The Effects of CO2 Injection and Barrel Temperatures on the Physiochemical and Antioxidant Properties of Extruded Cereals
2016
Thin, T., Kongju National University, Chungnam, Republic of Korea | Myat, L., Yezin Agricultural University, Pyinmana, Myanmar | Ryu, G.H., Kongju National University, Chungnam, Republic of Korea
The effects of CO2 injection and barrel temperatures on the physiochemical and antioxidant properties of extruded cereals (sorghum, barley, oats, and millet) were studied. Extrusion was carried out using a twin-screw extruder at different barrel temperatures (80, 110, and 140Celsius), CO2 injection (0 and 500 mL/min), screw speed of 200 rpm, and moisture content of 25%. Extrusion significantly increased the total flavonoid content (TFC) of extruded oats, and β-glucan and protein digestibility (PD) of extruded barley and oats. In contrast, there were significant reductions in 1,1-diphenyl- 2-picrylhydrazyl (DPPH) radical scavenging activity, PD of extruded sorghum and millet, as well as resistant starch (RS) of extruded sorghum and barley, and total phenolic content (TPC) of all extrudates, except extruded millet. At a barrel temperature of 140Celsius, TPC in extruded barley was significantly increased, and there was also an increase in DPPH and PD in extruded millet with or without CO2 injection. In contrast, at a barrel temperature of 140Celsius, the TPC of extruded sorghum decreased, TFC of extruded oats decreased, and at a barrel temperature of 110Celsius, PD of extruded sorghum without CO2 decreased. Some physical properties [expansion ratio (ER), specific length, piece density, color, and water absorption index] of the extrudates were significantly affected by the increase in barrel temperature. The CO2 injection significantly affected some physical properties (ER, specific length, piece density, water solubility index, and water absorption index), TPC, DPPH, beta-glucan, and PD. In conclusion, extruded barley and millet had higher potential for making value added cereal-based foods than the other cereals.
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