BS-6248-9-1984 ISO-5739-1983.pdf

BRITISH STANDARD BS 6248-9: 1984 ISO 5739:1983 Caseins and caseinates Part 9: Method for the determination of scorched particles ISO title: Caseins and caseinates Determination of scorched particles content NOTEThis Part should be read in conjunction with Part 1 “General introduction, including preparation of laboratory samples”, published separately. UDC 637.147.2.064:543.868 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 This British Standard, having been prepared under the direction of the Dairying Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 February 1984 © BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference DAC/3 Draft for comment 78/50231 DC ISBN 0 580 13768 6 National foreword This Part of BS 6248, which has been prepared under the direction of the Dairying Standards Committee, is identical with ISO 5739:1983 “Caseins and caseinates Determination of scorched particles content”, prepared by ISO/TC 34, Agricultural food products, of the International Organization for Standardization (ISO) in cooperation with the International Dairy Federation (IDF) and the Association of Official Analytical Chemists (AOAC). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Where the words “International Standard” appear, referring to this standard they should be read as “this Part of this British Standard”. Cross-references. Related British Standards for ISO/R 707 and ISO 3310-1, referred to in the text, are respectively BS 809:1974 “Methods for sampling milk and milk products” and BS 410:1976 “Specification for test sieves”. With reference to 6.8, a wire cloth test sieve of aperture size 500 4m, complying with BS 410:1976 is suitable. With reference to clause 7, the methods for sampling given in BS 809:1974 may be employed. It is expected that the revision of ISO/R 707 will be published, when available, as a dual-numbered revision of BS 809. Additional information. With reference to clause 5, water complying with BS 3978:1966 “Water for laboratory use” is suitable. 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 comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, 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. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 © BSI 12-1999i Contents Page National forewordInside front cover 1Scope and field of application1 2References1 3Definition1 4Principle1 5Reagents1 6Apparatus1 7Sampling2 8Procedure2 9Expression of results4 10Test report4 Annex A Testing of filtering disks5 Annex B Preparation of scorched particle standard disks6 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 © BSI 12-19991 1 Scope and field of application This International Standard specifies a method for the determination of the scorched particles content of caseins and caseinates. 2 References ISO 707, Milk and milk products Methods of sampling1). ISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth. 3 Definition scorched particles content of caseins and caseinates the amount of coloured residue, per 25 g or 10 g of sample, which is insoluble in a sodium carbonate, sodium polyphosphate, disodium ethylenediaminetetraacetate or sodium hydroxide solution, as determined and classified by the procedure specified in this International Standard 4 Principle Dissolution of a test portion in hot sodium carbonate, sodium polyphosphate or disodium ethylenediaminetetraacetate solution, or in sodium hydroxide solution at room temperature or at 60 °C, filtration of the solution through a filtering disk and visual comparison of the dried disk with scorched particle standard disks. 5 Reagents The reagents shall be of recognized analytical quality. The water used in the preparation of the reagent solutions and in the determination shall be distilled water or water of at least equivalent purity, filtered before use. 5.1 Sodium carbonate solution (for acid caseins and for caseinates). Dissolve 100 g of anhydrous sodium carbonate (Na2CO3) in water, dilute to 1 000 ml and filter. 5.2 Sodium polyphosphate solution (for rennet caseins). Dissolve 20 g of a sodium polyphosphate tripolyphosphate (Na5P3O10) or a higher polyphosphate as used in the manufacture of processed cheese in water, dilute to 1 000 ml and filter. 5.3 Disodium ethylenediaminetetraacetate solution (for calcium caseinates). Dissolve 100 g of EDTA, disodium salt, dihydrate (C10H14N2Na2O8·2H2O) in water, dilute to 1 000 ml and filter. 