ISO/TS 4985:2023

Milk and milk products — Determination of alkaline phosphatase activity — Fluorimetric microplate method

This document specifies a fluorimetric microplate method for the determination of alkaline phosphatase (ALP, EC 3.1.3.1)[5] activity in raw and heat-treated whole milk, semi-skimmed milk, skimmed milk, cream, flavoured milks and cheeses. This method is applicable to milk and milk-based drinks from cows, sheep and goats. Although the method was not tested in milk from other species, it can also be applicable to milk from other species with a similar composition to cow, sheep or goat milk, such as milk from buffalo and camelids. It is also applicable to milk powder after reconstitution and soft, semi-hard and hard cheeses provided that the mould is only on the surface of the cheese and not also in the inner part (e.g. blue veined cheeses). For large hard cheeses, specific conditions of sampling apply (see Clause 7). NOTE This method was adapted from Reference [6].

Lait et produits laitiers — Détermination de l’activité de la phosphatase alcaline — Méthode fluorimétrique sur microplaque

Le présent document spécifie une méthode fluorimétrique sur microplaque pour la détermination de l’activité de la phosphatase alcaline (ALP, EC 3.1.3.1)[5] dans les laits crus et traités thermiquement entiers, demi-écrémés, écrémés, dans la crème, les laits aromatisés et les fromages. La méthode est applicable au lait et aux boissons à base de lait de vache, de brebis et de chèvre. Bien que la méthode n’ait pas été testée sur le lait d’autres espèces, elle peut également s’appliquer au lait d’espèces dont la composition est semblable à celle du lait de vache, de brebis ou de chèvre, tel que le lait de bufflonne ou de camélidés. Elle est également applicable au lait en poudre après reconstitution et aux fromages à pâte molle, à pâte pressée non cuite et à pâte pressée cuite, à condition que la moisissure ne soit présente que sur la surface du fromage et ne se soit pas propagée à l’intérieur, comme dans le cas des fromages veinés de bleu, par exemple. Pour les gros fromages à pâte pressée cuite, des conditions spécifiques d’échantillonnage s’appliquent (voir Article 7). NOTE Cette méthode a été adaptée de la Référence [6].

General Information

• Status: Published
• Publication Date: 30-Jul-2023
• ICS: 67.100.10 - Milk and processed milk products
• Technical Committee: ISO/TC 34/SC 5 - Milk and milk products
• Drafting Committee: ISO/TC 34/SC 5 - Milk and milk products
• Current Stage: 6060 - International Standard published
• Start Date: 31-Jul-2023
• Due Date: 29-Apr-2023
• Completion Date: 31-Jul-2023

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 4985
IDF/RM 255
First edition
2023-07
Milk and milk products —
Determination of alkaline
phosphatase activity — Fluorimetric
microplate method
Reference numbers
IDF/RM 255:2023(E)
IDF/RM 255:2023(E)
© ISO and IDF 2023
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 on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office International Dairy Federation
CP 401 • Ch. de Blandonnet 8 Silver Building • Bd Auguste Reyers 70/B
CH-1214 Vernier, Geneva B-1030 Brussels
Phone: [phone] Phone: [phone]
Fax: [phone]
Email: [e-mail] Email: [e-mail]
Website: www.iso.org Website: www.fil-idf.org
Published in Switzerland
ii
IDF/RM 255:2023(E)
Contents Page
Forewords .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus and materials .3
7 Sampling . 4
8 Preparation . 4
8.1 Preparation of alkaline phosphatase-free sample . 4
8.1.1 General . 4
8.1.2 Alkaline phosphatase-free milk . 4
8.1.3 Alkaline phosphatase-free cheese . 4
8.2 Preparation of test sample . 5
8.2.1 Milk samples. 5
8.2.2 Cheese samples . 5
9 Procedure .5
9.1 Instrument . 5
9.1.1 Instrument settings . 5
9.1.2 Test the linearity range of the instrument . 6
9.1.3 Quality control . 6
9.2 Calibration . 6
9.2.1 General . 6
9.2.2 Preparation of the working standard solutions . 6
9.2.3 Preparation of the calibration curve . 7
9.3 Determination . 7
9.3.1 Milk samples. 7
9.3.2 Cheese samples . 8
9.3.3 Plate layout and fluorescence measurement . 9
9.4 Test sample-related controls. 9
9.4.1 Recommended negative and positive controls . 9
9.4.2 Interfering substance test . 10
9.4.3 Heat-stable microbial alkaline phosphatase control test . 10
10 Calculation and expression of results .10
10.1 Calibration curve . 10
10.2 Calculation of ALP activity of unknown samples . 11
10.2.1 Milk samples. 11
10.2.2 Cheese samples .12
10.2.3 Calculation example .13
10.3 Expression of results . . 14
11 Precision .14
11.1 Interlaboratory test . . 14
11.2 Repeatability . 14
11.3 Reproducibility . 14
12 Test report .15
Annex A (informative) Precision data .16
Annex B (informative) Method comparison .17
Annex C (informative) Examples of preparation of test sample .19
iii
IDF/RM 255:2023(E)
Bibliography .21
iv
IDF/RM 255:2023(E)
Forewords
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 electrotechnical standardization.
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of 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
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO
and IDF.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
IDF/RM 255:2023(E)
IDF (the International Dairy Federation) is a non-profit private sector organization representing the
interests of various stakeholders in dairying at the global level. IDF members are organized in National
Committees, which are national associations composed of representatives of dairy-related national
interest groups including dairy farmers, dairy processing industry, dairy suppliers, academics and
governments/food control authorities.
ISO and IDF collaborate closely on all matters of standardization relating to methods of analysis
and sampling for milk and milk products. Since 2001, ISO and IDF jointly publish their International
Standards using the logos and reference numbers of both organizations.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. IDF 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
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
This document was prepared by the IDF Standing Committee on Analyt
...