Starch is composed of two kinds of molecules:
A colorless and odorless polysaccharide which is available in plants as stored carbohydrates are termed as Starch. This is the main energy storage area for plants and starch is the main carbohydrate which humans consume. Starch is composed of two kinds of molecules:
Amylopectin is a water-soluble polysaccharide and structurally it is a highly branched polymer composed of α-glucose units available in plants. Every branch of the polymer has approximately 30 glucose units and the glucose-sugar units are linked together using the glycosidic bond. Amylose is water-soluble and can be hydrolyzed into numerous glucose units by using enzymes α-amylase and β-amylase. The main purpose of Amylopectin is to act as an energy supplement for plants. Foods such as Jasmine rice, Short grain rice, and few strains of potatoes are rich in Amylopectin. This food with Amylopectin is digested by Humans and other animals as an enzyme Amylase helps in the process. Food products like rice and grains contain 100% and 99% Amylopectin. These are mostly useful for wafer and waffle baking. The amylopectin molecules are larger when compared with amylose. Amylopectin has two important properties which are mostly quite popular for industrial purposes such as proper binding and starch retrogradation. These properties help in the usage of Amylopectin in the manufacturing of adhesives and Lubricants.
The chemical formula of Amylopectin is [C 6 H 10 O 5 ]n. Amylopectin is derived by a series of glucose units linked by glycosidic bonds. The glycosidic bond is formed by linking two monosaccharides. Hence making Amylopectin a polysaccharide. The structure of Amylopectin is compared to a branched tree. The length of the Amylopectin branching chain consists of 20 to 30 glucose units. The structure of Amylopectin can vary in size as it can be from 2,000 glucose units in length to more than 200,000 units. The structure of Amylopectin is branched because of the presence of six glucose units at every turn of the branch. This unit consists mainly of α-1, 4-glycosidic bonds but with occasional α-1,6-glycosidic bonds. These are responsible for the branching. Amylose Amylose is a linear polymer of glucose units. The amount of amylose in starch is determined by potentiometric titration which depends on the strength between Amylose and Iodine. Approximately 19.9% of iodine affinity is available in Potato and Wheat starches. Maize contains 19.0% of iodine affinity. The main reason behind choosing Amylose as a ligand is because of the feasibility of the coupling reaction with the native matrix. The combination of Amylose with Iodine forms a distinct blue color. Amylose may form strong hydrogen bonds that make molecules less susceptible to enzymatic degradation. This is widely used in the permanent textile finishes, plastics, film making, and paper pulp fiber bonding. This is also used as a binding agent on food products like French fries which gives a crisp coating and less oil absorption.
The collective unit subunit of oxygen atoms, carbon atoms, and CH 2 OH molecules together form a glucose molecule. These glucose molecules are linked together with the help of the glycosidic bonds. A combination of these glycosidic bonds together form an amylose chain.
The main function of Amylose is the storage of energy and acting as a food reserve. Amylose serves as a thickener water binder, emulsion stabilizer, and gelling agent in both industrial and food-based contexts. Due to the tightly-packed structure it is known as an effective prebiotic substance. Amylose is easily digested than amylopectin and due to this quality, it occupies less space.
The foods which contain more percentage of amylopectin or the glycemic index are Jasmine rice, Short grain sticky rice which is also known as Sushi, and few varieties of potatoes such as Russet Burbank, are easily digestible and absorb more foods with Amylose as the Amylose contains a low glycemic index. This food is mainly helpful for reducing hyperglycemia and hyperinsulinemia. The amount of starch present in the food is determined by the amylose: amylopectin ratio, ingredients along with starch, cooking technique, etc.
Amylopectin is a branched-chain polymer. Each branched chain has approximately 20 glucose units. The glucose sugar unit is linked with the help of a glycosidic bond. Amylopectin has two types of glycosidic linkages: α 1-4 and α 1-6. The function of amylopectin is to aid in energy supply for plants. It is even known as the ‘Energy house’ of the plant. The nutritional supply to plants is continuously generated from the amylopectin. It is even utilized by humans and the amylopectin is digested by breaking down the glucose units with the help of an enzyme known as Amylase.
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This is a linear polymer of D-glucose units
It is mainly composed of starch approximately 80%
Changes to blue colour when combined with Iodine
Stains to reddish-brown when combined with iodine.
Swelling is not observed when dissolved in hot water
Gel formation is possible when added to hot water