Alcohol from Grain—Corn, Wheat, Rice, and Other Cereals.
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| Alcohol from Grain—Corn, Wheat, Rice, and Other Cereals. |
220 lbs. Wheat gives 7.0 gallons pure alcohol
TABLE IV.
CHAPTER IX.Alcohol from Beets.
—Diffusion Battery.
—Diffusion Battery.
The different cereals constitute a very important source of alcohol in all countries, particularly of course for use in the manufacture of whiskey and gin.
All cereals contain an abundance of starchy substance which under the influence of diastase,—that is, malt,—is converted into fermentible sugar. The quantity of sugar and hence the yield of alcohol differs widely. The following table shows the results obtainable by good workmanship.
In addition to these there are other raw materials containing starch which are sometimes used, as millet (55 per cent starch), chestnuts (28 per[127] cent.), and horse chestnuts (40 per cent.). The last is very difficult to work however.
Rice, wheat, rye, barley and corn are more frequently employed than other grains. Wheat gives a malt which is as rich in diastase as barley. Barley and buckwheat are added to these in some proportions. Oats, owing to their high price,
are rarely used. Rice, of all the grain is the most productive to the distillers, but on account of its value as a food is not much used for the production of alcohol, unless damaged. Corn is the cereal most largely used for the production of industrial alcohol.
Great care should be exercised in making choice of grain for fermentation where the best results are desired. Wheat should be farinaceous, heavy and dry. Barley should be free from chaff, quite fresh and in large uniform grains of a bright color (see Malting,
Chapter VI).
Rice should be dull white in color, slightly transparent, without odor, and of a fresh, farinaceous taste.
The flour or farinaceous part of grain is composed of starch, gluten, albumen, mucilage, and some sugar. The following table gives the proportions of these substances in the commonest grains.
Under certain conditions the albumen or gluten in the grain has the power of converting starch into saccharine matter. This is better effected by an acid such as sulphuric acid, or by a diastase. This latter substance is a principle developed during the germination of all cereals
but especially of barley. It has the property of reacting upon starchy matters, converting them first into a gummy substance called dextrine, and then into glucose or
grape sugar, see Chapter II.
The action of diastase upon starch or flour made into a paste is remarkable, 50 grains of diastase being sufficient to convert 220 lbs. (100 kilogrammes) of starch into glucose.
The rapidity of this change depends on the quantity of water employed, and the degree of heat adopted in the operation.
Inasmuch as barley germinates very readily, and develops a larger proportion of diastase than any other grain, except wheat, it is generally used as a producer of diastase. Barley germinated according to proper methods is called malt, and its preparation is fully described in Chapter VI.
There are many methods of preparing grain for fermentation, but all use at least two of the following operations:—grinding, gelatinizing, steeping, or steaming, mashing saccharifying.
Grinding. Where cookers or the Henze steamers are not used every form of grain should be crushed or ground into a coarse flour. This is in order that the starchy interior may be easily acted on by the diastase. If the grain is not to be mixed with malt later it must be ground more finely so that it may be thoroughly penetrated by the water.
The grains should not be ground except as required, as ground grain is liable to heating and consequent loss of fermentability, and is also liable to become musty, in which condition it loses much of its fermentability.
Steeping. This operation is best carried on in vats or tanks of iron or cement, for the reason that wood absorbs impurities, which are communicated to the grain,
thus lessening its germinative power. Wooden vats should be thoroughly scrubbed after use, and be kept continually whitewashed. The steeping tub should hold about two-thirds more than the amount of ground grain to be steeped.
Steeping is affected by pouring on to the crushed grain hot and cold water in such quantity that after 10 minutes or so of brewing the mixture will have a temperature of 75° to 95° F.
This warmth makes the water more penetrating. The water should not be poured in all at once, but a little at a time, until the grain is covered to a depth of three or four inches. Care should be taken not to let the temperature get too high, not above 95° F., as a temperature above that point kills the germinating power.
