f FEBRUARY, 1939
INDUSTRIAL AND ENGINEERING CHEMISTRY
(8) Clark, H. L., Mjrs.’ Record, 106, No. 3, 30 (1937). (9) Clayton, R., Paper, 27, No. 5, 17 (1920); No. 8, 19 (1920). (IO) Ibid., 27, No. 10,162 (1920). (11) Dorner, B., U. S. Patent 1,038,730 (Sept. 17, 1912). (12) Feldtmann, G. A., ZeZZstof u. Papier, 18, 55 (1938). (13) Gibson, A. G., IND. ENG.CHEM.,22, 223 (1930). (14) Hartford, C. E., Zbid., 22, 1280 (1930). (15) Houseman, P. A., and Lacey, H. T., Ibid., 21, 915 (1929). (16) Lathrop, E. C., Ibid., 22, 449 (1930). (17) Lookett, J. L., Soil Sci., 44, 425 (1937). (18) McElhinnerv. T. R.. Whittemore. E. R.. and Lvnch. D. F. J.. paper Trade J., 106, No. 10, 37(1938). (19) Monsson, W. H., and Chidester, G. H., Zbid., 94, No. 6 (1932). (20) Norman, A. G., Biochem. J., 23, 1353 (1929). (21) Zbid., 31, 1575 (1937). (22) Ibid., 31, 1579 (1937). (23) Olsen, Fred, IND.ENG.CHEM.,30, 524 (1938). (24) Peterson, C. J., and Hixon, R. M., Ibid., Anal. Ed., 1, 65 (1929).
.--,
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(25) Phillips, Max, U. 8. Patent 1,750,903 (Maroh 18, 1930). (26) Phillips, Max, and Weihe, H. D., IND.ENG.CHBM.,23, 286 (1931). (27) Pomilio, Umberto, IND.ENG.CREM.,24, 1006 (1932). 128) Schafer. E. R.. and Brav. M. W.. Ibid.. 21. 278 (1929). (29j Sherrard, E. C., and Beglinger, E., U. S. Patents 1,923,756, (Aug. 22, 1933) and 1,932,255 (Oct. 24, 1933). (30) Traquair, J., U.S. Patents 1,843,464-6 (Feb. 2, 1932). (31) Traquair, J., and Rawling, F. G., Zbid., 1,880,587 (Oct. 4, 1932) and 1,942,622 (Jan. 9, 1934). (32) U. 5. Forest Products Lab., Mimeographed Bull. R1134 (April 16, 1937). (33) Whiting, G., Paper Trade J., 104, No. 8, 41 (Feb. 25, 1937). (34) Whittemore, E. R., Reid, J. D., and Lynch, D. F. J., IND.ENG. CAEM.,30, 1192 (1938). (36) Wingfield, B., Whittemore, E. R., etal., Natl. Bur. Standards, Misc. Pub. MI24 (1936).
RECEIVEDDecember 13, 1938.
INDUSTRIAL USE OF STARCH PRODUCTS W. B. NEWKIRK Corn Products Refining Company, Argo, Ill.
corn wet-milling industry of today is developed entirely around the production and utilization of starch. Our knowledge of starch and starch products is still largely empirical, in spite of the numerous investigations on this material recorded in the scientific literature. However, the industry does know how to produce a large number of satisfactory commercial products by methods which may be called a highly trained art controlled by a few physical and chemical tests. Generally speaking, the origin of the starch is of minor importance to the industry, in spite of the fact that the physical characteristics of the starch are essentially typical to the origin of the starch. There are a few cases where starch products from one particular origin supply the requirements more satisfactorily for certain products, such as tapioca for postage stamp adhesives; but even in these cases acceptable products can be made from starch of any origin. Another typical example is the superiority of cornstarch of certain modifications as dusting agents in the rubber industry, where large tonnages are used. On the whole, therefore, we are interested in the cost of only a fairly well-refined starch. The Corn Products Refining Company, which has plants throughout the world, uses starch made from corn, k a f i corn, rice, rye, potato, and manioc or tapioca. The choice depends
upon the availability and price of starch in the country in which the plant in operating. Although 30 per cent of its markets have been taken by cheap, duty-free, tropical starches, the industry as a whole has not felt the ups and downs of depression and prosperity periods as much as have other industries. The reason for this is not accidental but is the result of an intensive and continued effort on the part of all producers to meet the ever-changing needs of the purchasing industries by changes and modifications in our products so as to meet these requirements exactly. The industry as a whole is rather old compared to other American industries, but its organizations are youthful, open-minded, energetic, and research-conscious. The general public or even the various industrial chemists probably do not realize the diversification that exists in starch products and the different types of uses to which they have been put.
