SANS 21527-1-2009 Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of yeasts and moulds Part 1 Colony count technique in products with water a.pdf

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1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-23420-1 SANS 21527-1:2009Edition 1ISO 21527-1:2008Edition 1SOUTH AFRICAN NATIONAL STANDARD Microbiology of food and animal feeding stuffs

4、Horizontal method for the enumeration of yeasts and moulds Part 1: Colony count technique in products with water activity greater than 0,95 This national standard is the identical implementation of ISO 21527-1:2008 and is adopted with the permission of the International Organization for Standardizat

5、ion. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 21527-1:2009 Edition 1 ISO 21527-1:2008 Edition 1 Table of changes Change No. Date Scope National foreword This South African standa

6、rd was approved by National Committee SABS TC 1026, Microbiological evaluation of foods, feeds and beverages, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in November 2009. Reference numberISO 2152

7、7-1:2008(E)ISO 2008INTERNATIONAL STANDARD ISO21527-1First edition2008-07-01Microbiology of food and animal feeding stuffs Horizontal method for the enumeration of yeasts and moulds Part 1: Colony count technique in products with water activity greater than 0,95 Microbiologie des aliments Mthode hori

8、zontale pour le dnombrement des levures et moisissures Partie 1: Technique par comptage des colonies dans les produits activit deau suprieure 0,95 SANS 21527-1:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) PDF discla

9、imer 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 performing the editing. In downloading this file, parties ac

10、cept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the

11、 file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTEC

12、TED DOCUMENT ISO 2008 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 and microfilm, without permission in writing from either ISO at the address below or ISOs mem

13、ber body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reservedSANS 21527-1:2009This s tandard may only be used and printed b

14、y approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) ISO 2008 All rights reserved iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards

15、 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 p

16、art 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 in the ISO/IEC Directives, Part 2. The main task of technical committees is to

17、 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 % of the member bodies casting a vote. Attention is drawn to the possibility t

18、hat 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. ISO 21527-1 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 9, Microbiology. ISO 21527 consists of the followi

19、ng parts, under the general title Microbiology of food and animal feedings stuffs Horizontal method for the enumeration of yeasts and moulds: Part 1: Colony count technique in products with water activity greater than 0,95 Part 2: Colony count technique in products with water activity less than or e

20、qual to 0,95 This part of ISO 21527, together with ISO 21527-2, cancel and replace ISO 7698:1990, ISO 7954:1987 and ISO 13681:1995. SANS 21527-1:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) iv ISO 2008 All rights re

21、servedIntroduction Because of the large variety of food and feed products, the applications of the horizontal method specified in ISO 21527 (all parts) may not be appropriate for certain products. In this case, different methods, which are specific to these products, may be used if absolutely necess

22、ary for justified technical reasons. Nevertheless, every attempt shall be made to apply the horizontal method as specified in ISO 21527 (all parts) as far as possible. When ISO 21527 (all parts) is next reviewed, account will be taken of all information then available regarding the extent to which t

23、he horizontal method has been followed and the reasons for deviations from this method in the case of particular products. The harmonization of test methods cannot be immediate, and for certain groups of products International Standards and/or national standards may already exist that do not comply

24、with the horizontal method as specified in ISO 21527 (all parts). It is hoped that when such standards are reviewed they will be changed to comply with ISO 21527 (all parts) so that eventually the only remaining departures from this horizontal method will be those necessary for well-established tech

25、nical reasons. SANS 21527-1:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .INTERNATIONAL STANDARD ISO 21527-1:2008(E) ISO 2008 All rights reserved 1Microbiology of food and animal feeding stuffs Horizontal method for the enumeration of y

26、easts and moulds Part 1: Colony count technique in products with water activity greater than 0,95 WARNING It is essential that enumeration of moulds is carried out with the greatest care to protect the operator and to prevent contamination of the atmosphere with mould spores. 1 Scope This part of IS

27、O 21527 specifies a horizontal method for the enumeration of viable yeasts and moulds in products intended for human consumption or feeding of animals that have a water activity greater than 0,95 eggs, meat, dairy products (except milk powder), fruits, vegetables, fresh pastes, etc., by means of the

28、 colony count technique at 25 C 1 C (References 1, 2). This part of ISO 21527 does not allow the enumeration of mould spores. Neither the identification of fungal flora nor the examination of foods for mycotoxins lie within the scope of this part of ISO 21527. The method specified in this part of IS

29、O 21527 is not suitable for enumeration of heat-resistant fungi, such as Byssochlamys fulva or Byssochlamys nivea, in canned or bottled fruit and vegetables. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only t

30、he edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6887 (all parts), Microbiology of food and animal feeding stuffs Preparation of test samples, initial suspension and decimal dilutions for microbiological examinati

31、on ISO 7218, Microbiology of food and animal feeding stuffs General requirements and guidance for microbiological examinations ISO 8261, Milk and milk products General guidance for the preparation of test samples, initial suspensions and decimal dilutions for microbiological examination ISO/TS 11133

32、 (all parts), Microbiology of food and animal feeding stuffs Guidelines on preparation and production of culture media 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. NOTE There are some intermediate forms and the distinction between a yeast (3.1

