• Abstract and Figures
• Public Full-text

Production of White-Potato special methods of storage. The ease of storage of corn has made it possible to build large factories, which can process the raw material throughout the year, Starch but potato-starch factories operate or- dinarily only about 8 months of the R. H. Treadway, year, from October through May, Val- W. W. Howerton uable byproducts in corn wet milling (oil and gluten feed, for example) aid materially in making the industry prof- itable. The potato-starch industry has Starch from white potatoes was first no byproduct except the extracted produced in the United States in 1831 pulp, which a few manufacturers re- in a plant at Antrim, N. H. The indus- cover and sell as feed. try grew rapidly. By 1880, more than The higher cost of making potato 150 factories were operating in Maine, starch affected the industry greatly. New Hampshire, Vermont, Michigan, By 1900 the number of potato-starch Wisconsin, Ohio, and Minnesota. plants had fallen from more than 150 In some States, particularly Maine, to 63. Moreover, the industry tended varieties of potatoes w^cre grown spe- to be concentrated in Aroostook cifically for starch. They were not of County, Maine; 45 of the 63 factories high quality for cooking, but contained were there. Aroostook County became much more starch than the common a center for production of table-stock varieties now grown. The practice of and seed potatoes, and the starch in- growing different types of potatoes for dustry provided an outlet for the culls. eating and for nonfood uses still is fol- In 1920, the twenty-odd factories in lowed in the Netherlands and Ger- Maine had a daily capacity of less than many. 75 tons of starch. In 1940, Aroostook Late in the nineteenth century the County had 27 starch factories, whose industry began to lose its strong posi- total daily capacity was more than 150 tion to cornstarch, which could be tons of starch. This greatly increased manufactured to sell at a lower price. capacity was due mainly to construc- Potato starch then became one of the tion of three modern continuous-proc- specialty starches, which it still is. ess plants in 1938 and 1939. Now, 20 Several points account for the lower potato-starch factories in Maine have cost of cornstarch. Although the acre a capacity of about 135 tons a day. yields of starch from potatoes and corn In 1941, two plants were built in are comparable, corn is better adapted Idaho—one at Blackfoot and one at to mechanized methods of farming, Twin Falls. The Twin Falls plant was which lower production costs. Corn rebuilt on a larger scale in 1948. A dries out on the cob to a moisture con- third plant was built in 1942 at St. tent of 12 to 15 percent; in that con- Anthony. Another was established at dition it can be shelled, easily trans- Mcnan in 1944, but was later moved ported, and stored indefinitely before to Idaho Falls. With the construction processing. Potatoes contain about 80 of another plant at Idaho Falls and ipcrcent moisture, which means added conversion of a glucose-sirup plant at bulk and weight in transportation, and Jerome to starch manufacture in 1948-, they are so perishable that they require Idaho now has six potato-starch fac- i68 PRODUCTION OF WHITE-POTATO STARCH 169 tories with a total capacity of about to find new uses for potato starch. 140 tons a day. The country's total Since 1944, various techniques and capacity for potato-starch production, specialized equipment have been em- therefore, is now approximately 275 ployed there in the search for ways in tons a day, or 110 million pounds for which potato starch is unique among a 200-day operating year. Because the starches. industry uses cull and surplus potatoes^ the supply of raw material is not con- THE SIZE, STRUCTURE, AND SHAPE stant, and the industry rarely if ever of the starch granules have undergone operates at capacity for as much as 200 scrutiny by technicians using the opti- days a year. cal microscope. The molecular ar- rangement has been studied in detail ABOUT 98 percent of the starch we by X-ray specialists. The structure of produce is made from corn. Nearly the granules has been further explored two-thirds of the total cornstarch pro- with the electron microscope. The mol- duced, however, is used for manufac- ecular weight of potato-starch frac- ture of glucose sirup^ dextrose, and tions have been determined with spe- m.odified starches. About 90 percent of cially designed light-scattering equip- the starch used as such in the United ment. States, or 1,389 million pounds a year, Factors influencing the paste consist- is cornstarch. The maximum produc- ency and gel firmness of potato starch tion of the potato-starch industry is be- have been investigated at