BS EN 12143-1997 Fruit and vegetable juices - Estimation of soluble solids content - Refractometric method《水果汁和疏菜汁 可溶干料含量测定 折射法》.pdf

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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12143 : 1997 The Eu

2、ropean Standard EN 12143 : 1996 has the status of a British Standard ICS 67.160.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Fruit and vegetable juices Estimation of soluble solids content Refractometric methodBS EN 12143 : 1997 This British Standard, having been prepare

3、d under the direction of the Consumer Products and Services Sector Board, was published under the authority of the Standards Board and comes into effect on 15 May 1997 BSI 1997 The following BSI references relate to the work on this standard: Committee reference AW/21 Draft for comment 89/54814 DC I

4、SBN 0 580 26870 5 Amendments issued since publication Amd. No. Date Text affected Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee AW/21, Fruit and vegetable juices, upon which the following bodies were represented: Britis

5、h Fruit Juice Importers Association British Retail Consortium British Soft Drinks Association Limited Campden and Chorleywood Food Research Association Laboratory of the Government Chemist Leatherhead Food Research Association Ministry of Agriculture, Fisheries and Food Royal Society of ChemistryBS

6、EN 12143 : 1997 BSI 1997 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 12143 3ii BSI 1997 BS EN 12143 : 1997 National foreword This British Standard has been prepared by Technical Committee AW/21, and is the English language version of EN 12143

7、: 1996, Fruit and vegetable juices Estimation of soluble solids content Refractometric method, published by the European Committee for Standardization (CEN). EN 12143 was produced as a result of international discussions in which the United Kingdom took an active part. Cross-references Publication r

8、eferred to Corresponding British Standard EN ISO 3696 : 1987 BS EN ISO 3696 : 1995 Specification for water for laboratory use EN 12147 : 1996 BS EN 12147 : 1996 Method for determination of titratable acidity of fruit and vegetable juices ISO 5725 : 1986, to which informative reference is made in the

9、 text, has been superseded by ISO 5725-1 : 1994, ISO 5725-2 : 1994, ISO 5725-3 : 1994, ISO 5724-4 : 1994 and ISO 5725-6 : 1994 which are identical with BS ISO 5725 Accuracy (trueness and precision) of measurement methods and results, BS ISO 5725-1 : 1994 General principles and definitions, BS ISO 57

10、25-2 : 1994 Basic methods for the determination of repeatability and reproducibility of a standard measurement method, BS ISO 5725-3 : 1994 Intermediate measures of the precision of a standard measurement method, BS ISO 5725-4 : 1994 Basic methods for the determination of the trueness of a standard

11、measurement method, and BS ISO 5725-6 : 1994 Use in practice of accuracy values. 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, pages i and ii, the EN title page, pages 2 to

12、8, an inside back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. EN 12143 : 1996 E EUROPEAN STANDARD EN 121

13、43 NORME EUROPE ENNE EUROPA ISCHE NORM September 1996 ICS 67.160.20 Descriptors: Food products, beverages, fruit and vegetable juices, chemical analysis, determination of content, soluble matter, refractometric analysis English version Fruit and vegetable juices Estimation of soluble solids content

14、Refractometric method Jus de fruits et de le gumes Estimation des solides solubles Me thode re fractome trique Frucht- und Gemu sesa fte Bestimmung des Gehaltes an lo slicher Trockensubstanz Refraktometrisches Verfahren This European Standard was approved by CEN on 1996-05-09. CEN members are bound

15、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 standards may be obtained on application to the Cent

16、ral 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 member into its own language and notified to the Central Secretariat has the same status as

17、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, Sweden, Switzerland and United Kingdom.Page 2 EN 12143 : 1996 BSI 1997 Foreword This Europea

18、n Standard has been prepared by Technical Committee CEN/TC 174, Fruit and vegetable juices Methods of analysis, of which the Secretariat 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 the lat

19、est by March 1997, and conflicting national standards shall be withdrawn at the latest by March 1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland,

20、France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Principle 3 5 Reagents 3 6 Apparatus 3 7 Procedure 3 8 Calculation 4 9 Precision 4

21、 10 Test report 4 Annexes A (normative) Acid and temperature correction for citrus juices and citrus juice concentrates 5 B (informative) Bibliography 7 C (informative) Statistical results of the interlaboratory test 7Page 3 EN 12143 : 1996 BSI 1997 1 Scope This European Standard specifies a refract

