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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 ...
Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. 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]
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 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.
Retrogradation is a reaction that takes place when the amylose and amylopectin chains in cooked, gelatinized starch realign themselves as the cooked starch cools. [1]When native starch is heated and dissolved in water, the crystalline structure of amylose and amylopectin molecules is lost and they hydrate to form a viscous solution.
Raw starch granules resist digestion, e.g., raw bananas, raw potatoes. This does not depend on the amylose or amylopectin content, but rather the structure of the granule protecting the starch. When starch granules are cooked, water is absorbed into the granule causing swelling and increased size.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
In maize and some other plants, there is evidence of a starch molecule that is intermediate in size to amylose and amylopectin. [38] The intermediate fraction contains chains of (1–4)-linked alpha-D-anhydro-glucose residues, but the average length of these chains and the number of chains per molecule are different from those in either ...