FUNDAMENTALS OF FOOD TECHNOLOGY (1+1)

IV) Other polysaccharides

Other polysaccharides

• Many other polysaccharides are present in varying amounts in various plant foods. These include i) cellulose ii) fructosans iii) galactans iv) pentosans v) pectins and vi) Hemicellulose.
• All these are not acted upon by the digestive juices in the human intestinal tract. They help to increase faecal bulk and prevent constipation.
Cellulose

• Cellulose is a polysaccharide made up of glucose.
• Its chemical structure differs from starch in the mode of linkage of glucose molecules.
Fructosans

• Fructosans are polysaccharides formed by the combination of large no of fructose molecules.
  
• Fructosans are present in onions and Jerusalem artichoke.
Galactans

• Galactans are polysaccharides composed of galactose molecules.
  
• They occur in large amounts in sea weeds.
  
• The well known polygalactan is agar-agar.
Pentosans

• Pentosans are polysaccharides formed by the combination of a large number of pentoses.
  
• They occur in grass and straw.
Pectins

• Pectins are formed by the combination of large number of galacturonic acid molecules.
  
• In the presence of sucrose and citric acid, pectin forms a gel.
Hemicellulose

• Hemicelluloses are polysaccharides containing pentoses, hexoses and uronic acids.
  
• They are present in all vegetables, bran of cereals and hull of legumes.