22、ometric method for the estimation of the soluble solids in fruit and vegetable juices and related products. 2 Normative references This European Standard incorporates by dated or undated references, provisions from other publications. These normative references are cited at the appropriate places in

23、 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 incorporated in it by amendment or revision. For undated references the latest edition of the publication referred t

24、o applies. EN ISO 3696 : 1995 Water for analytical laboratory use Specification and test methods ISO 5725 : 1986 Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests EN 12147 : 1996 Fruit and vegetable juices Determination

25、of titratable acidity 3 Definitions For the purposes of this standard, the following definitions apply: 3.1 refractometric dry extract or Brix Soluble solids measured by refractometry and expressed as a mass fraction, i.e. in grams of sucrose per 100 g of solution. 3.2 Brix corrected As Brix (3.1),

26、after applying the acid correction (see clause 8 and annex A). 4 Principle The soluble solids content is estimated by refractometry. This is the percentage by mass of sucrose in an aqueous solution of sucrose which, under given conditions, has the same refractive index as the product analysed. The p

27、roducts soluble solids content is expressed in grams per 100 gram. The refractive index of the product is affected by the presence of other soluble materials, e.g. organic acids, minerals, amino acids etc. Due to the high acid content of citrus juices and citrus juice concentrates a correction to th

28、e Brix value is made in such cases. 5 Reagents 5.1 General Use only reagents of recognized analytical grade and only degassed water in accordance with at least grade 3 of EN ISO 3696 : 1995. 5.2 Standard solutions Prepared following the manufacturers instructions, for calibration of the refractomete

29、r. 6 Apparatus Usual laboratory apparatus and, in particular, the following: 6.1 Refractometer, with scale divisions to at least 0,1 % sucrose and with a temperature measurement facility of 0,5 C. 7 Procedure 7.1 General The refractometer shall be calibrated before each set of measurements, followin

30、g the manufacturers instructions. The soluble solids value of the sample is normally measured at 20 C 0,5 C. If the refractometer possesses a temperature compensation facility, the measurement may be made at a temperature other than 20 C but in any case between 10 C and 30 C and according to the ins

31、trument manufacturers instructions. If the refractometer does not possess a temperature compensation facility, the measurement may be made at a temperature other than 20 C, but between 15 C and 25 C. The values have to be corrected according to table A.2. Before each measurement or calibration step,

32、 rinse the glass surface of the refractometer with water and remove adhering water with a filter paper. 7.2 Preparation of the test sample Mix the sample well prior to measuring. Analyse the concentrates without dilution. 7.3 Test procedure Place a small portion of the sample on the lower prism of t

33、he refractometer (6.1). Ensure that the sample covers the glass surface evenly, when the prisms are clamped together. Wait for the sample to reach thermal equilibrium (approximately 30 s) and then take the measurement according to the apparatus instructions. It is important to keep the temperature c

34、onstant during the measurement. Read directly the percentage sucrose content to the nearest 0,1 %. At least two determinations should be made on the same sample.Page 4 EN 12143 : 1996 BSI 1997 8 Calculation The content of soluble solids is usually expressed in grams of sucrose per 100 grams of mater

35、ial. The result given is the percentage of sugar according to the refractometric method. The value is read directly. In citrus juices a so-called acid correction shall be made by making the following addition to the refractometer reading: 0,012 + 0,1933 m2 0,00043 m 2 where: m is the total acid expr

36、essed in grams per 100 gram, at pH = 8,1, expressed as anhydrous citric acid (EN 12147 : 1996). The calculated values for this expression are given in annex A. 9 Precision Details of the interlaboratory test on the precision of the method are summarized in annex C. The values derived from the interl

37、aboratory test may not be applicable to analyte concentration ranges and matrices other than given in annex C. 9.1 Repeatability The absolute difference between two single test results found on identical test material by one operator using the same apparatus within the shortest feasible time interva

38、l will exceed the repeatability limit r in not more than 5 % of the cases. The values are : juices: r = 0,15 Brix; concentrates: r = 0,2 Brix. 9.2 Reproducibility The absolute difference between two single test results on identical test material reported by two laboratories will exceed the reproduci

