Abstract:

Wet corn bran was washed with flowing water to remove residual starch and endosperm, centrifugalized, and dried. The dried corn bran was crushed and sieved into different particle sizes (60, 80, 100, 120 and 140 mesh) to prepare dietary fiber by removing fat, colored substances and odorous substances with supercritical carbon dioxide. Furthermore, the prepared corn dietary fiber was functionally treated by extrusion technology under 7 different combinations of water addition, extrusion temperature, feed rate and extrusion times. Effects of particle size of corn bran powder on oil retention capacity, expansion property, water holding capacity and water bonding capacity of prepared corn dietary fiber were investigated. The results showed that the comprehensive physical property of corn dietary fiber prepared from the corn bran powder with the particle size of 120 mesh (the particle size is 0.125 mm) was the best. When the extrusion was finished once under the conditions of water addition in corn dietary fiber 110%, temperature 180 ℃, feed speed 10 kg/h, the oil retention capacity and expansion property of extruded dietary fiber were the best, and the amount of soluble component was the highest.

Key words: corn dietary fiber, particle size, extrusion, functionalization, physical properties