Scope: Determination of the starch content of cereals, flour, milling products (bran, wheat-feed) and of some foods (e.g. rolled oats, semolina), potatoes and other starch-containing products. The method is not suitable for determination of the starch content of products with a very low starch level, such as germ or gluten.
Principle: The soluble, optically active compounds accompanying the substance under examination are extracted with 10 % ethanol and removed by centrifugation. The starch remaining in the residue is dissolved in a boiling calcium chloride solution; dissolved proteinanceous substances are precipitated with Carrez solution (I and II) and filtered off. The optical rotation of the starch solution in the filtrate is measured and from this the starch content is calculated.