The mixture of crushed grain and water is now stirred for 10
minutes and then left to subside for half an hour. It is then stirred again and the mixture left to steep for 30 or 40 hours, depending on the temperature of the atmosphere, the dryness of the grain, and the character of the water.
In very warm weather the water should be changed every few hours by running it off through a hole in the bottom of the tub and running in fresh at the top. This prevents fermentation setting in prematurely.
When the grain swells, and yields readily between the fingers it has been sufficiently steeped, and the water is run off. This is an old method of gelatinizing grain, but a better is by the use of cookers or high pressure steamers as described for potatoes.
Mashing. This consists in mixing the coarse flour with malt and then by means of certain operations and mechanisms bringing it to a condition most favorable to fermentation through the action of yeast. The mixing of the raw flour with barley or other malt effects the conversion of the starch of the grain into maltose. The yeast afterwards converts this maltose into sugar.
Saccharifying. To effect the action of the diastase of the malt on the grain, in the old methods, boiling water must be poured into the vat until the temperature of the mass reaches about 140° to 168° F., the whole being well stirred meanwhile;
when this temperature has been reached, the vat is again covered and left to stand for four hours, during which time the temperature should, if possible, be maintained at 140° F., and on no account suffered to fall below 122° F., in order to avoid the inevitable loss of alcohol consequent upon
the acidity always produced by so low a temperature. In cold weather the heat should of course be considerably greater than in hot. It should be also remarked that the greater the quantity of water employed, the more complete will be the saccharification, and the shorter the time occupied by the process.
Having undergone all the above processes, the wash is next drawn from the mash tub into a cistern, and from this it is pumped into the coolers.
When the wash has acquired the correct temperature, viz., from 68° to 78° F., according to the bulk operated upon, it is run down again into the fermenting vats situated on the floor beneath. Ten to twelve pints of liquid or 5½ to 6½ lbs. of dry brewer’s yeast are then added for every 220 lbs. of grain;
the vat is securely covered, and the contents are left to ferment. The process is complete at the end of four or five days, and if conducted under favorable conditions there should be a yield of about 61⁄6 gallons of pure alcohol to every 220 lbs. of grain employed.
There are a number of different methods of mashing, having each its advantages, and applicable to particular varieties of grain.
We will first consider the mashing of the steeped grain in general by one of the older and simpler processes.
The grain to be mashed, which has been ground and steeped as before described, is mixed with malt in the proportion of four to one, or even eight to one. In addition, three or four pounds of chaff to every hundred or so pounds of steeped grain should be used.
Mash. Water is then run into the mash tub in the proportion of about 600 gallons to each 60 bushels of grain. Its temperature should be between 120° and 150° F.
During the entrance of water, the mass is well stirred so as to cause the whole of the grain to be thoroughly soaked and to prevent the formation of lumps. It is best to add the grain to the water gradually and to stir thoroughly.
To this mass about 400 gallons of boiling water is gradually added to keep the temperature at about 145° F. During the addition of the boiling water the mash should be continually stirred so that the action of the water shall be uniform.
This operation should last about two and one half hours. The vat should be then covered and left to stand from three-quarters to one hour for saccharification.
Another method of saccharifying is to turn boiling water gradually into the mash tank until the mixture has acquired a temperature of from 140° to 180° F.
The mass is thoroughly stirred and the tub is covered and left to subside for from two to four hours, during which time the temperature should not be allowed to fall below 120° F. A small tub needs more heat than a larger tub, and more heat is required in winter than in summer.
A convenient method of regulating the temperature of the mash tank, would be by a coil of pipes on the bottom. This would be connected by a two-way cock to a steam boiler and to a source of cold water. Heat should never be carried over 180° F., and the best temperature is from 145° to 165° F.
The greatest effect of the diastase of the malt upon the gelatinized starch is at 131° F. For ungelatinized starch this is not great enough, hence the greater part of the mashing is carried on at the lower temperature and only towards the end should the temperature be raised to the maximum 150° F.
Every distiller uses his own judgment as to the amount of the mashing water used, its temperature, the length of time during which the mash rests, and the length of time for saccharification.
