BS ISO 762-2003 Fruit and vegetable products - Determination of mineral impurities content《水果和蔬菜制品 矿物杂质含量的测定》.pdf

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1、BRITISH STANDARD BS ISO 762:2003 Fruit and vegetable products Determination of mineral impurities content ICS 67.080.01 BS ISO 762:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 25 November 2003 BSI 25 November 2003 ISBN 0 580 42972 5 N

2、ational foreword This British Standard reproduces verbatim ISO 762:2003 and implements it as the UK national standard. There has been no UK participation in its preparation of this document. Any enquires on the text should be sent to Head of Standards International Content. Cross-references The Brit

3、ish Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This pu

4、blication does not purport to include all the necessary provisions of a contract. Users are responsible for its 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 c

5、over, the ISO title page, pages ii and iii, a blank page, pages 1 to 5 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 762:2003(E)INTERNATIONAL STANDARD

6、ISO 762 Second edition 2003-11-15 Fruit and vegetable products Determination of mineral impurities content Produits drivs des fruits et lgumes Dtermination de la teneur en impurets minrales dorigine terreuse BSISO762:2003DPlcsid Fremia ihTs PDF file mya ctnoian emdebt dedyfepcaes. In ccacnadrow eitA

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9、 cera neeb sah takne tsne oeru taht teh file is siutlbae fosu re yb ISO memdob rebeis. In tlnu ehikletneve y ttah lborp aem lertait gno it is f,dnuo plsaee ifnrom ttneC ehlar Secterirata ta teh serddaig sleb nevwo. ii BSISO762:2003 iiiForeword ISO (the International Organization for Standardization)

10、 is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing 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 repre

11、sented on that committee. International organizations, governmental and non-governmental, in liaison 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

12、 drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical 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 Internationa

13、l Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn 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 762 was prepar

14、ed by Technical Committee ISO/TC 34, Food products, Subcommittee SC 3, Fruit and vegetable products. This second edition cancels and replaces the first edition (ISO 762:1982), which has been technically revised. BSISO762:2003BSISO762:2003 1Fruit and vegetable products Determination of mineral impuri

15、ties content 1 Scope This international Standard specifies a method for the determination of the mineral impurities content (impurities generally originating from the soil) of fruit and vegetable products. 2 Principle Organic matter is separated by flotation and heavy impurities are separated by sed

16、imentation. The sediment is incinerated at approximately 525 C, and the residue obtained is weighed. 3 Apparatus Usual laboratory equipment and, in particular, the following. 3.1 Blender. 3.2 Beakers, of capacities 1 000 ml. 3.3 Filter paper, Whatman No. 41 1)or equivalent. 3.4 Incineration dishes,

17、made of quartz, porcelain or platinum. 3.5 Muffle furnace, capable of being maintained at 525 C 25 C. 3.6 Desiccator, provided with an efficient desiccant. 3.7 Analytical balance, capable of weighing to the nearest 0,000 2 g. 3.8 Heater, gas or electric. 3.9 Sieve, of pore size ca. 1 mm to 2 mm. 3.1

18、0 Stirring rod. 3.11 Washing equipment, for washing out the impurities (see Figure 1). 1) Whatman No. 41 is an example of a suitable product available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of

19、this product. BSISO762:20032 4 Preparation of test sample 4.1 General case Before taking the test portion, thoroughly mix the entire laboratory sample using, if necessary, the blender (3.1). Allow frozen or deep frozen products to thaw in a closed vessel and add the liquid formed during this process

20、 to the product before mixing. 4.2 Dried products Mix the laboratory sample well. Weigh 20 g 0,1 g of the product, transfer it to a beaker (3.2) and add 400 ml of filtered tap water. Bring to the boil, then leave overnight at room temperature to allow the product to rehydrate. 5 Procedure 5.1 Test p

21、ortion 5.1.1 General case Rapidly weigh 100 g 1 g of the test sample (4.1) into a beaker (3.2). If the mass of this sample is less than 100 g, weigh all of it. 5.1.2 Dried products Use all of the product taken in 4.2 as the test portion. 5.2 Determination 5.2.1 Separation of sediments Add filtered t

