Mono di and poly saccharides

  • Created by: Nicole
  • Created on: 22-06-11 09:45

Monosaccharides are carbohydrates.    They contain a single sugar molecule,    the formula is C six  H twelve  O six.   Glucose is a monosaccharide.   Other examples are fructose which is twice as sweet as glucose   and galactose which is found in milk. 

Disaccharides are also carbohydrates, they consist of two monosaccharides joined together.   The formula is C twelve  H twenty two  O eleven.    Disaccharides include maltose which is made up of glucose and glucose.   Another example is lactose which is made up of glucose and galactose. Lastly sucrose which is made up pf glucose and fructose.    The link that joins the monosaccharides together is called a glycosidic link. 

Simple polysaccharides are long chains of one type of monosaccharide joined together.    The formula is   C six   H ten  O five.  There are three important polysaccharides, which are starch, cellulose and glycogen.   Starch is stored as glycogen and cellulose.   The first type of starch is amylose which is made up of straight chains of alpha glucose units.  It readily geltanises and retrogradiation is likely.    The second type of starch is amylopectin which is made up of interconneting short chains with a branched structure.   It is more difficult to gelatinise and is resistant to retrogradiation.      Complex polysaccharides are long chains of more than one type of monosaccharide joined together.  A type of complex polysaccharide is pectin.    It is essential for jam making, it forms a gel with sugar and water.  The second type are gums.  These have the ability to absorb large quantites of water and form firm gels .  They can act as thickeners, stabilisers and emulsifiers. For example sodium alginate from seaweeds. Used as a stabiliser in ice cream. 

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