Wine making rests also largely upon chemical principles. In grapes we find large quantities of sugar combined with organic acids, of which tartaric acid is the chief, coloring matters, tannic principles, etc. The production of wine of fine flavor consists in securing the fermentation of the sugars of this mixture with appropriate ferments and under carefully controlled conditions of temperature. Only through the most careful chemical control are the most favorable conditions maintained. Consciously or unconsciously, the wine maker is a practical chemist, and under the influence of modern research the scientific principles of wine making are very much more firmly established and more easily practiced than they were before the conditions under which wine is produced were thoroughly understood. In wine making chemistry also exercises an important function in the utilization of the by-products. The tartaric acid present in grapes is very valuable in commerce, forming; in combination with potash, the well-known substance cream of tartar, which is so extensively employed in the manufacture of baking powders and for other purposes. By the application of the principles of chemical technology to the residues of the wine press and to the incrustations which form upon the vats the cream of tartar of commerce is secured.
Brewing is also largely a chemical science. The chief problem in the brewing industry is that of fermentation, and the development of fermentation has been due solely to the researches of chemists. In the brewing industry the first object is to collect the starch of the cereal into maltose and subsequently to change the maltose into alcohol by fermentation with yeast. By the researches of physiological chemists, it was discovered that the active principle in the eon version of starch into sugar is an enzymic ferment commonly called diastase, which is developed in barley by germination. This ferment rapidly converts starch into maltose, the conversion often taking place within a few minutes. By the researches of Pasteur and other distinguished chemists, the method of producing pure cultures of yeast was established. It is important, in order to secure a fine flavor to the finished product, that the ferment be as pure as possible. It is thus seen that in the chief problems which underlie the brewing industry chemistry takes a leading part.
The industry devoted to the manufacture of alcohol, whisky, and brandy is also chiefly of a chemical nature. The distilling industry naturally follows after the brewing industry. The manufacture of alcohol from starch may be described as the same in both industries. After the alcohol is formed it is separated from the mash by distillation. In spite, however, of the greatest care in the selection of yeasts, several varieties of alcohol as well as of organic acids are formed during the process of fermentation. After the distillation is finished, therefore, the separation of common alcohol from the impurities with which it is naturally mixed becomes a difficult chemical problem. The progress which has been made in this line, however, has been so great as to render the production of pure alcohol on a commercial scale an industrial proceeding of great magnitude. Chemical principles also of the utmost importance underlie the production of whisky and brandy, due to the elimination of objectionable alcohols by means of oxidations produced by storage under proper conditions of temperature and in suitable vessels. The whole process of aging a whisky or brandy or wine rests exclusively upon the proper conduct and control of the chemical reactions which take place.
From The Relation of Chemistry to the Progress of Agriculture by Dr. H.W. Wiley as published in the Yearbook of the Department of Agriculture. Wiley was he first commissioner of the FDA.
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