ISO-13681-1995.pdf
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1、INTERNATIONAL STANDARD IS0 13681 First edition 1995-l 2-l 5 grNsr Interrmat DW s43c Meat and meat products - Enumeration of yeasts and moulds - Colony-count technique Viandes et produits 2 base de viande - Dknombrement des levures et moisissures - Technique par comptage des colonies - - T Egg5 x =x.
2、! - Reference number IS0 13681 :I 995(E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 01:31:37 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 13
3、681:1995(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject f
4、or 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. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on
5、 all matters of electrotechnical standardization. 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 % of the member bodies casting a vote. International Standard
6、IS0 13681 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC 6, Meat and meat products. Annex A forms an integral part of this International Standard. Annex B is for information only. 0 IS0 1995 All rights reserved. Unless otherwise specified, no part of this
7、publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzer
8、land ii Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 01:31:37 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD 0 IS0 IS0 13681:
9、1995(E) Meat and meat products - Enumeration of yeasts and moulds - Colony-count technique 1 Scope This International Standard specifies a method for the enumeration of yeasts and moulds in all kinds of meat and meat products, including poultry, by means of a colony-count technique at between 20 “C
10、and 25 “C. IMPORTANT - IS0 7954Cll recommends chloram- phenicol or oxytetracycline as antibiotic. These rec- ommended antibiotics do not, however, sufficiently inhibit Gram-negative microorganisms occurring in meat, especially raw meat. To obtain sufficient inhibition in cases of heavy bacterial con
11、tamination, the addition of gentamicin is necessary. Since a com- bination of chloramphenicol and gentamicin inhibits certain types of yeasts, the alternatively specified antibiotic oxytetracycline is the antibiotic of choice. 2 Normative references The following standards contain provisions which,
12、through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility o
13、f applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 3100-2:1988, Meat and meat products - Samp- ling and preparation of test samples - Part 2: Prep- aration of test samples for microbiolog
14、ical examination. IS0 6887: 1983, Microbiology - Genera/ guidance for the preparation of dilutions for microbiological exam- ination. IS0 7218:-l , Microbiology of food and animal feed- ing stuffs - General rules for microbiological exam- inations. 3 Definition For the purposes of this International
15、 Standard, the following definition applies. 3.1 yeasts and moulds: Microorganisms that form colonies within 5 days at between 20 “C and 25 “C under the conditions specified in this International Standard. 4 Principle 4.1 Deep inoculation of poured plates, using a specified selective culture medium
16、contained in Petri dishes, with a specified quantity of the test sample if the initial product is liquid, or with a specified quantity of the initial suspension in the case of other products. Inoculation of other plates, under the same con- ditions, using decimal dilutions of the initial suspen- sio
17、n. NOTE 1 To distinguish, if necessary, between yeasts and moulds, the use of a surface plate is advisable. Surface plates are also recommended when heat-sensitive yeasts or moulds are expected. 4.2 Aerobic incubation of the plates at between 20 “C and 25 “C for 3, 4 or 5 days. 4.3 Calculation of th
18、e number of yeasts and moulds per gram or per millilitre of sample from the number of colonies obtained on plates chosen at dilution lev- els so as to give a significant result. I) To be published. (Revision of IS0 7218:1985) 1 Copyright International Organization for Standardization Provided by IHS
19、 under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 01:31:37 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 13681:1995(E) 5 Dilution fluid, culture medium and reagents 5.1 General For current laboratory practice, see IS0 72
20、18. 5.2 Dilution fluid See IS0 6887. 5.3 Agar medium of yeast extract, glucose and oxytetracycline/gentamicin 5.3.1 Base medium 5.3.1.1 Composition Yeast extract 59 Glucose (CaH,O,) 20 g Agar 8gto18g ) Water 1 000 ml 1) Depending on the gel strength of the agar. 5.3.1.2 Preparation Dissolve the comp
21、onents in the water by boiling. If necessary, adjust the pH so that after sterilization it is 6.6 at 25 “C. Transfer the medium to suitable containers (6.6). Sterilize for 10 min in the autoclave (6.1) set at 115C. 5.3.2 Oxytetracycline solution 5.3.2.1 Composition 5.3.3 Gentamicin solution 5.3.3.1
22、Composition 25 mg 1) 25 ml 1) According to the manufacturer s specification of the real gentamicin content of the powder. 5.3.3.2 Preparation Dissolve the gentamicin in the water and sterilize the solution by filtration. 5.3.4 Complete medium Add 5 ml of the oxytetracycline solution (5.3.2) and 5 ml
23、 of the gentamicin solution (5.3.3) to each portion of 100 ml of sterile base medium (5.3.1), melted and kept in a water bath (6.4) set at 47 “C. 6 Apparatus and glassware NOTE 2 Disposable apparatus is an acceptable alterna- tive to reusable glassware if it has suitable specifications. Usual microb
24、iological laboratory equipment and, in particular, the following. 6.1 Apparatus for dry sterilization (oven) or wet sterilization (autoclave) The autoclave can either operate separately or be part of a general apparatus for preparing and distributing media. See IS0 7218. 6.2 Mixer, working on the pr
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