1、 Reference numbers ISO 8851-2:2004(E) IDF 191-2:2004(E) ISO and IDF 2004INTERNATIONAL STANDARD ISO 8851-2 IDF 191-2 First edition 2004-05-15 Butter Determination of moisture, non-fat solids and fat contents (Routine methods) Part 2: Determination of non-fat solids content Beurre Dtermination des ten
2、eurs en eau, en matire sche non grasse et en matire grasse (Mthodes de routine) Partie 2: Dtermination de la teneur en matire sche non grasse ISO 8851-2:2004(E) IDF 191-2:2004(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be
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5、to ensure that the file is suitable for use by ISO member bodies and IDF national committees. In the unlikely event that a problem relating to it is found, please inform the ISO Central Secretariat at the address given below. ISO and IDF 2004 All rights reserved. Unless otherwise specified, no part
6、of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO or IDF at the respective address below. ISO copyright office International Dairy Federation Case postale 56 CH-
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8、ts reservedISO 8851-2:2004(E) IDF 191-2:2004(E) ISO and IDF 2004 All rights reserved iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out
9、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 liaison with ISO, also take part in the work. ISO coll
10、aborates 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 technical committees is to prepare International St
11、andards. 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 drawn to the possibility that some of the elements
12、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 8851-2IDF 191-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (
13、IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. ISO 8851IDF 191 consists of the following parts, under the general title Butter Determination of moisture, non-fat solids and fat contents (Routine methods): Part 1: Det
14、ermination of moisture content Part 2: Determination of non-fat solids content Part 3: Calculation of fat content ISO 8851-2:2004(E) IDF 191-2:2004(E) iv ISO and IDF 2004 All rights reservedForeword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a Nationa
15、l Committee in every member country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in the development of standard methods of analysis and sampling for milk and milk products. D
16、raft International Standards adopted by the Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the National Committees casting a vote. ISO 8851-2IDF 191-2 was prepared by Technical
17、Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. ISO 8851IDF 191 consists of the following parts, u
18、nder the general title Butter Determination of moisture, non-fat solids and fat contents (Routine methods): Part 1: Determination of moisture content Part 2: Determination of non-fat solids content Part 3: Calculation of fat content This first edition of ISO 8851-2IDF 191-2 cancels and replaces the
19、first edition of IDF 11A:1986, which has been technically revised. All work was carried out by the Joint ISO/IDF/AOAC Action Team on Water, of the Standing Committee on Main components of milk, under the aegis of its project leader, Mr J. Evers (NZ). INTERNATIONAL STANDARD ISO 8851-2:2004(E) IDF 191
20、-2:2004(E) ISO and IDF 2004 All rights reserved 1Butter Determination of moisture, non-fat solids and fat contents (Routine methods) Part 2: Determination of non-fat solids content WARNING The use of this International Standard may involve hazardous materials, operations and equipment. This standard
21、 does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This part of ISO 8851IDF 191 specifies the rout
22、ine method for the determination of the non-fat solids content of butter. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenc
23、ed document (including any amendments) applies. ISO 8851-1IDF 191-1, Butter Determination of moisture, non-fat solids and fat contents (Routine methods) Part 1: Determination of moisture content 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1
24、 non-fat solids content mass fraction of substances determined by the procedure specified in this part of ISO 8851|IDF 191 NOTE The non-fat solids content is expressed as a percentage by mass. 4 Principle The moisture is evaporated from a known mass of butter. The fat is extracted with light petrole
25、um ether and the mass of substances remaining is determined. 5 Reagents It is recommended to use reagents of recognized analytical grade. Technical grade reagents may be used only if the results produced therewith are not significantly different from those produced using analytical grade reagents. I
26、SO 8851-2:2004(E) IDF 191-2:2004(E) 2 ISO and IDF 2004 All rights reserved5.1 Petroleum ether, with any boiling range of between 40 C and 80 C. The use of petroleum ether (60 to 80) C BP is preferred over the use of petroleum ether (40 to 60) C BP for safety reasons. 6 Apparatus WARNING As the deter
27、mination involves the use of volatile flammable solvents, any electrical apparatus used shall comply with legislation relating to the hazards in using such solvents. Usual laboratory equipment and, in particular, the following. 6.1 Analytical balance, capable of weighing to the nearest 1 mg. 6.2 Dry
28、ing oven, electrically heated, ventilated, thermostatically controlled, capable of being maintained at a temperature of 102 C 2 C throughout its working space. 6.3 Heating apparatus, for example an electric hot plate, Bunsen burner, Teclu-burner or spirit (alcohol) burner. 6.4 Beaker, made of alumin
29、ium, stainless steel or glass, with smooth surface, of such dimensions that losses by spattering or frothing are avoided. If desired, the beaker may be provided with a glass stirring rod. Recommended dimensions are diameter 60 mm to 80 mm, and height 50 mm to 70 mm. NOTE A 250 ml glass beaker meets
