oSIST prEN ISO 660:2019

SLOVENSKI STANDARD
oSIST prEN ISO 660:2019
01-september-2019

Rastlinske in živalske maščobe in olja - Določevanje kislinskega števila in kislosti

Animal and vegetable fats and oils - Determination of acid value and acidity (ISO/DIS

Tierische und pflanzliche Fette und Öle - Bestimmung der Säurezahl und der Azidität

Corps gras d'origines animale et végétale - Détermination de l'indice d'acide et de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

Corps gras d'origines animale et végétale — Détermination de l'indice d'acide et de l'acidité

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be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

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 .................................................................................................................................... 4

10 Calculation .................................................................................................................................................................................................................. 5

10.1 Acid value..................................................................................................................................................................................................... 5

10.2 Acidity or free fatty acid content ............................................................................................................................................. 5

11 Precision ....................................................................................................................................................................................................................... 6

11.1 Repeatability ............................................................................................................................................................................................. 6

11.2 Reproducibility ....................................................................................................................................................................................... 6

12 Test report ................................................................................................................................................................................................................... 6

Annex A (informative) Results of interlaboratory tests.................................................................................................................... 7

Annex B (informative) Comparison of three coloured indicators .......................................................................................... 9

Bibliography .............................................................................................................................................................................................................................11

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 a technical

committee has been established has the right to 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

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

Any trade name used in this document is information given for the convenience of users and does not

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

This document was prepared by Technical Committee ISO/TC 34, Food Products, Subcommittee SC 11,

This fourth edition cancels and replaces the third edition (ISO 660:2009), which has been technically

— Addition of a non‐applicability statement for milk and milk products to the scope as ISO 1740

"Milkfat products and butter – Determination of fat acidity (Reference method)" applies,

— Additions in Annex of data from the collaborative trial carried out to support this modification.

This International Standard specifies three methods (two titrimetric and one potentiometric) for the

determination of the acidity in animal and vegetable fats and oils, hereinafter referred to as fats. The

acidity is expressed preferably as acid value, or alternatively as acidity calculated conventionally.

This International Standard is applicable to refined and crude vegetable or animal fats and oils, soap

stock fatty acids or technical fatty acids. The methods are not applicable to waxes.

Since the methods are completely non‐specific, they cannot be used to differentiate between mineral

acids, free fatty acids, and other organic acids. The acid value, therefore, also includes any mineral acids

Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain

number of milligrams of potassium hydroxide required to neutralize the free fatty acids present in 1 g

of fat, when determined in accordance with the procedure specified in this International Standard

content of free fatty acids determined according to the procedure specified in this International

Note 1 to entry: The acidity is expressed as a percentage by mass. If the result of the determination is reported as

acidity without further explanation, this is, by convention, the acidity based on the oleic acid content.

The sample is dissolved in a suitable solvent mixture, and the acids present are titrated with an

WARNING — Attention is drawn to the regulations which specify the handling of hazardous

substances. Technical, organizational and personal safety measures shall be followed.

As a replacement, tert‐butyl methyl ether, light petroleum (boiling range 40 °C to 60 °C) or toluene can

WA R N I NG — D ie t hy l e t her i s ver y f l a m m able a nd m ay f or m e x plo s i ve p er ox ide s . Us e w it h g r e at

5.3 Solvent mixture, mix equal volumes of solvent A and B, (e.g. φ = 50 ml/100 ml and

For hard or animal fats, a solvent mixture of one volume of solvent A (e.g. 25 ml) and three volumes of

Neutralize, just before use, by adding potassium hydroxide solution in the presence of 0,3 ml of the

5.5 Sodium hydroxide or potassium hydroxide, ethanolic or methanolic standard volumetric

solutions, amount of substance concentration c(NaOH) or c(KOH) = 0,1 mol/l and 0,5 mol/l. The

NOTE The ethanolic/methanolic sodium/potassium hydroxide solution can be replaced by an aqueous

sodium/potassium hydroxide solution, but only if the volume of water introduced does not lead to phase

5.6 Thymolphthalein or Alkali blue 6B, solution in ethanol, mass concentration, ρ = 2 g/100 ml or,

failing that, Phenolphthalein solution in ethanol, mass concentration, ρ = 1 g/100 ml (CAS number: