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

In 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.

为探究挤压加工参数对挤压处理红景天理化特性与抗氧化性能的影响，本研究以红景天为原料，设置不同水分含量（24%、26%、28%）、机筒温度（120、130、140℃）及螺杆转速（200、250、300 rpm）条件开展挤压试验。挤压处理后，红景天的水溶性指数显著高于原料，而吸水指数则显著低于原料。此外，受美拉德反应（Maillard reaction）影响，其色泽的L*值与a*值均显著降低。挤压处理后，玫瑰红景天（Rhodiola rosea）的可溶性物质、红景天苷（rhodioloside）、总黄酮与总酚类物质的提取率均显著高于原料（P < 0.05）。水分含量与机筒温度均对总酚含量与抗氧化活性具有重要影响；同时，当机筒温度显著影响总黄酮含量时，水分含量亦对红景天苷含量存在显著影响。而螺杆转速则显著影响总黄酮含量。综上，挤压加工工艺可促进红景天活性成分的提升，并显著增强其抗氧化能力。