Question

Mention the difference between Amylose and Amylopectin.

Answer 1

Hint: In organic chemistry, amylose and amylopectin are present side by side and interspersed in the starch granule. They have unique chemical and physical properties and their relative proportions influence the overall properties of starches. To bring into notice, amylose forms a colloidal dispersion in hot water whereas amylopectin is completely insoluble.

Complete step by step answer:

AMYLOSE:	AMYLOPECTIN:
Amylose a polysaccharide made up of several branched D-glucose units. They are linked by 1, 4-glycosidic bonds. It is soluble in water and can be hydrolyzed into glucose units by the enzymes α- amylase and β-amylase.	Amylopectin is a polymer of several D-glucose molecules. 80% of amylopectin is present in starch. These molecules are linked together by α-1,4-glycosidic bonds and α-1,6-glycosidic bonds. It readily dissolves in hot water. On cooling, it forms a starch paste or starch gel.
Amylose, also referred to as a linear polymer, is one of the two main components of starch. Amylose can be described as a linear polysaccharide in which anhydroglucose units are linked by a-d-1,4 glycosidic bonds. It forms about 20-30% of the starch structure.	It is a water-soluble polysaccharide and highly branched polymer of α-glucose units found in plants. Amylopectin is a highly branched structure composed by formation of 2000 to 200000 glucose units. Its inner chains are formed of 20-30 glucose subunits.
They are also good film formers and result in a firm gel when cooked. The molecules tend to adopt a helical structure. More importantly, amylose is known to interact with iodine, organic alcohols and fatty acids.	Amylopectin forms about 80-85% of starch, though the percentage varies depending on the source. For example, the content of amylopectin is 100% in medium grain rice, waxy potato starch, waxy corn and glutinous rice; and lower in long-chain rice, amylomaize and russet potatoes.
A common source of high amylose starch is a hybrid corn containing over 50% up to 70% amylose. Due to plant breeding, high amylose rice and potato starches are available.	Amylopectin is an energy source especially in animals. It gives a reddish brown color in iodine test and that helps in distinguishing it from others.
EXAMPLE: High‐amylose maize, barley, and potato, high‐amylose variants such as wheat and rice.	EXAMPLE: Higher in medium-grain rice to maximum in glutinous rice, waxy potato starch, and lower in long-grain rice, amylomaize, and russet potatoes.

Note: We need to know that the amylose molecules are formed from several glucose units arranged in a linear manner. Amylopectin is formed by arranging many glucose units in a branched manner. This is the key difference between amylose and amylopectin molecules present in starch. When an iodine solution is added to starch, it turns to a dark blue/ black colour. This colour change is given by amylase present in starch along with amylopectin. Amylose is more soluble in water than amylopectin.