超声辅助提取山茱萸熊果酸工艺优化及其抗氧化和抑菌性

在7种单因素实验的基础上,采用正交试验优化了山茱萸熊果酸超声辅助提取工艺,并通过还原能力、DPPH·、·OH和猪油氧化抑制实验进行抗氧化活性评价测定,采用琼脂扩散法和对倍稀释法,测定了山茱萸熊果酸对5种食品领域常见的病原菌的体外抑菌活性。结果表明:山茱萸熊果酸超声辅助提取最佳工艺为:超声浸提时间25 min,溶剂中乙醇浓度50%,超声功率225 W,超声工作/间歇比8 s/5 s,提取次数2次,提取温度40 ℃,料液比1:25 (g/mL),在此条件下平均得率可达13.16%;山茱萸熊果酸具有良好的抗氧化和抑菌能力,当浓度为 0.1 mg/mL时,对DPPH·清除率最大为88.1%,对·OH的清除率最大为68.6%;当添加量达到0.75%对猪油的抗氧化能力与0.25%的V_C接近;抑菌能力大小为:大肠杆菌>金黄色葡萄球菌>枯草杆菌>变形杆菌>黑曲霉菌;对大肠杆菌的MIC 为6.25 mg/mL,对金黄色葡萄球菌和枯草杆菌的MIC为12.5 mg/mL,对变形杆菌、黑曲霉 MIC 为 25 mg/mL。

Optimization of Ultrasonic-assisted Extraction Technology of Ursolic Acid from Cornus officinalis and Its Antioxidant and Antibacterial Activities

In this work,orthogonal test of ursolic acid from Cornus officinalis was performed to determine the optimum process conditions by ultrasound-assisted extraction technology,based on the results of 7 single-factor experiments. The antioxidant activities were evaluated by the antioxidant tests of reducing power,DPPH·,·OH and lard.By agar diffusion and double dilution methods,the antibacterial activities of ursolic acid from Cornus officinalis were studied on 5 common food-borne pathogens. The results showed that the optimum process conditions of ursolic acid extraction from Cornus officinalis by ultrasound-assisted extraction technology were as follows:ultrasound extraction time 25 min,alcohol concentration 50%,ultrasonic power 225 W,the ratio of treatment to intermission 8 s/5 s,extraction times twice,extraction temperature 40 ℃,ratio of solid to liquid 1:25 (g/mL),under these conditions,the yield could reach 13.16%. Ursolic acid from Cornus officinalis showed good antioxidant and antibacterial activities. As the concentration of ursolic acid was 0.1 mg/mL,the percentage scavenging of DPPH· and ·OH being 88.1% and 68.6%. As the concentration was 0.75%,the antioxidant effect of ursolic acid from Cornus officinalis came to V_C whose concentration was 0.25%. The order of inhibition was Escherichia coli>Staphylococcus aureus>Bacillus subtilis>Proteus>Aspergillus niger. The MIC was as follows:6.26 mg/mL to Escherichia coli,12.5 mg/mL to Staphylococcus aureus and Bacillus subtilis,25 mg/mL to Proteus and Aspergillus niger.