1、March 2009DEUTSCHE NORM English price group 12No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.100.40!$VW#“1515200ww
2、w.din.deDDIN EN ISO 7328Milk-based edible ices and ice mixes Determination of fat content Gravimetric method (Reference method) (ISO 7328:2008)English version of DIN EN ISO 7328:2009-03Speiseeis und Eis-Mischungen auf Milchbasis Bestimmung des Fettgehaltes Gravimetrisches Verfahren (Referenzverfahre
3、n) (ISO 7328:2008)Englische Fassung DIN EN ISO 7328:2009-03SupersedesDIN EN ISO 7328:2000-05www.beuth.deDocument comprises 22 pagesDIN EN ISO 7328:2009-03 2 National foreword This standard has been prepared by Technical Committee ISO/TC 34 “Food products” (Secretariat: AFNOR, France), Subcommittee S
4、C 5 “Milk and milk products” (Secretariat: NEN, Netherlands) in collaboration with Technical Committee CEN/TC 302 “Milk and milk products Methods of sampling and analysis” (Secretariat: NEN, Netherlands). The responsible German body involved in its preparation was the Normenausschuss Lebensmittel un
5、d landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Technical Committee Milch und Milchprodukte Probenahme- und Untersuchungsverfahren. Based on the results of parallel voting, ISO 7328:2008 has been adopted as a European Standard. For reasons of environmental and wo
6、rker protection, the German employers liability insurance associations and inspectorates forbid the open evaporation of diethyl ether, which this standard allows as an alternative method. One way of reducing risks is to substitute diethyl ether with an equivalent amount of tert-butyl methyl ether (t
7、-BME). This deviation from the specified procedure is to be stated in the test report. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 707 DIN EN ISO 707 ISO 835 DIN EN ISO 835 ISO 1042 DIN EN ISO 1042 ISO 4788 DIN EN ISO 4788 Amendment
8、s This standard differs from DIN EN ISO 7328:2000-05 as follows: a) Clause 1 “Scope” has been rendered more precise. b) Clause 2 “Normative references” and clause 7 “Sampling” have been revised. c) The standard has been revised in form and substance and brought in line with the current rules of pres
9、entation. d) The bibliography has been updated. Previous editions DIN EN ISO 7328: 2000-05 DIN EN ISO 7328:2009-03 3 National Annex NA (informative) Bibliography DIN EN ISO 707, Milk and milk products Guidance on sampling DIN EN ISO 835, Laboratory glassware Graduated pipettes DIN EN ISO 1042, Labor
10、atory glassware One-mark volumetric flasks DIN EN ISO 4788, Laboratory glassware Graduated measuring cylinders DIN EN ISO 7328:2009-03 4 This page is intentionally blank EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 7328October 2008ICS 67.100.40 Supersedes EN ISO 7328:1999 English VersionMil
11、k-based edible ices and ice mixes - Determination of fatcontent - Gravimetric method (Reference method) (ISO 7328:2008)Glaces de consommation et prparations pour glaces base de lait - Dtermination de la teneur en matire grasse - Mthode gravimtrique (Mthode de rfrence) (ISO 7328:2008)Speiseeis und Ei
12、s-Mischungen auf Milchbasis -Bestimmung des Fettgehaltes - Gravimetrisches Verfahren(Referenzverfahren) (ISO 7328:2008)This European Standard was approved by CEN on 14 October 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving thi
13、s EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (En
14、glish, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria,
15、 Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONC
16、OMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 7328:2008: EContents Page Foreword iv Foreword. v 1 Scope 1 2
17、Normative references 1 3 Terms and definitions .1 4 Principle2 5 Reagents.2 6 Apparatus .2 7 Sampling.4 8 Preparation of test sample4 8.1 Edible ices, ice mixes and concentrated ice mixes .4 8.2 Dried ice mixes.4 9 Procedure .4 9.1 Test portion 4 9.2 Blank tests5 9.3 Preparation of fat-collecting ve
18、ssel.5 9.4 Determination.5 10 Calculation and expression of results.8 10.1 Calculation8 10.2 Expression of results 8 11 Precision.8 11.1 Interlaboratory test 8 11.2 Repeatability.8 11.3 Reproducibility.9 12 Test report 9 Annex A (informative) Notes on procedures 10 Annex B (informative) Alternative
