starch

—starchless, adj. —starchlike, adj.

/stahrch/, n.

1. a white, tasteless, solid carbohydrate, (C₆H₁₀O₅)_n, occurring in the form of minute granules in the seeds, tubers, and other parts of plants, and forming an important constituent of rice, corn, wheat, beans, potatoes, and many other vegetable foods.

2. a commercial preparation of this substance used to stiffen textile fabrics in laundering.

3. starches, foods rich in natural starch.

4. stiffness or formality, as of manner: He is so full of starch he can't relax.

5. Informal. vigor; energy; stamina; boldness.

v.t.

6. to stiffen or treat with starch.

7. to make stiff or rigidly formal (sometimes fol. by up).

[1375-1425; (v.) late ME sterchen orig., to stiffen, OE stercean to make stiff, strengthen, deriv. of stearc STARK; c. G stärken to strengthen; (n.) late ME starch(e), sterche, deriv. of the v.]

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Any of several white, granular organic compounds produced by all green plants.

They are polysaccharides with the general chemical formula (C₆H₁₀O₅)_n, where n may range from 100 to several thousand; the constituent monosaccharides are glucose units made in photosynthesis. The glucose chains are unbranched in amylose and branched in amylopectin, which occur mixed in starches. Starch consumed by animals is broken down into glucose by enzymes during digestion. Commercial starch is made mainly from corn, though wheat, tapioca, rice, and potato starch are also used. Starch has many uses in foods and the food industry, as well as in the paper, textile, and personal-care products industries and in adhesives, explosives, and oil-well drilling fluids and as a mold-release agent. Animal starch is another name for glycogen. See also carbohydrate.

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▪ chemical compound

      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. Starch is a polysaccharide (q.v.) comprising glucose monomers joined in α 1,4 linkages. 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. When required, starch is broken down, in the presence of certain enzymes and water, into its constituent monomer glucose units, which diffuse from the cell to nourish the plant tissues. In humans and other animals, starch is broken down into its constituent sugar molecules, which then supply energy to the tissues.

      Most commercial starch is made from corn, although wheat, tapioca, and potato starch are also used. Commercial starch is obtained by crushing or grinding starch-containing tubers or seeds and then mixing the pulp with water; the resulting paste is freed of its remaining impurities and then dried. 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.

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