Saccharification may be recognized by the following signs: The mash loses its first white mealy look, and changes to dark brown. It also becomes thin and easily stirred. The taste is sweet and its odor is like that of fresh bread.
Corn and other grain may be mashed conveniently in such an apparatus as that described on page 10, as used for potatoes the steam being introduced under pressure.
The water is first placed in the steamer. Steam is introduced into the water and it is brought to a boil. The corn is then introduced gradually,
the steam pressure increased to its maximum, and the mass blown out as described in Chapter VII. Hellefreund’s apparatus (see page) may also be used with ground corn.
The corn or grain not previously crushed or ground is introduced into a steamer in the proportion of 200 lbs. of corn to 40 gallons of water. The steamer should have about 100 gallons of steam space for this amount.
The mashes described above are thick, more or less troublesome to distil, and only simple stills can be used. By the following method a clear saccharine fluid or wort can be obtained.
A mash vat is used having a double bottom. The upper bottom is perforated and between the two bottoms is a draw-off pipe and a pipe for the inlet of water.
Upon the upper perforated bottom is first placed a layer of between two and three pounds of chaff. Upon this is turned in a mixture of 400 lbs. corn and malt in the proportions of 1/5 malt to 4⁄5 grain. Eighty-seven gallons of water at a temperature of from 85° to 105° F. is then let in to the bottom, while the mixture is thoroughly agitated for 10 minutes. It is then left to subside for half an hour.
After this steeping process, the mass is again agitated while 175 gallons of water at 190° F. are let into the tub while the mass is continually and thoroughly stirred by mechanical stirrers. Brewing lasts for half an hour, and the liquid is then left to stand for seven hours.
At the end of this period the grain is covered by clear liquid which is drained off through the draw-off cock into the fermenting back.
To the contents left in the steeping tank 135 gallons of boiling water are added as before and the liquid therefrom drawn into the fermenting back.
It usually requires three infusions to extract the whole of the saccharine and fermentiscible matters contained in the grain. In some places, it is customary to boil down the liquors from the three mashings until they have acquired a specific gravity of about 1.05, the liquor from a fourth mashing being used to bring the whole to the correct degree for fermentation,
the liquors from the third and fourth being boiled down to the same density and then added to the rest. In a large Glasgow distillery, the charge for the mash tubs is 29,120 lbs. of grain together with the proper proportion of malt. Two mashings are employed, about 28,300 gallons of water being required;
the first mashing has a temperature of 140° F., and the second that of 176° F. In Dublin the proportion of malt employed is only about one-eighth of the entire charge. One mashing is employed, and the temperature of the water is kept at about 143° F. The subsequent mashings are kept for the next day’s brewing.
By this process the grain is entirely deprived of all fermentible substances which have been carried away in a state of liquid sugar.
The whole operation of preparing and saccharifying grain is to-day carried on in steamers, such as described on page and cooking apparatus such as shown in or in the Henze high pressure steamers and preparatory mash vats described in Chapter II.
In steaming grain without pressure, the finely crushed grain is poured slowly into a vat previously nearly filled with water at a temperature of about 140 degrees F. A little less than half a gallon of water is used for each pound of grain. Care must be taken to stir the mass constantly to prevent lumping.
When all the corn is mixed in, steam is allowed to enter and the temperature raised to about 200 degrees F. It should be left at this temperature for an hour, or an hour and a half, when the temperature is reduced to 140° F. when about 10 per cent. of crushed malt is added and the temperature reduced to 68° F. by means of suitable cooling devices.
When steam cookers are used, the cylindrical boiler is first filled to the proper degree with water at a temperature of 140° F. The meal is then let in gradually being constantly stirred the while.
The boiler is then closed and steam gradually let in while the mass is stirred until a pressure of 60 pounds and a temperature of 300° F. has been reached. The starch then becomes entirely gelatinized, the pressure is relieved, and the temperature reduced to 212° F. and then rapidly brought to 145° F.
