Amylose

Amylose is a component of starch, the carbohydrate storage polymer in plants. It is a mainly linear polymer of α-D-glucose units linked by α-1,4 glycosidic bonds, and it typically accounts for about 20–30% of starch, with the remainder being amylopectin. The exact proportion varies by botanical source and cultivar.

In contrast to the highly branched amylopectin, amylose has relatively few branch points and tends to form fairly long chains. These chains can adopt helical structures and can influence the physical properties of starch, including gelatinization, viscosity, and gel formation. When treated with iodine, amylose forms a characteristic blue color, which is used in analytical assays to estimate amylose content.

Digestibility of amylose differs from that of amylopectin. It is hydrolyzed by human α-amylases to smaller sugars more slowly than amylopectin, contributing to a lower glycemic response for some starches. When cooked and cooled, high-amylose starches can form resistant starch, which resists digestion in the small intestine and functions as dietary fiber.

Amylose occurs in many plant starches, including corn, potato, wheat, and rice. It is valued in the food industry for texture and stability and is also explored in nonfood applications, such as biodegradable films and controlled-release materials. Variation in amylose content among starches influences their culinary behavior, textural properties, and nutritional attributes.