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1、BRITISH STANDARD BS EN ISO 10520:1998 Native starch Determination of starch content Ewers polarimetric method The European Standard EN ISO 10520:1998 has the status of a British Standard ICS 67.180.20 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy,
2、(c) BSI BS EN ISO 10520:1998 This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Committee, was published under the authority of the Standards Committeee and comes into effect on 15 November 1998 BSI 04-1999 ISBN 0 580 30395 0 National forewor
3、d This British Standard is the English language version of EN ISO 10520:1998. It is identical with ISO 10520:1997. This British Standard 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,
4、there has been no UK participation in the preparation of EN 10520. Any queries relating to the EN should be directed to BSI quoting the reference AW/100. Cross-references Attention is drawn to the fact that CEN and CENELEC standards normally include an annex which lists normative references to inter
5、national publications with their corresponding European publications. The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by
6、 using the “Find” facility of the BSI Standards Electronic Catalogue. 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 immu
7、nity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO title page, page 2, the ISO title page, pages ii to iv, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and
8、may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 10520:1998 BSI
9、04-1999i Contents Page National forewordInside front cover Foreword2 Forewordiii Text of ISO 105201 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Unco
10、ntrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 10520 September 1998 ICS 67.180 Descriptors: See ISO document English version Native starch Determination of starch content Ewers polarimetric method (ISO 10520:1997) Amidons et fcules natifs Dosage de lamidon Mthode pol
11、arimtrique de Ewers (ISO 10520:1997) Native Strke Bestimmung des Strkegehaltes Polarimetrisches Verfahren nach Ewers (ISO 10520:1997) This European Standard was approved by CEN on 10 August 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions
12、 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 Central Secretariat or to any CEN member. This European Standard exists in three offic
13、ial 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 the official versions. CEN members are the national standards bodies of Austria, B
14、elgium, Czech Republic, Denmark, 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 Secre
15、tariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 10520:1998 E Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 105
16、20:1998 BSI 04-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC 93 “Starch (including derivatives and by-products” of the International Organization for Standardization (ISO) has been taken over as an European Standard by CEN/CS. This European Standard shall be
17、given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 1999, and conflicting national standards shall be withdrawn at the latest by March 1999. According to the CEN/CENELEC Internal Regulations, the national standards organizatio
18、ns of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text
19、 of the International Standard ISO 10520:1997 has been approved by CEN as a European Standard without any modification. NOTENormative references to International Standards are listed in Annex ZA (normative). Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled
20、 Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 10520:1998 ii BSI 04-1999 Contents Page Forewordiii 1Scope1 2Normative references1 3Principle1 4Reagents1 5Apparatus1 6Preparation of test sample1 7Procedure1 8Expression
21、of results2 9Precision2 10Test report3 Annex A (informative) Ewers method Collaborative study 19904 Annex B (informative) Bibliography6 Annex ZA (normative) Normative references to international publications with their relevant European publicationsInside back cover Table 12 Table 23 Table A.15 Lice
22、nsed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 10520:1998 BSI 04-1999iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing
23、International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaiso
24、n with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication
25、as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 10520 was prepared by Technical Committee ISO/TC 93, Starch (including derivatives and by-products). Annex A and Annex B of this International Standard are for information
26、only. Descriptors: Food starch, chemical analysis, determination of content, starches, polarimetric method. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 20
27、06, Uncontrolled Copy, (c) BSI EN ISO 10520:1998 BSI 04-19991 1 Scope This International Standard specifies a polarimetric method for the determination of the starch content of native starch, with the exception of starch with high amylose content. It is not applicable to modified or pregelatinized (
28、water-soluble) starch. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to a
29、greements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 1666:1996, Starch Determination of moisture co
30、ntent Oven-drying method. ISO 3696:1987, Water for analytical laboratory use Specification and test methods. 3 Principle The method includes two intermediate determination steps. 3.1 A portion of the sample is hydrolysed with dilute hydrochloric acid and the optical rotation measured polarimetricall
31、y after clarification and filtration. 3.2 A second portion of the sample is treated with 40 % (V/V) ethanol to extract soluble sugars and polysaccharides of lower molecular mass. The filtrate is then subjected to the procedure given in 3.1. The difference between the measurements 3.1 and 3.2, multip
32、lied by a factor, gives the starch content of the sample. NOTEKey parameters of the method are the time and temperature of the hydrolysis, and the correct use and calibration of the polarimeter. Consequently, the method includes constant agitation in the water bath, which should be of a size appropr
33、iate to ensure rapid temperature rise and steady temperature conditions. 4 Reagents Use only reagents of recognized analytical grade, unless otherwise specified, and water complying with grade 2 in accordance with ISO 3696. 4.1 Dilute hydrochloric acid, c(HCl) = 7,7 mol/l Dilute 63,7 ml of hydrochlo
34、ric acid (20 = 1,19 g/ml) with water up to 100 ml. 4.2 Dilute hydrochloric acid, c(HCl) = 0,309 mol/l Dilute 25,6 ml of hydrochloric acid (20 = 1,19 g/ml) with water up to 1 000 ml. NOTEThe concentration should be verified using sodium hydroxide solution c(NaOH) = 0,1 mol/l and Methyl red as indicat
35、or: 10 ml HCl should consume 30,94 ml of 0,1 mol/l NaOH. 4.3 Dilute ethanol, 40 % (V/V) (20 = 0,948 g/ml) 4.4 Carrez solution I Dissolve 10,6 g of potassium hexacyanoferrate(II) trihydrate K4Fe(CN)6.3H2O in water. Dilute to 100 ml with water. 4.5 Carrez solution II Dissolve 21,9 g of zinc acetate di
36、hydrate Zn(CH3COO)2.2H2O and 3 g of glacial acetic acid in water. Dilute to 100 ml with water. 5 Apparatus Usual laboratory apparatus and, in particular, the following. 5.1 Volumetric flasks, of capacity 100 ml. 5.2 Shaking boiling water bath, or boiling water bath equipped with a magnetic stirrer.