19、procedure using fat-extraction tubes with siphon or wash-bottle fittings .12 Bibliography 15 2EN ISO 7328:2008 (E) DIN EN ISO 7328:2009-03 Foreword This document (EN ISO 7328:2008) has been prepared by Technical Committee ISO/TC 34 “Agricultural food products“ in collaboration with Technical Committ
20、ee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis” the secretariat of which is held by NEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2009, and conflicting natio
21、nal standards shall be withdrawn at the latest by April 2009. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes
22、 EN ISO 7328:1999. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Icelan
23、d, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 7328:2008 has been approved by CEN as a EN ISO 7328:2008 without any modification. 3EN IS
24、O 7328:2008 (E) DIN EN ISO 7328:2009-03 WARNING The use of this International Standard may involve hazardous materials, operations and equipment. This International Standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this Inte
25、rnational Standard to establish safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This International Standard specifies the reference method for the determination of the fat content of most milk-based edible ices and ice mixes. The method is
26、also applicable to concentrated and dried ice mixes. The method is not applicable to some milk-based edible ices and ice mixes, in which the level of emulsifier, stabilizer or thickening agent or of egg yolk or of fruits, or of combinations of these constituents makes the Rse-Gottlieb method unsuita
27、ble. NOTE With such products, a method utilizing the Weibull-Berntrop principle (see ISO 8262-2IDF 124-23) is suitable. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated
28、references, the latest edition of the referenced document (including any amendments) applies. ISO 835, Laboratory glassware Graduated pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3889IDF 219, Milk and milk products Specification of Mojonnier-type fat extraction flasks ISO 4
29、788, Laboratory glassware Graduated measuring cylinders 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 fat content of milk-based edible ices and ice mixes mass fraction of substances determined by the procedure specified in this Internationa
30、l Standard NOTE The fat content is expressed as a percentage mass fraction. 4EN ISO 7328:2008 (E) DIN EN ISO 7328:2009-03 4 Principle An ammoniacal ethanolic solution of a test portion is extracted with diethyl ether and light petroleum. The solvents are removed by distillation or evaporation. The m
31、ass of the substances extracted is determined. NOTE This is usually known as the Rse-Gottlieb principle. 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified, and only distilled or demineralized water or water of equivalent purity. The reagents shall leave no appre
32、ciable residue when the determination is carried out by the method specified (see 9.2.2). 5.1 Ammonia solution, containing a mass fraction of NH3of approximately 25 % (20= 910 g/l). NOTE If ammonia solution of this concentration is not available, a more concentrated solution of known concentration m
33、ay be used (see 9.4.2). 5.2 Ethanol (C2H5OH), or ethanol denatured by methanol, containing a volume fraction of ethanol of at least 94 %. (See Clause A.5.) 5.3 Congo red solution Dissolve 1 g of Congo red (C32H22N6Na2O6S2) in water in a 100 ml one-mark volumetric flask (6.16). Make up to the mark wi
34、th water. NOTE The use of this solution, which allows the interface between the solvent and aqueous layers to be seen more clearly, is optional (see 9.4.4). Other aqueous indicator solutions can be used provided that they do not affect the result of the determination. 5.4 Diethyl ether (C2H5OC2H5),
35、free from peroxides (see Clause A.3), containing no more than 2 mg/kg of antioxidants, and complying with the requirements for the blank test (see 9.2.2, Clauses A.1 and A.4). WARNING The use of diethyl ether can lead to hazardous situations. Observe current safety precautions for handling, use, and
