Amylose is important in plant energy storage. It is less readily digested than [[amylopectin]]; however, because it is more linear than amylopectin, it takes up less space. As a result, it is the preferred starch for storage in plants. It makes up about 30% of the stored starch in plants, though the specific percentage varies by species. The digestive enzyme α-[[amylase]] is responsible for the breakdown of the starch molecule into [[maltotriose]] and [[maltose]], which can be used as sources of energy.
Amylose is also an important thickener, water binder, emulsion stabilizer, and gelling agent in both industrial and food-based contexts. Loose helical amylose chains have a [[hydrophobic]] interior that can bind to hydrophobic molecules such as [[ lipids]] and [[ aromatic compounds]]. The one problem with this is that, when it crystallizes or associates, it can lose some stability, often releasing water in the process ([[ syneresis (chemistry)|syneresis]]). When amylose concentration is increased, gel stickiness decreases but gel firmness increases. When other things including [[amylopectin]] bind to amylose, the [[ viscosity]] can be affected, but incorporating κ-[[ carrageenan]], [[ alginate]], [[ xanthan gum]], or low-molecular-weight sugars can reduce the loss in stability. The ability to bind water can add substance to food, possibly serving as a fat replacement.<ref>H.-J. Chung, Q. Liu, Impact of molecular structure of amylopectin and amylose on amylose chain association during cooling, Carbohydr. Polymers 77 (2009) 807-815</ref> For example, amylose is responsible for causing white sauce to thicken, but, upon cooling, some separation between the solid and the water will occur.
In a laboratory setting, it can act as a marker. [[ Iodine]] molecules fit neatly inside the [[helix|helical structure]] of amylose, binding with the starch polymer that absorbs certain known [[wavelengths]] of light. Hence, a common test is the [[iodine test]] for starch. Mix starch 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. It is also possible to use [[starch indicator|starch as an indicator]] in titrations involving iodine reduction.<ref>http://dwb.unl.edu/Teacher/NSF/C10/C10Links/mills.edu/RESEARCH/FUTURES/JOHNB/structurefunction/722.html</ref> It is also used in amylose magnetic beads and resin to separate [[ maltose-binding protein]]<ref>http://www.neb.com/nebecomm/products/productE8035.asp</ref>