SUGAR-BEET-CULTURE.

Waikato Times, Volume XVI, Issue 1369, 9 April 1881, Page 2

SUGAR-BEET- CULTURE.

*, —, .' ▼ In Mr MaclVor'slecture recently delivered under the auspices of the Cambridge Farmers' Club, the above named subject was specially alluded to, and a decided opinion expressed that the soil and climatic agencies of this locality were admirably adapted for the purpose. Although to some extent anticipated by experiments already made, the intelligence was nevertheless welcomed, inasmuch as it confirmed opinions already entertained. on the subject. The manufacture of sugar, from beet is an industry of great importance, and has added not a little to commercial enterprise throughout the world. If, as we have a perfect right to assume, the industry is one which can be established in New Zealand on advantageous terms, .no , pains should be spared for deseminating information on the subject. The following is culled from the latest authorities by whom the question is dealt with in its relations to this colony.

Treatment of the Root. In the manufacture of sugar from beetroot, the first operation to which the roots are to be submitted is to cleanse them thoroughly from any adhering soil or foreign matters. When thoroughly cleansed the roots* are rasped, grated, or sliced, in order to facilitate the extraction of the juice by pressure. In most continental factories the process of rasping is now used in preference to slicing, because the cells containing the sugary juice are more thoroughly broken open, and the root is reduced to a fine pulo. The form of the rasping machine 13 generally cylindrical, and au arrangement is attached to it which presses the roots regularly and gently against the rasp, turned by steam or water power at the rate of from 800 to 1000 revolutions per minute. In order to prevent the teeth of the rasp becoming blocked up by small particles of the root, a jet of water is allowed to trickle over the cylinder, which thoroughly removes any impedimenta into the receiving vessel underneath.

Deliterious substances. Besides sugar, water, and salts, the nitrogenised organic matters occurring* in beet require special notice, because they present, like the salts, a great obstacle to the process of manufacturing. The exact chemical composition of these substances has not yet been accurately determined, but we know that they exist in several different conditions, and that they are liable to rapid changes. In the absence of air they remain unaltered, but in its presence they are readily decomposed, and then act as ferments on the sugar. Hence the necessity of carefully harvesting beetroot, so as to prevent their getting injured. The juice, freshly expressed, and heated immediately, does not coagulate, but when it is allowed to stand for twenty-four hours a .small quantity of gray flakes is separated on boiling. These flakes have been assumed to be albumen, and we find consequently this substance mentioned in most analyses. But the result of recent trials has been to disprove its presence. A recent improvement, to counteract the formation of sugar iuto molasses, and to check fermentation as ranch as possible, is to use bisulphate of lime. For the double purpose of checking fermentation by the presence of sulphurous acid in this salt, and of neutraliting the sulphuric acid as quick as it is formed, this process is followed in several continental factories, and is said to answer well the purpose for which it ia employed. Separating tke Juice From the pulp is done by submitting the pulp, inclosed in circular bags, to hydraulic pressure. At first a very gentle pressure is applied, and when all the juice removable by a slight pressure has drained off, gradually increased pressure is eraployed to squeeze oub as much as possible of the juice. Geuerally a number of bags are piled on each other in tha press, each being seperated from the other by a perforated metallic plate, and after remaining in the press about twenty minutes the position of the bags is reversed, so that their points of contact may be changed, or, better still, the cake in the bags is broken in pieces before it is again enclosed in the bai?s, and submitted to a second and greatly increased pressure. Between each part of the operation the bags should be dipped in a weak solution of tannic acid (two to three parts per 1000), which, by combining with the nitrogenised substances of the external surface of the pulp in contact with air, prevents the formation of ferment which would change the crystalhzable sugar into molasses. In some manufactories, the process of pressing is repeated twice, in others three or four times, and some times a little water is added to the cake of the first pressing, before it is placed in the press a second time. The juice obtained in this manner is turbid, and more or less yellow or dark colored. It has to be clarified and decolorised before it can be evaporated to the point of crystallization. To effeot this the juice is placed in a large pan, heated by steam, and evaporated down to a certain specific gravity; when it is sufficiently concentrated, a certain quantity of hydrate of lime is added, and the boiling continued for about an hour. According to the quantity of impurities present in the juice four, to eight parts of lime are required to render the juice perfectly clear. The effects of the lime consist, not merely in the separation of the nitrogenised matters in the juice, but also in the remoyal of a portion of the fatty and colouring matters, as well as several salts, such as mrlates and phosphates. The various compounds resulting from the mixture of lime with the juice at au elevated temperature partly rise to the surface, and are removed in the chape of a scum; partly settle at the bottom of the pan. The clarified juice is poured off from the dregs, and filtered as hot as possible through animal charcoal. After having passed through a series of filtering vessels the juice has lost all colour. It is then evaporated by means of Bteam to a thickish syrup, and as it always becomes browner during evaporation, the concentrated syrup has to be passed once or twice again through animal charcoal.

The Refuse grated root serves as cattle food, and as it possesses considerable nutritive properties, is used with much advantage for that pur* pose.

The Molasses usually contains half its weight of sugar, and when mixed with water, slightly acidulated with uulphuric acid and sub« mitted to fermentation, will yield from 24 to 30 per cent, of pure spirit."

The Yield of sugar is also affected by the length of time the root is kept. For instance, the fresh root used in the latter part of March or early in April will yield 7 per cent, of sugar,- but if kept till July will only yield 5 per cent., and in August less than 4 per cent.

The Quantities of sugar in large and small roots of augarbeet are very marked, it having been found that roots weighing 4ozs. yield 13 per cent., whilst roots of Bozs. ahow 11,13

per cent., and those weighing 21b and 31b produce but 8 10 and 6.7 per cent, of - sugar respectively.

The Syrup when perfectly decolorised has only to be concentrated as usual, and is then run intd^moulds to crystallize. The larger portion-here assumes a solid crystalline font), 1 ' ana the uncrystallizable sugar, together with alkaline salts, and some other impurities, is allowed to drain through the pointed ends of the conical moulds. The mechanical contrivances to assist the crystallization and to effect the separation of the molasses from the loaves are the same as those employed in the refineries of cane sugar.

Saline Constituents, at least the greater portion of them, are soluble in water ; they pass, consequently into the juice, and their presence in the inspissate juice presents a great obstacle to the ready crystallisation of the sugar. Especially it has been found that alkaline chlorides greatly oppose the process of crystallisation without, however, exercising a decomposing action on the sugar, and as beetroot grown with the employment of much salt or saline matter always contains more soluble saline constituents than roots in the cultivation of which the abundant use of such manures have been avoided, the yield of crystallized sugar will be the more considerably diminished the more freely the land has been manured with saline substance.

The Manures exercise a great importance to the cultivation of beet-root for sugar making. Saline manures, though beneficial when applied in moderate quantities, act prejudicially when used in too largo proportions. Common ealt applied above has been found to greatly favor the growth of the root, but is apt to lessen the percentage of sugar. Ammonical manure will increase the crop, and can be used with advantage on lands not in the best condition, but when applied to rich land in a good state of cultivation is found to increase tho bulk jbut to diminish the percentage of the sugar, adding also largely to the proportion of water, and rendering the subsequent operations more difficult and expensive. An excess of decomposed animal manure substances will also tend to promote the formation of alkaline nitrates instead of sugar.