Amylose vs. Amylopectin

There are two types of starch, the Amylose and Amylopectin. Both are coiled structure. They are digested by humans to simple glucose, which then subsequently used for generating energy. The Amylose and Amylopectin are both working gears and machinery of starch. They are both polysaccharides but main difference being amylose that is made up of D- glucose units is 20-30 percent of total starch structure while the Amylopectin is composed of the remaining percentage.

What is Amylose?

Amylose is unique to plants. It has alpha-one-four linkage. Amylose molecules are long chain of starch in a granule. It is amorphous granules. Amylose is not necessary for granular formation of starch. For example rice with lower Amylose is soft and sticky while with high Amylose rice is firm and separate from each other and rice go very hard when cooling. If we see potatoes with low Amylose has waxy and creamy texture while potatoes with high amylose are hard and starchy. Amylose in starch may range from zero percent to thirty percent. Amylose is essentially a linear molecule and the glucose unit is linked to the carbon of -1 glucose molecule with carbon -4 of the next, creating straight chains. The way we measure Amylose is iodine solution. Iodine molecule will bind with the helical chain of starch. The combat forms a blue solution and we measure the absorption of Amylose-iodine complex at 620nm.  Amylose is not easily dissolved in water.

What is Amylopectin?

Amylopectin is closely related to Amylose. It involves in plant energy. Amylopectin is made up of short chains. It is extremely branched and is insoluble in water. It is analogous to glycogen in plants. It also has alpha- one four linkage that connects glucose linearly. In addition to this it also has alpha- one- six linkages, which is seen between the branched linage but it is less branched as compared to glycogen.  Every 24 to 30 unit the branching occurs. Amylopectin forms the body of starch granule, around 2000 to 200,000 molecules of glucose units participate in its formation. It is a crystalline granule of starch. It is non-rigid thus easily mixes or dissolves in water. It forms 70-80 percent of starch granule. So typically there will be greater Amylopectin to Amylose ratio in starch. It is with no trouble degraded using enzymes.

Key Differences

  1. Amylose is insoluble in water while Amylopectin are soluble in water.
  2. Body and internal system hardly absorbs Amylose as compared to Amylopectin which is readily dissolved in water and then absorbed.
  3. The structure or linkage of Amylose is linear; in a straight line while Amylopectin is highly branched.
  4. Amylose is great storage system for energy while Amylopectin stores small amount of energy.
  5. Amylose is used more in cooking as compare to Amylopectin.
  6. Amylose chain range from 300 to several thousand while Amylopectin is branched, every 20 to 30 glucose unit.
  7. In Amylose only alpha- , 4 glycosidic bonds participates whereas in the other alpha- 1, 4- glycosidic bonds and alpha- 1, 6- glycosidic bonds takes part.
  8. Amylose is rigid- very hard, while Amylopectin is soft.
  9. If performed iodine test, Amylose can easily be distinguish as it gives blue color while Amylopectin stain as reddish brown.
  10. Alpha- beta amylase can hydrolyze Amylose chain “α-1, 4-glycosidic bonds” while it cannot hydrolyze Amylopectin completely as it has “α-1, 6-glycosidic bonds”.
  11. Amylose is soluble in hot water and does not form gel or paste while Amylopectin is soluble in hot water forming gel and pasty solution.

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