starch

Scope note: Substance made of carbohydrate granules of varying sizes obtained from roots, bulbs, and seeds of most plants. Starch is primarily obtained from rice, wheat, corn, potatoes, cassava (tapioca), sago, and arrowroot. It is a mixture of the soluble straight-chain amylose molecules and the insoluble, branched-chain amylopectin molecules. When starch is heated, the granules swell and form a thick, tacky jelly upon cooling. Starchy adhesives have been used since at least 3500 BCE in Egypt. More recently starch has been used for sizing fabric, canvas, and paper, as an adhesive for paper cartons, bottle labels, gummed tape, and envelopes. Soluble starch has been used for priming canvas and as a binder in watercolor paints. Starch is sensitive to moisture and biodegradation. Starchy paste films become brittle with age.

300012959

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