Effects of Die Temperature and CO2 Injection on Physical Properties and Anti oxidant Activity of Extruded Rice with Tomato Flour

摘要

The study was designed to investigate the effects of die temperature and CO2 injection on the physical and antioxidant properties of extruded rice with tomato flour. Moisture content and screw speed were fixed at 25% and 150 rpm, respectively. Die temperatures and CO2 injection were adjusted to 80, 110, and 140°C and 0, and 300 mL/min, respectively. Specific mechanical energy input decreased as die temperature increased from 80 to 140°C. The expansion index increased, while bulk density decreased with CO2 injection. All extrudates showed increased water soluble index (WSl) and water absorption index through the extrusion process. WSl increased as die temperature increased. l,l-Diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and totalphenolic compounds increased as die temperature increased from 80 to 140°C. Total carotenoid and lycopene contents decreased through the extmsion process. Total carotenoid and lycopene contents upon 0 mL/min CO2 injection and 140°C die temperature werehighest at 6.65 mug/g and 2.69 mg/kg, respectively. In conclusion, CO2 injection affects expansion properties while an increased die temperature leads to increased DPPH radical scavenging activity and total phenols.