Starch: Difference between revisions
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== Structure == | == Structure == | ||
Starch is a [[Polysaccharide|polysaccharide]] with the basic [[Monosaccharide|monosaccharide]] being [[Glucose|glucose]]. the [[Glucose|glucose]] molecules are joined together by [[Glycosidic bonds|glycosidic bonds]] | Starch is a [[Polysaccharide|polysaccharide]] with the basic [[Monosaccharide|monosaccharide]] being [[Glucose|glucose]]. the [[Glucose|glucose]] molecules are joined together by [[Glycosidic bonds|glycosidic bonds]] straight chains are made up of 1-4 glycosidic bonds while branching chain are made up of 1-6 glycosidic bonds. Starch is made up of two fractions: [[Amylose|amylose]] and [[Amylopectin|amylopectin]]. Natural starches are made up of about 20% [[Amylose|amylose]] and 80% [[Amylopectin|amylopectin]]. [[Amylose|Amylose]] is soluble in hot water whereas [[Amylopectin|amylopectin]] is insoluble. [[Amylose|Amylose]] has no branching chains, but instead is made up of only 1-4 [[Glycosidic bonds|glycosidic bonds]]. This causes the [[Amylase|amylase]] to form a [[Alpha-helix|helix]] shape. [[Amylopectin|Amylopectin]] however contains both straight chains and branching chains.<br> | ||
== Testing == | == Testing == | ||
Starch can be tested for using [[Iodine solution| | Starch can be tested for using [[Iodine solution|iodine solution]]. If starch is present then a dark blue-black colour will be seen. This dark blue-black colour is due to the [[Iodine|iodine]] reacting with the [[Amylose helix|amylose helix]]. | ||
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Revision as of 22:15, 7 January 2011
Structure
Starch is a polysaccharide with the basic monosaccharide being glucose. the glucose molecules are joined together by glycosidic bonds straight chains are made up of 1-4 glycosidic bonds while branching chain are made up of 1-6 glycosidic bonds. Starch is made up of two fractions: amylose and amylopectin. Natural starches are made up of about 20% amylose and 80% amylopectin. Amylose is soluble in hot water whereas amylopectin is insoluble. Amylose has no branching chains, but instead is made up of only 1-4 glycosidic bonds. This causes the amylase to form a helix shape. Amylopectin however contains both straight chains and branching chains.
Testing
Starch can be tested for using iodine solution. If starch is present then a dark blue-black colour will be seen. This dark blue-black colour is due to the iodine reacting with the amylose helix.