STARCH 



5530 



STARCH 



THE MILL LEAF CELLS 



Raw Material: Wheat ' Carbon diox- 



ide, water 

 Energy : Steam, electrical Sunlight 



or water power 



Manufactured product : Flour Starch 



By-product: Bran, etc. Oxygen 



The reserve starch made by the leaves and 

 other green parts of the plant is changed to 

 some other form and carried to the storage re- 

 gion of the plant to be reconverted into starch. 

 The underground stems and roots, and the 

 stems, pith and seeds of various plants are 

 important reservoirs for storing starch; it is 

 also found in pulpy fruits and in the juice of 

 most vegetables. It is especially abundant in 

 wheat, potatoes, and in such starchy foods as 

 arrowroot and sago. 



Characteristics. Under the microscope starch 

 is seen to consist of minute, oval or pear- 

 shaped grains, each of which contains a central 

 portion, or nucleus, and a series of envelopes, 

 arranged about the nucleus and having a com- 

 mon center. The size of the grains and the 

 arrangement of layers vary in different plants, 

 which enables one to determine the source of 

 any particular starch. Starch will not dissolve 

 in water, alcohol or ether, but in boiling water 

 the grains swell and break up, forming a stiff 

 paste, when cooled. 



An infallible test for starch is the addition of 

 tincture of iodine to the starch paste, which pro- 

 duces a deep blue color. This color disappears 

 if heat is applied. The iodine tett is useful in 

 determining the presence of starch in foodstuffs. 

 If starch is heated dry it will change to a yel- 

 lowish substance called dextrin. Dextrin sub- 

 jected to heat and an acid or ferment is con- 

 verted into dextrose, or grape sugar, which is 

 contained in ripe fruit, honey and sweet wine. 

 The starch in bread dough is by fermenta- 

 tion converted into dextrose, which is further 

 changed into alcohol. 



How Starch Is Prepared for Use. Starches 

 are divided into two general groups those used 

 for food and those used in laundering, in the 

 finishing of certain textiles and as a thickening 

 material in calico printing. Some starches come 

 under both groups. Starch is also used indi- 

 rectly in the preparation of dextrin and starch 

 sugar, potato starch being the principal va- 

 riety employed for this purpose. The chief 

 food starches are arrowroot, sago and tapioca; 

 the preparation of these is described under 

 their respective titles. 



Cornstarch, widely known and used, is the 

 starch of Indian corn, or maize. The starch is 

 first separated from the grain by steeping for 

 a long time in water; it is then crushed be- 

 tween cylinders and strained through a sieve. 

 The milky fluid containing the starch grains is 

 allowed to flow over a series of surfaces having 

 a slight inclination, and in this process the 

 heavier grains are deposited, while the lighter 

 particles are carried into settling tanks. The 

 deposit in the tanks is purified by a series of 

 straining and settlings, the final product being 

 dried by artificial heat until it forms the fine 

 white flour sold as cornstarch. 



Wheat, rice and potatoes are extensively 

 used in making starches for industrial pur- 

 poses, rice starch being preferred for use in the 

 laundry. Wheat starch is separated from the 

 grain by two methods fermentation and a 

 mechanical process. In the former process 

 whole wheat or wheaten meal is soaked in 

 water for the purpose of softening the wheat 

 grains and causing them to swell. The grains 

 are then reduced to a pulp, and a thick fluid 

 is formed by mixing the pulp with water. The 

 mixture is then placed in tanks and subjected 

 to fermentation, after which the starch is sepa- 

 rated in a washing drum, and purified by re- 

 peated washing and settling, being finally dried 

 by gentle heat. 



By the mechanical process a stiff paste is 

 made by kneading wheaten flour. This ia 

 washed over a fine sieve, in the course of which 

 the starch is separated from the gluten, the lat- 

 ter remaining in the sieve as an elastic, sticky 

 mass. The starch is then purified and dried. 

 The gluten mass is utilized in various ways, 

 notably as a food for patients suffering with 

 diabetes and as an ingredient of macaroni. 



Potato starch is made by steeping and wash- 

 ing the potatoes, and then rasping them down 

 to a fine pulp, which is deposited in water in 

 the form of raw starch. The starch is washed 

 over fine sieves so the impurities and pure 

 starch may be separated; only the latter passes 

 through the meshes of the sieve. Potato starch 

 is widely used as an adulterant and as a sub- 

 stitute for the pure food starches. 



Production. Starch products valued at about 

 $16,000,000 are made annually in the United 

 States. Illinois is the leading state in value of 

 output, being followed in order by Iowa, New 

 Jersey and Indiana. The town of Argo, 111., a 

 suburb of Chicago, was founded in 1905 for the 

 sole purpose of starch making. It is the world's 

 largest center for this industry. The second 