Thick-Boiling Starch Let us first consider the old thick-boiling starch which was supposed to be the natural starch of the corn. No starch on the market is starch as it exists in the grain or in the tuber, but is starch which has been modified by the operating process and the enzymatic action of nature’s converting agents. Nevertheless, the industry has discovered how to treat these modified starches to bring back some of the desirable characteristics of nature’s starch. For example, some companies have developed a thick-boiling starch which is thicker than is customarily produced by the industry and retains its thickness and viscosity in spite of the hydrolyzing action to which it may be exposed in some of its uses. As an illustration, cream soups must contain starches which will undergo the converting at high temperatures with organic acids during the pasteurization period of the packed product without a
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material reduction of their viscosity. This has been accomplished. Other companies have been able to produce thick-boiling starches which withstand the hydrolyzing action of strong electrolytes so that they can be used to produce the jell consistency of the electrolyte mass in dry batteries. This same product has been so modified that it is about to supplant sodium silicate in the production of laminated and corrugated containers, since it produces a stronger bond on the one hand and more board feet per hour from the corrugating machines on the other hand, a t prices which show considerable saving during the process.
Thin-Boiling Starches Thin-boiling starches made by mild acid conversions of the starch milk have been produced in numbers and are of such restricted specifications that the needs of each individual paper manufacturer can be met. In other words, proper sizings of paper can be produced which range from coarse boards to the finest linen bonds. Each grade of starch is specifically made for the conditions existing in the mill to which it is delivered. The same breadth of type, each adapted for a specific purpose, is being produced for the textile trade, rubber manufacturers, and confectioners. An interesting development for. the rubber industry is the production of a dusting starch. This starch must be so made that, when delivered in the consumer’s plant, the starch will
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flow freely and uniformly over the sheet rubber, a condition which is actually accomplished in a manner similar to that of dispersing colloids in solution. That is, the starch is arranged to disperse into a fluffy, free-flowing suspension in air. Oxidized Starches Starches are treated with oxygen derived from an oxidizing reagent such as chlorine, hypochlorite, etc. Each of these oxidizing reagents imparts general characteristics along rather parallel lines but entirely different specific characteristics when compared among themselves. Different treatments depend upon the requirements of the purchaser. If they are to be used for colors in paper printing, one type of chlorination and its series of chlorinated starches are used. If printing of cloth is the object, another series of chlorinated products is produced. Special sizings also bring about special oxidizing treatments. An interesting characteristic of chlorinated starches is a greatly increased power of acting as a protective colloid. This property is made use of in some of the applications in the paper industry.
