大黄酶促褐变相关酶学特性研究

Enzymatic Properties of Rhubarb Related to Enzymatic Browning

目的研究大黄鲜切晾干过程中指标化学成分变化及大黄多酚氧化酶(polyphenol oxidases,PPO)、过氧化物酶(peroxidases,POD)的相关酶学特性。方法利用高效液相色谱(HPLC)技术对指标成分峰面积进行测定,采用紫外光谱(UV)技术考察底物种类、底物浓度、温度及pH值对大黄中PPO及POD的酶活性影响。结果没食子酸、儿茶素及表儿茶素的峰面积变化率高于蒽醌类成分,PPO最佳底物为没食子酸、最佳底物浓度为0.06 mol·L^(-1),最佳温度为30℃,最佳pH为7.0,POD的最佳底物为愈创木酚,最佳底物浓度为0.06 mol·L^(-1),最佳温度为30℃,最佳pH为8.0。结论大黄在产地加工过程中调节温度和pH值均可抑制PPO及POD的酶活性,从而有效提升大黄药材品质,同时也为其他类药材酶促褐变的控制提供思路。

OBJECTIVE To investigate the enzymatic properties of the indicator chemical components changes and the related enzymatic properties of polyphenol oxidase(PPO)and peroxidase(POD)during the drying process of fresh-cut rhubarb.METHODS HPLC was used to determine the peak areas of the indicator components.UV was used to investigate the effects of different substrate types,substrate concentrations,temperatures,and pH values on the activities of PPO and POD in rhubarb.RESULTS The peak areas of gallic acid,catechin and epicatechin showed high rates of change.The optimum substrate for PPO was gallic acid,optimum substrate concentration was 0.06 mol·L^(-1),optimum reaction temperature was 30℃ and optimum pH was 7.0.The optimum substrate for POD was guaiacol,optimum substrate concentration was 0.06 mol·L^(-1),optimum reaction temperature was 30℃ and optimum pH was 8.0.CONCLUSION Adjusting both temperature and pH during the processing of rhubarb can inhibit the activities of PPO and POD,thus effectively enhancing the quality of rhubarb herbs,which providing ideas for the control of enzymatic browning of other herbs.