1、 Reference number ISO 23392:2006(E) ISO 2006INTERNATIONAL STANDARD ISO 23392 First edition 2006-09-01 Fresh and quick-frozen maize and peas Determination of alcohol-insoluble solids content Mas et petits pois frais et congels Dtermination de la teneur en rsidus insolubles dans lalcool ISO 23392:2006
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6、 country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2006 All rights reservedISO 23392:2006(E) ISO 2006 All rights reserved iii Contents Page Foreword iv
7、1 Scope1 2 Terms and definitions .1 3 Principle1 4 Reagents.1 5 Apparatus.1 6 Procedure.2 6.1 Sample preparation.2 6.1.1 Preparation of fresh or quick-frozen peas 2 6.1.2 Preparation of fresh or quick-frozen maize 2 6.2 Determination.3 6.3 Number of determinations 3 7 Calculation and expression of r
8、esults.3 7.1 Calculation3 7.2 Expression of results 3 8 Repeatability.3 9 Test report4 ISO 23392:2006(E) iv ISO 2006 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing
9、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
10、n with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of tec
11、hnical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is dra
12、wn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 23392 was prepared by Technical Committee ISO/TC 34, Food Products, Subcommittee SC 14, Fresh, dry and dried frui
13、ts and vegetables. INTERNATIONAL STANDARD ISO 23392:2006(E) ISO 2006 All rights reserved 1 Fresh and quick-frozen maize and peas Determination of alcohol-insoluble solids content 1 Scope This International Standard specifies a method for the determination of the alcohol-insoluble solids content of f
14、resh or quick-frozen peas and maize, as well as whole kernel maize. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 alcohol-insoluble solids content whole of the compounds determined by the method specified in this International Standard and
15、expressed as a percentage by mass 3 Principle A properly prepared test portion is boiled with ethanol, followed by filtration and washing the solids with ethanol until the filtrate is clear. The alcohol-insoluble solids are dried and weighed. The result is used as a guide to maturity index. 4 Reagen
16、ts Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or demineralized water or water of equivalent purity. 4.1 Ethanol, a volume fraction of 95 % denatured with a volume fraction of 5 % methanol. 4.2 Diluted ethanol, a volume fraction of 80 %. Dilute 8 volum
17、es of ethanol (4.1) with 1,5 volumes of water. 5 Apparatus Usual laboratory apparatus and, in particular, the following. 5.1 Analytical balance, capable of weighing to the nearest 0,001 g. 5.2 Flask, of capacity 250 ml, with a standard taper ground-glass joint, fitted with a reflux condenser. 5.3 Bu
18、chner funnel. 5.4 Drying dish, flat-bottomed, with a close-fitting lid. 5.5 Boiling water bath. ISO 23392:2006(E) 2 ISO 2006 All rights reserved5.6 Thawing water-bath, with continuous flow at room temperature maintained at room temperature. 5.7 Plastic bag or vessel with screw-cap, of sufficient cap
19、acity to contain the entire test sample 5.8 Clamps or weights. 5.9 Sieve, of woven metal wire cloth, with square openings of 2,8 mm 2,8 mm. 5.10 Desiccator, containing freshly activated dry silica gel, or an equivalent desiccant, with a water content indicator. 5.11 Oven, well-aerated thermostatical
20、ly controlled at 100 C 2 C. 5.12 Filter paper. 5.13 High-speed blender or chopper. 5.14 Vacuum pump or water aspirator. 6 Procedure 6.1 Sample preparation 6.1.1 Preparation of fresh or quick-frozen peas Allow deep-frozen peas to thaw before homogenization. Place the deep-frozen sample in the plastic
21、 bag (5.7) and tie it. Immerse the bag in the water bath (5.6). Avoid agitation of the bag during thawing, if necessary by using clamps or weights (5.8). When completely thawed, remove the bag from the water bath and blot off any adhering water. Transfer the peas from the bag to the sieve. (5.9). If
22、 liquid is present, wash by gently spraying with water at room temperature until the liquid is removed. Without disturbing the peas, incline the sieve to facilitate drainage and allow draining for 2 min. Wipe the bottom of the sieve. Mix the thawed or fresh laboratory sample to obtain a representati
23、ve test sample. Blend approximately 250 g of the test sample in the blender (5.13) with an equivalent mass of water until a smooth paste is obtained. Weigh, to the nearest 10 mg, approximately 20 g of the paste and transfer to the flask (5.2). Add 120 ml of the ethanol (4.1) into the flask and stir.
