123/1 Determination of Starch Content by Hydrochloric Acid Dissolution

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Methods Type: Generic Methods
Key data
Number: 123/1
Analyte: Starch Content (Hydrochloric Acid Dissolution)
Matrix: Cereals flour, milling products (bran, wheatfeed) and of some foods (e.g. rolled oats, semolina), potatoes and other starch containing products
Year of Approval: 1976
Year of Last Revision: 1994
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 compound accompanying the substance under examination are extracted with 10 % ethanol and removed by filtration or centrifugation. The starch remaining in the residue is dissolved in hot, dilute hydrochloric acid, dissolved proteinanceous substances are precipitated with Carrez solution (I and II) and filtered. The optical rotation of the starch solution in the filtrate is measured and from this the starch content is calculated.

Definition

According to the method described below, the starch content is that portion of the substance under examination, the optical rotation of which is measured by means of a polarimeter after dissolving in dilute hydrochloric acid. Any high molecular break-down products of the starch substance present in the material under examination are also considered as starch.

 

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