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Brewing and Distillation (Casks of different sizes)
casks of different sizes; a large funnel; two or three clean pails, and a hand-pump. for an indefinite period of time. To induce fer- | wooden bowls; a thermometer; half a dozen mentation, a portion of some nitrogenous body, itself undergoing decomposition, must be added.
Such ferments are albumen (white of egg), fibrin (fibre of flesh), casein (basis of cheese), gluten (the pasty matter of flour). Yeast consists of vegetable egg-shaped cells, which is increased during its action as a ferment.
Circumstances influencing Fermentation.
In order that fermentation shall begin we require, besides the contact of the ferment, the presence of air. The most easily decomposed articles of food may be preserved for an indefinite period by hermetically sealing them in jars, after drawing out the air. When once begun, however, fermentation will go on, if the air be excluded. Temperature is important. The most favorable temperature ture is between 68° and 77° Fahr. At a low temperature fermentation is exceedingly slow.
Bavarian or lager beer is brewed between 32º and 464° Fahr. A boiling heat instantly stops fermentation, by killing the ferment. To check fermentation we may remove the yeast by filtration. Hops, oil of mustard, sulphurous acid (from burning sulphur), the sulphites, sulphuric acid, check the process by killing the ferment.
Too much sugar is unfavorable to fermentation, the best strength for the syrup is ten parts of water to one of sugar.
Changes during Fermentation, etc.
The grape-sugar breaks up into carbonic acid which escapes as gas, alcohol and water which remain. In malting the grain is allowed to germinate, during which process the starch of the grain is changed into gum and sugar: the rootlets make their appearance at one end and the stalk or acrospire at the other. The germination is then checked by heating in a kiln; if allowed to proceed a certain portion of the sugar would be converted into woody matter, and lost.
In brewing the saccharine matter is extracted from the malt during the mashing. Yeast is added to cause fermentation; an infusion of hops afterwards, to add to the flavor and to check fermentation. In wine making there is sufficient albuminous matter in the grape to cause fermentation without the use of yeast.
Distillation separates the alcohol in great part from the water. Alcohol boils at 179° Fahr., and water at 212°. It is not possible, however, to separate entirely alcohol and water by distillation. Acetic Fermentation.
Weak fermented liquors will become sour on exposure to the air. This is owing to the conversion of their alcohol into acetic acid (see Vinegar). This change is due to the absorption of the oxygen of the air, and is much promoted by the presence of a peculiar plant, the mother of vinegar. It is sometimes called the acetous fermentation.
Viscous Fermentation.
By the action of yeast on beet-sugar a peculiar fermentation is set up; but little alcohol is formed. The same gives ropiness to wines and beer. It is checked by vegetable astringents.