1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 26642:2010Food products Determination of the glycaemicindex (GI) and recommendationfor food classificationBS ISO 26642:2010 BRITISH STANDARDNational forewordThis British S
2、tandard is the UK implementation of ISO 26642:2010.The UK participation in its preparation was entrusted to TechnicalCommittee AW/-/3, Food analysis - Horizontal methods.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport
3、 to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 56630 1ICS 67.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Pol
4、icy and Strategy Committee on 30 November 2010.Amendments issued since publicationDate Text affectedBS ISO 26642:2010Reference numberISO 26642:2010(E)ISO 2010INTERNATIONAL STANDARD ISO26642First edition2010-10-01Food products Determination of the glycaemic index (GI) and recommendation for food clas
5、sification Produits alimentaires Dtermination de lindex glycmique (IG) et recommandations relatives la classification des aliments BS ISO 26642:2010ISO 26642:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or v
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10、+ 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 26642:2010ISO 26642:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Terms and definitions .1 3 Classification of GI3 4 Qualifying facto
11、rs3 5 Requirements.3 5.1 Ethics committee approval.3 5.2 Testing facility .3 5.3 Subjects3 5.4 Reference food 4 5.5 Test food 5 6 Experimental procedure .6 7 Analysis6 7.1 Analysis of blood samples .6 7.2 Analysis of test data6 8 Report .10 Annex A (informative) Amount of carbohydrate11 Annex B (inf
12、ormative) Recommended categories of GI13 Annex C (informative) Example of data and GI calculation14 Bibliography18 BS ISO 26642:2010ISO 26642:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodie
13、s (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 represented on that committee. International organizations,
14、 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 drafted in accordance with the rules given in the ISO
15、/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 International Standard requires approval by at least 75 % of the m
16、ember 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 26642 was prepared by Technical Committee ISO/TC 34, Food products.
17、BS ISO 26642:2010ISO 26642:2010(E) ISO 2010 All rights reserved vIntroduction The development of this International Standard originated from a recognized need to standardize the determination of glycaemic index (GI) of foods for practice and research purposes, particularly with its increasing use as
18、 a nutrition claim, illustrating the importance of GI within human nutrition. The objective of this International Standard is to establish the recognized scientific method as the standard method for the determination of the GI of foods. This International Standard is intended for use by: a) food man
19、ufacturers; b) accreditation bodies; c) regulators; d) educational institutes; e) testing laboratories; f) research organizations. This International Standard is based on a Joint FAO/WHO Expert Consultation, Carbohydrates in human nutrition (Reference 6). Additional recommendations have been taken f
20、rom References 1 to 3. The GI is a property of the carbohydrates in different foods, specifically the blood glucose-raising ability of the digestible carbohydrates. It compares carbohydrates on a mass for mass basis in single foods or food items, in the physical state in which they are normally cons
21、umed (Reference 1). Low GI foods are those containing carbohydrates that have less impact on blood glucose levels, because their digestion and absorption is slowed or because the sugars present (e.g. fructose, lactose) are inherently less glycaemic. When combined in actual meals, low GI foods produc
22、e less fluctuation in blood glucose and insulin levels than high GI foods. The clinical and practical value of the GI continues to be studied and there is growing consensus that there are benefits to health when low GI foods replace high GI foods in a balanced diet (Reference 2). Historically, not a
23、ll GI values on food labels have been reliable (Reference 4). Some claims have been based on extrapolation or inappropriate methodology. While a digestibility or hydrolysis index can be obtained by in vitro methods of assessing the rate of carbohydrate digestion (Reference 5), the results should not
24、 be referred to as GI values. The method set out in this International Standard should be applied to ensure that GI values are determined by recognized methodology. GI testing is appropriate only when the food in question contributes physiologically relevant amounts of digestible carbohydrate to a m
25、eal or diet. For the purposes of this International Standard, the minimum amount is specified as 10 g or more of glycaemic carbohydrate per serving. Low-digestibility or non-digestible carbohydrates (resistant starch, some sugar alcohols, polydextrose, etc.) are not to be intentionally counted in th
26、e specified carbohydrate portion (50 g or 25 g) used in GI testing. Small amounts of resistant starch may be inadvertently included because the methods of assay of starch are not yet adequate to clearly differentiate between digestible and non-digestible starch. Foods containing large amounts of low
27、-digestibility carbohydrates or resistant starch are not suitable for GI testing if the amounts consumed during the test are likely to provoke gastrointestinal discomfort. BS ISO 26642:2010ISO 26642:2010(E) vi ISO 2010 All rights reservedCaution should be exercised with foods containing significant
28、amounts of low-digestibility carbohydrates. By definition, a low GI food contains glycaemic carbohydrate, i.e. “providing carbohydrate for metabolism” (Reference 6). Distinguishing between low-GI carbohydrate-containing foods and sources of low-digestibility carbohydrate or low carbohydrate content
29、is important. BS ISO 26642:2010INTERNATIONAL STANDARD ISO 26642:2010(E) ISO 2010 All rights reserved 1Food products Determination of the glycaemic index (GI) and recommendation for food classification 1 Scope This International Standard specifies a method for the determination of the glycaemic index