5.4 Sodium hydroxide, approximately 1 mol/l solution (for caseins and caseinates which do not dissolve completely in the other reagents). Dissolve 40 g of sodium hydroxide in water, dilute to 1 000 ml and filter. 5.5 Ethanol, 95 ± 2 % (V/V) (for caseinates). 6 Apparatus Usual laboratory equipment, and 6.1 Balance, accurate to 0,1 g. 6.2 Conical flask, of capacity 600 ml. 6.3 Measuring cylinders, of capacities 100 and 500 ml. 6.4 Water bath, capable of being controlled at 60 ± 1 °C. 6.5 Filtering disks, of cotton lintine, diameter 32 mm (1.25 in), suitable for use in the filtering device (6.6). The cotton lintine shall be of approximately 135 g/m2 (4 oz/yd2) No. 1 filter cotton fibres. The disks shall be tested by the method specified in Annex A and shall meet the requirements specified therein. 6.6 Filtering device, aspirator or pressure type, with a filtering area of diameter 28,6 mm (1.125 in). 1) At present at the stage of draft. (Revision of ISO/R 707:1968.) Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 2 © BSI 12-1999 6.7 Grinding device, for grinding the laboratory sample if necessary (see 8.1.4), without development of undue heat and without loss or absorption of moisture. A hammer-mill shall not be used. 6.8 Test sieve, of metal wire cloth, diameter 200 mm and nominal aperture size 500 4m with receiver, complying with the requirements of ISO 3310-1. 6.9 Scorched particle standard disks, indicating increasing scorched particles contents by the classification letters A, B, C and D respectively. NOTE 1Prints of these standard disks are available from the United States Department of Agriculture, Agriculture Marketing Service, Dairy Division, Washington, D.C. 20250, USA. For illustrative purposes only, a black-and-white reproduction of these standard disks is given below. These illustrations shall not be used for official classification of scorched particle contents. NOTE 2Instructions for the preparation of these standard disks, if required, are given in Annex B. 7 Sampling See ISO 707. 8 Procedure 8.1 Preparation of the test sample 8.1.1 Thoroughly mix the laboratory sample by repeatedly shaking and inverting the container (if necessary, after having transferred all of the laboratory sample to an airtight container of sufficient capacity to allow this operation to be carried out). 8.1.2 Transfer about 50 g of the thoroughly mixed laboratory sample to the test sieve (6.8). 8.1.3 If the 50 g portion directly passes or almost completely passes the sieve, use for the determination the sample as prepared in 8.1.1. Otherwise, grind the 50 g portion, using the grinding device (6.7), until it passes the sieve. Immediately transfer all the sieved sample to an airtight container of sufficient capacity and mix thoroughly by repeatedly shaking and inverting. During these operations, take precautions to avoid any change in the water content of the product. 8.1.4 After the test sample has been prepared, proceed with the determination as soon as possible. 8.2 Test portion 8.2.1 Spray-dried caseinates or edible acid caseins Weigh 25,0 ± 0,1 g of the test sample (8.1) and transfer to the flask (6.2). 8.2.2 Roller-dried caseinates, rennet caseins or industrial acid caseins Weigh 10,0 ± 0,1 g of the test sample (8.1) and transfer to the flask (6.2). Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 © BSI 12-19993 8.3 Determination 8.3.1 Addition of reagent 8.3.1.1 Acid caseins Add to the 25 g test portion of edible casein or to the 10 g test portion of industrial acid casein, as the case may be, 300 ml or 150 ml, respectively, of filtered water. Allow to stand for at least 10 min, swirling at frequent intervals until all the casein is dispersed. Then add, respectively, 30 ml or 15 ml of the sodium carbonate solution (5.1), and swirl. Take care to wash down any of the casein adhering to the walls of the flask. 8.3.1.2 Rennet caseins Add to the test portion 100 ml of filtered water, shake and allow to stand for 3 h. Then add 200 ml of the sodium polyphosphate solution (5.2). Take care to wash down any of the casein adhering to the walls of the flask. 