The crushed potato pulp passes between the rolls and into a bin beneath, having adjustable walls made of boards F, sliding in suitable guides f, from which the pulp may be shoveled into the mashing tank or “back.” The crusher might, however, be arranged to deliver immediately into the mashing tank, if the latter is provided with means for stirring the delivered pulp.
Fig. 44.—Potato Steamer and Crusher.
The pulp or paste thus made is now placed in a vat, holding about 650 to 850 gals., in which the saccharification takes place. About 2200 lbs. of the crushed potatoes and 155 lbs of broken malt are introduced, and immediately afterwards water is run in at a temperature of about 97° F. to 104° F., the contents being well stirred with a fork meanwhile. The vat is then carefully closed for half an hour, after which boiling water is added until the temperature reaches 140° F., when the whole is left for three or four hours. The process of fermentation is conducted in the same vat. Alternate doses of cold and boiling water are run in upon the mixture, until the quantity is made up to 700 or 775 gallons, according to the size of the vat, and so as finally to bring the temperature to 75° F. or 79° F. Five and a half to six gallons of liquid brewer’s yeast are then added, and fermentation speedily sets in. This process complete, the fermented pulp is distilled in the apparatus devised by Cellier-Blumenthal (see Fig. [15]) for distilling materials of a pasty nature; the product has a very unpleasant odor and taste.
The process above described is the old method of pulping the potatoes by using steam. Under the modern method, however, and with modern apparatus, in preparing potatoes for distillation in large quantities, the steaming of the material is accomplished at one time and under a high steam pressure. The apparatus is also used for the preparation of corn, potatoes and other starch-containing substances.
There are many apparatuses which have been devised for the purpose, but the principle on which they work is practically the same in all cases. They comprise a closed tank, fitted with stirrers, agitators, or other means for mixing and comminuting the contents, means for admitting steam under pressure, means for cooling the mixture to the proper mashing temperatures, and means for forcing the steamed material out of the tank.
Fig. 45.—Bohn’s Steamer and Crusher.