Gelatinized Starches Gelatinized or precooked starches are made in dried form so that they will be suitable for use when merely suspended in cold or tepid water. Characteristics of these starches depend upon the treatment given the starch before gelatinization and upon the gelatinizing treatment.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
A gelatinized starch for the brewing industry is a different product from that used by foundries for core binding purposes and molding sand. Other gelatinized starches are employed in the baking trade as bread conditioners and have properties suitable for this purpose. These, again, are entirely different from the products forming the foundation of cold water pastes and poster paints. Let us discuss the gelatinized starch for foundry purposes in detail. The requirements are for a starch that has rapid dispersing characteristics so as to cover the wetted sand in the minimum length of time, yet coat each grain of sand with a film of adhesive material. This adhesive material must have sufficient bonding strength when wet so that the molds and cores can be handled without breaking or disintegrating. It must maintain these adhesive characteristics during and after the baking of the core to remove water which, if present during the casting, would cause blowholes. It must lose its adhesive characteristics by the heat developed from the molten metal so that the casting can be properly cleared of molding and core sand. During the molding operations it must not produce an excessive amount of combustion products. All of these conditions can be met and will vary from foundry to foundry, depending upon mixing equipment and sand, the size of the piece being molded, and the character of the metal being cast. Another use of these gelatinized starches is in the manufacture of doll heads and similar molded articles, where s p e cia1 requirements, including water resistance, are necessary. Mining Similarly modified starches are used extensively in the mining industry. Pregelatinized starches are added to hasten the settling of the suspended, slimy materials in the water which has been used for washing Pennsylvania coal.
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British Gums and Dextrins These dry roasted and converted products are made by roasting starch for different lengths of time under different temperature conditions and with different amounts and kinds of catalytic acids. Their characteristics can also be changed by preliminary modification before they are delivered to the roasting oven. The range of requirements on dextrins seems to be almost limitless. Adhesives must be made from these products which have almost instantaneous development of its full adhesive strength to be used in such places as the wrappers of cigarets, etc.; the other extreme is the production of adhesives which permit movement of the joint without tearing or distorting the paper or cloth, until it is in the final position desired, such as the finishing of candy boxes, cosmetic boxes, etc. Other adhesives must be partially water repellent for the production of shotgun shells, fireworks tubes, etc. The burning time and completeness of combustion is of importance in other fields such as fireworks display pieces, dynamite, etc. Another characteristic required of dextrins is the ability to make fibers unite without causing the bundles of fibers to be stuck together in the sizing of yarn, etc. Textile manufacturers demand that for goods going to the bleacheries and printers, the sizing shall be easily removable so that the bleach, dye, or print can reach each fiber in its particular place. These products, together with modified starches, actually make up a large part of the printing ink od cotton and linen goods. The requirements in this case are that the combined mixture should have sufficient viscosity so as not to spread and create fuzzy edges where the printing ink has run, but should at the same time permit the ink to penetrate part way into the thread so that the printed pattern will be resistant to washing operations.
FRONTEND OF STARCHKIL;NS
Similar settling agents are used in other mining industries to settle slimy mine waters. By slight modifications these gelatinized products can be changed into suspending agents which prevent the separation of dispersed sand and clay particles so that these slurries can be used for hydraulic well drilling or for hydraulic stowing of abandoned operations in underground mining.
A diversified use of these mixed modified starches and dextrins ranges from dustless crayons to coal and coke briquets. Probably one of the largest prospective outlets is the construction of wallboard where starch products are used within the body of the building material and on the exterior coating. About half of the starch made is used to produce refinery products such as glucose and sugar. In the presence of
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water, acid converts starch into dextrins and sugars. This classical discovery of Kirckoff in 1811 (2) was first commercialized in Germany in 1812 and in America by Guthrie in 1831, As it is now made, starch milk is introduced into a pressure vessel (6). The acid with which the starch is hydrolyzed was originally sulfuric, but since 1895 hydrochloric acid has been used. The conversion of the starch goes from starch to dextrin to maltose to dextrose to polysaccharides. The converted liquor is neutralized and filtered to remove proteins, fats, and cellulose. The filtered liquor is refined over bone black or its equivalent and concentrated to gravities required for the production of commercial products. Amidex is made by a mild conversion and contains only a small percentage of reducing sugars (6). It is used in brewing and baking and for adhesives. Corn sirup stands in about the middle of the converting range with dextrose.equivalent reducing powers on the dry basis of about 40 to 50 per cent ( 2 ) . This product is used in confections, sirup mixtures, and brewing. Slab and chip sugars are converted to a dextrose equivalent on the dry basis of approximately 90 per cent. They are evaporated so that they contain a dextrose equivalent of 70 to 80 per cent and are cast in slabs. Generally the slabs are chipped (2). These sugars are used in the production of caramel coloring and in the tanning, rayon, and tobacco industries. Owing to the formation of polysaccharides in the converter, these sugars are not pure dextrose. Further processing is required to remove these noncrystallizable sugars. The least effective process is the pressing of the slab sugars just mentioned in hydraulic presses (8). An improvement on the removal of these noncrystallizb,ble liquors was the so-called anhydrous process of quiet crystallization; the cakes thus formed were centrifuged and attempts were made to wash the centrifuged cakes ( I ) . Although this process lasted for over 30 years, it could not compete economically with the older pressed sugar and ultimately had to be abandoned.
