直鏈澱粉
维基百科，自由的百科全书
直鏈澱粉(糖澱粉) (CAS# 9005-82-7)是一種由葡萄糖組成的線性聚合物，各葡萄糖單體主要以α(1→4)糖苷鍵連接，每個直鏈澱粉分子通常含有數千個葡萄糖單體。直鏈澱粉與支鏈澱粉(膠澱粉)組成生物中常見的澱粉。
α(1→4)糖苷鍵導致直鏈澱粉應承螺旋狀結構，右圖為其分子結構式，其重複的葡萄糖但體數目通常由300個到3000個。
直鏈澱粉的水解消化作用比支鏈澱粉緩慢，但作為能量儲存物質，直鏈澱粉佔據較少空間，因而植物中有約20%的澱粉是直鏈澱粉。澱粉酶在直鏈澱粉分子的末端，通過水解作用把直鏈澱粉拆散為葡萄糖單體，因支鏈澱粉擁有更多的末端，所以相對水解速度較快。
Iodine molecules fit neatly inside the helical structure of amylose, binding with the starch polymer, causing it to absorb certain wavelengths of 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 colour will be observed. The intensity of the colour can be tested with a colorimeter using a red filter, to indicate the concentration of starch present in the solution.
High-amylose varieties of rice have a much lower glycemic load which could be beneficial for diabetics.
