1、DD ISO/TS27265:2009ICS 67.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWDRAFT FOR DEVELOPMENTDried milk Enumerationof the speciallythermoresistantspores of thermophilicbacteriaThis Draft for Developmentwas published under theauthority of the StandardsPolicy and Strategy
2、Committee on 31 October2009 BSI 2009ISBN 978 0 580 66458 8Amendments/corrigenda issued since publicationDate CommentsDD ISO/TS 27265:2009National forewordThis Draft for Development is the UK implementation of ISO/TS27265:2009.This publication is not to be regarded as a British Standard.It is being i
3、ssued in the Draft for Development series of publications andis of a provisional nature. It should be applied on this provisional basis,so that information and experience of its practical application can beobtained.Comments arising from the use of this Draft for Development arerequested so that UK e
4、xperience can be reported to the internationalorganization responsible for its conversion to an international standard.A review of this publication will be initiated not later than 3 years afterits publication by the international organization so that a decision can betaken on its status. Notificati
5、on of the start of the review period will bemade in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period,the responsible BSI Committee will decide whether to support theconversion into an international Standard, to extend the
6、life of theTechnical Specification or to withdraw it. Comments should be sent tothe Secretary of the responsible BSI Technical Committee at BritishStandards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to TechnicalCommittee AW/5, Chemical analysi
7、s of milk and milk products.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard ca
8、nnot confer immunityfrom legal obligations.DD ISO/TS 27265:2009Reference numbersISO/TS 27265:2009(E)IDF/RM 228:2009(E)ISO and IDF 2009TECHNICAL SPECIFICATION ISO/TS27265IDF/RM228First edition2009-08-01Dried milk Enumeration of the specially thermoresistant spores of thermophilic bacteria Lait sec Dn
9、ombrement des spores spcialement thermorsistantes des bactries thermophiles DD ISO/TS 27265:2009ISO/TS 27265:2009(E) IDF/RM 228:2009(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
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15、ISO/TS 27265:2009ISO/TS 27265:2009(E) IDF/RM 228:2009(E) ISO and IDF 2009 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 is normally car
16、ried 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.
17、 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 prepare Interna
18、tional 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. In other circumstances, particularly when there is an u
19、rgent market requirement for such documents, a technical committee may decide to publish other types of document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for publication if it is approved by more than
20、 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote. An ISO/PAS or ISO/TS is r
21、eviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
22、 International Standard or be withdrawn. 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. ISO/TS 27265IDF/RM 228 was prepared by Technical Committee I
23、SO/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. DD ISO/TS 27265:2009ISO/TS 27265:2009(E) IDF/RM 228:2009(E) iv ISO and IDF 2009 All rights reservedForeword IDF (the International Dairy Fed
24、eration) is a non-profit organization representing the dairy sector worldwide. IDF membership comprises National Committees in every member country as well as regional dairy associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right to be represented on
25、the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in the development of standard methods of analysis and sampling for milk and milk products. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the
26、 Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the IDF National Committees casting a vote. In other circumstances, particularly when there is an urgent market requirement for s
27、uch documents, a Standing Committee may decide to publish an other type of normative document which is called by IDF: Reviewed method. Such a method represents an agreement between the members of a Standing Committee and is accepted for publication if it is approved by at least 50 % of the committee
28、 members casting a vote. A Reviewed method is equal to an ISO/PAS or ISO/TS and will, therefore, also be published jointly under ISO conditions. 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
29、 identifying any or all such patent rights. ISO/TS 27265IDF/RM 228 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and ISO. All work was carried out by the Joint
30、 ISO-IDF Action Team on Harmonization of the Standing Committee on Microbiological methods of analysis under the aegis of its project leaders, Ms S. Miller (NZ) and Mr B. Hill (NZ). DD ISO/TS 27265:2009TECHNICAL SPECIFICATION ISO/TS 27265:2009(E)IDF/RM 228:2009(E) ISO and IDF 2009 All rights reserve
31、d 1Dried milk Enumeration of the specially thermoresistant spores of thermophilic bacteria 1 Scope This Technical Specification specifies a method for the enumeration of colony-forming units (CFU) of specially thermoresistant spores of thermophilic bacteria in dried milk products by using a colony-c
