Amylose (CAS# 9005-82-7) is a planar
polymerof glucoselinked mainly by α(1→4) bonds. It can be made of several thousand glucose units. It is one of the two components of starch, the other being amylopectin.
The α(1→4) bonds promote the formation of a
helixstructure. The structural formulaof amylose is pictured at right. The number of repeated glucose subunits (n) can be many thousands (usually in the range of 300 to 3000).
starchis less readily digested than amylopectin; however, it takes up less space so is preferred for storage in plants: it makes-up about 30% of the stored starch in plants. The digestive enzyme amylaseworks on the ends of the starch molecule, breaking it down into sugars. Iodinemolecules fit neatly inside the helical structure of amylose, binding with the starch polymer that absorbs certain known wavelengthsof light. Hence, a common test for starch is to mix it with a small amount of yellow iodine solution. In the presence of amylose, a blue-black color will be observed. The intensity of the color can be tested with a colorimeter, using a red filter to discern the concentration of starch present in the solution.
High-amylose varieties of
ricehave a much lower glycemic load, which could be beneficial for diabetics.
* [http://www.mendosa.com/gilists.htm glycemic load]
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