Extrusion and extrudate properties of rice flour

Abstract

Rice flour was extruded with a fully intermeshing, corotating twin-screw extruder (APV Baker MPF 50/25). Rice bran was added at levels of 10, 20 and 30%. All treatments were run at screw speeds of 200 and 300 rpm. Both specific energy and product temperature in the metering section decreased with the addition of rice bran and increased at the higher screw speed. Both radial and axial expansion increased at 10% rice bran and decreased at higher levels. Shear strength increased with bran levels over 10% and with the increase in screw speed: Extrudates that contained bran were darker than those that did not. An examination of the puff microstructure showed an increase in structural organization at 10% rice bran and decreased cell size and incomplete cells at higher levels.