Effects of soybean oil, cellulose, and SiO2 addition on the lubrication and product properties of rice extrusion

The feed rate, specific mechanical energy (SME), and product properties of rice extruded with soybean oil, cellulose, and SiO2 were investigated using a co-rotating twin-screw extruder. A reduction in both feed rate and SME were observed with increase in soybean oil levels. Decreases in feed rate were observed with increase in cellulose levels up to 8% and SiO2 levels up to 2%. Decreases in SME were also observed with increase in cellulose levels up to 8% and SiO2 levels up to 4%. Moreover, decreases in both feed rate and SME could be observed a synergistic effect as 3% soybean oil co-added cellulose or SiO2. Added cellulose and SiO2 increased water solubility index (WSI) of extrudates. Microstructure of cellulose and SiO2 added extrudates showed a fine and friable texture of extrudate with thinner cell walls and more cell numbers. Increasing the levels of cellulose and SiO2 could decrease moisture content (MC), cross-sectional expansion (CE), and specific volume (SV) but increase longitudinal expansion (LE) of extrudates. Shear force (SF) of extrudates increased with increase in cellulose and SiO2 levels but all of them were lower than extrudate without any additive. The microstructure of 3% soybean oil co-added extrudates could not improve further but could be increase in WSI and CE as well as decrease in MC, LE, SV, and SF.