32、ount technique at 55 C after heating the sample at 106 C. The applicability of this Technical Specification is limited to dried whole milk, skim milk, and buttermilk products that are destined to be recombined and used in the manufacture of sterilized (e.g. UHT or retort-treated) milk products. 2 No
33、rmative references The following referenced documents are indispensable for the application 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. ISO 7218, Microbiology of food
34、 and animal feeding stuffs General requirements and guidance for microbiological examinations ISO 6887-5, Microbiology of food and animal feeding stuffs Preparation test samples, initial suspension and decimal dilutions for microbiological examination Part 5: Specific rules for the preparation of mi
35、lk and milk products 1)ISO/TS 11133-1, Microbiology of food and 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 Terms and definitions For the purposes of this docu
36、ment, the following terms and definitions apply. 3.1 specially thermoresistant spores of thermophilic bacteria bacterial spores surviving a heat treatment of 106 C for 30 min forming colonies aerobically at 55 C in a non-selective medium under the conditions specified in this Technical Specification
37、 1) Supersedes ISO 8261IDF 122. DD ISO/TS 27265:2009ISO/TS 27265:2009(E) IDF/RM 228:2009(E) 2 ISO and IDF 2009 All rights reserved4 Principle A specified quantity of an initial suspension of the test sample is heat treated at 106 C for 30 min. Poured Petri dishes are prepared using a specified non-s
38、elective culture medium and a specified quantity of the heat-treated initial suspension. Other dishes may be prepared, under the same conditions, using decimal dilutions of the heat-treated initial suspension. The dishes are incubated aerobically at 55 C for 48 h. The number of CFU of specially ther
39、moresistant spores of thermophilic bacteria per gram of product is calculated from the number of colonies on dishes chosen at dilution levels so as to give a significant result. The specially thermoresistant spores of thermophilic bacteria enumerated by the method have the potential to survive comme
40、rcial sterilization processes (e.g. UHT or retort processing). 5 BCP plate count skim milk agar with 0,2 % mass fraction starch For general guidance, see ISO 7218. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or demineralized water or w
41、ater of equivalent purity. 5.1 Bromocresol purple 5.1.1 Components Bromocresol purple Ethanol 95 % volume fraction 4 g 100 ml 5.1.2 Preparation Dissolve the bromocresol purple in the ethanol. Store the solution in a securely stoppered bottle to prevent evaporation. 5.2 Complete medium 5.2.1 Componen
42、ts Tryptone Yeast extract Glucose monohydrate Skimmed milk powder aAgar Starch, soluble cBromocresol purple c(5.1) Water 5,0 g 2,5 g 1,0 g 1,0 g 8 g to 15 g b2,0 g 1 ml 1 000 ml aThe skimmed milk powder shall be free from inhibitory substances. bDepending on the gel strength of the agar. cAdditional
43、 components added to plate count skim milk agar. DD ISO/TS 27265:2009ISO/TS 27265:2009(E) IDF/RM 228:2009(E) ISO and IDF 2009 All rights reserved 35.2.2 Preparation Dissolve each component in the water by heating to boiling while stirring frequently until all are completely dissolved. Adjust the pH,
44、 if necessary, so that after sterilization it is 7,0 0,2 at 25 C. Sterilize in an autoclave at 121 C 1 C for 15 min. The medium may also be prepared from a suitable commercial, dehydrated plate count skim milk agar to which the additional components are added. 6 Apparatus Usual microbiological labor
45、atory apparatus, the apparatus required for the preparation of test samples and dilutions as specified in ISO 7218 and ISO 6887-5 and, in particular the following. Disposable apparatus is an acceptable alternative to reusable glassware if it has suitable specifications. 6.1 Incubator, capable of bei
46、ng maintained at 55 C 1 C. 6.2 Water baths, capable of being maintained at temperatures of between 15 C and 25 C and at 45 C 1 C. 6.3 pH-meter, temperature-compensated, capable of being read to 0,1 pH units at 25 C. 6.4 Sample heating equipment, pressure vessel or small autoclave capable of raising
47、the sample temperature from 100 C to 105,5 C in 6 min, and of maintaining the temperature of a pilot tube at 106 C 0,5 C throughout the treatment period. The pressure vessel shall be capable of being rapidly cooled to 100 C after completion of the heat treatment. Generally that requires this vessel
48、has a steam vent. Unless already installed, the pressure vessel requires modification (e.g. by attaching a compression fitting with rubber seals to the lid) so that a temperature sensor can pass through the lid into the vessel. A detailed description of an example for constructing a suitable pressur
49、e vessel is given in Annex A. 6.5 Digital thermometer, fitted with a narrow gauge temperature sensor which is accurate to 106 C 0,1 C and able to pass through the compression fitting into the pressure vessel lid. 6.6 Heat source, gas or electric equipment. 6.7 Test-tubes, screw-capped and of sufficient capacity to leave adequate head-space for mixing 10 ml of test sample. The screw cap of the pilot tube (see 8.2.2) should be so designed that the temperature sensor (6.5) used can be fitted her
