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 ISO 26642 |
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2014/07/21 22:43 |
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https://www.iso.org/obp/ui/#iso:std:iso:26642:ed-1:v1:en
Foreword
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 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 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 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 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 26642 was prepared by Technical Committee ISO/TC 34, Food products.
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* 落葉 *(kang9909) 於 2014-07-21 22:46 回覆： |
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Introduction
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 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 manufacturers;
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 from 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 consumed (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 produce 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 all 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 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 meal 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 the 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-digestibility carbohydrates or resistant starch are not suitable for GI testing if the amounts consumed during the test are likely to provoke gastrointestinal discomfort.
Caution should be exercised with foods containing significant 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 is important.
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* 落葉 *(kang9909) 於 2014-07-21 22:49 回覆： |
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1 Scope
This International Standard specifies a method for the determination of the glycaemic index (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 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 carbohydrate or, if the portion size is unreasonably large, 25 g of glycaemic carbohydrate
2.3
coefficient of variation
CV
standard deviation divided by the mean
[SOURCE: ISO 3534-1:2006[11], 2.38]
Note 1 to entry: In the context of this International Standard, the CV is expressed as a percentage, i.e the 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 to entry: The glycaemic carbohydrate content is total carbohydrate content minus non-glycaemic carbohydrate (see 2.8) content.
Note 2 to entry: Some glycaemic carbohydrate can be slowly absorbed and have minimal effect on blood glucose levels.
2.5
glycaemic index
GI
property of the carbohydrate in different foods, specifically the blood glucose-raising ability of the digestible carbohydrates in a given food
Note 1 to entry: 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 carbohydrate 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 to entry: The italicized terms are defined because alternate interpretations 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 1 to entry: The IAUC can be calculated geometrically by applying the trapezoid 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 the small intestine and not directly providing carbohydrate for metabolism
Note 1 to entry: 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 mono- 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 that set
[SOURCE: ISO 5725-1:1994[12], 3.21]
EXAMPLE:
GI value for a particular subject that falls outside the range of mml_m1, where mml_m2 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
glucose, having by definition a GI of 100
2.12
test food
food whose GI value is being determined
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* 落葉 *(kang9909) 於 2014-07-21 22:50 回覆： |
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Bibliography
[1] Wolever, T.M.S, Vorster, H.H, Björck, I., Brand-Miller, J., Brighenti, F., Mann, J.I., Ramdath, D.D., Granfeldt, Y., Holt, S., Perry, T.L., Venter, C., Wu, X. Determination of the glycaemic index of foods: Interlaboratory study. Eur. J. Clin. Nutr. 2003, 57, pp. 475–482
[2] Brouns, F., Björck, I., Frayn, K.N., Gibbs, A.L., Lang, V., Slama, G., Wolever, T.M.S. Glycaemic index methodology. Nutr. Res. Rev. 2005, 18, pp. 145–171
[3] Wolever, T.M.S., Brand-Miller, J., Abernethy, J., Astrup, A., Atkinson, F., Axelsen, M., Björck, I., Brighenti, F., Brown, R., Brynes, A., Casiraghi, M.C., Cazaubiel, M., Dahlqvist, L., Delport, E., Denyer, G.S., Erba, D., Frost, G., Granfeldt, Y., Hampton, S., Hart, V.A., Hätönen, K.A., Henry, C.J., Hertzler, S., Hull, S., Jerling, J., Johnston, K.L., Lightowler, H., Mann, N., Morgan, L., Panlasigui, L.N., Pelkman, C., Perry, T., Pfeiffer, A.F., Pieters, M., Ramdath, D.D., Ramsingh, R.T., Robert, S.D., Robinson, C., Sarkkinen, E., Scazzina, F., Sison, D.C., Sloth, B., Staniforth, J., Tapola, N., Valsta, L.M., Verkooijen, I., Weickert, M.O., Weseler, A.R., Wilkie, P., Zhang, J. Measuring the glycemic index of foods: Interlaboratory study. Am. J. Clin. Nutr. 2008, 87, pp. 247S–257S
[4] Brand-Miller, J., Holt, S. Testing the glycaemic index of foods: In vivo not in vitro. Eur. J. Clin. Nutr. 2004, 58, pp. 700–701
[5] Englyst, K.N., Englyst, H.N., Hudson, G.J., Cole, T.J., Cummings, J.H. Rapidly available glucose in foods: An in vitro measurement that reflects the glycemic response. Am. J. Clin. Nutr. 1999, 69, pp. 448–454
[6] Agriculture and Consumer Protection Department. Carbohydrates in human nutrition: Report of a Joint FAO/WHO Expert Consultation, Rome, 14–18 April 1997. Rome: Food and Agriculture Organization, 1998. (FAO Food and Nutrition Paper No. 66.)
[7] Valangi, A., Fernandes, G., Wolever, T.M.S. Evaluation of a glucose meter for determining the glycemic responses of foods. Clin. Chim. Acta 2005, 356, pp. 191–198
[8] Livesey, G. Health potential of polyols as sugar replacers, with emphasis on low glycaemic properties. Nutr. Res. Rev. 2003, 16, pp. 163–191
[9] Hugget, A.G., Nixon, D.A. Use of glucose oxidase, peroxidase and o-dianisidine in determination of blood and urinary glucose. Lancet 1957 Aug 24, 273(6991), pp. 368–370
[10] Kunst, A., Draeger, B., Ziegenhorn, J. UV-methods with hexokinase and glucose-6-phosphate dehydrogenase. In: Bergmeyer, H.U., Bergmeyer, J., Grassl, M., editors. Methods in enzymatic analysis, 3rd edition, Vol. 6, pp. 163–172. Weinheim: Verlag Chemie, 1984
[11] ISO 3534-1:2006, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in probability
[12] ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles and definitions
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