An official website of the United States government.
A complete assessment of the rationale behind the proposed classification and measurement scheme for dietary carbohydrates will be undertaken. The focus will be on providing an analytical perspective of the requirements for specific and reproducible procedures to determine the carbohydrate content of foods. The resultant report will bring together the salient points relevant to this complex field and provide a rationale for the comprehensive classification and measurement scheme addressed in this project.
<p>
Standardised methods for the determination of sugars, oligosaccharides and starch, within an integrated procedure, will be developed. This task will focus on optimising the extraction, isolation and detection of each carbohydrate fraction. The information obtained will therefore be of generic value in describing the individual measurement of each fraction. Optimisation of each stage of the procedure will use the most appropriate purified materials and food matrices for each fraction.
<p>
Uncertainties associated with the integrated and non-starch polysaccharide (NSP) methods, will be identified and quantified in order to and establish an integrated quality control system for total carbohydrate and the individual fractions.
<p>
The need for valid analytical measurements is particularly important when total carbohydrates are to be measured as the sum of their parts. Errors in uncertainty and measurement may be compounded when values are added together. For this reason, it is essential that the validated methods used are robust and rigorous, specific for the measurand, and the uncertainties associated with the method are both known and kept to a minimum.
<p>
Furthermore, the existing bioavailability procedure for the determination of rapidly available glucose (RAG), and slowly available glucose (SAG) and resistant starch (RS) will be modified and subsequently validated.
The purpose of nutrition labels is to describe composition accurately, and to provide information of nutritional relevance. The traditional calculation of carbohydrate 'by difference' is unacceptable with respect to either of these criteria as:
<p>
it combines the analytical uncertainties of the other macronutrient measures as well as any unidentified material present
a single value for carbohydrate cannot reflect the range of carbohydrate components or their diverse nutritional properties.
Consequently, in 1998, an Food and Agriculture Organization/World Health Organisation(FAO/WHO) Expert Consultation recommended that food carbohydrate should always be measured as the sum of chemically identified components, with the further provision that additional groupings and subdivisions could be made on the basis of physiological properties.
<p>
Switching from the 'by difference' approach to specific chemical measurement has increased awareness of method uncertainties. This has highlighted the fact that the sum of measured food components does not always equal 100%, an issue for all food components, including fat and protein. The focus here is to investigate how best to limit the uncertainties associated with measuring food carbohydrates.
<p>
Food carbohydrates encompass a wide range of compounds, each with their own specific properties. The challenge is to apply chemical, physical and enzymatic approaches to exploit these characteristic differences, in order to achieve specific measurements for each carbohydrate fraction.
<p>
This research project will assess each carbohydrate species using agreed criteria to ascertain the optimal procedure for their determination. The overall aim is to achieve an integrated approach to the classification and measurement of dietary carbohydrates. This will be based on a scheme for chemically identified components that accommodates groupings and sub-divisions of nutritional interest.
<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food
Standards Agency Research webpage</a>.