Barley seeds were loaded with starch, that provides energy for seeds to grow into sprouts. It consists of hundred of sugar molecules linked together to form long chains. Starch is a polysaccharides, alpha-glucan and can be divided into straight-chain amylase and branched chain amylopectin.
These starch granules contain traces of lipids, minerals, protein and nucleotide.
The “diastatic” enzymes responsible for degrading the starch in germination are phosphorylase, alpha glucosidase, alpha-amylase, beta-amylase, debranching enzymes, and transglucosylase.
These starches in the endosperm are 95% deposited in 11-28 days after ear emergence and the ratio of amylopectin increases to the final ratio. Starch granules of the starchy endosperm are embedded in the protein matrix. This association of starch granules and protein in the starchy endosperm helps to give the endosperm its structure.
The starch granules in the barley endosperm are laid down within amyloplasts and fall into two size groups: 1.7-2.5 um and 22.5 – 47.5 um. About 90% of the starches granules are small and about 10% are large.
Large starch granules are composed of 25% amylose and 75% amylopectin. Small starch granules are reported to have similar contents of amylose and amylopectin but the very small starch granules (less than 4 um) can contain as much as 40% amylose.
In normal barleys the ration of amylase to amylopectin is about 1:3, in high amylase Glacier about 1:1 and waxy barley is 97-100% amylopectin.
Starch content in barley
