ALCOHOL FROH BEET.—Beet contains 85 per cent. of water, and about 10 per cent, of sugar, the remainder being woody fibre and albumen. The conversion of the sugar into alcohol is effected in several different waysi, of which the following are the principal :—(1) By rasping the roots and submitting them to pressure, and fermenting the expressed juice; (2) By maceration with water and heat ; (3) By direct distillation of the roots.
By Rasping and Pressure—The spirit obtained by this process is much preferable to that obtained by the others, but it is considerably higher iu price, as it requires a larger stock and much more labour. The process is adopted chiefly in the large sugar factories, where all the necessary utensils are always at hand, and the only additional expense incurred is the distilling apparatus. The roots are washed, rasped, and pressed exactly as in the manufacture of sugar (see Sugar). By this means, 80 or 85 per cent. of juice is obtained, but this proportion is much increased by permitting a stream of water to flow upon the rasping instrument. The utmost cleanliness is essential to these processes; all the utensils employed should be washed daily with lime-water to counteract acidity. Before fermentation, the juice from the rasp and the press is brought into a boiler and heated by steam to about 28°; at this temperature it is run off into the fermenting vats. Here it is necessary to add to the juice a small quantity of concentrated sulphuric acid, for the purpose of neutralizing the alkaline salts which it contains, and of rendering it slightly acid in order to hasten the process; this quantity must not exceed 21 kilos. to every 1000 litres of juice, or the establishment of fermentation would be hindered instead of promoted. The addition of this acid tends also to prevent the viscous fermentation to which the juice obtained by rasping and pressure is so liable. Although the beet contains albumen, which is in itself a ferment, it is necessary, in order to develop the process, to have recourse to artificial means. A small quantity of brewer's yeast— about 50 grammes per 100 litres of juice—is sufficient for this ; the yeast must previously be mixed with a little water. An external temperature of about 20° must be carefully maintained.
The fermentation of acidulated beet-juice sets in speedily. The chief obstacle to the process is the mass of thick scum which forms upon the surface of the liquor. This difficulty is sometimes obviated by using several vats and mixing the juice, while in full fermentation, with a fresh quantity. Thus, when three vats are employed, one is set to ferment ; at the end of four or six hours, half its contents are run into the second vat and here mixed with fresh juice. The process
is arrested, but soon starts again in both vats simultaneously ; the first is now allowed to ferment completely, which is effected with much less difficulty than would have been the case had the vat not been divided. Meanwhile the second vat, as soon as the action is at its height, is divided in the same manner, one-half its contents being run into the third. When this method is employed, it is necessary to add a little yeast from time to time when the action becomes sluggish.
By Maceration.—The object of this process is to extract from the beets by means of water or spent liquor all the sugar which they contain, without the aid of rasping or pressure Spirit is thus produced at considerably less expense, although it is not of so high a quality as that yielded by the former process. The operation consists in slicing up the beets with a root-cutter, and then allow ing the slices to macerate in a series of vats at stated temperatures. It is essential that the knives by which the roots are cut should be so arranged that the roots are divided into slices having a width of 1 centimetre and a thickness of 1 millimetre, and a variable length ; the roots are, of course, well washed before being placed in the hopper of the cutter. When cut, the beets are covered with boiling water in a macerator of wood or iron for one hour ; the water should contain 2 kilos. of • sulphuric acid to every 1000 kilos. of beets. After this, the water is drawn off into a second vat in which are placed more beets, and allowed to macerate again for an hour. This is repeated a third time in another vat, and the juice, which has now acquired a density equal to that obtained by rasping, is run off into the fermenting vat. When the first vat is empty it is immediately refilled with boiling water and fresh beets; the juice from this operation is run into the second vat, when the contents of that one are run into the third. To continue the operation, the beets are completely exhausted by being macerated for an hour with a third charge of boiling water (acidulated as in the former case). The exhausted pulp is removed to make room for fresh slices ; and the first vat is then charged with juice which has already passed through the second and third vats. After macerating the fresh beets for one hour, the charge is ready for fermentation. In ordinary weather, the juice should now be at the right heat for this process, viz. about 22° or but in very cold weather it may require some re-heating. The fermentation is precisely similar to that of the pressed juice and calls for no special remark. It is usually complete in from 24 to 30 hours.