Dextrose
HYDRATEAProduction started in 1923 when a method was developed for crystallizing hydrate dextrose in a fluid massecuite by crystallization in motion (3). This method permitted proper removal of the noncrystallizable sugars by centrifugal separation and permitted the washing of the centrifugal cake to such an extent that pure dextrose could be made a t competitive prices. This sugar is used in all of the food industries such as baking, beverages, confections, prepared flours, etc., and for the production of organic and glassine paper. ANEYDROUB. Anhydrous dextrose is produced by an improved process which permits the production of anhydrous dextrose of extreme purity (4). This sugar is used in fat filling, canning, pharmaceuticals, and in the production of polyalcohols. Research Developments
The corn products industry is directly allied with agriculture on the one hand and industry on the other. The industry grinds between 80,000,000 and 100,000,000 bushels of corn per year. Although this is a small percentage of the total corn grown, it represents from 30 to 60 per cent of all the cash corn delivered to markets, depending upon the abundance of the crop. These purchasers influence to no small extent the price of cash corn and indirectly, therefore, the price of hogs and fattened cattle. The products enter, in one form or another, practically everything that i s made or packaged today. It is vital, therefore, that business conditions shall be normal, which means prosperous labor as well as prosperous farmers. Given reasonable markets the industry will be satisfied with a good price of corn to the farmer, which, in turn, means general good business for everyone.
EVAPORATOR
FLOOR
WHEREBOTHLIGHT AND HEAVYEVAPOR A T I O N O F DEXTROSE
LIQUORS
TAKEPLACE
Triple pans are wed for light evaporation and single pans for
heavy evaporation.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
The industry is under a pressure which is forcing a definite change in the character of its business. With the industrialization of Asia and its cheap labor conditions, tapioca and cassava starches are entering the United States duty free a t prices comparable to the price of starch in corn without any processing charges. This has reached such a serious point that between 30 and 40 per cent of the industry's starch markets have been taken over by this low-priced product. To meet this situation there are only two possible choiceswe must either develop starch products to a point where they compete with other high-priced materials, or we must take over the handling of these starch products now being made from these low-priced starches. This is causing the corn grinders to become chemical processing houses to a greater and greater extent. It is also creating a mutual development of fundamental research within the industry. The industry as a whole has developed a program of research in fundamentals which has included fellowships at Harvard Medical School, Rochester University, and other research institutions to demonstrate the biological superiority of its products in order to increase their consumption ultimately in the food fields and maintain prices above the levels of competing products because of their superior biological advantages. The industry has undertaken joint research work with processing associations under such men as Lewis, of the Meat Packers Association, and Fellers, of Massachusetts State College, to develop the use of the products of corn into food fields which it has heretofore never entered, such as the curing of preserved meats and the processing of fruit. It is supporting pure fundamental fellowships under such men as Hudson, of the Public Health Service, and in universities and industrial laboratories, in the effort to develop a true knowledge of the constitution of starch and starch products, so that the product may be better adapted to industrial uses beyond the price competition of the cheap starches. The industry is turning its attention to the rather neglected field of morphologic investigation of starch and its modifications, and is carrying out research by means of the microscope which will make it possible t o penetrate below the surface of the phenomena and thus contribute to a better understanding and to the explanation of the behavior and transformations of the starch granule. Ultimately investigations of this nature should serve as a guide and aid to the development of new products. Exhaustive cooperative research has been undertaken with the manufacturing companies towards the development of new chemicals of economic value so as to place the products in an advantageous price territory. A notable example is the joint work that led to the production of sirupy and crystalline hexaalcohols, mannitol, and sorbitol. Sorbitol substitutes €or glycerol which is made in the manufacture of soap, and soap is now meeting serious competition. Sorbitol is a hexaalcohol and as such has an inexhaustible number of possibilities. With six positions for substitutions, products will be made which fulfill the exact requirements for plasticizers, wetting agents, etc. Mannitol is meeting the demand for a friction-proof detonator through nitration. It also has the same potentialities as sorbitol with slightly different characteristics in the same type of compound. Considerable research work is being carried on in the d e velopmen t of high-priced products from by-products. A striking example is the development of purified protein material from gluten feed, which sells for about 20 cents a pound, instead of its being put on the market as feed for around 1.5 cents a pound. This protein is showing its ability to enter the plastic and coating field and to hold its own because of certain superior qualifications in competition with high-priced resinous products such as Bakelite, etc.
