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1、 Reference numbers ISO 13559:2002(E) IDF 153:2002(E) ISO and IDF 2002 INTERNATIONAL STANDARD ISO 13559 IDF 153 First edition 2002-11-01 Butter, fermented milks and fresh cheese Enumeration of contaminating microorganisms Colony-count technique at 30 C Beurre, laits ferments et fromage frais Dnombrem
2、ent des micro- organismes contaminants Technique par comptage des colonies 30 C Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license
3、 from IHS -,-,- ISO 13559:2002(E) IDF 153:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer
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6、m relating to it is found, please inform the ISO Central Secretariat at the address given below. ISO and IDF 2002 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 a
7、nd microfilm, without permission in writing from either ISO or IDF at the respective address below. ISO copyright office International Dairy Federation Case postale 56 CH-1211 Geneva 20 Diamant Building Boulevard Auguste Reyers 80 B-1030 Brussels Tel. + 41 22 749 01 11 Tel. + 32 2 733 98 88 Fax + 41
8、 22 749 09 47 Fax + 32 2 733 04 13 E-mail copyrightiso.org E-mail infofil-idf.org Web www.iso.org Web www.fil-idf.org Printed in Switzerland ii ISO and IDF 2002 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980
9、755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 13559:2002(E) IDF 153:2002(E) ISO and IDF 2002 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national stan
10、dards 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 org
11、anizations, 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. International Standards are drafted in accordance with the rules given
12、 in the ISO/IEC Directives, Part 3. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75
13、 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 13559IDF 153 was pre
14、pared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. Copyright International Organiz
15、ation for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 13559:2002(E) IDF 153:2002(E) iv ISO and IDF 2002 All rights reserved Foreword IDF (the Int
16、ernational Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in t
17、he development of standard methods of analysis and sampling for milk and milk products. Draft International Standards adopted by the Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 %
18、of the National Committees casting a vote. International Standard ISO 13559IDF 153 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jo
19、intly by ISO and IDF and separately by AOAC International. All work was carried out by the Joint ISO/IDF/AOAC Action Team, Non-Pathogen Contaminants, under the aegis of its project leader, Mr D. van den Berg (NL). Copyright International Organization for Standardization Provided by IHS under license
20、 with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 13559:2002(E) IDF 153:2002(E) ISO and IDF 2002 All rights reserved 1 Butter, fermented milks and fresh cheese Enumeration o
21、f contaminating microorganisms Colony-count technique at 30 C 1 Scope This International Standard specifies a method for the enumeration of contaminating microorganisms by means of the colony-count technique at 30 C. The method is applicable to butter, fermented milks and fresh cheese. 2 Normative r
22、eferences 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
23、 this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently
24、 valid International Standards. ISO 6887-1, Microbiology of food and animal feeding stuffs Preparation of test samples, initial suspension and decimal dilutions for microbiological examination Part 1: General rules for the preparation of the initial suspension and decimal dilutions ISO 7218, Microbi
25、ology of food and animal feeding stuffs General rules for microbiological examinations ISO 8261IDF 122:2001, Milk and milk products General guidance for the preparation of test samples, initial suspensions and decimal dilutions for microbiological examination ISO/TS 11133-1, Microbiology of food and
26、 animal feeding stuffs Guidelines on preparation and production of culture media Part 1: General guidelines on quality assurance for the preparation of culture media in the laboratory 3 Term and definition For the purposes of this International Standard, the following term and definition applies. 3.
27、1 contaminating microorganisms non-lactic acid bacteria, yeasts and moulds forming countable colonies under the conditions specified in this International Standard NOTE 1 Product-specific lactic acid bacteria will not be detected by this method. NOTE 2 In certain types of fermented milks, non-lactic
28、 acid bacteria, yeasts or moulds can be part of the microflora contributing to the desired characteristics of the product. In such cases, care should be taken when applying the method described in this International Standard. 4 Principle 4.1 Poured plates are prepared using a specified culture mediu
29、m, followed by surface plating of a specified quantity of an initial suspension of the product. Under the same conditions, poured plates are prepared, followed by surface plating of a specified quantity of decimal dilutions of an initial suspension. Copyright International Organization for Standardi
30、zation Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 13559:2002(E) IDF 153:2002(E) 2 ISO and IDF 2002 All rights reserved 4.2 The plates are aerobically incubated
31、at 30 C 1 C for 72 h. 4.3 The number of microorganisms per gram of test sample is calculated from the number of colonies obtained on plates chosen at dilution levels so as to give a significant result. 5 Diluents, culture media and reagents 5.1 General For current laboratory practice, see ISO 7218.