39、bility limit R in not more than 5 % of the cases. The values are: juices: R = 0,42 Brix; concentrates: R = 0,6 Brix. 10 Test report The test report shall contain the following data: all information necessary for the determination of the sample (kind of sample, origin of sample, designation); a refer

40、ence to this European Standard; the date and type of sampling procedure (if known); the date of receipt; the date of test; the 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

41、; any operations not specified in the method or regarded as optional, which might have affected the results.Page 5 EN 12143 : 1996 BSI 1997 Annex A (normative) Acid and temperature correction for citrus juices and citrus juice concentrates A.1 Acid correction (for citrus juices and citrus juice conc

42、entrates) The correction values given should be added to the refractometer values obtained at 20 C (expressed in gram per 100 gram or Brix) as given in table A.1. Table A.1. Total acid (pH 8,1) expressed as anhydrous citric acid (g acid/100 g juice) Correction value 0,2 0,04 0,4 0,08 0,6 0,12 0,8 0,

43、16 1,0 0,20 1,2 0,24 1,4 0,28 1,6 0,32 1,8 0,36 2,0 0,39 2,2 0,43 2,4 0,47 2,6 0,51 2,8 0,55 3,0 0,58 3,2 0,62 3,4 0,66 3,6 0,70 3,8 0,74 4,0 0,78 4,2 0,81 4,4 0,85 4,6 0,89 4,8 0,93 5,0 0,97 5,2 1,01 5,4 1,04 5,6 1,07 5,8 1,11 6,0 1,15 6,2 1,19 6,4 1,23 6,6 1,27 6,8 1,30 7,0 1,34Page 6 EN 12143 : 1

44、996 BSI 1997 A.2 Temperature compensation for refractometric solids (see table A.2) Table A.2. Temperature C Sucrose content in g/100 g of material 51 01 52 03 04 05 06 07 07 5 minus 15 0,25 0,27 0,31 0,31 0,34 0,35 0,36 0,37 0,36 0,36 16 0,21 0,23 0,27 0,27 0,29 0,31 0,31 0,32 0,31 0,23 17 0,16 0,1

45、8 0,20 0,20 0,22 0,23 0,23 0,23 0,20 0,17 18 0,11 0,12 0,14 0,15 0,16 0,16 0,15 0,12 0,12 0,09 19 0,06 0,07 0,08 0,08 0,08 0,09 0,09 0,08 0,07 0,05 plus 21 0,06 0,07 0,07 0,07 0,07 0,07 0,07 0,07 0,07 0,07 22 0,12 0,14 0,14 0,14 0,14 0,14 0,14 0,14 0,14 0,14 23 0,18 0,20 0,20 0,21 0,21 0,21 0,21 0,2

46、2 0,22 0,22 24 0,24 0,26 0,26 0,27 0,28 0,28 0,28 0,28 0,29 0,29 25 0,30 0,32 0,32 0,34 0,36 0,36 0,36 0,36 0,36 0,37Page 7 EN 12143 : 1996 BSI 1997 Table C.1. Sample A B Number of laboratories retained after eliminating outliers 20 20 Number of outliers (laboratories) Number of accepted results 72

47、72 Mean value ( ) (Brix) x 2 14,0 5,5 Repeatability standard deviation (s r ) (Brix) 0,0518 0,0574 Repeatability relative standard deviation (RSD r ) (%) 0,037 1,04 Repeatability limit (r) (Brix) 0,14 0,16 Reproducibility standard deviation (s R ) (Brix) 0,1592 0,1406 Reproducibility relative standa

48、rd deviation (RSD R ) (%) 1,14 2,56 Reproducibility limit (R) (Brix) 0,45 0,39 Annex B (informative) Bibliography 1 Determination of soluble solids (indirect method by refractometry), No. 8, 1996. In: The collected analyses of the International Federation of Fruit Juice Producers. Loose-leaf edition

49、 of 1996. Zug: Swiss Fruit Union. 2 BOLAND, F. E. Report on fruits and fruit products, General referee reports, 66, No. 2, 371372, 1983. In: Journal of the Association of Official Analytical Chemists. 3 Solids of Syrups: 932.14/C, Vol. 2, 10111012, 1990. In: Official Methods of Analysis. Published by the Association of Official Analytical Chemists (AOAC). Annex C (informative) Statistical results of the interlaboratory test In accordance with ISO 5725 : 1986