Effect Of Operation Parameters Of Twin-screw Extrusion On Expansion And Antioxidant Properties Of Extruded Rhodiola

In order to explore the influence of operation parameters of twin-screw extrusion on the expansion and antioxidant properties of Rhodiola.This experiment took rhodiola as raw material,and extruded it under the conditions of different material moisture content,barrel temperature and screw speed,and measured a series of indicators of expansion properties and antioxidant properties.The operation parameters in the process of this study were set as follows: the barrel temperature was100-140?;screw speed was 200-300 rpm;the moisture content of Rhodiola was22%-30%,the feed rate was 100 g/min,and the die hole diameter was 3 mm.The results show that:1.The expansion ratio and specific length of Rhodiola were significantly different(P < 0.05),and the water solubility index,water absorption index,color and the soluble material extraction yield were significantly changed(P < 0.05)compared with that before extrusion.2.Among the 17 samples in the response surface experiment,the expansion ratio of Rhodiola extrusion sample 3(24% moisture content,barrel temperature 130?,screw speed 300 rpm)was inversely proportional to the specific length,and the expansion ratio was the largest,and the expansion effect was the best.It is suitable to develop the puffed health food of Rhodiola.Among the 17 samples in the response surface test,Rhodiola extruded sample 12(moisture content of 26%,barrel temperature of 140?,screw speed of 200 rpm)has the highest water-solubility index,which is 22.06%,higher than that of Rhodiola original powder before extruded.It is suitable for the development of Rhodiola powder granule health food.3.The contents of total flavonoids,total phenols and salidroside were 6.42,18.32 and 10.94 mg/g,respectively.The DPPH free radical scavenging rate,ABTS free radical scavenging rate and reducing power were 53.24%,51.35% and 1.31,respectively.After extrusion,the contents of total flavonoids,total phenols and salidroside changed significantly,the DPPH free radical scavenging rate,ABTS free radical scavenging rate and reducing power were increased,and the antioxidant capacity was enhanced.4.Among the 17 samples in response surface test,Rhodiola extrusion sample 17(moisture content of 28%,barrel temperature of 140?,screw speed of 250 rpm)had the highest total flavonoids content,which was 11.75 mg/g.The highest total phenol content of Rhodiola extrusion sample 3(24% moisture content,barrel temperature130?,screw speed 300 rpm)was 90.63 mg /g.The salidroside content of Rhodiola extrusion sample 14(moisture content 28%,barrel temperature 120?,screw speed250 rpm)was the highest,which was 13.10 mg/g.The DPPH free radical scavenging rate of sample 4(24% moisture content,140? barrel temperature,screw speed 250rpm)was the highest,which was 70.12%.The highest ABTS free radical scavenging rate of sample 2(24% moisture content,130? barrel temperature,200 screw speed rpm)was obtained by Rhodiola extrusion,which was 58.12%.The reducing power of Rhodiola extrusion sample 16(moisture content of 28%,barrel temperature of 130?,screw speed of 300 rpm)is the strongest,which is 1.61.