32、5.2 Basic materials See ISO 8261IDF 122:2001, subclause 5.1. 5.3 Diluents for general use See ISO 8261IDF 122:2001, subclause 5.2. 5.4 Diluents for special purposes See ISO 8261IDF 122:2001, subclause 5.3. 5.5 Distribution, sterilization and storage of diluents See ISO 8261IDF 122:2001, subclause 5.
33、4. 5.6 Culture medium 5.6.1 General All components of the culture medium shall be free from carbohydrates. The absence of carbohydrates in the culture medium used here is essential for the method described. The quality of the carbohydrate-free medium used shall be assured in accordance with ISO/TS 1
34、1133-1. 5.6.2 Composition Peptone from casein 7,5 g Peptone from gelatin 7,5 g Sodium chloride (NaCl) 5,0 g Agar 1) 10 g to 15 g Water 1 000 ml 5.6.3 Preparation 5.6.3.1 Preparation from commercial dehydrated complete medium Follow the manufacturers instructions. Adjust the pH, if necessary, so that
35、 after sterilization it is 7,5 0,1 at 25 C. For fermented milks, adjust the pH, if necessary, so that after sterilization it is 8,0 0,1 at 25 C. 1) Depending on the gel strength of the agar. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aram
36、co HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 13559:2002(E) IDF 153:2002(E) ISO and IDF 2002 All rights reserved 3 5.6.3.2 Preparation from dehydrated basic components Dissolve and disperse by heating in the water,
37、in the following order, the peptone from casein, the peptone from gelatin and the sodium chloride. Add the agar and heat to boiling while stirring frequently until the agar is completely dissolved, or steam for about 30 min. Filter through filter paper, if necessary. Adjust the pH so that, after ste
38、rilization, it is 7,5 0,1 at 25 C. For fermented milks, adjust the pH, if necessary, so that after sterilization it is 8,0 0,1 at 25 C. 5.6.3.3 Distribution, sterilization and storage Dispense the medium into test tubes (6.8), in quantities of 12 ml to 15 ml per tube, or into flasks or bottles (6.9)
39、, in quantities of 100 ml to 150 ml. Sterilize in an autoclave set at 121 C 1 C for 15 min. If the medium is to be used immediately, cool it in the water bath (6.5) to between 44 C and 47 C. If not used immediately, store it in the dark at between 1 C and 5 C for no longer than 3 months. In order to
40、 avoid any delay when pouring the medium and before commencing the microbiological examination, completely melt the medium in a boiling water bath, then cool it in another water bath set at between 44 C and 47 C before use. 6 Apparatus Disposable apparatus is an acceptable alternative to reusable gl
41、assware if it has suitable specifications. Reusable glassware should be capable of undergoing repeated sterilization and should be chemically inert. Sterilize all apparatus that will come into contact with the test sample and the diluents or culture medium in accordance with ISO 8261. Usual microbio
42、logical equipment (see ISO 7218 and ISO 8261) and, in particular, the following. 6.1 Incubator, capable of operating at 30 C 1 C. 6.2 Oven or incubator, ventilated by convection, capable of operating at 50 C 1 C, or a laminar air-flow cabinet. 6.3 Petri dishes, made of glass or plastic, of diameter
43、90 mm to 100 mm, or, when an inoculum of more than 0,1 ml is used, dishes of diameter 140 mm. 6.4 Graduated pipettes, of nominal capacity of 1 ml 0,02 ml or 10 ml 0,2 ml. 6.5 Water baths, capable of operating at between 44 C and 47 C, and capable of boiling. 6.6 Colony-counting equipment, consisting
44、 of an illuminated base with a dark background, fitted with a magnifying lens to be used at a magnification of 1,5 and a mechanical or electronic digital counter. 6.7 pH-meter, accurate to 0,1 pH unit at 25 C, with readability to 0,01 units. 6.8 Test tubes, with plugs or caps, of capacity of approxi
45、mately 20 ml. 6.9 Bottles or flasks, with plugs or caps, of nominal capacity 150 ml to 250 ml. Bottles or flasks with non-toxic metal screw-caps may be used. 6.10 Sterile spreaders, with diameter of approximately 3,5 mm and length of 20 cm, bent at right angles about 3 cm from one end. The cut ends
46、should be made smooth by heating. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 06:56:21 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 13559:2002(E) IDF 153:2002
47、(E) 4 ISO and IDF 2002 All rights reserved 7 Sampling It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended samplin
48、g method is given in ISO 707. 8 Procedure 8.1 Preparation of test portion and initial suspension 8.1.1 General For general requirements see ISO 6887-1, and for specific requirements see ISO 8261. Take normal aseptic precautions. The operations described in 8.1 and 8.2 shall not be carried out in direct sunlight. 8.1.2 Butter See ISO 8261:2001, subclause 8.2.6. 8.1.3 Fresh cheese See ISO 8261:2001, subclause 8.2.4. 8.1.4 Fermented milks See ISO 8261:2001, su