chain of sugar molecules linked together that serves as a form of energy storage in plants (see carbohydrate).
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods such as wheat, potatoes, maize (corn), rice, and cassava (manioc).
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| Identifiers | |
|---|---|
| ChemSpider |
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| ECHA InfoCard | 100.029.696 |
| EC Number |
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| (C 6H 10O 5) n | |
| Molar mass | Variable |
| Appearance | White powder |
| Density | Variable |
| Melting point | decomposes |
| insoluble (see starch gelatinization) | |
| Thermochemistry | |
Std enthalpy of
combustion (ΔcH⦵298) |
4.1788 kilocalories per gram (17.484 kJ/g) (Higher heating value) |
| Hazards | |
| 410 °C (770 °F; 683 K) | |
| NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp) |
| Safety data sheet (SDS) | ICSC 1553 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. Glycogen, the energy reserve of animals, is a more highly branched version of amylopectin.
In industry, starch is often converted into sugars, for example by malting. These sugars may be fermented to produce ethanol in the manufacture of beer, whisky and biofuel. In addition, sugars produced from processed starch are used in many processed foods.
Mixing most starches in warm water produces a paste, such as wheatpaste, which can be used as a thickening, stiffening or gluing agent. The principal non-food, industrial use of starch is as an adhesive in the papermaking process. A similar paste, clothing or laundry starch, can be applied to certain textile goods before ironing to stiffen them.