33、) and a mould (3.2) can be arbitrary. SANS 21527-1:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) 2 ISO 2008 All rights reserved3.1 yeast mesophilic aerobic microorganism which, at 25 C using mycological agar medium u

34、nder the conditions described in this part of ISO 21527, develops matt or shiny round colonies (3.4) on the surface of the medium, usually having a regular outline and a more or less convex surface NOTE Yeasts within, rather than on, a medium develop round, lenticular, colonies. 3.2 mould mesophilic

35、 aerobic filamentous microorganism which, on the surface of mycological agar medium under the conditions described in this part of ISO 21527, usually develops flat or fluffy spreading propagules/germs (3.3) or colonies (3.4) often with coloured fruiting or sporing structures. NOTE Moulds within, rat

36、her than on, a medium can develop round, lenticular, colonies. 3.3 propagule germ viable entity capable of growth in a nutrient medium EXAMPLE Vegetative cell, group of cells, spore, spore cluster, or a piece of fungal mycelium. ISO 6107-6:2004, 65 3.4 colony localized visible accumulation of microb

37、ial mass developed on or in a solid nutrient medium from a viable particle ISO 6107-6:2004, 15 4 Principle 4.1 Surface-inoculated plates are prepared using a specified selective culture medium. Depending on the expected number of colonies, a specified quantity of the sample (if the product is liquid

38、), or of an initial suspension (in the case of other products), or decimal dilutions of the sample/suspension are used. Additional plates can be prepared under the same conditions, using decimal dilutions of the test sample or of the initial suspension. 4.2 The plates are then aerobically incubated

39、at 25 C 1 C for 5 d. If necessary, the agar plates are left to stand in diffuse daylight for 1 d to 2 d. 4.3 Colonies/propagules are then counted and, if required (to distinguish yeast colonies from bacterial colonies), the identity of any doubtful colonies is confirmed by examination with a binocul

40、ar magnifier or microscope. 4.4 The number of yeasts and moulds per gram or per millilitre of sample is calculated from the number of colonies/propagules/germs obtained on plates chosen at dilution levels producing countable colonies. Moulds and yeasts are counted separately, if necessary. SANS 2152

41、7-1:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) ISO 2008 All rights reserved 35 Diluent and culture medium For current laboratory practice, see ISO 6887 (all parts) and ISO 8261. 5.1 Diluent 5.1.1 General See ISO 6

42、887 (all parts), ISO 8261 and the specific International Standard dealing with the product concerned. NOTE It is possible to add surface-active agents such as sodium poly(oxyethylene)sorbatitanmonooleate 1)0,05 % (mass concentration) to diluents to reduce clumping of mould spores and conidia (Refere

43、nce 2). Except for specific preparation of the test sample, the use of 0,1 % (mass concentration) peptone water broth as diluent is recommended. 5.1.2 Composition of 0,1 % (mass concentration) peptone water broth Enzymatic digest of animal or vegetal tissues 1,0 g Water 1 000 ml 5.1.3 Preparation of

44、 0,1 % (mass concentration) peptone water broth Dissolve the components in the water, by heating if necessary. If necessary, adjust the pH so that, after sterilization, it is 7,0 0,2 at 25 C. 5.2 Culture medium 5.2.1 Dichloran-rose bengal chloramphenicol agar (DRBC) (References 3, 4) 5.2.1.1 Composi

45、tion Enzymatic digest of animal and plant tissues 5,0 g D-Glucose (C6H12O6) 10,0 g Potassium dihydrogenphosphate (KH2PO4) 1,0 g Magnesium sulfate (MgSO4 H2O) 0,5 g Dichloran (2,6-dichloro-4-nitroaniline) 0,002 g Rose bengal 0,025 g Agar 12 g to 15 g aChloramphenicol 0,1 g Water, distilled or deioniz

46、ed 1 000 ml aDepending on the gel strength of the agar. 1) Tween 80 is an example of a suitable product available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product. SANS 21527-1:2009This s

47、 tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 21527-1:2008(E) 4 ISO 2008 All rights reserved5.2.1.2 Preparation 5.2.1.2.1 General Suspend all the ingredients except chloramphenicol in the water and bring to the boil to dissolve completely. If

48、 necessary, adjust the pH (6.4) so that after sterilization it is 5,6 0,2 at 25 C. Add 10 ml of a 1 % (mass concentration) solution of chloramphenicol in ethanol and mix. Dispense the medium in quantities into suitable containers (6.5) of suitable capacity. Sterilize by autoclaving at 121 C for 15 m

49、in. Immediately, cool the medium in a water bath (6.3) maintained at a temperature of 44 C to 47 C. Cool to below 50 C and dispense 15 ml amounts into sterile Petri dishes (6.6). Allow the medium to solidify, and dry, if necessary, the surface of the plates as described in ISO 7218 and ISO/TS 11133 (all parts). Use immediately, or store in the dark, according to ISO/TS 11133 (all parts) until required. CAUTION Avoid exposure of the medium to light, since cytotoxic breakdown pr