Starch

For the Urhobo cuisine dish known as starch, see Usi (food). For the video game, see Starch (video game).
Starch
Cornstarch being mixed with water
Identifiers
ChemSpider
  • none
ECHA InfoCard 100.029.696 Edit this at Wikidata
EC Number
  • 232-679-6
RTECS number
  • GM5090000
UNII
Properties
(C
6H
10O
5)
n
Molar mass Variable
Appearance White powder
Density Variable[1]
Melting point decomposes
insoluble (see starch gelatinization)
Thermochemistry
4.1788 kilocalories per gram (17.484 kJ/g)[2] (Higher heating value)
Hazards
410 °C (770 °F; 683 K)
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)[3]
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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Structure of the amylose molecule
Structure of the amylopectin molecule

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).

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.[4] 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.

  1. ^ Whistler RL, BeMiller JN, Paschall EF (2 December 2012). Starch: Chemistry and Technology. Elsevier Science. p. 219. ISBN 9780323139502. OCLC 819646427. Archived from the original on 14 May 2022. Retrieved 13 May 2022. Starch has variable density depending on botanical origin, prior treatment, and method of measurement
  2. ^ CRC Handbook of Chemistry and Physics, 49th edition, 1968-1969, p. D-188.
  3. ^ NIOSH Pocket Guide to Chemical Hazards. "#0567". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ Brown WH, Poon T (2005). Introduction to organic chemistry (3rd ed.). Wiley. p. 604. ISBN 978-0-471-44451-0.