Application of alkaline steeping method and enzymatic method in rice starch isolation

Abstract

In Sri Lanka, farmers get a very good yield in some rice growing seasons, and as a result there is excess rice in the country causing storage problems. Rice starch production is a way of adding value to this excess rice, there by reducing post harvest losses. There are many useful applications of rice starch in the food industries such as noodles, rice bread, baby foods and it is also used as dairy alternatives. In addition, it is being used as a dusting powder and as a filler in the pharmaceutical industry and as a laundry stiffening agent in the textile industry (Burrell, 2003). Currently there is no rice starch production in Sri Lanka and the total local requirement is met by imported starches. Hence it will be beneficial to produce rice starch locally to meet the demand for starch in Sri Lanka. Most important part of the production of rice starch is to remove rice protein and the separation of small starch granules by using an appropriate method. The removal of rice protein is important as the surface activity of protein can lead to foaming in starch processing, reduction of starch yield by endoamylolytic activity of some surface-bound enzymes and formation of Maillard products during hydrolysis of starch. Rice protein consists of glutelin (80%), albumin (5%), globulin (12%) and prolamin (3%) which is dissolved in alkali, water, salt and ethanol respectively (Juliano, 1985). Chemical, physical and biological methods are used in rice starch manufacturing process.