ISO INTERNATIONAL STANDARD 15598 First edition 1999-06-01 Tea Determination of crude fibre content Thé - Deétermination de l'indice d'insoluble dit cellulosique" (so Reference number ISO15598:1999(E) No r IHSunder Not for Resale ISO 15598:1999(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO committees. Each member body interested in a subject for which a technical committee has been established has liaison with ISO, also take part in the work. iSsO collaborates closely with the International Electrotechnical Commission(lEC)onallmattersofelectrotechnicalstandardization International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 3. International Standard ISO 15598 was prepared by Technical Committee ISO/TC 34, Agricultural food products Subcommittee SC 8, Tea. Annex A of this International Standard is for information only. ?ISO1999 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic nternationalOrganizationforStandardization Casepostale 56·CH-1211Geneve 20·Switzerland Internet [email protected] Printed in Switzerland ational Organization for Standardizatior INTERNATIONAL STANDARD ISO ISO 15598:1999(E) Tea Determination of crude fibre content 1 Scope This International Standard specifies a method for the determination of crude fibre content in tea. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1573:1980, Tea -Determination of loss in mass at 103 °C. Iso 3696, Water for analytical laboratory use -Specification and test methods. 3 Term and definition For the purposes of this International Standard, the following term and definition apply 3.1 crude fibre content the whole of the substances which are insoluble and combustible under the operating conditions specified in this International Standard NOTE 4 Principle The suitably ground sample is successively treated with boiling sulfuric acid solution and sodium hydroxide solution The residue is separated by filtration, washed, dried, weighed and then ashed. The loss in mass resulting from ashing is called the crudefibre content. 5 Reagents Use only reagents of recognized analytical grade. 5.1 Water, complying with grade 3 of ISO 3696 5.2 Sulfuric acid stock solution, c(V/2H2sO4) = 2,040 ± 0,040 mol/l (corresponding to 100 g of sulfuric acid per litre of solution). Copyright Inte lal Organization for Standardizatior 1