双频超声协同强化提取黑米黑色素的试验研究

为进一步提高超声辅助提取黑米黑色素的效果，研究探讨了双频超声协同强化提取的方法。通过对pH值、提取时间、提取温度、液料比、乙醇浓度进行单因素试验，考察各因素对黑色素提取效果的影响，利用正交试验，优化其工艺条件。试验结果表明：各因素对黑米黑色素提取的影响大小依次为：pH＞乙醇浓度＞液料比＞温度＞时间。优化后的提取工艺条件为：pH值为2、超声时间为30?min、提取温度为50℃、液料比为30?mL/g、乙醇浓度为70%。在此条件下，得出平均提取率为6.85%。对比浸渍法、加热回流提取法，超声法提取黑米黑色素具有工艺简单、节省提取时间、溶剂用量少、提取效率高、减少黑色素损失的优点。

Experiment on dual-frequency ultrasound extraction of black rice melanin

To improve extraction rate of black rice melanin, dual-frequency ultrasound assisted extraction method of black rice melanin was used. Orthogonal array design was employed for investigating the effects of pH, extraction time, extraction temperature, liquid ratio, concentration of ethanol. The results showed that the impact of various factors on the black rice melanin extraction was followed by pH, concentration of ethanol, liquid ratio, extraction temperature, extraction time. The optimal conditions were as follow: pH value of 2, ultrasound time of 30 min, extraction temperature of 50°C, the liquid-solid ratio of 30mL/g, ethanol concentration of 70%. Under these conditions, average extraction rate was 6.85%. Compared to impregnation and ultrasound extraction methods, dual-frequency ultrasound assisted extraction method exhibited simple, saving time, less solvent, high extraction efficiency and less melanin.