30、the recommended dimensions. 6.5 Beaker tongs, to hold the beaker (6.4) by its outer surface only. 6.6 Stone or metal plate, flat, to allow rapid cooling of the beaker (6.4). 6.7 Measuring cylinders, of capacity 100 ml or, alternatively, dispensing equipment, to measure the volume of the petroleum et
31、her. 6.8 Desiccator, containing a suitable drying agent, for example freshly dried silica gel with hygrometric indicator. 6.9 Sloping stand, used for the beakers (6.4). 6.10 Glass rods. 7 Sampling It is important that the laboratory receive a sample that is truly representative and that has not been
32、 damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 707. The laboratory sample should be received in an airtight container. The capacity of the container shall be such that one-hal
33、f to two-thirds is filled by the sample. Store the samples in the closed container at a temperature of between 5 C and 14 C until commencing the preparation of the test sample. ISO 8851-2:2004(E) IDF 191-2:2004(E) ISO and IDF 2004 All rights reserved 38 Preparation of test sample 8.1 Warm the test s
34、ample in the original unopened container to a temperature at which the sample will be soft enough to facilitate thorough mixing to a homogeneous state (either by a mechanical shaker or by hand) without any rupture of the emulsion. The temperature of mixing should typically be between 24 C and 28 C,
35、and shall normally not exceed 35 C. 8.2 Where applicable, cool the test sample to ambient temperature while mixing until cooling is complete. As soon as possible after cooling, open the sample container and stir briefly for no longer than 10 s with a suitable device (e.g. a spoon or spatula) before
36、weighing. 9 Procedure 9.1 Test portion If the test portion has already been used to analyse the moisture content according to ISO 8851-1| IDF 191-1, start the procedure to determine the non-fat solids content at step 9.3.3 by the addition of 30 ml of petroleum ether (5.1) to the dried test portion r
37、emaining from the moisture analysis. However, if a fresh test portion is taken from the test sample, then start the procedure at step 9.2. 9.2 Preparation of the beaker 9.2.1 Dry the empty beaker (6.4) (with rod if used) in the drying oven (6.2), set at 102 C, for at least 1 h. 9.2.2 Allow the empty
38、 beaker to cool on the stone or metal plate (6.6). Weigh it to the nearest 1 mg. NOTE Generally a cooling time of 15 min is sufficient. 9.3 Determination 9.3.1 Weigh, to the nearest 1 mg, 9,5 g to 10,5 g of test sample (8.2) into the prepared beaker (9.2.2). 9.3.2 Heat the beaker and its contents, a
39、gitating continuously by swirling the beaker on or over the heating apparatus (6.3), or by stirring the contents with the glass rod. Use beaker tongs (6.5), if necessary, to handle the beakers. Control the heating and agitation so that losses by spattering and frothing are avoided. Continue the heat
40、ing until frothing stops, the foam has broken and the colour of the non-fat solids has become light brown or yellow brown. If using a hot plate (6.3), it is recommended to use a heating temperature between 120 C and 160 C. However, butter manufactured according to the Ammix process may require a low
41、er temperature than 120 C at the beginning of the heating process to avoid spattering of the test portion. In this case, the final temperature of the hot plate shall be between 140 C and 160 C to ensure all moisture is removed. NOTE Normally, the heating time should not exceed 20 min. WARNING From s
42、tep 9.3.3 to 9.3.12, the procedure should take place in a fume hood or on a vent bench. 9.3.3 Remove the beaker from the heating apparatus. Add 30 ml of petroleum ether (5.1) to its contents. 9.3.4 Heat the beaker and its contents so that the petroleum ether boils, while taking adequate precautions
43、against fire. Then cool on the stone or metal plate (6.6). This heating step will prevent any non-fat solids floating in the petroleum ether. NOTE When petroleum ether with a boiling point of (60 to 80) C is used, the appearance of gentle bubbles is sufficient; vigorous boiling is not required. ISO
44、8851-2:2004(E) IDF 191-2:2004(E) 4 ISO and IDF 2004 All rights reserved9.3.5 Add 60 ml of petroleum ether (5.1) to the beaker contents. Mix carefully by rotating the beaker. 9.3.6 Place the beaker in the sloping stand (6.9). Allow the non-fat solids to settle for 5 min or until all the non-fat solid
45、s have settled on the bottom of the beaker. 9.3.7 Decant the petroleum ether to waste. Wipe the outside of the beaker, and especially the area from where the solvent is decanted, with a tissue dampened with clean petroleum ether (5.1), to remove fat residues. Ensure that there is no loss of non-fat
46、solids particles during decanting, as this will cause an underestimation of the non-fat solids content. 9.3.8 Repeat the petroleum ether solvent extraction steps described in 9.3.5 to 9.3.7. 9.3.9 Heat the beaker and its contents gently e.g. between 70 C and 80 C on a hot plate (6.3) until all solve
47、nt and moisture have been removed and the non-fat solids are thoroughly dried. Beware of the non-fat solids crusting and bursting. Heat the beaker gently. The drying period usually takes between 10 min and 15 min. It is important that the non-fat solids are completely dried at this stage, otherwise
48、it is difficult to break up the lumps (step 9.3.10). 9.3.10 Repeat the petroleum ether extraction by adding 40 ml of petroleum ether (5.1) and breaking up the lumps with a glass rod (6.10). Rinse the glass rod with 20 ml of petroleum ether, adding the rinsings to the beaker. Mix the contents careful
49、ly by rotating the beaker. Repeat steps 9.3.6 and 9.3.7. 9.3.11 Heat the beaker and its contents gently e.g. between 70 C and 80 C on a hot plate (6.3) until the non-fat solids are thoroughly dried. This usually takes 10 min. 9.3.12 Cool the beaker and its contents in a desiccator (6.8), then weigh to the nearest 1 mg. 10 Calculation and expression of results 10.1 Calculation Calculate the non-fat solids content of the test sample, w s , in percent by mass, by using the fol
