Amylose is a component of starch. The other component, amylopectin, is structurally different from amylose. Amylose is composed of a polymer of glucose with links exclusively in the 1,4 orientation, whereas amylopectin contains 1,6 branches in addition to the 1,4 linkages.The unbranched structure of amylose causes the polymer to exist as a long, coiled helix under conditions when it can be stabilized. One substance that will stabilize an amylose helix is iodine, which fits into the hollow core of the structure. Binding of iodine to amylose helices produces an intense blue color and has long been used as a qualitative test for starch. Polymers consisting solely of glucose are called glucans.