1、BRITISH STANDARD BS EN ISO 5377:1994 Starch hydrolysis products Determination of reducing power and dextrose equivalent Lane and Eynon constant titre method The European Standard EN ISO5377:1994 has the status of a BritishStandard UDC 664.28:664.162.036:543.24BSENISO5377:1994 This BritishStandard, h
2、aving been prepared under the directionof the, was published under the authority of the Standards Board and comesintoeffect on 15December1994 BSI01-2000 The following BSI reference relates to the work on this standard: Draft announced in BSI News March1993 ISBN 0 580 23185 2 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 CommentsBSENISO5377:1994 BSI 01-2000 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 1 Scope and field of application 3 2 References
7、 3 3 Definitions 3 4 Principle 3 5 Reagents 3 6 Apparatus 4 7 Procedure 4 8 Expression of results 6 9 Test report 6 Annex Method for testing standard reference anhydrous D-glucose forcompliance with the requirements in5.2 c) 7 National annex NA (informative) Cross-references Inside back coverBSENISO
8、5377:1994 ii BSI 01-2000 National foreword This BritishStandard has been prepared under the direction of the BSI Standards Board and is the English language version of EN ISO5377:1994 Starch hydrolysis products Determination of reducing power and dextrose equivalent Lane and Eynon constant titre met
9、hod, published by the European Committee for Standardization (CEN). It is identical with ISO5377:1981 Starch hydrolysis products Determination of reducing power and dextrose equivalent Lane and Eynon constant titre method, published by the International Organization for Standardization (ISO). This B
10、ritishStandard has been produced to fulfil BSIs obligation to publish all approved European Standards but, because of the absence of interest in the UK in the subject concerned, there has been no UK participation in the preparation of EN ISO5377. Any queries relating to the EN should be directed to
11、BSI. A British Standard does not purport to include all the necessary provisions of a contract. 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 compr
12、ises a front cover, an inside front cover, pagesi andii, theENISOtitle page, pages2 to8, 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.EUROPE
13、AN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO5377 August1994 UDC 664.28:664.162.036:543.24 Descriptors: Starches, tests, determination, mass losses, dry matter, titration English version Starch hydrolysis products Determination of reducing power and dextrose equivalent Lane and Eynon constantti
14、tre method (ISO5377:1981) Produits dhydrolyse de lamidon ou de la fcule Dtermination du pouvoir rducteur et de lquivalent en dextrose Mthode Lane et Eynon titre constant (ISO5377:1981) Strkehydrolyseprodukte Bestimmung des Reduktionsvermgens und des Dextrosequivalents Verfahren mit konstantem Titer
15、nach Lane und Eynon (ISO5377:1981) This European Standard was approved by CEN on1994-08-22. 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
16、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 versions (English, French, German). A version in any other language made by translation under the re
17、sponsibility 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, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Nor
18、way, Portugal, Spain, Sweden, 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.ENISO5377:1994EENISO5377:1994 B
19、SI 01-2000 2 Foreword The text of the International Standard ISO5377:1981, prepared by ISO/TC93, Starch, was submitted to the formal vote and was approved by CEN as EN ISO5377:1994 on1994-08-22 without any modifications. This European Standard shall be given the status of a national standard, either
20、 by publication or by endorsement, at the latest by February1995, and conflicting national standards shall be withdrawn at the latest by February1995. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark,
21、Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, UnitedKingdom.ENISO5377:1994 BSI 01-2000 3 1 Scope and field of application This International Standard specifies a Lane and Eynon constant titre method for the determina
