BS EN 1142-1995 Method for determination of sulfate content of fruit and vegetable juices《果汁和蔬菜汁中硫酸盐含量的测定》.pdf

1、BRITISH STANDARD BS EN 1142:1995 Method for Determination of sulfate content of fruit and vegetable juices The European Standard EN1142:1994 has the status of a BritishStandard UDC 663.81/.82:620.1:546.226BSEN1142:1995 This BritishStandard, having been prepared under the directionof the Consumer Pro

2、ducts and Services SectorBoard, was published undertheauthority of the StandardsBoard and comes into effect on 15 January1995 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference AW/21 Draft for comment90/51497DC ISBN 0 580 23174 7 Cooperating organization

3、s The European Committee for Standardization (CEN), under whose supervision this European Standard was prepared, comprises the national standards organizations of the following countries: Austria Oesterreichisches Normungsinstitut Belgium Institut belge de normalisation Denmark Dansk Standard Finlan

4、d Suomen Standardisoimisliito, r.y. France Association franaise de normalisation Germany Deutsches Institut fr Normung e.V. Greece Hellenic Organization for Standardization Iceland Technological Institute of Iceland Ireland National Standards Authority of Ireland Italy Ente Nazionale Italiano di Uni

5、ficazione Luxembourg Inspection du Travail et des Mines Netherlands Nederlands Normalisatie-instituut Norway Norges Standardiseringsforbund Portugal Instituto Portugus da Qualidade Spain Asociacin Espaola de Normalizacin y Certificacin Sweden Standardiseringskommissionen i Sverige Switzerland Associ

6、ation suisse de normalisation UnitedKingdom BritishStandards Institution Amendments issued since publication Amd. No. Date CommentsBSEN1142:1995 BSI 01-2000 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Normative references 3 3 Symbols 3 4 P

7、rinciple 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Calculation 4 9 Precision 4 10 Test report 4 Annex A (informative) Bibliography 5 Annex B (informative) Statistical results of the inter-laboratory test 5 National annex NA (informative) Committees responsible Inside back cover National annex NB

8、(informative) Cross-references Inside back cover Table B.1 5BSEN1142:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared under the direction of the Consumer Products and Services Sector Board and is the English language version of EN1142:1994, Fruit and vegetable juices Dete

9、rmination of sulfate content, published by the European Committee for Standardization (CEN). EN1142 was produced as a result of international discussions in which the UnitedKingdom took an active part. A British Standard does not purport to include all the necessary provisions of a contract. Users o

10、f British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to6, an inside back c

11、over and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN1142 October1994 UDC 663.81/.82:620.1:546.226 Descriptors:

12、Food products, beverages, fruit and vegetable juices, chemical analysis, determination of content, sulfates, incineration analysis English version Fruit and vegetable juices Determination of the sulfate content Jus de fruits et de lgumes Dosage des sulfates Frucht- und GemsesfteBestimmung des Sulfat

13、gehaltes This European Standard was approved by CEN on1994-09-29. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical

14、references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN memb

15、er into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Swed

16、en, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1994 Copyright reserved to CEN members Ref No. EN1142:1994 EEN1142:1994 BSI 01-2000 2 Foreword This Eur

17、opean Standard has been prepared by the Technical Committee CEN/TC174, Fruit and vegetable juices Methods of analysis, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a National Standard, either by publication of an identical text or by endorsement, at

18、the latest by April1995, and conflicting national standards shall be withdrawn at the latest by April1995. Annexes designated “informative” are given only for information. In this standard Annex A and Annex B are informative. According to the CEN/CENELEC Internal Regulations, the following countries

19、 are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom.EN1142:1994 BSI 01-2000 3 1 Scope This European Standard specifies a method fo

20、r the determination of the sulfate content of fruit and vegetable juices and related products. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and

21、the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. ISO

22、5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. ISO3696:1987, Water for analytical laboratory use Specification and test methods. 3 Symbols For the purposes of this standard, the following symbols apply: 4

23、Principle The sulfate ions present in the test sample are precipitated by means of barium chloride. Co-precipitated barium phophate is eliminated by treatment of the precipitate with hydrochloric acid. The precipitate is weighed after ashing. 5 Reagents Use only reagents of recognized analytical gra

24、de and only water in accordance with at least grade3 of ISO3696. 5.1 Barium chloride solution, r (BaCl 2 .2H 2 O)=200g/l 5.2 Hydrochloric acid, c (HCl)=2mol/l 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1 Centrifuge, capable of producing a centrifugal force of3000 g a

25、t the base of the centrifuge tubes(6.2) (the value of g is fixed for the purpose of this European Standard at9,81). 6.2 Centrifuge tubes, 50ml. 6.3 Platinum dish, minimum volume30ml. 6.4 Analytical balance, accurate to0,1mg. 6.5 Water bath 6.6 Dessicator, with a drying agent. 7 Procedure 7.1 Prepara

26、tion of the test sample Normally products shall not be pretreated and their analysis by this method shall be on a volumetric basis. The analysis of concentrated products may also be carried out on a volumetric basis, after dilution to a known relative density. In this case, the density shall be indi

27、cated. Based on a weighed sample and taking the dilution factor for analysis into account, the results may also be expressed per kilogram of product. In products with high viscosity and/or very high content of cells (for example pulp), determination on the basis of a weighed test sample is the usual

