Friday, January 20, 2012

Basic Fermentation

"Fermentation is a spontaneous and intestine motion, which takes place amongst the principles of organic substance deprived of life, the maximum of which always tends to change the nature of bodies, and gives rise to the formation of new productions."

-- Bouillon la Grange.—Manual of a Course of Chymistry.

Fermentation has long since been divided into spirituous, acid, and putrid.

It is incontestable that spirits are produced by the saccharine substance (sugar). Grains, however, supply it, although they are not sensibly sweet. This has made me suspect that the fermentation is at first saccharine, which produces the sweet substance that is necessary for the formation of spirit. It is thus that, by a series of internal motions, the fermentation causes the formation of the spirit to be preceded by a slight production of acid; that it transforms the vinous liquor into vinegar, which the same fermentation changes in time into an animal substance, destroyed in its turn by the putrid fermentation. Such are the progressive changes operated by this all-disorganizing phenomenon, and the unerring march of nature to bring back all substances to their respective elements.

The necessary conditions for the formation of vinous fermentation, are—

1st. The presence of the saccharine substance.
2dly. That of a vegeto-animal substance, commonly called ferment, and soluble in water.
3dly. A certain quantity of water.
4thly. A temperature of 70° to 75°.
5thly. A sufficient mass.

When these are obtained, in a short time the liquor becomes turbid; it bubbles, from the disengaging of the carbonic acid gas, and the heat increases considerably. After some days, these impetuous motions subside; the fermentation ceases by degrees; the liquor clears up; then it emits a vinous smell and taste. As soon as it ferments no more, it must be distilled. However, some distillers have asserted that a greater quantity of spirit is obtained when the liquor has acquired a certain degree of acidity. Others are of opinion that it must be distilled as soon as it is calm. I am of this opinion, because the acid can only be formed at the expense of a little of the spirit, which is one of the principles of the acetous acid. Besides, the longer the liquor remains in a mass, the more spirit is wasted by evaporation.

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