Cereal Chem 61:116 - 119.  |  VIEW ARTICLE
Minerals and Phytate in the Analysis of Dietary Fiber from Cereals. I.

T. F. Schweizer, W. Frolich, S. Del Vedovo, and R. Besson. Copyright 1984 by the American Association of Cereal Chemists, Inc. 

Considerable amounts of ash were found in dietary fiber in foods and especially in soluble-fiber components from cereal products in assays with an enzymatic gravimetric method. With wheat bran as a source of fiber, several digestion and isolation procedures were modified to identify the component minerals and the nature of their association with insoluble-and soluble-fiber components. When buffers with low ionic strength were used, citrate was substituted for phosphate, and soluble fibers were isolated with dialysis instead of precipitated with ethanol, as much as 90% of the ash in the fiber fractions was reduced. On the other hand, more residual protein remained in the fiber fractions. From the assay of the quantitatively important minerals and of phytic acid in all fiber fractions and from separate solubility tests, coprecipitation was determined to be partly responsible for the ash in the soluble-fiber fractions. These results shoud be helpful in improving current analytical methods for determining dietary fiber.