In vitro mineral binding capacity of three fiber sources for Ca, Mg, Cu and Zn by two different methods

Acid-washing centrifugation (AWC) and cold-hot-water-enzyme incubation (WEI) methods were used to study the binding capacity (BC) of wheat bran, rice bran, and oat fiber for calcium, magnesium, copper, and zinc. Treated fibers were analyzed for protein, phytic acid (PA), total dietary fiber (TDF), and minerals. Protein content was significantly (P < 0.05) lower in WEI fibers than AWC fibers. WEI fibers had low protein concentration and no PA but higher TDF values (P < 0.05). Levels of Mg were the highest among the minerals studied. AWC treatment was significantly (P < 0.05) more efficient in stripping minerals than the WEI treatment. AWC fibers bound more minerals. Results indicate that the BC values of the fibers for minerals by the two methods were not comparable.