Corn starch water removal

Hydrocolloidal water is an integral part of the dispersed phase and travels at the same velocity with it this is considered tightly bound water. Yakubu et al. (1990) identified three other forms of water in potato and com starch, viz., weakly bound, surface trapped, and bulk water. All forms were not present in potato starch containing less than 35% moisture, but were present in corn starch. Water, far removed from the solute surface (unbound or free water in the outer volume), travels at a different rate from hydrocolloidal water (Lechert et al., 1981). 

Isolation of Starch.—Starch is also used as a food in its pure form. To obtain this the plant part, e.g., potatoes, corn, etc., is macerated and then stirred up with a large amount of water. The watery mass is passed through seives to remove the fibrous material while the starch, in suspension, passes through. On allowing the starchy liquid to settle the starch is obtained as a sediment in quite pure condition. As the materials used contain relatively little else than starch and water there is not much foreign substance present. Starch so prepared is the common form in which it is sold under the names of corn starch, and laundry starch, the former used as a food and the latter as a laundry sizing material. 

Bacterial fermentation is used to produce lactic acid from corn starch or cane sugar which is further processed to produce lactide monomer. Because lactic acid is difficult to polymerize directly to high polymers in a single step on a commercial scale, most companies used a two-step process. Lactic acid is first oligomerized to a linear chain with a MW of less than 3,000 by removing water. 

The 7-dextrin is isolated from an enzymolysate of 5% potato or corn starch paste and macerans amylase prepared in a manner similar to that for dextrin. However the reaction is allowed to proceed in the absence of precipitant although thymol is added to inhibit extraneous bacterial growth. The final digest is concentrated to about one-fourth the original volume and cyclic dextrins are precipitated with trichloroethylene. The precipitate is dissolved in hot water to about 25% solids concentration and allowed to stand at room temperature for 24 hrs to remove the less soluble dextrin. The precipitated dextrin is removed by filtration and the clear filtrate is diluted to about 3% solids. The y-dextrin is precipitated with bromobenzene. The y-dextrin is collected, dissolved in boiling water and concentrated to about 20% solids. 

Starch from surplus corn has been converted into a superabsorbent material known as SUPER SLURPER. This is being marketed under license by several companies for use in removing water from refined petroleum products and as an absorbent in bandages and diapers. Biodegradable plastic films of starch mixed with other polymers find application as mulches in agriculture and as a... 

Starch Sweet potato has the advantage of remaining as a high starch-producing crop with 30 and 49% greater starch yield than rice, corn, or wheat, respectively, under the same conditions. In China, at the former level process, sweet potatoes are cut up by hand, crushed by machine, and sieved to remove waster such as peel and fiber. The starch is left to settle in a tank and then removed. Water is added to the starch, which is once more sieved and settled. Wet starch is transferred to jute bags and allowed to drip-dry for 1 d, and air-dried outside at ambient temperatures [25]. 

Starch is a widely distributed material, occurring in the roots, seeds and fruits of plants. Seeds usually contain 40-70% starch whilst roots and fruits contain about 5-25%. The principal commercial source of starch is corn sources of lesser importance include tapioca, wheat and potato. In the extraction of starch, the plant material is ground with water the resulting slurry is filtered to remove coarse tissue fragments, and a suspension of starch granules is obtained. The granules are collected by centrifuging and dried in warm air. 

The other alternative is to remove water from ethanol obtained by fermentation of fermentable sugar. Fermentation is a well-known technology that has been used for a long time. The interest to replace fossil fuel (gasoline) in cars with renewable fuel has increased the interest in bioethanol tremendously. The main sources are sugar from sugar cane (Brazil) or starch from corn (USA) or wheat (Europe). The production has increased steeply in the last 10-15 years [17] (see Figure 6.2). 

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