The process would be as follows:—After washing in a revolving apparatus, by which means the adherent earth would be got quit of, and almost the whole of the thin dark colored cuticle become detached, the roots could be reduced to pulp in a rasping-mill, without the use of water; the pulp might be compressed in bags by hydraulic pressure, whereby the juice, together with a small portion of the starch, would be expressed. After allowing the starch to subside, the juice should be concentrated to about the density of 1.4. The starch would be washed, purified, and dried. The contents of the bags would then be broken up and dried in the sun or in a current of air, after which the meal would be sifted through a coarse sieve to separate the coarser parts, which, if their amount was considerable, could be ground and added to the rest. In this state of rough meal it is fit for making the cassava cakes. If ground to flour it might be used to mix with wheat, rye, or barley flour.
The process is usually conducted as follows:—The squeezed pulp is broken up, sifted, and exposed to the sun on trays or mats till it is fully more than half dry. An iron hoop of the size and thickness of the cake to be made is then laid on a griddle or hot plate, and the space within the hoop is filled evenly with the somewhat moist meal, no previous kneading or rolling having been employed. As soon as the coarse meal coheres, the ring is lifted and the cake is turned and heated on the opposite side. The heat should not be sufficient to brown the cake. The cakes are finally dried by exposure to the sun. From the dry cassava meal cakes may be prepared by sprinkling it with as much cold water as to moisten it to the proper point, and then proceeding as above. Hot water cannot be employed, neither can kneading, or any considerable degree of compression be used, otherwise the water does not evaporate readily enough; the starch gets too much altered by the heat, and the cake becomes tough.
If an acre of well-tilled thorough-drained land yield 10 tons of fresh roots, and I have every reason to believe that such a return might be obtained, I have ascertained that the produce would be 3½ tons of meal, 598 lbs. of casareep, and 2 cwt. of starch; and estimating the meal at 1d. per lb., the casareep at 1s. 5d. per lb., and the starch at 40s. per cwt., the gross amount would be £78 13s. 4d. per acre. In ascertaining these proportions, very simple machinery was employed, and had the pulp been better pressed the quantity of casareep would have been considerably greater.
From the table given in a former note it will be seen that the cassava meal prepared in this way contains but a very small proportion of matter nutritive in the sense of contributing to the formation of blood, and that the expressed juice carries off fully one-half of the proteine compounds contained in the plant.
Lichenin is a variety of starch occurring in Cetraria islandica, or Iceland moss.
Indian corn starch.—The advance of science has recently brought to our knowledge the preparation and use of another article, not only important as food, but also essential in the arts. I have had occasion to mention the high value of the Indian corn, and I might with advantage allude to many of its uses and properties; at present I must confine my remarks to a product from this valuable grain, known as corn starch, and yet another as the fecula of maize. In the close of 1849, Mr. Willard and his associates, of Auburn, established extensive works at Oswego, for the preparation of these important products, their establishment covering an area of 49,000 square feet. As the proprietors have to some extent held unrevealed the process by which they produce a starch more pure than the starch of commerce, we may not indulge in speculative curiosity; yet I can hardly doubt their great success is mainly attributable to perfect machinery, guided by science and talent. The rapid and extended demand for these new products presents sufficient evidence of their character, as we are told that about three millions of pounds of this corn starch are demanded annually by the trade, notwithstanding the usual supply of wheat starch is undiminished. A remarkable feature of maize starch is the absence of impurities; upon being subjected to analysis, it is found that only 2 76-100 parts in 1000 are of other matter than pure starch. According to Dr. Ure, wheat yields only 35 to 40 per cent, of good starch, a material extensively used in arts and manufactures.
In addition to starch, the Oswego starch-factory produces from Indian corn a fecula, peculiarly adapted to culinary purposes, presenting to our domestic economy one of the most acceptable, pure, and nutritious articles of food. Already has it become an indispensable household article, and is consumed largely at home and abroad. The factory, though in its infancy, consumes annually 150,000 bushels of corn, equal to about nine millions of pounds in weight. Hitherto the quantities of starch used for laundry purposes and in the manufactories of America, have been produced from costly wheats, though it may be found in many vegetable substances, such as potatoes, the horse chesnut and other seeds. In England, where breadstuffs, particularly wheat, have been raised in quantities inadequate to the demand for food, attempts have been made to convert the viscid matter of lichens into a gum, for the use of calico printers, paper-makers, and ink makers; for the stiffening of silks, crapes, and the endless variety of dry goods, which, by means of these gums or starch, are made to appear of greater consistency. Most of these attempts had partial success, yet the making of starch from wheat has not been arrested.
The Oswego starch factory has happily introduced the use of Indian corn, as a grain producing a larger proportion of pure amylaceous properties than any other known vegetable substance, proffering to the American manufacturer another economic advantage, sustaining, in a most legitimate matter, sound rivalry and competition with all the world. I am not aware whether the Oswego factory has converted its starch into gum—a process easily accomplished by heat, and thus rendered soluble in cold water, which cannot be done while in its condition of starch. Here is another result of vast importance derivable from Indian corn; and we can well conceive that, in a short period of time, the advantages now derived from the production of corn starch, may have grown into a national benefit.
Rice (according to Prof. Solly) contains on an average about 84 per cent of starch; but till comparatively a few years ago, no starch was manufactured from it, notwithstanding its low price, and the large quantity of starch which exists in it. The reason of this was, that the old process of fermentation, by means of which starch is procured from grain, was not found to be applicable to rice; and hence the latter only became available as a source of starch in 1840, when Mr. Orlando Jones introduced his new process, for which he obtained a patent. This process consisted in macerating the rice for about 20 hours in a dilute solution of caustic potash, containing about 200 grains of the alkali in every gallon; the liquor is then drawn off, the rice dried, reduced to powder by grinding, then a second time digested in a similar alkaline lye for 24 hours, repeatedly agitated. After this it is allowed to settle, and well washed with pure cold water. A prize medal was awarded for this rice starch at the Great Exhibition.
Mr. S. Berger, of Bromley, also received a prize medal. He adopts a different mode of preparation. In place of employing a dilute solution of caustic potash to dissolve the gluten and other insoluble matters of the grain, Mr. Berger uses a solution of carbonate of soda, containing half a pound to the gallon. The rice is steeped, in cold water for 48 hours, levigated in a suitable mill, and the pulp thus formed is treated with the solution of carbonate of soda for 60 or 70 hours, being repeatedly stirred; it is then allowed to settle for some hours, the alkaline liquor is drawn off, and the starch is washed and purified. This process was patented by Mr. Berger, in December, 1841. A third process was patented in February, 1842, by Mr. J. Colman; he uses dilute muriatic acid for the same purpose as Messrs Jones and Berger.