微波辅助提取黎豆种皮黑色素

目的]研究微波辅助碱提酸析法提取黎豆黑色素的工艺条件。方法]分别采用碱提酸析法和微波辅助碱提酸析法提取成熟黎豆种皮中的黑色素,以紫外分光光度法测定黎豆黑色素的含量。结果]黎豆种皮黑色素含量为2.41%;碱提酸析法最佳提取工艺为1.0mol/L NaOH溶液为提取剂、料液比1∶20(g/ml),浸提时间4～6 h,再调提取液pH值为2,进行酸析;在此条件下,黑色素粗提物得率为(91.2±2.0)%,黑色素纯度为(36.5±2.1)%;微波辅助碱提酸析最佳工艺为料液比1∶20(g/ml)、1.0 mol/L NaOH溶液为提取剂、微波高档功率处理25 min;在此条件下,黑色素粗提物得率为(95.3±1.5)%,黑色素纯度达到(37.4±1.5)%。结论]黎豆种皮中含有较为丰富的植物黑色素,值得进一步研究和开发利用;微波辅助较常规碱提酸析工艺明显提高了黎豆种皮黑色素粗提物得率,且大大缩短了提取时间。

Extraction of Melanin from the Seed Coat of Mucuna prurients ( L.) by Microwave-assisted Method

Objective] To research on the extraction technology of melanin from the seed coat of Mucuna prurients(L.) by microwave-assisted alkaline extraction and acid precipitation.Method] Melanin was extracted from the seed coat of M.prurients by the method of microwave-assisted alkaline extraction-acid precipitation and the method of alkaline extraction-acid precipitation.Content of melanin in M.prurients was detected by UV spectrophotometry.Result] The melanin content of the seed coat was 2.41%.The optimal conditions for alkaline extraction-acid precipitation were 1.0 mol/L NaOH solution,1∶20(g/ml) solid-liquid ratio,4-6 h extraction time,and pH=2 for the precipitation of melanin.Under these conditions,the extraction rate of the crude extracts of melanin was(95.3±1.5)%;and the purity of melanin reached(37.4±1.5)%.Conclusion] The seed coat of M.prurients was rich in melanin,which deserved further research and development.Microwave assistance could significantly enhance the extraction rate of the crude extracts of melanin and greatly shortened extraction time remarkably.