amyloseamylopectin

Amylose and amylopectin are the two principal polysaccharides that make up starch, the storage carbohydrate in plants. Together they determine starch’s structural and functional properties.

Amylose is predominantly linear, composed of α-1,4-linked glucose units, typically forming a helical structure. Amylopectin is highly branched, with long α-1,4 chains and α-1,6 branches about every 24–30 residues.

Starch sources vary in amylose to amylopectin ratio. Common cereal starches contain roughly 20–30% amylose and 70–80% amylopectin; waxy starches have very little amylose; high-amylose varieties may reach 40–50% amylose.

During heating with water, starch granules gelatinize: they absorb water, swell, and lose crystalline structure. Amylose tends to leach out and form gels, while amylopectin maintains viscosity. The amylose content influences gel strength, retrogradation, and textural properties such as bread staling.

In digestion, enzymes such as amylases break both components down to glucose. Amylose, being less branched, can form tighter structures that resist rapid digestion, whereas amylopectin provides many accessible ends for enzymes. Overall, starch with higher amylose content often yields a lower glycemic response and greater resistant starch potential.

Analytical aspects: iodine binds to the helical amylose, yielding a blue-black color, while amylopectin gives a reddish-brown coloration. The amylose content is commonly estimated by iodine binding or enzymatic/ chromatographic methods.