8.3.1.3 Caseinates Add to the 25 g test portion of spray-dried soluble caseinate or to the 10 g test portion of roller-dried soluble caseinate, as the case may be, 50 ml or 20 ml, respectively, of the ethanol (5.6) and shake until all the caseinate has been moistened. If necessary, add more ethanol. Then add 300 ml or 150 ml, respectively, of filtered water. Allow to stand for at least 10 min, swirling at frequent intervals until all the caseinate is dispersed. Then add 30 ml or 15 ml, respectively, of the sodium carbonate solution (5.1), and swirl. Take care to wash down any of the caseinate adhering to the walls of the flask. In the case of calcium caseinates or other insoluble caseinates, add, before the addition of the sodium carbonate solution, 30 ml or 15 ml of the disodium ethylenediaminetetraacetate solution (5.3). Allow to stand for at least 10 min, swirling at frequent intervals until all the caseinate is dispersed. Take care to wash down any of the caseinate adhering to the walls of the flask. Then add the 30 ml or 15 ml of the sodium carbonate solution (5.1). 8.3.2 Heating and filtration 8.3.2.1 Swirl the flask, cover, and heat in the water bath (6.4), controlled at 60 °C, swirling the flask at intervals, until all the test portion is dissolved; the time required shall not exceed 45 min. 8.3.2.2 Swirl the flask once more and then filter the contents through one of the filtering disks (6.5) mounted in the filtering device (6.6). Rinse the flask with two successive 100 ml portions of filtered water at 60 °C, and pass the rinsings through the filtering disk in such a way that the rinsings are allowed to run down the walls of the filtering device and the filtering disk is thoroughly washed. 8.3.2.3 Remove the filtering disk and allow it to dry, or dry it at 30 to 40 °C, protected from dust. 8.3.2.4 If difficulties are encountered in passing the solution through a disk, or if a significant quantity of gelatinous material appears on the disk, repeat the determination using the procedure specified in 8.3.3 and 8.3.4, using the sodium hydroxide solution (5.4) instead of the sodium carbonate solution (5.1) or the disodium ethylenediaminetetraacetate solution (5.3). 8.3.3 Alternative addition of reagent (when the casein or caseinate dissolves unsatisfactorily according to 8.3.1 and 8.3.2) 8.3.3.1 Acid caseins Proceed as specified in 8.3.1.1, but, instead of adding 30 ml or 15 ml of the sodium carbonate solution (5.1), add, respectively, 30 ml or 15 ml of the sodium hydroxide solution (5.4). 8.3.3.2 Rennet caseins Add to the 10 g test portion of rennet casein, 150 ml of filtered water, swirl and allow to stand for at least 10 min. Add 15 ml of filtered sodium hydroxide solution (5.4) and swirl. 8.3.3.3 Caseinates Proceed as specified in 8.3.1.3, but instead of adding 30 ml or 15 ml of the sodium carbonate solution (5.1), add, respectively, 30 ml or 15 ml of the sodium hydroxide solution (5.4). 8.3.4 Heating and filtration when sodium hydroxide solution is added (alternative to 8.3.2) 8.3.4.1 Cover the flask and allow to stand at room temperature, swirling at frequent intervals, until all the test portion appears to be dissolved. Proceed as specified in 8.3.2.2 and 8.3.2.3. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 13:15:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6248-9:1984 4 © BSI 12-1999 8.3.4.2 If the test portion in not completely dissolved, or if filtering is difficult, heat the covered flask in the water bath (6.4), controlled at 60 °C, for 20 min, swirling the flask at intervals, until all the test portion is dissolved. Proceed as specified in 8.3.4.1. 9 Expression of results 9.1 Evaluation Compare the test disk (8.3.2) with the scorched particles standard disks (6.9), viewing from directly above in uniform indirect light, and assign the appropriate classification letter to the test disk. A test disk falling between two standard disks shall be assigned the classification letter corresponding to the higher scorched particles content. Examine the disk for hair, wood, metal, dust or insect fragments. If there are indications of their presence, determine the extraneous matter content of the sample.2) 9.2 Repeatability If the test method is carried out in duplicate, the duplicate test disks shall indicate the same classification. Otherwise, repeat the determination in duplicate. 10 Test report The test report shall show the method used and the result obtained and shall record any extraneous matter observed. It shall also mention all operating conditions not specified in this International Standard, or regarded as optional, as well as any circumstances that may have influenced the result. The test report shall include all the details required for the complete identification of the sample. 2) A method for the determination of extraneous matter content will form the subject of a future International Standard. Licensed Copy: sheffieldun sheffi