Develop extruded high-fiber corn cereals using microfluidized corn bran.
Corn bran is an ideal source of both dietary fiber and bioactive phytochemicals. However, incorporating high levels of native bran into extruded cereals can have detrimental effects on the sensory properties of these products.
Such adverse effects could be minimized by modifying the microstructure and physicochemical properties of the bran using microfluidization to create tiny fluid-like particles. So, scientists at North Carolina A&T State University set out to determine the optimum microfluidization parameters that would result in the highest quality extrudates produced from blends of corn grits and microfluidized corn bran.
The researchers believed that microfluidization could change corn bran's physicochemical properties, which would essentially be based on the microfluidization parameters selected by the scientists. Moreover, optimum processing parameters would be chosen that would minimize any negative effects of corn bran on the quality of the extrudates. It appears that corn bran microfluidized under optimum conditions could be used to develop quality high-fiber extruded cereal products.
The scientists processed aqueous suspensions of ground corn bran through an interaction chamber of a commercial microfluidizer under conditions determined by a second-order central composite design, an experimental design. They used two variables: pressure and the number of passes.
The treated bran was collected using centrifugation. Then it was air-dried. The researchers extruded blends of corn grits (70% on a wet basis) and modified bran (30% on a wet basis) through a laboratory co-rotating twin-screw extruder.
The results indicated that the quality of the extrudates from blends of corn grits and microfluidized corn bran was acceptable at the 30% wet basis level. The best extrudate had a sectional expansion index of 5.45, a bulk density of 0.31gram per [cm.sup.3], and a breaking strength of 0.14 N per [mm.sup.2].
Furthermore, those quality attributes did correlate with microfluidization parameters. By using response surface methodology, the investigators were able to obtain the optimum processing parameters in terms of the highest overall quality possible.
Further information. Guibing Chen, Center for Excellence in Post-Harvest Technologies, North Carolina A&T State University, 500 Laureate Way, Suite 4222, Kannapolis, NC 28081; phone: 704-250-5701; email: firstname.lastname@example.org.