The major storage polysaccharide in barley endosperm cells. Produced by the polymerisation of glucose molecules starch has two molecular species, the linear polymer amylase (around 20%) and the branched polymer amylopectin (around 80%). Starch molecules are condensed into rigid starch grains during growth of the barley grain. These grains provide an inert energy store for when the grain germinates and are of two types, small grains 1-5m diameter and large grains 10-25m diameter. Mashing rapidly dissolves the small grains but most dissolved starch derives from the larger grains.