ISO INTERNATIONAL STANDARD 660 Fourth edition 2020-03 Animal and vegetable fats and oils ： Determination of acid value and acidity Corps gras d'origines animale et vegétale -Détermination de I'indice d'acide et de I'acidite Reference number IS0 660:2020(E) ISO @IS0 2020 IS0 660:2020(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2020 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting below orIso's member body in the country of therequester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122 749 0111 Fax: +41 22 749 09 47 Email: [email protected] Website: www.iso.org Published in Switzerland i @IS0 2020 - All rights reserved IS0 660:2020(E) Contents Page Foreword iv 1 Scope. 1 2 Normative references 1 3 Terms and definitions 1 4 Principle .2 5 Reagents. .2 6 Apparatus. .3 7 Sampling. .3 8 Preparation of test sample .3 9 Procedure .3 9.1 Cold solvent method using indicator (reference method) .3 9.2 Cold solvent method using potentiometric titration (reference method) .4 9.3 Hot ethanol method using indicator 10 .5 Calculation 10.1 General 5 10.2 Acid value. .5 Acidity or free fatty acid content 5 10.3 11 Precision 6 11.1 Repeatability 6 11.2 Reproducibility 6 12 Test report. 6 AnnexA(informative)Resultsofinterlaboratorytests. .7 AnnexB (informative)Comparison ofthree coloured indicators. .10 Bibliography .12 IS0 2020 -All rights reserved iii