Physicochemical and antioxidant properties of extruded Rhodiola as affected by twin-screw extrusion

Abstract

ABSTRACTIn order to explore the effect of extrusion operating parameters on the physicochemical and antioxidation properties of the extruded Rhodiola, Rhodiola was extruded as raw material under different moisture content (24, 26, 28%), barrel temperature (120, 130, 140°C) and screw speed (200, 250, 300 rpm) conditions. After extrusion, the water solubility index of Rhodiola was significantly higher than that of raw material, while the water absorption index was significantly lower than that of raw material. In addition, due to Maillard reaction, L* and a* values of color decreased significantly. The extraction rate of soluble substances, rhodioloside, total flavonoids and total phenols of Rhodiola rosea after extrusion were significantly higher (P < .05) than those of the raw material. Both moisture content and barrel temperature had important effects on the total phenolic content and antioxidant activity. At the same time, moisture content also significantly affected the rhodioloside content when the barrel temperature significantly affected the total flavonoid content. Whereas, the screw speed significantly affected the total flavonoid content. In conclusion, the extrusion process facilitated the increase of active ingredients of Rhodiola and significantly enhanced its antioxidant capacity.

Keywords

• Rhodiola
• Twin-screw extrusion
• Operation parameters
• Physicochemical characteristics
• Antioxidant properties