ISO INTERNATIONAL STANDARD 11213 First edition 1995-02-01 Modified starch Determination of acetyl content -Enzymatic method Amidon modifié -Dosage de I'acetyle Methode enzymatique X ISO Reference number ISO11213:1995(E) Coovriaht Intemational Oranization for Standardization ISO 11213:1995(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which atechnical committeehasbeen establishedhasthe rightto be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. Iso collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International a vote. International Standard ISO 11213 was prepared by Technical Committee ISO/TC 93, Starch (including derivatives and by-products). Annexes A, B and C of this International Standard are for information only. C ISO 1995 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56· CH-1211 Geneve 20· Switzerland Printed in Switzerland ISO 11213:1995(E) INTERNATIONAL STANDARD ISO Modified starch Determination of acetyl content - Enzymatic method 1 Scope then reacts with oxaloacetate to form citrate in the presence of citrate synthase (Cs). This International Standard specifies an enzymatic The oxaloacetate required for the reaction is formed methodforthedeterminationof theacetyl content from malate and nicotinamide adenine dinucleotide of modified starch, both granular and soluble in cold (NAD) in the presence of malate-dehydrogenase water. Total and free acetyl contents are determined (MDH). In this reaction, the NAD is reduced to NADH and the bound acetyl content is calculated. and the formation of NADH can be determined by The method is suitable for determining acetyl con- measuring the increase in absorbance at a specified tents up to 2 % (m/m). wavelength. (See reference [1] in annex C.) The free acetyl content is determined by making a 2 Normative references suspension of the modified starch in water, filtering, and determining the acetyl content of the filtrate as The following standards contain provisions which, already described. The bound acetyl content is calcu- through reference in this text, constitute provisions lated by subtracting the free acetyl content from total of this International Standard. At the time of publi- acetyl content. cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged 4 Reagents and materials toinvestigatethepossibilityof applyingthemostre- The reagents used shall be of recognized analytical centeditionsofthestandardsindicatedbelow Members of IEC and ISO maintain registers of cur- grade, unless otherwise specified. The water used rently valid International Standards. shall comply with the specifications of IsO 3696, grade 2. The enzymes used shall be of a quality ISO1666:1973,Starch-Determinationof moisture equivalent to the relevant enzymes of Boehringer content Oven-drying methods. Mannheim1). Iso 3696:1987,Water for analytical laboratory use NOTE1 Suitable test kits which are commercially avail- Specificationandtestmethods. able can be used. 3Principle 4.1 Hydrochloric acid, 1 mol/l solution. The total acetyl content is determined by heating the 4.2 Sodium hydroxide, 5 mol/l soluti