Cereal Chem 62:238-242 | VIEW
Minerals and Phytate in the Analysis of Dietary Fiber from Cereals. III.
W. Frolich and N.- G. Asp. Copyright 1985 by the American Association of Cereal Chemists, Inc.
Bread dough made from wheat flour and bran, with a dietary fiber content of 24% dry matter, was fermented up to 17 hr and baked. During the process, changes were measured in content of dietary fiber and phytate and mineral association to these components in vitro. Total dietary fiber content was not influenced by fermentation or baking, even though a slight decrease in soluble fiber and increase in insoluble fiber components was observed. Ash was mainly associated with the soluble fiber fraction. During fermentation and breadmaking, there was a decrease in fiber-associated ash. Even with extremely long fermentation it was impossible to obtain complete hydrolysis of phytate; after 17 hr it was reduced only to half of that present in the dough just before fermentation. Nearly three quarters of the phytate was detectable in the soluble fiber fraction, but there was none in the insoluble fiber fraction. Specific analysis showed that minerals behave differently, both in binding to fiber fractions before fermentation and in behavior during fermentation. Up to 60% of the total iron was associated with components other than phytate in the dietary fiber complex. Only 10% of the total iron seemed to be associated with phytate. Zinc (24%) and calcium (60%) seemed to be associated with the phytate in the soluble fiber fraction and were released during fermentation. Nine percent of the magnesium was also found associated to this fraction and released during fermentation. All phosphorus in the soluble fiber fraction seemed to be present as phytate.