22、ap water to the beaker containing the test portion (4.1 or 4.2) until the beaker is almost completely full. Mix by agitating, if necessary using a stirring rod (3.10). Allow the suspension to stand for 5 min, then put the beaker under the water tube as shown in Figure 1. The important part of the wa

23、shing equipment (3.11) is the water tank equipped with a leak tube for equalizing the pressure. In the tank, the water level shall be constant and 13 cm high; the overflow leaves the tank through the leak tube. One or more glass tubes, with 0,4 cm internal diameter, are connected to the bottom of th

24、e tank by rubber tubes. Their end parts are extruded. The distance between the bottom of the tank and the top end of the glass tube shall be 55 cm, the extruded part shall be 1 cm long and its internal diameter shall be 0,2 cm. The opening and closing of the stream is controlled by a clamp. Keeping

25、these conditions, the flow rate through one glass tube shall be 200 ml/min. Put a glass tube filled loosely with cotton- or glass-wool between the tap and the tank to retain floating impurities. Immerse the glass tube in the beaker containing the suspension in such position that the tip of it is 6 c

26、m from the bottom of the beaker. Open the stream and continue the washing for 35 min to 40 min. During this time the fine fragments of plant fibre are washed out, while the sand, other mineral impurities and the larger fragments of seeds and skins settle, and the water becomes colourless and transpa

27、rent in the beaker. BSISO762:2003 3Dimensions in centimetres Key 1 water tank 2 leak tube 3 glass tube 4 end part of glass tube 5 clamp 6 cotton- or glass-wool 7 beaker containing the suspension 8 water Figure 1 Washing equipment BSISO762:20034 5.2.2 Determination If, after the washing-out procedure

28、 (5.2.1), there are no visible fragments of plant but only the sand on the bottom of the beaker, remove the glass tube from the beaker. Wait for 3 min then decant carefully most of the water, avoiding any agitation of the settled fragments. Quantitatively filter the residue through a filter paper (3

29、.3). If, after the washing-out procedure (5.2.1), there remains a lot of plant fibres and larger fragments of seeds and plant skins on the bottom of the beaker, decant most of the water. Transfer the residue to a sieve (3.9) which is placed on a porcelain dish having an appropriate size. Wash the sa

30、nd into the dish with water. Pour the water in 100 ml portions to separate the sand from the fragments of skin, seed and fibre. About 1 000 ml water are needed for this purpose. 5.2.3 Preparation of the dish Heat the empty incineration dish (3.4) in the muffle furnace (3.5) set at 525 C. Allow it to

31、 cool in the desiccator (3.6) and weigh to the nearest 0,000 2 g. Repeat until a constant mass is achieved. 5.2.4 Incineration Transfer the filter paper and residue to the prepared incineration dish (5.2.3). Heat the incineration dish for a few minutes using the heater (3.8), then transfer it to the

32、 muffle furnace (3.5) set at 525 C. Incinerate it for 1 h. Cool in the desiccator (3.6) and weigh to the nearest 0,000 2 g. Repeat until a constant mass is achieved. 5.2.5 Number of determinations Carry out at least two determinations of the same sample. 6 Expression of results 6.1 Calculation The m

33、ineral impurities content, expressed as a percentage by mass, is given by the formula () 21 0 100 % mm m where m 0is the mass, in grams, of the test portion (5.1); m 1is the mass, in grams, of the empty dish (5.2.3); m 2is the mass, in grams, of the dish and incinerated residue (5.2.4). Take as the

34、result the arithmetic mean of the values obtained in two determinations, provided that the requirement for repeatability (6.2) is satisfied. Report the result to two decimal places. BSISO762:2003 56.2 Repeatability The absolute difference between two independent single test results, obtained using t

35、he 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 more than 5 % of cases be greater than 3 % of the mean value. 7 Test report The test report shall specify: a) all information necessary for the

36、complete identification of the sample; b) the sampling method used, if known; c) the 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

37、influenced the test result(s); e) the test result(s) obtained or, if the repeatability has been checked, the final quoted result obtained. BSISO762:2003BS ISO 762:2003 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for prep

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