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Figure out what happens with the components in the food sample by dragging them to the right place.

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Not completely right. The first part of this scheme is similar to the scheme in the previous part of the case (about total carbohydrate analysis by direct analysis of sugar and starch). Study this part again to understand how alcohol, water, fat, free sugars and starch are extracted from the sample.

Not completely right. After extraction of alcohol, water, fat, free sugars and starch the remaining residue contains not only all indigestible carbohydrates (+ lignin), but also protein and ash (minerals). To determine total dietary fibre (i.e. indigestible carbohydrates + lignin) the weight of protein and ash need to be subtracted from the total weight of the residue. The resulting fibre values are based on the amount of resistant starch, lignin, non starch polysaccharides and non-specific polysaccharides (like waxes, gums and mucilages).

Right. Summarized, the AOAC fibre method is based on the simulation of food digestion in the small intestine. Thus the resulting fibre values contain all non digestible polysaccharides. Go to the next page to learn more about an other methods for fibre analysis (the Englyst method).

First you will study the AOAC (or Prosky) method, an enzymatic gravimetric method, in which dietary fibre is defined as indigestible carbohydrates (and lignin). This method mimics food digestion in the small intestine. Below you see the same scheme (although slightly simplified) used to explain total carbohydrate measurement. The AOAC method can most easily be understood as an elaboration of this scheme. The AOAC approach consist s of a sequence of steps (in order to sequentially remove all non fibre compounds from the sample. Than total dietary fibre can be determined.