37、5.3 Polarimeter, adjusted to a wavelength of 589,3 nm, with 200 mm tubes. 5.4 Analytical balance, capable of weighing to the nearest 0,001 g. 6 Preparation of test sample If the particle size of the laboratory sample exceeds 0,5 mm, grind the sample to pass a sieve with 0,5 mm apertures. Homogenize
38、the sample thus prepared. 7 Procedure Carry out weighings to the nearest 0,001 g (see 5.4). 7.1 Determination of optical rotation of a total portion 7.1.1 Weigh 2,5 g 0,05 g (m1) of the test sample and transfer it to a volumetric flask (5.1). Add 25 ml of the dilute hydrochloric acid (4.2) and agita
39、te to distribute the test sample evenly. Add a further 25 ml of the dilute hydrochloric acid (4.2). 7.1.2 Immerse the flask in the boiling water bath (5.2) and shake continuously or immerse the flask in the boiling water bath equipped with a magnetic stirrer and stir at minimum speed. 7.1.3 Leave th
40、e flask for 15 min 5 s in the boiling water bath and stop shaking or stirring shortly before removing it. Immediately add 30 ml of cold water and cool rapidly under flowing water to 20 C 2 C Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 14:01:54 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN
41、 ISO 10520:1998 2 BSI 04-1999 7.1.4 Add 5 ml of the Carrez solution I (4.4) and shake for 1 min. 7.1.5 Add 5 ml of the Carrez solution II (4.5) and shake for 1 min. 7.1.6 Dilute to the mark with water. Homogenize and filter the solution through a suitable filter funnel and paper. If the filtrate is
42、not perfectly clear, repeat the operations with 10 ml of each of the Carrez solutions. 7.1.7 Measure the optical rotation (1) of the solution in a 200 mm tube with the polarimeter (5.3). 7.2 Determination of optical rotation of substances soluble in 40 % (V/V) ethanol 7.2.1 Weigh 5 g 0,1 g (m2) of t
43、he sample and transfer to a 100 ml volumetric flask (5.1). Add about 80 ml of the ethanol solution (4.3). Leave the flask to stand for 1 h at room temperature; shake vigorously six times during the hour to ensure thorough mixing of the test sample with the ethanol. Dilute to 100 ml with ethanol (4.3
44、), homogenize and filter. 7.2.2 Pipette 50 ml of the filtrate (equivalent to 2,5 g of the test portion) into a volumetric flask (5.1). Add 2,1 ml of the dilute hydrochloric acid (4.1) and shake vigorously. Fit a reflux condenser to the flask and immerse the flask in a boiling water bath. Remove the
45、flask from the boiling water bath after 15 min 5 s. Cool to 20 C 2 C. 7.2.3 Clarify the solution using Carrez I and II solutions as in 7.1.4, 7.1.5 and then continue as in 7.1.6. 7.2.4 Measure the optical rotation (2) of the solution as in 7.1.7. 7.3 Determination of dry matter content Determine the
46、 moisture content of the test sample, w0, in accordance with the method given in ISO 1666. Then calculate the dry matter content, w1, of the test sample using the following equation: w1 = 100 w0 8 Expression of results Calculate the starch content of the dry matter content of the test sample, w, as
47、a percentage by mass, using the following equation: where Table 1 Round the result to one decimal place. 9 Precision The precision of the method was established by an interlaboratory test organized by ISO/TC 93/WG 1, Determination of starch content, in 1990 and carried out in accordance with ISO 572
48、51. In this test, 12 laboratories participated. Samples investigated included maize starch, potato starch and wheat starch. The statistical results are summarized in Annex A. 9.1 Repeatability The absolute difference between two independent single test results, obtained using the same method on iden
49、tical test material in the same laboratory by the same operator using the same equipment within a short interval of time, should not be greater than the repeatability limit shown in Table 2 for the type of starches listed. 1 is the numerical value of the total optical rotation measured in 7.1, in degrees; 2is the numerical value of the optical rotation of the ethanol-soluble substances measured in 7.2, in degrees; m1is the numerical value of the mass of the test portion in 7.1.1, in grams; m2is the numerica