GC: n
CT: Normal native starches consist of a mixture of 15-30 per cent. amylose and 70-85 per cent. amylopectin. Amylose approximately between 40 000 and 340 000, the chains containing 250 to 2000 anhydroglucose units. Amylopectin is considered to be composed of anhydroglucose chains with many branch points; the molecular weight may reach as high as 80 000 000 (Re. WHO). Amylose is an unbranched chain which is coiled in the shape of a helix. If iodine is added to a solution containing amylose molecules, the iodine inserts itself into the helix making it rigid. This changes the color of the starch mixture to blue or purple depending on the length of the amylose molecule. Amylopectin is a branching molecule which does not form a helical coil. Thus the iodine is not able to bind to the starch molecule. Amylose contributes to the gelling property of starch whereas amylopectin contributes high viscosity. This classic statement, however, may not be entirely valid. Both properties are used in the preparation of foods.
S: Starch – http://www.starch.dk/isi/starch/starch.asp (last access: 4 November 2014)
N: 1. From amyl (hydrocarbon radical, 1850, from Latin amylum, from Greek amylon “fine meal, starch,” noun use of neuter of adjective amylos “not ground at the mill, ground by hand,” from a-, privative prefix, “not” + myle “mill”; so called because first obtained from the distilled spirits of potato or grain starch (though it also is obtained from other sources) and -ose (standard ending in chemical names of sugars, originally simply a noun-forming suffix, taken up by French chemists mid-19c.; it has no etymological connection with sugar; it appears around the same time in two chemical names, cellulose, which would owe it to the French suffix, and glucose, where it would be a natural result from the Greek original. Flood favors origin from glucose).
A component of starch characterized by its straight chains of glucose units.
First Known Use of amylose: 1833.
2. As in land plants, the major carbohydrate storage product of the green algae is usually starch in the form of amylose or amylopectin. These starches are polysaccharides in which the monomer, or fundamental unit, is glucose. Green algal starch comprises more than 1,000 sugar molecules, joined by alpha linkages between the number 1 and number 4 carbon atoms.
S: 1. OED – http://www.etymonline.com/index.php?term=amyl&allowed_in_frame=0; http://www.etymonline.com/index.php?allowed_in_frame=0&search=ose&searchmode=none (last access: 31 December 2014); MW – http://www.merriam-webster.com/dictionary/amylose (last access: 31 December 2014). 2. EncBrit – http://global.britannica.com/EBchecked/topic/22074/amylose (last access: 31 December 2014).
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CR: bioethanol , ethanol .