36、 disposal. 5.5 Light petroleum, with any boiling range between 30 C and 60 C or, as equivalent, pentane (CH3CH23CH3) with a boiling point of 36 C and complying with the requirements for the blank test (see 9.2.2, Clauses A.1 and A.4). The use of pentane is recommended because of its higher purity an
37、d consistent quality. 5.6 Mixed solvent Shortly before use, mix equal volumes of diethyl ether (5.4) and light petroleum (5.5). 6 Apparatus WARNING Since the determination involves the use of volatile flammable solvents, all electrical apparatus employed shall comply with legislation relating to the
38、 hazards in using such solvents. Usual laboratory equipment and, in particular, the following. 6.1 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg. 5EN ISO 7328:2008 (E) DIN EN ISO 7328:2009-03 6.2 Centrifuge, capable of holding the fat-extraction flasks or
39、tubes (6.6) and capable of spinning at a rotational frequency of 500 min1to 600 min1to produce a radial acceleration of 80g to 90g at the outer end of the flasks or tubes. The use of the centrifuge is optional but recommended (see 9.4.7). 6.3 Distillation or evaporation apparatus, for distilling the
40、 solvents and ethanol from the boiling or conical flasks, or evaporating from beakers and dishes (see 9.4.14) at a temperature not exceeding 100 C. 6.4 Drying oven, electrically heated, with ventilation port(s) fully open, capable of being maintained at a temperature of 102 C 2 C throughout its work
41、ing space. The oven shall be fitted with a suitable thermometer. 6.5 Water bath, capable of being maintained at a temperature of 65 C 2 C. 6.6 Mojonnier-type fat-extraction flasks, as specified in ISO 3889IDF 219. NOTE It is also possible to use fat-extraction tubes, with siphon or wash-bottle fitti
42、ngs, but then the procedure is different. The alternative procedure is given in Annex B. The fat-extraction flasks shall be provided with good quality cork bungs or stoppers of other material (e.g. silicone rubber or polytetrafluoroethylene) unaffected by the reagents used. Cork bungs shall be extra
43、cted with the diethyl ether (5.4), kept in water at a temperature of 60 C or more for at least 15 min, and shall then be allowed to cool in the water so that they are saturated when used. 6.7 Rack, for holding the fat-extraction flasks (or tubes) (6.6). 6.8 Wash bottle, suitable for use with the mix
44、ed solvent (5.6). A plastics wash bottle shall not be used. 6.9 Fat-collecting vessels, such as boiling flasks (flat-bottomed), of capacities 125 ml to 250 ml, conical flasks, of capacity 250 ml, or metal dishes. If metal dishes are used, they shall be of stainless steel, flat-bottomed with a diamet
45、er of 80 mm to 100 mm and a height of approximately 50 mm. 6.10 Boiling aids, fat-free, of non-porous porcelain or silicon carbide (optional when metal dishes are used). 6.11 Measuring cylinders, of capacities 5 ml and 25 ml, complying with the requirements of ISO 4788, class A, or any other apparat
46、us suitable for the product concerned. 6.12 Pipettes, graduated, of capacity 10 ml, complying with the requirements of ISO 835, class A. 6.13 Tongs, made of metal, for holding flasks, beakers or dishes. 6.14 Pipette, with a wide tip, capable of delivering a liquid test portion. NOTE The use of this
47、pipette is optional (see 9.1). 6.15 High-speed blender, with a blender jar of capacity 1 l fitted with lid, or other suitable apparatus for the preparation of the test sample. 6.16 Volumetric flask, one-mark, of capacity 100 ml, complying with the requirements of ISO 1042, class A. 6EN ISO 7328:2008
48、 (E) DIN EN ISO 7328:2009-03 7 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO
49、707IDF 501. Store laboratory samples, except dried ice mixes, at a temperature of not more than 18 C from the time of sampling to the time of commencing the procedure. 8 Preparation of test sample 8.1 Edible ices, ice mixes and concentrated ice mixes 8.1.1 Do not allow the temperature to exceed 12 C at any time during the preparation of the (ice) pieces. Remove any coating of non-ice character from the test sample. 8.1.2 If possible, separate the layers of multilayer products, in which the layers possibl
