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Information on common practice and expected precision will be sought from, for example, public analysts and contract laboratories. Guidance on these and also appropriate interpretation will be given.
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Method evaluation will be undertaken using three model foods. Using previously identified Standard Methods, concentrations of sugars, non-starch oligosaccharides, starch, resistant starch and dietary fibre will be determined within the model foods and their ingredients. Other proximates will also be determined.
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The performance of the employed methods will be evaluated against ingredient composition, inputs and summation of proximates to 100%. Subsequently the methods will be applied to a selection of breakfast cereals (previously analysed for the Agency) and the results compared with those of the model foods.
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All data and information gained during the practical stages of the research project will be critically reviewed. Subsequently guidance for analysts (and others) on method selection for determination of carbohydrate fractions in foods will be prepared. In support of this, a flow diagram/decision tree of a suggested scheme for sequential determination of carbohydrate fractions will be constructed. Additional information on expected uncertainty of measurements will be provided.
Traditionally, the carbohydrate content of foods is determined by 'difference'. This is when the sum of the protein, fat, ash and moisture content (as a % or as g/100g sample) is subtracted from 100. Some data produced from this approach have been included in national nutritional databases.
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During the last 25 years, a range of methods have been developed to determine sugars, maltodextrins, starch, resistant starch, and various dietary fibre fractions. When some, or all of these carbohydrate fractions are determined in foods, the effect of the empirical nature of some of the methods and the combined measurement uncertainty often makes summation of total 'proximates' to 100% problematic. Combinations of some methods may account twice for some carbohydrate fractions and some fractions may not be measured.
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Methods for the determination of carbohydrate fractions are already issued by Standards bodies and well accepted in-house procedures. Rather than develop new methods for carbohydrate determination, the aim of this project is to undertake a structured study of existing methods on well-characterised foodstuffs.
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This research project seeks to assess the applicability of various Standard Methods and approaches to foods of particular composition, with an appreciation of the carbohydrate fractions that are and are not included in measurements, the magnitude of the differences in results obtained by various methods, and the magnitude and effect of the combined uncertainty of the methods applied.
<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>.