The malt is added mixed with cold water, at such a stage before the saccharifying temperature is reached that the cold malt and water will bring it to 145° F. The malt is stirred and mixed with the mash for five or ten minutes and the mixed mass let into a drop tub when saccharification is completed. It is then cooled as described.
When the Henze steamers are used the grain may be treated in either the whole grain or crushed, as the high pressure to which it is subjected and the “blowing out” act to entirely disintegrate it. In this mode of operation, water is first let into the steamer and brought to a boil by the admission of steam.
The grain is then slowly let into the apparatus. The water and grain should fill the steamer about two thirds full. The steamer is[138] left open and steam circulated through the grain and water for about an hour, but without any raising of pressure. This acts to thoroughly cook and soften the grain.
When sufficiently softened the steam escape cock in the upper part of the steameris regulated to allow a partial flow of steam through it and a greater flow of steam is admitted through the lower inlet. This keeps the grain in constant ebullition under a pressure of 30 lbs. or so.
After another period of an hour the pressure in the steamer is raised to 60 lbs. at which point it is kept for half an hour, when the maximum steam pressure is applied, and the greater portion of the disintegrated mass blown out into a preparatory mass tub, into which malt has been placed mixed with water.
The blowing out should be so performed that the temperature in the mass in the tubs shall not exceed 130° F. The mass is stirred and cooled and then the remainder of the mass in the steamer admitted to the tub which should bring the temperature of the mass up to 145° F. It is kept at this temperature for a period varying from half an hour to one and one-half hours and is then cooled to the proper fermenting temperature.
Another method of softening corn so that its starch is easily acted upon by the diastase of the malt is to steep it in a sulphurous acid solution at a temperature of about 120° F. for from fifteen to twenty hours. The mass is then diluted to form a semi-liquid pulp and heated to about[139] 190° F. for an hour or two during which the mass is constantly stirred. The malt is then added, the mass is saccharified, cooled and then fermented.
Another method is to place mixed grain and hot water in a cooker of the Bohn variety. After half an hour of stirring and cooking under ordinary pressure,
the steam pressure is raised to 45 lbs. This is kept up for from two to three hours when the grain is reduced to a paste. Concentrated muriatic acid equal to 2½ per cent of the weight of grain is then forced in, under steam pressure. In half an hour the grain will be entirely saccharified and ready for fermenting.
Cultivation. The beetroot (Beta vulgaris), indigenous to Europe, is cultivated in France, Germany, Belgium, Holland, Scandinavia, Austria, Russia, and to a very small extent in England and New Zealand, and to a very large extent in the United States and Canada. There are many varieties.
The most important to the sugar-maker is the white Silesian, sometimes regarded as a distinct species (B. alba); it shows very little above ground, and penetrates about 12 in.; it has a white flesh, the two chief forms being distinguished by one having a rose-colored skin and purple-ribbed leaves, the other a white skin and green leaves. Both are frequently grown together, and exhibit no marked difference in sugar-yielding qualities.
Good sugar-beets possess the following broad characteristics: (1) Regular pear-shaped form and smooth skin; long, tapering, carrot-like roots are considered inferior; (2) white and firm flesh, delicate and uniform structure, and clean sugary flavor; thick-skinned roots are spongy and watery;
those with large leaves are generally richer; (3) average weight 1½ to 2½ lbs., neither very large nor very small roots being profitable to the sugar-manufacturer; as a rule, beets weighing more than 3½ lbs. are watery, and poor in sugar; and roots weighing less than ¾ lb. are either unripe or too woody, and in either case yield comparatively little sugar;
the sp. gr. of the expressed juice, usually 1.06 to 1.07, even reaching 1.078 in English-grown roots, indicating over 14 per cent. of crystallizable sugar, is the best proof of quality; juice poor in sugar has a density below 1.060; (4) in well-cultivated soil, the roots grow entirely in the ground, and throw up leaves of moderate size.
Composition of the Roots. Internally the root is built up of small cells, each filled with a juice consisting of a watery solution of many bodies besides sugar.
