Comparison of dietary fiber methods for foods

In order to evaluate several proposed dietary fiber methods, 12 food samples, representing different food classes, were analyzed by (1) neutral and acid detergent fiber methods (NDF, ADF); (2) NDF with enzyme modification (ENDF); (3) a 2-fraction enzyme method for soluble, insoluble, and total dietary fiber, proposed by Furda (SDF, IDF, TDF); (+) a 1-fraction enzyme method for total dietary fiber proposed by Hellendoorn (TDF). Foods included cereals, fruits, vegetables, pectin, locust bean gum, and soybean polysaccharides. Results show that TDF by Furda and Hellendoorn methods agree reasonably well with literature values by the Southgate method, but ENDF is consistently lower; that ENDF and IDF (Furda method) agree reasonably well; that except for corn corn bran fiber (insoluble) and pectin and locus bean fiber (soluble), all materials have significant fractions of both soluble and insoluble fiber. The Furda method was used on numerous food and ingredient samples and was found to be practical and informative and to have acceptable precision (RSD values of 2.65-7.05%). It is suggested that the Furda (or similar) method be given consideration for the analysis of foods for dietary fiber.