1、BRITISH STANDARD BS EN1132: 1995 Method for Determination of the pH-value of fruit and vegetable juices The European Standard EN1132:1994 has the status of a BritishStandard UDC663.81/.82:620.1:66-915BSEN 1132:1995 This BritishStandard, having been prepared under the directionof the Consumer Product
2、s and Services Sector Board (W/-), was published underthe authority of the Standards Board and comesintoeffect on 15 January1995 BSI01-2000 The following BSI references relate to the work on this standard: Committee reference AW/21 Draft for comment89/54813DC ISBN 0 580 23148 8 Cooperating organizat
3、ions 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 Fin
4、land 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
5、Unificazione 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 Ass
6、ociation suisse de normalisation United Kingdom BritishStandards Institution Amendments issued since publication Amd. No. Date CommentsBSEN 1132:1995 BSI 01-2000 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN1132 3 National annex NA (informati
7、ve) Committees responsible Inside back cover National annex NB (informative) Cross-references Inside back coverBSEN 1132:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Technical Committee AW/21, Fruit juices, and is the English language version of EN1132 Fruit and ve
8、getable juices Determination of the pH-value published by the European Committee for Standardization (CEN). EN1132 was produced as a result of international discussions in which the United Kingdom took an active part. A British Standard does not purport to include all the necessary provisions of a c
9、ontract. Users of 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, the EN title page, pages2 to6,
10、 an inside back cover 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 EN1132 October1994 UDC663.81/.82:620.1:66-91
11、5 Descriptors: Food products, beverages, fruit and vegetable juices, chemical analysis, measurements, pH English version Fruit and vegetable juices Determination of the pH-value Jus de fruits et de lgumes Mesure du pH Frucht- und Gemuesfte Bestimmung des pH-Wertess This European Standard was approve
12、d 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 references concerning such national standar
13、ds may be obtained on application to the Central Secretariat or to any CEN member. Up-to-date lists and bibliographical 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 versio
14、ns (English, French, German). A version in any other language made by translation under the responsibility of a CEN member 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, De
15、nmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36
16、, B-1050 Brussels 1994 Copyright reserved to CEN members Ref. No. EN1132:1994EEN 1132:1994 BSI 01-2000 2 Foreword This European 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 St
17、andard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at 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 thi
18、s standard Annex A and Annex B are informative. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, S
19、pain, Sweden, Switzerland, United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definition 3 4 Principle 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Expression of results 4 9 Precision 4 10 Test report 4 Annex A (informative) Bibliography 5 Annex B (informative) Statistical
20、 results of the interlaboratory test 5 Table B.1 5EN1132:1994 BSI 01-2000 3 1 Scope This European Standard specifies a method for the determination of the pH-value of fruit and vegetable juices and related products. 2 Normative references This European Standard incorporates by dated or undated refer
21、ence, provisions from other publications. These normative references are cited at the appropriate places in the text and 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 incorpora
22、ted in it by amendment or revision. For undated references the latest edition of the publication referred to applies. ISO5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. ISO3696:1987, Water for analytical la
23、boratory use Specification and test methods. 3 Definition For the purposes of this standard, the following definition applies: pH value the negative common logarithm of the concentration of hydrogen ions in moles per litre of solution 4 Principle The pH value of the sample is measured potentiometric
24、ally. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and only degassed water in accordance with at least grade3 of ISO3696:1987. 5.2 Buffer solution with a pH of 6.88 at 20 C Dry anhydrous potassium dihydrogen phosphate, KH 2 PO 4 , and anhydrous disodium hydrogen phosphate,
25、 Na 2 HPO 4 , at120 C 10 C to constant mass. After cooling in a desiccator(6.5), weigh3,40g KH 2 PO 4and3,55g Na 2 HPO 4and dissolve in approximately800ml water, then make up to1000ml at a temperature of20 C. This solution is stable for about1month. 5.3 Buffer solution with a pH of 3.57 at 20 C Diss
26、olve30g potassium hydrogen tartrate, KHC 4 H 4 O 6 , in about1l water. Shake the container vigorously to give a saturated solution. Remove the undissolved residue by filtration. This solution contains at least5,7g KHC 4 H 4 O 6 . It is preferable to prepare this solution on the day of use, since it
27、deteriorates. The solution may be preserved by the addition of0,05g thymol per100ml of solution. It is then stable for about2 months at20 C. 5.4 Commercially available buffer solutions (alternative to5.2 and5.3) Commercially available buffer solutions with pH values similar to(5.2) and(5.3) may also
28、 be used. Observe the buffer solution manufacturers instructions for their preparation, storage and date of expiry. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1 pH meter accurate to at least0,05pH units. 6.2 pH glass electrode 6.3 Reference electrode e.g.calomel elec
