CHAPTER ONE
1.0  INTRODUCTION
1.1     Background of Study
Starch is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store. It is the most common carbohydrate in the human diet and is contained in large amounts in such staple foods as potatoes. Wheat maize (corn) rice and cassava (Michael et al, 2005). Pure starch is white tasteless and odorless power that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylase and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylase and 75 to 80% amylopectin. Glycogen, the glucose store of animals is a more branched Version of amylopectin (Mclver et al, 1999).
Starch is processed to produce many of the sugars in processed foods. Dissolving starch in warm water gives wheatpaste that can be used as a thickening; stiffening or gluing agent. The biggests industrial non-food use of starch is as adhesive in the papermaking process (Miller et al, 2008) Starch molecules among themselves in the plant in semi-crystalline granules. Each plant species has a unique starch granular size: rice starch is relatively small (about 2µm) while potato starches have large granules (up to 100um). Although in absolute mass only about one quarter of the starch granules in plants consist of amylase; there are about 150 times more amylase molecules than amylopectin molecules. Amylase is a much smaller molecule than amylopectin. (Willem et al, 2003).
Starch becomes soluble in water when heated the granules swell and burst; the semi-crystalline