STARCH

INTRODUCTION The word starch came from German for root which means strong, stiff and strengthen. Starch is also known as amylum. Starch is a carbohydrate consisting of numerous glucose units joined by a glycosidic bond. Starch is the most common form of carbohydrate and is available in large number of food ingredients mainly in tubers and cereals, such as rice, wheat, potatoes, maize etc. We often think of potatoes as a “starchy” food, yet other plants contain a much greater percentage of starch (Potatoes 15%, Wheat 55%, Corn 65%, and Rice 75%).

- Harsha Pore

Starch is a white or off-white, odorless, tasteless powder. It is granular organic chemical compound produced by plants. It is a polysaccharide comprising glucose monomers. The formula for starch is (C6H10O5)n.(H2O)

The simplest form of starch is amylose and amylopectin, which is a mixture of these two molecules. Natural starches consist of 10 30 % of amylase and 70 - 90 % of amylopectin. Amylose is a linear polysaccharide composed entirely of D-glucose units joined by the α-1,4glycosidic linkages. Amylopectin is a branched-chain polysaccharide composed of glucose units linked primarily by α-1,4-glycosidic bonds but with occasional α-1,6-glycosidic bonds, which are responsible for the branching.

ENERGY SOURCE

Starch is the storage of energy. In humans and other animals, starch from plants is broken down into its constituent sugar molecules, which supply energy to the tissues. The human digestive process breaks down the starches into glucose units with the aid of enzymes, and those glucose molecules can circulate in the bloodstream as an energy source. Tillery, et al. point out an interesting example of this enzyme-catalyzed breakdown process. If you chew a piece of bread for a while, it will begin to taste sweet because of the enzymes in saliva are already beginning to break down the starch into glucose, a sugar.

STARCH INDUSTRY

The starch industry extracts and refines starches from seeds, roots and tubers, by wet grinding, washing, sieving and drying. The main commercial refined starches are cornstarch, tapioca, arrowroot, wheat, rice, and potato starches. These are natural starches, the chemically modified starch is also available in the market.