These include several crystallized salts (mostly of which are present in minute traces only), such as the phosphates, oxalates, malates, and chlorides of potassium, sodium, and calcium, the salts of potash being by far the most important;
and several colloid bodies (albuminous [nitrogenous and pectinous compounds); as well as a substance which rapidly blackens on exposure to the air. The greater part of the sugar in ripe beets is crystallizable, and, when perfectly pure, is identical in composition and properties with crystallized cane-sugar;
but it is more difficult to refine this sugar so as to free it from the potash salts, and commercial samples have not nearly so great sweetening power as ordinary cane-sugar.
Beets contain no uncrystallizable sugar; the molasses produced in beet-sugar manufactories is the result of changes which cannot be entirely avoided in extracting the crystallizable sugar.
Soil. The best soil for beets contains a fair proportion of organic matter, is neither too stiff nor too light, and crumbles down into a nice friable loam; it must be capable of being cultivated to a depth of at least 16 in.
The subsoil should be thoroughly well drained, and rendered friable by autumn-cultivation and free admission of air. A deep friable turnip-loam, containing fair proportions of clay and lime, appears to be the most eligible land for sugar-beets. Lime is a very desirable element.
Well-worked clay-soils, especially calcareous clays, are well adapted, if properly drained and of sufficient depth. Peaty soils and moorlands are quite unsuitable, as well as lands which are too dry, like the thin gravelly soils resting on siliceous gravel sub-soils, or too wet and cold, like many of the thin soils above impervious chalk marl.
Speaking generally, the best soils for sugar-beet are precisely those on which other root-crops can be grown to perfection, that is, land which is neither too heavy nor too light, which has a good depth, is readily penetrated by the roots, and naturally contains lime, potash, clay, and sand, as well as organic matter, is such proportions as in good friable clay-loams.
An analysis of the soil should be made previous to planting it with the sugar-beet, as the salts presented in solution in the soil will pass into the juice, and greatly interfere with the processes of sugar manufacture.
Certain soils may be at once indicated as unsuitable; they are clover-land, recent sheep-pastures, forest-land grubbed during the preceding 15 years, the neighborhood of salt works, volcanic and saline soils of all kinds.
The beet requires a certain supply of potash and soda salts in the soil, but if these are present in excess, as in recent forest-land, the juice does not work well, nor give its proper yield of sugar.
Manures. Sugar-beets should be grown with as little farmyard manure as possible; when dung has to be used, as in the case of very poor soils, it should be applied in autumn, or as early as possible during the winter months.
The effect of heavy dressings of animal nitrogenous matters or ammoniacal salts, is to produce abundance of leaves, and big watery roots; the latter are comparatively poor in sugar, and contain potash salts derived from the animal matters, which greatly interfere with the extraction of sugar in a crystallized state.
Common salt, and saline manures in general, though useful in moderate doses (224 lbs. to 336 lbs. per acre on light soils), should be avoided on the majority of soils, for sugar-beets grown on soils highly manured with common salt produce juice largely impregnated with salt, which is[144] dreaded by the manufacturer even more than albuminous impurities, and nearly as much as excess of potash salts.
If the land is in good condition, containing sufficient available nitrogen to meet the requirements of the crop, neither guano nor sulphate of ammonia should be used. They largely increase the weight of the produce per acre; but heavy crops are generally poor in sugar, and furnish a juice that presents much difficulty to the manufacturer.
If the land is very poor, and if farmyard manure cannot be obtained and be applied in autumn, 336 to 448 lbs. of Peruvian guano, or 224 lbs. of sulphate of ammonia, mixed with 224 lbs. of superphosphate of lime, per acre, may be sown broadcast in autumn, and 224 lbs. more of superphosphate may be drilled in with the seed in spring.
Superphosphate of lime and bones are excellent for sugar-beets, and never injure the quality of the crop, like the indiscriminate use of ammoniacal manures. On light soils, in which potash is often deficient, the judicious use of potash salts has been found serviceable, but only in conjunction with superphosphate and phosphatic guanos.
