Improved Methods for Analysis and Biological Characterization of Fiber

Abstract
Dietary fibers are not uniform, chemically or in their nutritive and biological properties, the only common ground being their resistance to mammalian digestive enzymes. The AOAC method for total fiber is subject to inferences from ash, protein, tannins and resistant starches. These interferences can be reduced by urea enzymatic dialysis. The measurement of soluble and insoluble fiber is nutritionally relevant, since physical properties greatly modify dietary effects of fiber. Insoluble fiber is conveniently measured as neutral-detergent fiber. This procedure has been improved by reducing the starch interference and the time of analysis. Physical and biological properties of dietary fiber can be measured by using relevant procedures for hydration capacity, metal ion exchange capacity and rate of fermentation. The lignin and tannin content modify the characteristics of dietary fiber.