24、 6.1.2 Preparation of fresh or quick-frozen maize Allow the deep-frozen maize to thaw in a closed vessel (5.7) in the water-bath (5.6), and add the liquid formed during this process to the product before homogenization. Remove whole grains from the cob using a suitable instrument taking care not to
25、damage individual grains. Spread the grains on a white background and remove the silk, husk cob and other extraneous vegetable material. By successive combing and quartering operations, reduce the sample to a representative subsample of mass approximately 100 g. Blend the subsample to a smooth paste
26、 in the high-speed blender or chopper (5.13). If necessary, add cold water in the ratio of 25 g of water to 100 g of sample. Weigh, to the nearest 10 mg, approximately 10 g of the subsample and transfer to the flask (5.2). If water was added, take a test portion of 12,5 g. Add 300 ml of the ethanol
27、(4.1) into the flask and stir. ISO 23392:2006(E) ISO 2006 All rights reserved 3 6.2 Determination Boil the content of the flask obtained by 6.1.1 or 6.1.2 under reflux on the boiling water-bath (5.5) for 30 min. Place the filter paper (5.12) in the dish (5.4), and dry in the oven (5.11), at 100 C 2
28、C, for 2 h, with the lid removed but alongside the dish. Cover the dish, allow it to cool in the desiccator (5.10) to ambient temperature for approximately 30 min and weigh to the nearest 1 mg. Fit the prepared filter paper into the Buchner funnel (5.3), with the edge of the paper at least 13 mm up
29、the vertical sides of the funnel. Apply suction and transfer the contents of the flask to the Buchner funnel. Do not allow any of the material to run over the edge of the paper. Suck dry and wash the material on the filter paper with diluted ethanol (4.2) until the washings are clear and colourless.
30、 Transfer the filter paper containing the residue into the dish and place it in the cold oven avoiding, in this way, the formation of a crust with the lid removed but alongside the dish. Heat to 100 C 2 C and maintain at this temperature for at least 2 h. Remove the dish, cover it, and allow it to c
31、ool in the desiccator for approximately 40 min. Weigh to the nearest 1 mg. Continue the operations of heating, cooling and weighing until the difference between two successive weighings does not exceed 1 mg. 6.3 Number of determinations Carry out two determinations on the same sample. 7 Calculation
32、and expression of results 7.1 Calculation The alcohol-insoluble solids content, w, expressed as a percentage by mass, is equal to 21 0 100 mm w m = where 0 m is the mass, in grams, of the paste obtained by 6.1.1 or 6.1.2 and transferred to the flask (5.2); 1 m is the mass, in grams, of the dish, lid
33、 and filter paper; 2 m is the mass, in grams, of the dish, lid, filter paper and alcohol-insoluble solids. If water was added (see 6.1), multiply the result by 1,25. Take as the result the arithmetic mean of the values obtained in the two determinations (6.3). 7.2 Expression of results Express the a
34、nalysis result to the first decimal place. 8 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not
35、more than 5 % of cases be greater than 5 % of the arithmetic mean of the two results. ISO 23392:2006(E) 4 ISO 2006 All rights reserved9 Test report The test report shall specify: a) all information necessary for the complete identification of the sample; b) the sampling method used, if known; c) the
36、 test method used, with reference to this International Standard; d) all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test result(s); e) the test result(s) obtained, or, if the repeatability has been checked, the final quoted result obtained. ISO 23392:2006(E) ICS 67.080.20 Price based on 4 pages ISO 2006 All rights reserved