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It is already being used in the making of buttons and findings at prices comparable to imported casein. With it coated papers can be prepared a t the mill, since the glazed coating is receptive to ink impressions, whereas the average coating must be applied after the printing. It has demonstrated its ability to make laminated paper products which have all the advantages of Bakelite laminations but are markedly superior in working characteristics. Amino acids, such as glutamic acid, monosodium glutamate, tyrosine, and leucine, and the corresponding alkyl amines from the gluten are being prepared. This entire line is bringing the industry directly into the field of manufacturing chemists. To increase the price level of starch products, we have been able to enter competition with gelatin in the formation of transparent starch films which have been used in Germany in the production of photographic films and papers, waterproof wallpapers, water-resistant cloths, etc. Another line of starch development has been the formation of a starch product which will react with formaldehyde to form a series of waterproof adhesives superior to the casein adhesives and will meet the naval requirements for both naval and air use. Starch esters have been investigated, and the industry is almost ready to introduce some starch esters in competition with cellulose esters. Exhaustive work is being done under fellowships in universities and in the various companies on-the chemistry involved in the conversion of starch and the production of sugars from it. A number of fundamental concepts have been the result of this work, and it has resulted in reducing the cost and increasing the unit machinery capacity to date. I n dextrose we have one of the most active and versatile chemical raw materials as a starting point for innumerable synthetic organic products. Through oxidation methods dextrose can be converted into a whole series of carboxylic acids with carbon chains up to six, such as saccharic, propionic, etc. ; when their development follows the same course as that of c. P. dextrose, they can be sold a t prices which make them attractive to the manufacturing chemist as raw materials. A whole series of polyvalent alcohols can be produced. For example, the Atlas Powder Company is now manufacturing sorbitol and mannitol. These longer chained alcohols are finding extensive industrial uses and are also the starting point for a new series of industrially valuable esters and acids of different configurations. For example, vitamin C (ascorbic acid) is being made from sorbitol which, in turn, is made from dextrose. Arsenates, mercurials, and phenols can be introduced to form many toxic compounds which possess germicidal and insecticidal properties, such as aminobenzoic acid glucose esters. In similar manner the amino compounds can be added to dextrose to form a series of wetting and dispersing agents for textiles and rubber, such as glucose naphthylamine, and glucose alkylamine. Most of the active principles of materia medica are naturally formed dextrose derivatives. There is now available a starting point for the synthetic production of these active principles in a pure state.
Literature Cited (1) Behr, U. S. Patents 256,622-3 (1881). (2) Kirckoff, Acad. Imp. Sci. St. Petersburg, 4,27 (1811). (3) Newkirk, U.S. Patent 1,471,347(1923). (4)Ibjd., 1,640,717(1927). (5) Riley, Ibid., 7148 (1850); Dubrunfaut, Darmstaedter's Geschichte Natur Wissenschaft, 1840,445. (6) Wagner, U.S. Patent 855,599 (19On. RECBIVED September 12, 1938.
