EVALUATION OF DIETARY FIBER IN POTATO CRISPS: INFLUENCE OF THE ANALYTICAL METHOD USED

Dietary fiber in ready salted potato crisps was determined by two methods, i.e., the official AOAC method, and the modified method of Englyst, recommended in the U. K. The ultimate aim was to compare the results and to evaluate the advantages and limitations of each method for the analysis of this food in order to obtain a figure to be included on the package. The AOAC method is an enzymatic-gravimetric procedure to determine the total dietary fiber (TDF). The Englyst method consists of an enzymatic-chemical extraction and fractionation of the nonstarch polysaccharides (NSP) and their subsequent determination as neutral sugars by GLC. We modified the original chromatographic method. The AOAC method gave a value of 5.39 g/100g (dry matter) for TDF, and the Englyst method of a value of 1.70 g/100g (dry matter) for NSP. It is assumed that the gravimetric method gives a higher fiber value than the Englyst method due to a contribution from retrograded starch. For this particular food, the AOAC method is faster and much easier to carry out and does not overestimate dietary fiber, if the resistant starch is regarded as part of it.