See also: starch - rice starch - corn starch - wheat starch - potato starch
What is that
Rice starch differs from other types of starch by the small volume of its granules (5/6 μm in diameter), which when viewed at the microscopic level appear polyhedral, isolated or variously joined together to form oval or roundish groups.
When added to bath water, rice starch is also an excellent soothing and skin softener for children, certainly to be preferred to more aggressive soaps.
Production
Rice starch is obtained from the grains of the homonymous plant ( Oryza sativa ), which contain about 85% starch. The kernels are then immersed in a solution of sodium hydrate, so that the caustic soda disintegrates the grain; the material obtained is then ground and reduced to a diluted suspension, which is skimmed; followed by sieving cycles (to eliminate cellulose), further washing, sedimentation and centrifugation.
Once purified and dried, rice starch appears as a white, very fine, tasteless powder that creaks under finger pressure and is practically insoluble in cold water and in alcohol.
Property and uses
Like all types of starch, also rice is made up of two polymers of glucose, one linear, called amylose, and one branched, called amylopectin. The latter, due to its branched structure, is easier to digest because it is easily attacked by digestive enzymes, to which it exhibits a greater specific surface.
Amylose, in addition to being less digestible, does not gelatinize during cooking; consequently, grains containing amylose-rich starch tend to remain well separated during cooking. This is the case of long-grain rice, also called up or superfine, which moreover does not overcook, because amylose keeps cooking very well by stiffening, and has a low glycemic index, given its lower digestibility.
Varieties rich in amylopectin, such as small and round rice, appear to be sticky; therefore grains containing amylopectin-rich rice starch are indicated above all for soups and desserts, as they tend to release starch during cooking.