Sowing. The best time for sowing beetroot is the beginning or middle of April. If sown too early, the young plants may be partially injured by frost; if later than the first week in May, the crop may require to be taken up in autumn, before it has had time to get ripe. About 10 to 12 lbs. of seed is required per acre.
As regards the width between the plants, generally speaking, the distance between the rows and from plant to plant should not be less than 12 nor greater than 18 in. Should the young plants be caught by a night’s frost, and suffer ever so little, it is best to plough them up at once and re-sow, for they are certain to run to seed, and are then practically useless for the manufacture of sugar. Sugar-beets require to be frequently horse- and hand-hoed. As long as the young plants are not injured, the application of the hoe from time to time is attended with great benefit to the crop. It is advisable to gather up the soil round each plant,
in order that the head may be completely covered with soil. Champonnois’ researches point to the advantage of planting in ridges, by which the supply of air to the roots is greatly facilitated.
The conditions best calculated to ensure the roots possessing the characters most desirable from a sugar-maker’s point of view are chiefly as follows: (1) Not to sow on freshly-manured land; it is eminently preferable not to manure for the beet crop, but to manure heavily for wheat in the preceding year; (2) not to employ forcing manures, nor to apply manure during growth; (3) to use seed from a variety rich in sugar; (4) to sow early, in lines 16 in. apart, at most, the plants being 10 to 11 in. from each other; there will then be 38,000 beets on an acre, weighing 21 to 28 ounces[146] each, or 52,800 to 70,400 lbs. per acre; (5) to weed the fields as soon as the plants are above ground, to thin out as early as possible, and to weed and hoe often, till the soil is covered with the leaves of the plants; (6) never to remove the leaves during growth; (7) finally, not to take up the roots, if it can be avoided, before they are ripe, the period of which will depend upon the season.
Good seed may be raised by the following means: The best roots, which show least above ground, are taken up, replanted in good soil, and allowed to run to seed.
This seed is already good; but it may be further improved by sowing it in a well-prepared plot possessing all the most favorable conditions; the resulting plants are sorted, set out in autumn, put into a cellar, and in the spring,
before transplanting, those of the greatest density, and which will give seeds of the best quality, are separated. These are transplanted at 20 in. between the rows and 13 in. between the feet, which are covered with about 1½ in. of earth. Finally they are watered with water containing molasses and superphosphate of lime, as recommended by Corenwinder.
Harvesting. Sugar-beets must be taken up before frost sets in. When the leaves begin to turn yellow and flabby, they have arrived at maturity, and the crop should be watched, that it may not get over-ripe.
If the autumn is cold and dry, the crop may be safely left in the ground for seven to ten days longer than is needful, but should the autumn be mild and wet, if the roots are left in the soil, they are apt to throw up fresh leaves,
and nothing does so much injury. In watching the ripening of the crop, a good plan is to test the sp. gr. of the expressed juice.
A root or two may be taken up at intervals, and reduced to pulp on an ordinary hand-grater, the juice obtained by pressing the pulp through calico, and the density observed by a hydrometer. As long as the gravity of the juice continues to increase,
the crop should be left in the land. Good sugar-yielding juice has a sp. gr. of about 1.065, rising to about 1.070. Immature roots, cut across, rapidly change color on the exposed surface, turning red, then brown, and finally almost black.
If newly-cut slices turn color on exposure, the ripening is not complete; but if they remain some time unaltered, or turn only slightly reddish, they are sufficiently ripe to be taken up. The crop should be harvested in fine, dry weather
. In order that the roots may part with as much moisture as possible, they are left exposed to the air on the ground before being stacked, but not for longer than a few days, and they need to be guarded against direct sunlight. Perhaps the best plan is to cover them loosely with their tops in the field for a couple of days, then trim them, and at once stack them.
Storing. For storing roots, especial care should be taken to prevent their germinating and throwing out fresh tops, which is best done by selecting a dry place for the storage ground.
