# Commission Regulation (EC) No 152/2009 of 27 January 2009 laying down the methods of sampling and analysis for the official control of feed (Text with EEA relevance), Division 2: Principle

Extent: E+W+S+N.I.

The method comprises two determinations. In the first, the sample is treated with dilute hydrochloric acid. After clarification and filtration the optical rotation of the solution is measured by polarimetry.
In the second, the sample is extracted with 40 % ethanol. After acidifying the filtrate with hydrochloric acid, clarifying and filtering, the optical rotation is measured as in the first determination.
The difference between the two measurements, multiplied by a known factor, gives the starch content of the sample.

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Source: https://www.legislation.gov.uk/eur/2009/152/annex/III/division/L/division/1/division/2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2009-152/annex-III/division-L/division-1/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.