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The cut surface of an apple stained with iodine, indicating a starch level of 4–5. The iodine–starch test is a chemical reaction that is used to test for the presence of starch or for iodine. The combination of starch and iodine is intensely blue-black. [1] [2] The interaction between starch and the triiodide anion (I − 3) is the basis ...
Damaged starch can be produced, for example, during the wheat milling process, or when drying the starch cake in a starch plant. [5] There is an inverse correlation between gelatinization temperature and glycemic index. [4] High amylose starches require more energy to break up bonds to gelatinize into starch molecules.
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.
In enzymology, a starch synthase (EC 2.4.1.21) is an enzyme that catalyzes the chemical reaction. ADP-glucose + (1,4-alpha-D-glucosyl) n ADP + (1,4-alpha-D-glucosyl) n+1 Thus, the two substrates of this enzyme are ADP-glucose and a chain of D-glucose residues joined by 1,4-alpha-glycosidic bonds, whereas its two products are ADP and an elongated chain of glucose residues.
β-amylase catalyses the hydrolysis of starch into maltose by the process of removing successive maltose units from the non-reducing ends of the chains. γ-Amylase will cleave the last α(1–4)glycosidic linkages at the nonreducing end of amylose and amylopectin , yielding glucose.
The starch iodine test, a development of the iodine test, is based on colour change, as α-amylase degrades starch and is commonly used in many applications. A similar but industrially produced test is the Phadebas amylase test, which is used as a qualitative and quantitative test within many industries, such as detergents, various flour, grain ...
Glucose syrup on a black surface. Glucose syrup, also known as confectioner's glucose, is a syrup made from the hydrolysis of starch. Glucose is a sugar. Maize (corn) is commonly used as the source of the starch in the US, in which case the syrup is called "corn syrup", but glucose syrup is also made from potatoes and wheat, and less often from barley, rice and cassava.
Working from the non-reducing end, β-amylase catalyzes the hydrolysis of the second α-1,4 glycosidic bond, cleaving off two glucose units at a time. During the ripening of fruit, β-amylase breaks starch into maltose, resulting in the sweet flavor of ripe fruit. β-amylase is present in an inactive form prior to seed germination.