They may be piled in pyramidal stacks, about six feet broad at base, and seven feet high. At first, the stacks should be thinly covered with earth, that the moisture may readily evaporate; subsequently, when frosty weather sets in, another layer of earth, not exceeding one foot in thickness, may be added. This is essentially the method generally adopted for storing potatoes and beets.
In continental Europe and Canada, extra precaution is necessitated by the rigorous climate. In S. Russia, the plan shown in is sometimes used. The beets are disposed completely below the surface of the soil, in a trench dug with sharply sloping sides. At about 15 in. from the bottom, is an openwork floor of reeds, on which the beets are piled to within a few inches of the level of the exterior soil. On the top, and following the apex of the heap, is laid a triangular ridge-piece a, for the purpose of facilitating evaporation.
The whole is covered with a layer b of straw and[149] fine earth, the thickness of which is varied according to the indications of the thermometer c placed in the center of the mass.
Between the floor of the trench and the openwork floor is a space d, communicating with two vertical channels leading to the outer air, thus providing ventilation. The outlets of the channels can be opened and closed at will. The Russians also often employ regular cellars, as shown in .
The structure consists of two stories, covered with a bed of earth, each furnished with a floor of hurdles or open planking, on which the beets are piled to the depth of about one yard. Lateral passages facilitate ventilation, and openings in the roof permit the heated air to escape.
The cost of erecting these cellars is heavy, but there is great saving of labor in storing the beets, as it suffices to simply pile them up on the floors. Moreover, the arrangement permits the examination of the contents beyond the indications of a thermometer; and enables any portion to be removed, even during snowy weather.
Alcohol from Beets. Beets contain 85 per cent. of water, and about 10 per cent. of cane sugar, the remainder being woody fibre and albumen; cane sugar not being in itself fermentible,— as is grape sugar,—it has to be converted into “inverted sugar” by a ferment as yeast. Either the sugar beets may be mashed or the molasses which remains from the manufacture of beet sugar (as described in Chapter X)
. The conversion of the sugar into alcohol is effected in several different ways, of which the following are the principal:
By rasping the roots and submitting them to pressure, and fermenting the expressed juice.
By maceration with water and heat.
By direct distillation of the roots.
The first two methods are the best as by them the woody fibre of the plant which is non-fermentible is separated from the fermentible juice. In both the first and second processes the beets must first be entirely cleaned of adhering dirt, trash and clods of earth, and then rasped, pulped or sliced by certain machinery.
Cleaning. Care must be taken in this operation that the beets shall be freed from small stones and adhering hard lumps of earth which would otherwise get into the rasping machinery to the damage and stoppage of the mechanism.
There are many forms of cleaners but all are alike in this,— that the beets shall be subjected to the action of water while traveling through or over a perforated casing.
The simplest machine, and one easily constructed by any carpenter, comprises an elongated cylinder formed of lathes or strips spaced apart such distance as will allow dirt and stones to pass between them. This is mounted on a central shaft and revolves in a tank of water.
It should be slightly inclined so that the potatoes or beets to be washed may feed downward from the open upper end-disk or wheel, to the lower end where they are thrown out. At the upper end is a hopper and at the lower,
the end disk has inwardly projecting lips, which as the cylinder revolves lifts the beets up and tumbles them out on to an incline which carries them to the rasping machine.
Another form of machine comprises a perforated cylinder of sheet iron, revolving in a tank of water. A better form of cleaner than either of those consists of an inclined trough in which a spiral feeding screw of sheet iron rotates.
The beets are fed into the trough at its lower end and are carried upward, slowly, by the feeding screw. Above the trough is a water pipe having a number of outlets by which water may fall on to the beets and into the trough.
The water rushing down the inclined trough carries with it all dirt and stones, and by the time the beets have reached the upper end they are entirely cleaned and ready for slicing or rasping.
For pressing out the juice, the beets are mashed into a pulp, while for diffusion the beets are sliced.
Rasping.shows one form of rasping machine. On a suitable supporting frame is mounted a cylinder a having a diameter of about 24 inches.
