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Amylopectin / ˌ æ m ɪ l oʊ ˈ p ɛ k t ɪ n / is a water-insoluble [1] [2] polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. Relation of amylopectin to starch granule. Plants store starch within specialized organelles called amyloplasts. To ...
Starch gelatinization is a process of breaking down of intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the starch granule in water. Water acts as a plasticizer.
It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. [4] Glycogen, the energy reserve of animals, is a more highly branched version of amylopectin.
It is made up of a mixture of amylose (15–20%) and amylopectin (80–85%). Amylose consists of a linear chain of several hundred glucose molecules, and Amylopectin is a branched molecule made of several thousand glucose units (every chain of 24–30 glucose units is one unit of Amylopectin). Starches are insoluble in water.
Starch hydrolyses during roasting under acidic conditions, and short-chained starch parts partially rebranch with α-(1,6) bonds to the degraded starch molecule. [5] See also Maillard reaction . Dextrins are white, yellow, or brown powders that are partially or fully water-soluble, yielding optically active solutions of low viscosity .
The starch of normal dent maize is characterised by a content of about 25% amylose with the remainder being amylopectin and the intermediate fraction (see 3.5 Biochemistry). But these percentages vary among cultivars and with kernel development. For example, amylose percentage ranged from 20 to 36% for 399 cultivars of normal maize.
Amylose A is a parallel double-helix of linear chains of glucose. Amylose is made up of α(1→4) bound glucose molecules. The carbon atoms on glucose are numbered, starting at the aldehyde (C=O) carbon, so, in amylose, the 1-carbon on one glucose molecule is linked to the 4-carbon on the next glucose molecule (α(1→4) bonds). [3]
Glycogen is a branched biopolymer consisting of linear chains of glucose residues with an average chain length of approximately 8–12 glucose units and 2,000-60,000 residues per one molecule of glycogen. [20] [21] Like amylopectin, glucose units are linked together linearly by α(1→4) glycosidic bonds from one glucose to the next. Branches ...