Effects of extrusion on physiochemical properties and antioxidant activity of whole purple waxy wheat flour

The effects of the different extrusion conditions on the physiochemical properties of whole purple waxy wheat flour were investigated. The results showed that the expansion ratio,WSI,TDF,SDF,TPC increased and WAI decreased with the increase of barrel temperature and screw speed. SDF of the extrudate increased 6%~26% compared to raw purple waxy wheat flour. There was the highest TPC(1.03mg/g) at 160℃ and 13% feed moisture. The WSI and WAI of puffing powder increased by 70% and 37% than the raw material. Increasing feed moisture content resulted in lower WSI and TPC,but higher WAI and some other properties. The total antioxidant activity significantly decreased with the increase of barrel temperature,screw speed and feed moisture content.