length. Al- lieved to be approximately 89 million though it has long been known that the pounds, attained in the 1946-47 season, presence of calcium lowers the con- when Maine produced an estimated 44 sistency of pastes, workers in the East- •million pounds and Idaho 45 million ern Laboratory found that even traces pounds. The average production in re- of calcium have a pronounced eñect. cent years has been somewhat below So sensitive is the paste consistency that record. to minute amounts of calcium that Potato starch is used in industry in changes in the hardness of processing about the following percentages : Tex- water from season to season result in tiles, 30; foods, 20; paper, 20; dextrins, changes in the final product^ previously 15; confectionery, 5; and miscellane- unexplained. ous, 10. Little by little the fundamental The textile industry uses potato causes for the unique properties of starch mainly in sizing cotton warps, potato starch—its large granule size, its but some also for sizing spun rayon and relatively high molecular weight, and worsted warps. Potato-starch pastes re- the pecuHar packing of matter in its vert slowly to the gel state upon cooling molecule—are being unfolded. Re- and thus penetrate better into the in- search on technical applications will terstices of the warp than do pastes of follow the fundamental studies. The some other starches. Better penetration largest potential fields of expansion results in a better anchored film, which appear to be in the paper and food protects the warp from abrasion in the industries. loom. Potato starch is outstanding in Apparently it is not economical now the strength it imparts to paper in for American farmers to grow potatoes beater sizing. Potato dextrins give just for industrial use. Starch manu- relatively flexible films, which resist facture, however, is to be regarded as checking and remoisten readily. an integral part of a well-organized The Eastern Regional Research Lab- potato industry, which markets its best oratory has undertaken studies to com- potatoes for eating and processes the pare the physical and chemical prop- substandard grades. Marketing agree- erties of potato starch with those of ments in the potato industry are lead- other commercial starches. The aim is ing to these practices now more than 170 1950-1951 YEARBOOK OF AGRICULTURE ever before. Starch factories provide an has perforated holes 0.03 inch in di- outlet for potatoes that should be kept ameter. Here the starch milk (princi- off the food market in order to make pally starch granules suspended in wa- cficctive the slogan, "Sell the best— ter) passes through, and the pulp dis- and process the rest." The higher price charges over the end of the sieve. The that the public will pay for uniformly pulp is diluted with water and passes high-quality potatoes should make it into an attrition—or disc—mill for possible to place a lower value on sub- further grinding-rubbing to release standard potatoes diverted to indus- more starch. The mill has two carbo- trial processing. rundum-type plates mounted closely to- gether, one of which rotates. The starch IN OUR MORE MODERN potato-starch milk, along with finely divided pulp factories, the operations are essentially from the bottom sieve, falls onto the continuous. A typical Maine factory bottom 80-mesh shaker screen. The can produce about 10 tons of starch in starch milk runs through, and most of a 24-hour day, for which it will use 80 the fine pulp drops off the end of the to 90 tons of potatoes. An analysis of screen and is combined with the re- the potatoes processed shows these ground pulp from the attrition mill. components, in percentages: Starch The combined pulp is pumped to the 13; protein, 2; ccllulosic material, 1.5; top sieve (which has perforated holes sugars, 0.5; mineral (ash), 1; miscel- 0,02 inch in diameter) and is washed laneous minor constituents, 1 ; water, with a spray of water. The fine pulp 81. (Potatoes received by the Idaho and starch milk pass through the sieve starch plants average 15 or 16 percent and drop onto the top 100-mesh shaker starch.) screen. The starch milk continues Storage facilities in the factory can through to the bottom shaker screen, handle as much as 4,000 barrels, each and the fine pulp from the top shaker weighing 165 pounds, of potatoes. screen and the coarse pulp from the A description of the process used by top sieve combine and are discharged one of the modern plants is given here, to the sewer. but we must stress that the equipment The starch milk from the screening and methods used in other modern fac- battery—that is, the starch milk tories may differ in some respects from through the bottom shaker screen— the one we describe.

Load more

  7

Copy Link