Starch Essays - Starch, Modified Starch, Corn Starch, Dextrin

Starch STARCH Starch is a white, granular, organic chemical that is produced by all green plants. Starch is a soft, white, tasteless powder that is insoluble in cold water, alcohol, or other solvents. The basic chemical formula of the starch molecule is (C6H10O5)n. The simplest form of starch is the linear polymer amylose; amylopectin is the branched form. Starch is manufactured in the green leaves of plants from excess glucose produced during photosynthesis and serves the plant as a reserve food supply. Starch is stored in chloroplasts in the form of granules and in such organs as the roots of the tapioca plant; the tuber of the potato; the stem pith of sago; and the seeds of corn, wheat, and rice. PROGRESS MADE IN DEVELOPMENT: Most starch is used for industrial purposes. Starch is tailor made to meet the requirements of the end-user giving rise to a range of speciality products. Many and sophisticated techniques are applied. A most versatile principle comprises a three step wet modification: Preparation ? Reaction ? Finishing By applying different reaction conditions - temperature, pH, additives - and strict process control speciality products with unique properties are made. These speciality products are named modified starches, because they still retain their original granule form and thereby resemble the native (unmodified) starch in appearance. But the modification has introduced improved qualities in the starch when cooked. The paste may have obtained improved clarity, viscosity, film-forming ability etc. Although native starch does have its industrial uses, most often industry requires the functionality of modified starch. The modification is achieved in one of two ways - either by the starch producer, who modifies the starch without disrupting the granules, or by the end-user who cooks and modifies the starch in a single step operation. The first method results in a granular product good for storage and the other in a ready-to-use paste. The two methods do not always act as a substitute for the other. Crush or grind containing gather the pulp and free the resulting the tubers or seeds ? mix with water ?resulting paste from impurities ?dry THE ENZYME USED TO SYNTHESISE STARCH; Starch molecules are susceptible to the action of amylases. The a-amylases are endo enzymes, hydrolyzing a1, 4-glycosidic in the inner regions of the molecules. Products are of varying size and include oligosaccharides and low molecular weight dextrins. The b-amylases are exo enzymes, splitting unmodified amylose chains into maltose units, beginning at the non-reducing end. Amylolytic enzymes are useful in the conversion of cornstarch to corn syrup. USES: Aside from their basic nutritional uses, starches are used in brewing and as thickening agents in baked goods and confections. Starch is used in paper manufacturing to increase the strength of paper and is also used in the surface sizing of paper. Starch is used in the manufacture of corrugated paperboard, paper bags and boxes, and gummed paper and tape. Large quantities of starch are also used in the textile industry as warp sizing, which imparts strength to the thread during weaving. THE RELATION OF PROPERTIES TO USE: Properties of starch. Surface of starch granules app. 30 ha/g Specific density app. 1.55 g/ml Specific heat 1.22 kJ/g Bulk weight of starch 80% DS app. 0.7 g/ml DS of moist centrifugate app. 0.6 g/ml Brightness (MgO2 = 100%) app. 95 % Starch is abundant. All major agricultural crops contain starch. Colder climates favour potato growing, the tropics cassava, while grain varieties are grown all over the world. With sun and water as the main limitations, fifteen tons of starch dry mater can be achieved per hectare. Modern techniques enable starch to be extracted from agricultural crops with high yield and extreme purity, making starch the most versatile crop used within the food and chemical industries. The starch granule is a compact package of pure glucose polymer. The purity and efficient moisture absorbing properties of starch have made it indispensable in the production of medicinal tablets and as a moisture regulator. Polymer releases from the granule during cooking. At 60 oC, the polymer begins to hydrate, adding its viscosity and gelling power to the water. This is the way puddings are made in the home - just by using native starch. The food industry also employs native starch as a binder and thickening agent in snacks, meat products,