29、trode. 6.4 Combination pH glass electrode (alternative to6.2 and6.3. 6.5 Dessicator with drying agent. 7 Procedure 7.1 General The pH meter and electrodes shall be calibrated and serviced according to the instrument manufacturers instructions. The pH-value of the sample is normally measured at20 C 2
30、 C. If the pH meter possesses a temperature compensation facility, the measurement may be made at a temperature other than20 C but in any case between10 C and30 C and according to the instrument manufacturers instruction. Before each measurement or calibration step, rinse the electrode(s) well with
31、water and remove adhering water with a filter paper. Calibration and measurement should be carried out while gently stirring the solution or test sample. 7.2 Preparation of the test sample If the sample contains appreciable quantities of carbon dioxide, degas it by shaking in a stoppered conical fla
32、sk (remove the stopper from time to time), or by using vacuum or ultrasound treatment, until no more gas evolves. 7.3 Calibration Perform two-point calibration of the pH meter with buffer solutions(5.2 and5.3), following the instrument manufacturers instructions. The calibration may alternatively be
33、 carried out using commercially available buffer solutions (see5.4).EN1132:1994 4 BSI 01-2000 7.4 Measurement Measure the pH-value of the test sample, according to the instrument manufacturers instructions. 8 Expression of results Report the pH-value to two decimal places. 9 Precision Details of the
34、 inter-laboratory test on the precision of the method are summarized in Annex B. The values derived from the inter-laboratory test may not be applicable to analyze concentration ranges and matrices other than given in Annex B. 9.1 Repeatability The absolute difference between two single results foun
35、d on identical test material 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=0,03. 9.2 Reproducibility The absolute difference between two single test results on identical test
36、material reported by two laboratories will exceed the reproducibility value R in not more than5% of the cases. The value is: R=0,12. 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, desi
37、gnation); a reference to this European Standard; date and type of sampling procedure (if possible); date of receipt; date of test; test results and units in which they have been expressed; whether the repeatability has been verified; any particular points observed in the course of the test; any oper
38、ations not specified in the method or regarded as optional, which might have affected the resultsEN1132:1994 BSI 01-2000 5 Annex A (informative) Bibliography 1 Determination of the pH-value: No11,1989 In: AnalysesCollection/International Federation of Fruit Juice Producers Loose-leaf edition, as of1
39、989 Zug: Swiss Fruit Union. 2 Untersuchung von Lebensmitteln: Messung des pH-Wertes in Fruchtsften: L31.00-2, 1980-05 Food Analysis: Measurement of the pH-value in fruit juices: L3.00-2,1980-05 In: Amtliche Sammlung von Untersuchungsverfahren nach 35LMBG: Verfahren zur Probenahme und Untersuchung vo
40、n Lebensmitteln, Tabakerzeugnissen, kosmetischen Mitteln und Bedarfsgegenstnden/Bundesgesundheitsamt In: Collection of official methods under article35 of the German Federal Foods Act: Methods of sampling and analysis of foods, tobacco products, cosmetics and commodity goods. Federal Health Office L
41、oseblattausgabe. Stand31.12.1991, Bd.1. Loose-leaf edition, as of1991-12-31, Vol.1. Berlin, Kln: Beuth Verfag GmbH. 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 liter
42、ature pertaining to the method seeAnnex A). The test was conducted by the Max von Pettenkofer Institute of the Federal Health Office, Food Chemistry Department, Berlin, BRD: Table B.1 Sample types Ablackcurrant nectar Bapple juice Cgrape juice, white Dorange juice Year of interlaboratory test 1977 N
43、umber of laboratories 11 Number of samples 4 Sample A B C D Number of laboratories retained after eliminating outliers Number of outliers (Laboratories) Number of accepted results 9 2 46 10 1 51 10 1 53 10 1 52 Mean value () 2,98 3,34 3,43 3,82 Repeatability standard deviation (s r ) Repeatability r
44、elative standard deviation (RSD r ) % 0,0119 0.38 0,0082 0,25 0,0076 0,22 0,0085 0,22 Repeatability limit (r) 0,033 0,023 0,021 0,024 Reproducibility standard deviation (S R ) Reproducibility relative standard deviation (RSD R ) % 0,0447 1,50 0,0336 1,01 0,0476 1,39 0,0402 1,05 Reproducibility limit
45、 (R) 0,125 0,094 0,133 0,133 x6 blankBSEN 1132:1995 BSI 01-2000 National annex NA (informative) Committees responsible The United Kingdom participation in the preparation of this European Standard was entrusted to Technical Committee AW/21, Fruit juices, upon which the following bodies were represen
46、ted: British Food Manufacturing Industries Research Association British Fruit juice Importers Association British Retail Consortium British Soft Drinks Association Limited Campden Food and Drink Research Association Department of Trade and Industry (Laboratory of the Government Chemist) Ministry of
47、Agriculture, Fisheries and Food Royal Society of Chemistry National annex NB (informative) Cross-references International Standard Corresponding BritishStandard ISO3696:1987 BS3978:1987 Specification for water for laboratory use ISO5725:1986 BS5497 Precision of test methods Part1:1987 Guide for the
48、determination of repeatability and reproducibility for a standard test method by inter-laboratory testsBS EN1132: 1995 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on s
49、tandards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretary of the technical committee resp
