BS 4325-6-1989 Methods for analysis of oilseed residues Determination of urease activity of soya bean products《油料种子残余物分析方法 大豆产品脲酶活性测定》.pdf
《BS 4325-6-1989 Methods for analysis of oilseed residues Determination of urease activity of soya bean products《油料种子残余物分析方法 大豆产品脲酶活性测定》.pdf》由会员分享,可在线阅读,更多相关《BS 4325-6-1989 Methods for analysis of oilseed residues Determination of urease activity of soya bean products《油料种子残余物分析方法 大豆产品脲酶活性测定》.pdf(8页珍藏版)》请在麦多课文档分享上搜索。
1、BRITISH STANDARD BS 4325-6: 1989 ISO 5506: 1988 Methods for Analysis of oilseed residues Part 6: Determination of urease activity of soya bean products ISO title: Soya bean products Determination of urease activity UDC 633.85 157.63.002.6:543.8 + 635.853.52 157.63.002.6:577.15:543.866:543.25BS 4325-
2、6:1989 This British Standard, having been prepared under the directionof the Food and Agriculture Standards Policy Committee, was published underthe authority of the Board ofBSI and comes into effect on 29September 1989 BSI10-1999 First published March1980 First revision September1989 The following
3、BSI references relate to the work on this standard: Committee reference FAC/17 Draft (ref. 88/53838) announced inBSI News September 1988 ISBN 0 580 17380 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Food and Agriculture Standards Po
4、licy Committee (FAC/-) to Technical Committee FAC/17, upon which the following bodies were represented: British Food Manufacturing Industries Research Association Department of Trade and Industry (Laboratory of the Government Chemist) FOSFA International Grain and Feed Trade Association Internationa
5、l Association of Seed Crushers Intervention Board for Agricultural Produce Ministry of Agriculture, Fisheries and Food National Farmers Union National Institute of Agricultural Botany Overseas Development Natural Resources Institute Royal Society of Chemistry Seed Crushers and Oil Processors Associa
6、tion Tropical Growers Association Amendments issued since publication Amd. No. Date of issue CommentsBS 4325-6:1989 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definition 1 4 Principle 1 5 Reagents 1 6
7、 Apparatus 1 7 Sampling 1 8 Preparation of the test sample 2 9 Procedure 2 10 Expression of results 2 11 Test report 2 Publications referred to Inside back coverBS 4325-6:1989 ii BSI 10-1999 National foreword This Part of BS 4325 has been prepared under the direction of the Food and Agriculture Stan
8、dards Policy Committee. It is identical with ISO 5506:1988 “Soya bean products Determination of urease activity”, published by the International Organization for Standardization (ISO), and in the preparation of which the United Kingdom played a full part. It is a revision of BS 4325-6:1980, which is
9、 withdrawn, and from which it differs principally in that the presentation has been changed to produce a clearer and more logical text, and that it is now recommended that samples having a fat content of higher than 10% (m/m) be defatted by cold extraction. Terminology and conventions. The text of t
10、he 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 marke
11、r. In British Standards it is current practice to use a full point on the baseline as the decimal marker. The symbol “l” has been used to denote litre (and in its submultiples). In British Standards it is current practice to use the symbol “L”. Wherever the words “International Standard” appear, ref
12、erring to this standard, they should be read as “Part of BS 4325”. Additional information. With reference to clause5, water complying with grade 3 of BS 3978 “Specification for water for laboratory use” is suitable. In relation to 6.1, requirements for suitable test sieves are given in BS 410 “Speci
13、fication for test sieves”. Textual errors. When adopting the text of the International Standard, the textual errors given below were discovered. They have been marked in the text and have been reported to ISO in a proposal to amend the text of the International Standard. In clause 2 and clause 7 ISO
14、 5505 should be read as ISO5500. 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. Cross-re
15、ferences International Standard Corresponding British Standard BS 4325 Methods for analysis of oilseed residues ISO 771:1977 Part 1:1978 Determination of moisture and volatile matter content (Technically equivalent) ISO 5502:1983 Part 9:1984 Preparation of test samples (Identical) ISO 5500:1986 BS 6
16、606:1987 Methods for sampling oilseed residues (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. T
17、his will be indicated in the amendment table on the inside front cover.BS 4325-6:1989 BSI 10-1999 1 Introduction The method specified in this International Standard is based on the property of soya bean products of being able to liberate ammoniacal nitrogen from a urea solution when they have not be
18、en sufficiently cooked. 1 Scope This International Standard specifies a method of determining the urease activity of products derived from soya beans. The method allows inadequate cooking of these products to be detected. It applies to products having a urease activity of less than 1mg of nitrogen p
19、er gram of product as received, under the conditions specified. For more active products, the method applies provided that the mass of the test portion is reduced (see note 1 to9.1). 2 Normative references The following standards contain provisions which, through reference in this text, constitute p
20、rovisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the sta
21、ndards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 771:1977, Oilseed residues Determination of moisture and volatile matter content. ISO 5502:1983, Oilseed residues Preparation of test samples. ISO 5505:1986, Oilseed residues Sampling 1) .
22、3 Definition For the purposes of this International Standard, the following definition applies. 3.1 urease activity amount of ammoniacal nitrogen liberated per minute under the operating conditions specified in this International Standard, expressed as milligrams of nitrogen per gram of the product
23、as received 4 Principle Mixing of a ground test portion with a buffered urea solution. After keeping the mixture for 30 min at30 C, neutralization of the ammonia liberated, with an excess of hydrochloric acid solution, and back-titration with standard volumetric sodium hydroxide solution. 5 Reagents
24、 All the reagents shall be of analytical quality and the water used shall be distilled water or water of equivalent purity. 5.1 Urea, buffer solution (pH 6,9 to 7,0). Prepare a buffer solution by dissolving 4,45 g of disodium hydrogen phosphate dihydrate (Na 2 HPO 4 2H 2 O) and 3,40g of potassium di
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