22、tion of the reducing power and dextrose equivalent of all starch hydrolysis products. 2 References ISO385-1, Laboratory glassware Burettes Part1: General requirements 1) . ISO385-2, Laboratory glassware Part2: Burettes for which no waiting time is specified 1) . ISO648, Laboratory glassware One-mark
23、 pipettes. ISO1042, Laboratory glassware One-mark volumetric flasks. ISO1741, Dextrose Determination of loss in mass on drying Vacuum oven method. ISO1742, Glucose syrup Determination of dry matter content Vacuum oven method. ISO1743, Glucose syrup and dextrose Determination of dry matter content Re
24、fractive index method. ISO1773, Laboratory glassware Boiling flasks (narrow-necked). ISO5809, Starch, including derivatives and by-products Determination of sulphated ash 2) . 3 Definitions 3.1 reducing power the content of reducing sugars, expressed as the number of grams of anhydrous D-glucose per
25、100g of the sample, when determined by the method specified in this International Standard 3.2 dextrose equivalent the content of reducing sugars, expressed as the number of grams of anhydrous D-glucose per100g of the dry matter in the sample, when determined by the method specified in this Internat
26、ional Standard 4 Principle Titration of a prescribed volume of mixed Fehlings solution with a solution of a test portion under specified conditions, using methylene blue as internal indicator. 5 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water o
27、r water of equivalent purity. 5.1 Fehlings stock solutions Prepare the following solutions, using apparatus in accordance with clause6. 5.1.1 Stock solutionA 5.1.2 Stock solution B Before use, decant the clear solution from any sediment that may form. 5.1.3 Mixed Fehlings solution Transfer into a dr
28、y stock glass bottle, in the following order,100ml of solution A(5.1.1) and100ml of solution B(5.1.2). Mix well. NOTEDo not keep Fehlings solution. Prepare this mixed solution just before use and standardize it as specified in7.1. 5.2 Anhydrous D-glucose, complying with the following requirements: a
29、) a solution containing400g/l shall be free from haze and sediment and shall show no more colour than the water used in its preparation when examined downwards in50ml Nessler tubes(6.5) filled to the marks; b) the sulphated ash content shall be not greater than0,01%(m/m) when determined by the metho
30、d specified in ISO5809 amended as follows: 1) the mass of the test portion shall be increased to20g, 2) only a platinum dish shall be used for incineration, 3) the platinum dish shall be weighed to the nearest0,1mg before and after the incineration; c) the maltose and/or isomaltose content shall not
31、 exceed0,1%(m/m) and no sugar of greater relative molecular mass shall be detected. 1) At present at the stage of draft. (Revision, in part, of ISO/R385.) 2) At present at the stage of draft. Copper(II) sulphate pentahydrate (CuSO 4 .5H 2 O) 69,3g Water to 1000,0ml Potassium sodium tartrate tetrahyd
32、rate (KNaC 4 H 4 O 6 .4H 2 O) 346,0g Sodium hydroxide (NaOH) 100,0g Water to 1000,0mlENISO5377:1994 4 BSI 01-2000 5.3 D-glucose, standard reference solution. 5.3.1 Determine the dry matter content of the anhydrous D-glucose by the method specified in ISO1741. 5.3.2 Weigh, to the nearest0,1mg, a mass
33、 of the anhydrous D-glucose(5.2) containing0,600g of solids, dissolve it in water, transfer the solution quantitively into a100ml one-mark volumetric flask(6.4), dilute to the mark with water and mix. Prepare this solution freshly on each day of use. 5.4 Methylene blue (C 16 H 18 ClN 3 S.2H 2 O), in
34、dicator,1g/l aqueous solution. 6 Apparatus Ordinary laboratory apparatus and in particular 6.1 Narrow-necked boiling flask, of capacity250ml, complying with the requirements of ISO1773. 6.2 Burette, of capacity25ml, graduated in subdivisions of0,05ml, complying with the requirements of ISO385-2, cla
35、ss A. 6.3 One-mark pipettes, of capacity1ml and25ml, complying with the requirements of ISO648, classA. 6.4 One-mark volumetric flasks, of capacity100ml,500ml and1000ml, complying with the requirements of ISO1042, class A. 6.5 Nessler tubes, of capacity50ml. 6.6 Heating device, suitable for maintain
36、ing boiling as required in7.1.4 whilst enabling the colour change at the end-point of the titration to be observed without the flask having to be removed from the heating device. 6.7 Stop-watch 7 Procedure NOTE 1A boiling aid (for example glass beads) may be added, if desired, to ensure freedom from
