition when wet, and this decomposition passes through several stages, ending in complete putrefaction. In these different points of its progress to putrefaction, the gluten of barley and other grains acts as a ferment, but with different results in the early, from what it produces in the late stages. It is only in the first stage of decomposition that gluten saccharizes, and it is in this state in barley which has been moistened and begun to germinate. Yeast is still only the same gluten, but farther decomposed; it is then capable of decomposing saccharine matter, and resolving it into alcohol and carbonic acid, that is of producing the vinous fermentation. Diastase, therefore, is a peculiar condition of the glutinous part of malted grain rather than a distinct principle; the name, however, is still retained in this sense by chemists, as being a convenient term for certain purposes." My friend, Mr. Maugham, also, some years ago, at my suggestion, made some experiments in respect to diastase; and he afterwards