The cylinder is formed of alternate saw blades and wooden washers holding them a slight distance apart. The saws or teeth are so set on the cylinder as not to slice the beets but to shred them up into a fine pulp.
The cylinder rotates at a speed of 800 to 1000 revolutions a minute in front of an inclined table, having a jigger whereby the beets are fed downward against the toothed cylinder. The teeth carry the pulp downward and it falls into a receptacle beneath.
It is best to add to this pulp a small portion of sulphuric acid, say two-tenths of one per cent. This prevents by-fermentations.
Pressing. The pulp obtained from the raspers has now to be expressed. This is either done by platen presses or by roller presses. With platen presses the first pressing may be done by screws, but the final pressing should be accomplished by hydraulic presses.
For the hydraulic press, the pulp is placed in woolen sacks, containing 10 to 12 lbs., superposed in the press with their mouths doubled under, and separated by iron plates; about 25 are collected, and the pile is put into a screw-press, called a “preparatory” press, which extracts about 45 to 50 per cent. of the juice.
These pressed sacks are piled anew on the movable plate of a powerful hydraulic press, which takes 50 at a charge. Each preparatory press can supply four hydraulic presses, which are ranged around it, so that of the four presses,
there will be one charging, one commencing to press, one in full pressure, and one discharging, at the same moment.
Motion is communicated to the four hydraulic presses by four pumps mounted on the same bed, and tended by the same workman who directs the pressing.
An improvement upon the general form of hydraulic press is that devised by Lalouette, which enables two workmen and one boy to work five presses.
These presses turn out about 34,200 lbs. per 24 hours in the first pressing, and 68,400 lbs. in the second. Hydraulic presses are rapidly falling into disuse in the beet-sugar industry, by reason of the superior merits of continuous presses, and the extended adoption of the diffusion system.
Continuous presses for beet were suggested by the roller-mills used in the cane-sugar industry.
But the conditions in the two cases are widely different; the begass of the cane is solid, and readily parts from the juice; whereas the pulp and juice of the beet have a strong tendency to combine, and the roller-surface must therefore be permeable only by the juice.
In Poizot et Druelle’s press, the pulp passes between two cylinders, carried by endless cloths. The object is to unite the best features of the hydraulic press. To this end, a first gentle pressing is produced against the first cylinder by the elasticity of the principal cloth on which it is borne.
Then, encountering a series of four little rollers, performing the functions of the preparatory press, it is next seized between the second and first cylinders, and deprived of the maximum quantity of juice.
Dujardin’s roll press is shown in , which is a vertical section of the machine, the side plate being removed. The pulp is forced upward through a pipe C under high pressure. This has a regulating slide valve D.
The rolls B B revolve towards and nearly in contact with each other, and they are perforated so that the expressed juice may run off through the rolls. These perforations are conical in form with the apex of the cone outward.
The cylinders are also covered with a webbing of cloth or horse hair. Below the rolls is block C′, which with the outer walls of the chamber, form diverging passages which extend upward, as shown, on either side of the rolls and then downward
[156] along the lower faces of the rolls to the point when they contact. The pulp is compressed with great force against and between the rolls, the juice is forced through the perforations and the residue passes upward and outward under the presser bar E in the form of a ribbon which is guided away by the trough F.
The pressure of the bar E is regulated by screws and the tighter said bar is pressed against the rolls the greater will be the pressure of the pulp behind the bar and against the rolls, and the greater the juice expressed.
The vessels, 1, 2, 3 and 4 are of wood or sheet iron. Each vessel has a bottom sieve and a top sieve between which the beet slices are to be placed. From the bottom of each vessel below the sieve a pipe D runs to the top of the vessel next in order.
From the bottom of the last vessel 4 of the series a pipe C runs back to the top of the one first used. Pipes A and B are connected to each vessel for the admission of water and spent wash respectively. A discharge pipe E leads from each vessel to a collecting vat 5.
The same operation is repeated as to vessel 4 and in three-quarters of an hour all the vessels are connected, hot water or spent wash is admitted to 1 and the sugar solution drawn off from 4 into the vat.
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