30、 (GI) of carbohydrates in foods. This International Standard defines the GI, outlines qualifying factors, and specifies requirements for its application. This International Standard recommends criteria for classification of foods into low, medium and high GI. 2 Terms and definitions For the purposes
31、 of this document, the following terms and definitions apply. 2.1 blood glucose response change in blood glucose concentration over a 2 h period following the start of ingestion of the test or reference food 2.2 carbohydrate portion weighed portion of food containing either 50 g of glycaemic carbohy
32、drate or, if the portion size is unreasonably large, 25 g of glycaemic carbohydrate 2.3 coefficient of variation CV positive random variable standard deviation divided by the mean ISO 3534-1:200611, 2.38 NOTE In the context of this International Standard, the CV is expressed as a percentage, i.e the
33、 ratio of the standard deviation to the mean is multiplied by 100. 2.4 glycaemic carbohydrate available carbohydrate carbohydrate absorbed into the bloodstream as carbohydrate and capable of increasing blood glucose levels when consumed NOTE 1 The glycaemic carbohydrate content is total carbohydrate
34、 content minus non-glycaemic carbohydrate (see 2.8) content. NOTE 2 Some glycaemic carbohydrate can be slowly absorbed and have minimal effect on blood glucose levels. BS ISO 26642:2010ISO 26642:2010(E) 2 ISO 2010 All rights reserved2.5 glycaemic index GI property of the carbohydrate in different fo
35、ods, specifically the blood glucose-raising ability of the digestible carbohydrates in a given food NOTE 1 In common usage, this property is referred to simply as the GI of the food. It is defined as the incremental area under the (blood glucose response) curve (IAUC) after consumption of the carboh
36、ydrate portion (see 2.2) of a test food expressed as a percentage of the average IAUC response to the same amount of carbohydrate from a reference food (see 2.11 and 5.4.1) taken by the same subject (see 5.3) on a separate occasion. NOTE 2 The italicized terms are defined because alternate interpret
37、ations may affect the final results obtained. 2.6 incremental area under the curve IAUC area under the curve calculated as the incremental area under the blood glucose response curve, ignoring the area beneath the fasting concentration NOTE The IAUC can be calculated geometrically by applying the tr
38、apezoid rule (see Clause 7 for details). 2.7 in vivo GI testing glycaemic index testing carried out by the determination of glycaemic (blood glucose) responses in human volunteers 2.8 non-glycaemic carbohydrate non-digestible carbohydrate including fibre carbohydrate largely escaping digestion in th
39、e small intestine and not directly providing carbohydrate for metabolism NOTE Non-glycaemic carbohydrate is, wherever possible, excluded from the determination of the carbohydrate portion for GI testing (see Table A.1). EXAMPLE Partly or completely non-glycaemic carbohydrates include: hydrogenated m
40、ono- and disaccharides (synonyms include sugar alcohols, polyols); non-digestible oligosaccharides (fructooligosaccharides, oligofructose, inulin); galactooligosaccharides; and xylooligosaccharides. See Annex A. 2.9 outlier member of a set of values which is inconsistent with the other members of th
41、at set ISO 5725-1:199412, 3.21 EXAMPLE GI value for a particular subject that falls outside the range of G2I s , where GI is the mean and s the standard deviation, of a group of 10 or more. 2.10 per serving amount of a normal single serve of the test food as per common use 2.11 reference food glucos
42、e, having by definition a GI of 100 2.12 test food food whose GI value is being determined BS ISO 26642:2010ISO 26642:2010(E) ISO 2010 All rights reserved 33 Classification of GI This International Standard recommends a classification of foods as low, medium or high GI (see Annex B). 4 Qualifying fa
43、ctors The GI value of a food shall be applied only to the specific test food in the physical state in which it was consumed. The qualifying factors shall be: a) only tested foods shall have a GI assigned; b) the method by which glycaemic carbohydrate has been obtained, as well as the glycaemic carbo
44、hydrate content, shall be provided in the test report. The GI of heterogeneous foods can only be determined by testing according to this International Standard and not by mathematical calculation of GI of individual ingredients or food items. Small formulation changes and seasonal variations in ingr
45、edients do not dictate re-testing. Re-testing may be required when the: 1) formulation of the product is changed by changing the macronutrient composition; 2) processing method changes; 3) concentration, osmolality, acidity or other physical or chemical factor changes. 5 Requirements 5.1 Ethics comm
46、ittee approval The testing organization (laboratory) shall obtain written, ethics clearance from an appropriate human research ethics committee, and shall consider and address relevant issues raised in the national statement on ethical conduct of research involving humans and other relevant guidelin
47、es, available in the country. Individual countries should apply their own guidelines. 5.2 Testing facility The testing organization shall have a food preparatory area separate from that in which blood is taken and appropriate instrumentation and consumables to analyse blood glucose content according
48、 to acceptable methodology (see 7.1). 5.3 Subjects 5.3.1 Inclusion and exclusion criteria Selection of a minimum of 10 healthy subjects shall be made on the basis of: a) no known food allergy or intolerance; b) no medications known to affect glucose tolerance (excluding oral contraceptives) stable d
49、oses of oral contraceptives, acetylsalicylic acid, thyroxin, vitamins and mineral supplements or drugs to treat hypertension or osteoporosis are acceptable. BS ISO 26642:2010ISO 26642:2010(E) 4 ISO 2010 All rights reservedExclusion of subjects shall be made on the basis of: 1) a known history of diabetes mellitus or the use of antihyperglycaemic drugs or insulin to treat diabetes and related conditions; 2) a major medical or surgical event requiring hospitalization within the preceding 3 months; 3) the pres