28、 procedure. Clear juices are used without any particular preparation of the sample. Cloudy juices are centrifuged at3000 g and the determination is conducted on the clear supernatant liquid. 7.2 Determination Pipette40,0ml of clear or clarified sample(7.1) into a centrifuge tube, add2,0ml of hydroch

29、loric acid(5.1) and2ml of barium chloride solution (5.1) and mix thoroughly with a glass rod. Rinse the glass rod with water. Leave the centrifuge tube to stand for5min and then centrifuge for5min at3000g. Carefully decant the clear supernatant solution into a beaker. c Substance concentration; Mass

30、 concentration; g Acceleration due to gravity at the surface of the earth.EN1142:1994 4 BSI 01-2000 The barium sulfate precipitate is then washed as follows. The precipitate is treated first with10ml of hydrochloric acid(5.2) any co-precipitated barium phosphate being dissolved by stirring several t

31、imes. Centrifuge again for5min at3000 g and carefully decant the supernatant clear liquid. The precipitate is washed twice in the same manner with15ml water. Transfer the washed residue quantitively with water to a previously weighed platinum crucible (mass=m 1 ) and evaporate to dryness on the wate

32、r bath. Next heat the platinum crucible several times over an open flame, until the residue is white. Weigh the crucible (mass=m 2 ) after cooling to room temperature in a desiccator(6.6). 8 Calculation Calculate the sulfate content , expressed in milligrams per litre, using the equation: =(m 2 m 1

33、) 10,29 where: (m 2 m 1 ) is the mass of BaSO 4 , in milligrams, precipitated from40ml of sample. The factor10,29 results as follows: 10,29=25 0,4116 (Factor25 for calculation in1litre of sample; factor0,4116 for conversion of BaSO 4to sulfate content). Take into account the dilution factor and the

34、relation of the value to mass or volume. If a concentrated product has been diluted to single strength, report the relative density of the single strength sample. Report the sulfate content in milligrams per litre of test sample to the nearestmg. 9 Precision Details of the inter-laboratory test on t

35、he precision of the method are summarized in Annex B. The values derived from the interlaboratory test may not be applicable to analyte concentration ranges and matrices other than given in Annex B. 9.1 Repeatability The absolute difference between two single test results found on identical test mat

36、erial by one operator using the same apparatus within the shortest feasible time interval will exceed the repeatability value r in not more than5% of the cases. The value is: R=26mg/l. 9.2 Reproducibility The absolute difference between two single test results on identical test material reported by

37、two laboratories will exceed the reproducibility value R in not more than5% of the cases. The value is: R=26mg/l. 10 Test report The test report shall contain the following data: all information necessary for the identification of the sample (kind of sample, origin of sample, designation); a referen

38、ce to this European Standard; date and type of sampling procedure (ifpossible); date of receipt; date of test; test results and units in which they have been expressed; whether the repeatability of the method has been verified; any particular points observed in the course of the test; any operations

39、 not specified in the method or regarded as optional, which might have affected the results.EN1142:1994 BSI 01-2000 5 Annex A (informative) Bibliography 1 Determination of the sulfate content: No36,1987 In: Analyses Collection/International Federation of Fruit Juice Producers Loose-leaf edition, as

40、of1989. Zug: Swiss Fruit Union. Annex B (informative) Statistical results of the interlaboratory test In accordance with ISO5725:1986, the following parameters have been defined in an interlaboratory test. (For literature pertaining to the method see Annex A). The test was conducted by the Max von P

41、ettenkofer Institute of the Federal Health Office, Food Chemistry Department, Berlin, BRD: Table B.1 Sample types: A apple juice B grape juice, white Year of interlaboratory test 1986 number of laboratories 14 number of samples 2 Sample A B Number of laboratories retained after eliminating outliers

42、Number of outliers (Laboratories) Number of accepted results 12 2 60 10 3 55 Mean value ()(mg/l) 77 233 Repeatability standard deviation (s r )(mg/l) Repeatability relative standard deviation (RSD r )% 2,72 3,53 2,72 1,68 Repeatability limit (r)(mg/l) 7,6 7,6 Reproducibility standard deviation (s R

43、)(mg/l) Reproducibility relative standard deviation (RSD R ) % 9,63 12,5 8,56 3,67 Reproducibility limit (R)(mg/l) 27 24 NOTENO dependency between r, R and .xx6 blankBSEN1142:1995 BSI 01-2000 National annex NA (informative) Committees responsible The UnitedKingdom participation in the preparation of

44、 this European Standard was entrusted by the Consumer Products and Services Sector Board to Technical Committee AW/21, upon which the following bodies were represented: British Food Manufacturing Industries Research Association British Fruit Juice Importers Association British Retail Consortium Brit

45、ish Soft Drinks Association Limited Campden Food and Drink Research Association Department of Trade and Industry (Laboratory of the Government Chemist) Ministry of Agriculture, Fisheries and Food Royal Society of Chemistry National annex NB (informative) Cross-references Publication referred to Corr

46、esponding BritishStandard ISO3696:1987 BS3978:1987 Specification for water for laboratory use ISO5725:1986 BS5497 Precision of test methods Part1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory testsBS EN 1142:1995 BSI 389 Chiswick

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