WINE AND It may have been design, but it was probably an acci dent, that first led man to crush or to press grapes in order to obtain a palatable and stimu lating beverage. As long as the juice is con fined within the grape, it becomes sweeter and sweeter as the fruit grows riper and riper. But when the skin is broken by crushing or press ing, and when the juice is allowed to remain a short time exposed to warmth and air, it changes its character and develops new and un suspected qualities or properties.
The changes from the fresh grape juice to an alcoholic drink are briefly as follows: When the juice, or "must,* is exposed to temperatures ranging from 59' F. to 6a F. the liquid very soon begins to become turbid, small bubbles collect on the surface and the grape skins, stems and other solid particles form a dense cover or 'cap' on the top. Carbonic gas, which is developed in increasing quantities, es capes with a loud bubbling sound, and, as the temperature rises the juice appears as though it were really boiling. After a few days, and sometimes atter a few hours, the ebullition sub sides and gradually the crust and undissolved substances fall to the bottom. Meanwhile, the must has lost its sweetish taste and its original character and chemical composition; among other things, it has acquired a richer, deeper color, a vinous flavor and odor, and a certain amount of alcohol.
This interesting natural process, which leads to the formation of alcohol, was described by the term from the Latin ter neentims, the root word being tervere, to boil. This feature of the phenomena, whereby the evolution of the gas makes the liquid appear to boil, evidently struck the early wine-makers and natural philosophers as most important. It was a long time before the true nature of the proc ess of vinous or alcoholic fermentation was clearly perceived and properly understood.
Early in the last century (from 1810-25) chemical analyses by Gay-Lussac, Thenard and De Saussure fixed accurately the composition of sugar in the must and of alcohol in the wine. In 1835 Cagniard de Latour found that the globules were definite organisms, capable of re producing themselves by budding, and thus ap parently belonging to the vegetable kingdom. He came to the conclusion that, in the course of vegetation, these globules. or 'ferments,'
disengaged carbonic acid gas and converted the liquid into an alcoholic liquor.
This discovery was confirmed two years later (1E37) by Scbwann at Jena and Kutzing at Ber lin_ The newly-found organism was regarded by some as belonging to the fungi and by others to the alga.. Mcyen showed that the organism a fungus and established a ucw genus for it under the name of Sthcharusnyees. In other the agents of alcoholic fermentation are called 'yeasts' and belong to the order Sac cturoret3ces.
Recent Researches in Alcoholic Fermen The work of the great chemist Pasteur threw a flood of light upon the whole process of fermentation. His investigations extending over a series of years were first slimmed up in his 'Studies on Wine' ('Etudes sur le Vin'), published in 1872, and further in his book 'Studies on Beer' ('Etudes sur la Bire'), pub: lished in 1876.
To Pasteur belongs the honor of establish ing beyond question that fermentations were the work of infinitely small organisms called 'mi crobes.' He classified and described many of these micro-organisms. He divided them into two classes: aerobic, those which cannot live without the presence of free air; and anaerobic, those which can exist in the absence of air. The former saccharomyces arc found at or near the top of the liquid during fermentation; the latter are at work lower down in the body of the liquid.
The microscopical examination of the agents of alcoholic fermentation has revealed quite a number of different forms and varieties. Some 25 or 30 types of the genus Saccharomyces have been identified.
The question may very naturally be asked: Where do these yeast organisms come from? l'asteur showed very clearly that the ripe grape is covered with a mass of micro-organisms. These microbes collect on the fruit and stems, and constitute the 'bloom' of the grape. Just why they should fix themselves on the fruit, and remain, as it were, in readiness to be trans formed from their dormant state to one of great activity when carried into the juice of the fruit is a mystery. At the same time a great number of other and less desirable yeast cells (bacteria) become submerged in the grape juice, or must, and these foreign yeasts are the ones that give the wine-maker trouble and lead to many dis eases of wine.