Abstract:

Helianthus tuberosus L. is a natural herb with excellent health care function. Ultrasound is widely used for auxiliary extraction of natural ingredients. Using dual-frequency countercurrent energy-gathered ultrasonic-assisted extraction technology, this paper studied the effect of ultrasound on extraction ratio and antioxidant activity of inulin polysaccharide, influence of each factor sorting order was power density > solid/liquid ratio > time > temperature > pulse/interval ratio. The optimum technology parameter was ultrasound dual-frequency combination of 20 kHz/35 kHz, ultrasound pulse/interval ratio of 4 s/3 s, ultrasound power density of 250 W/L, solid-liquid ratio of 1∶20, extraction temperature of 55℃ and extraction time of 15 min. Under this condition, the inulin extraction ratio was 56.35%, while under the same condition by hot water extraction method the extraction ratio was 33.89%. Inulin showed rather good antioxidant activity. Ultrasound had no obvious influence on antioxidant activity. Antioxidant activities of samples treated by diverse methods were significantly different, in which water crude extraction had the greatest·DPPH depleting capacity, and ultrasonic ethanol sediment showed the best reduction force and Fe2+ chelating ability, and the purified ultrasonic ethanol sediment had the highest hydroxyl radical scavenging rate.

Key words: inulin, polysaccharide, ultrasound, extraction, antioxidant

摘要：

菊芋是一种天然草本植物，具有优良的保健功能。超声波广泛用于天然成分的辅助提取，采取双频逆流聚能式超声波辅助提取技术，研究了超声波对菊粉多糖提取率及其抗氧化活性的影响，各因素影响程度排序为：功率密度>料液比>时间>温度>脉冲/间歇时间比。获得最佳的工艺参数为：超声频率组合20 kHz/35 kHz、超声脉冲间歇时间比4 s/3 s、超声功率密度250 W/L、料液比1∶20、提取温度55℃、提取时间15 min，此条件下菊粉提取率为56.35%，同条件下的热水浸提法得率为33.89%。菊粉呈现出良好的抗氧化活性，超声波对菊粉的抗氧化活性没有明显影响。不同纯化方法得到的菊粉抗氧化活性差异较大，其中菊粉水提粗提物具有最高的·DPPH清除能力，超声粗提醇沉物具有最高的还原力和Fe2+螯合能力，超声后的纯化醇沉物具有最高的羟基自由基清除率。

关键词: 菊粉, 多糖, 超声波, 提取, 抗氧化