37、 super-heating. NOTE 2Shield the burette from the source of heat(6.6) at all times. 7.1 Standardization of the mixed Fehlings solution(5.1.3) 7.1.1 Using a pipette(6.3), place25,0ml of the Fehlings solution(5.1.3) in the clean, dry boiling flask(6.1). 7.1.2 Fill the burette(6.2) to the zero mark wit
38、h the D-glucose standard reference solution(5.3). 7.1.3 Run into the boiling flask from the burette,18,0ml of the D-glucose solution(5.3). Swirl the flask to mix the contents. 7.1.4 Place the boiling flask on the heating device(6.6), previously adjusted so that the boiling commences in120 15s as tim
39、ed by the stop-watch(6.7). Do not adjust the heating device subsequently. This ensures that once boiling has commenced the evolution of steam is brisk and continuous throughout the whole of the titration process, thus preventing to the maximum possible extent the entrance of air to the titration fla
40、sk with consequent re-oxidation of its contents. 7.1.5 Bring the contents of the flask to the boil and continue boiling for120s (timed by the stop-watch). Add1ml of the methylene blue solution(5.4) towards the end of this period. After expiry of the120s period, commence adding the D-glucose solution
41、 to the flask from the burette in0,5ml increments until the colour of the methylene blue is discharged, boiling being continued during the whole titration. Note the total volume of the D-glucose solution(V ml), added up to and including the penultimate0,5ml increment. NOTEThe disappearance of the co
42、lour of the methylene blue is best seen by looking at the upper layers and the meniscus of the contents of the titration flask, as these will be relatively free from the precipitated, red copper(I) oxide. The colour disappearance is more easily seen when indirect lighting is used. A white screen beh
43、ind the titration flask is helpful. 7.1.6 Repeat7.1.1 and7.1.2. 7.1.7 From the burette run into the boiling flask a volume of the D-glucose solution equal to(V 0,3)ml. 7.1.8 Repeat7.1.4. 7.1.9 Bring the contents of the flask to the boil and continue boiling for120s (timed by the stop-watch). Add1ml
44、of the methylene blue solution towards the end of this period. After expiry of the120s period, commence adding the D-glucose solution to the flask from the burette, initially in0,2ml increments and finally drop by drop, until the colour of the methylene blue(5.4) is just discharged, boiling being co
45、ntinued during the whole titration. Towards the end of this action, add the successive increments of the D-glucose solution at intervals of10 to15s. Complete these additions within60s to give a total time of boiling not longer than180s. A third titration with a slightly larger, appropriately adjuste
46、d, initial addition of the D-glucose solution may be necessary to achieve this. 7.1.10 Note the volume of the D-glucose solution used up to the end-point of the final titration. 7.1.11 It is essential that the titre is between19,0 and21,0ml of the D-glucose solution. If it is outside these limits, a
47、djust the concentration of the Fehlings solution A(5.1.1) appropriately and repeat the standardization process. 7.1.12 Repeat7.1.6 to7.1.10 and calculate the mean of the two titres(V 1 ml).ENISO5377:1994 BSI 01-2000 5 7.1.13 For the day-to-day standardization of the mixed Fehlings solution, asV 1is
48、known with accuracy, a single titration only is necessary, using an initial addition of(V 1 0,5)ml of the D-glucose solution. NOTEAs there is a personal factor involved, it is essential that each operator carries out his own standardization titration and uses his own value ofV 1in the calculation(8.
49、1.1). 7.2 Determination 7.2.1 Preparation of test sample If the sample is in powder or crystalline form, remove it from its container, break down any lumps, mix in an appropriate manner and place in a suitable airtight container. If the sample is in massive, solid form, e.g.starch sugar (solid glucose), melt it in a closed container immersed in a hot water bath at60 to70 C, allow to cool to ambient temperature and shake a number of times without removing the closure, in order to mix any condensed moisture on the in
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