以香蕉皮为原料,采用微波提取法,以单宁提取率为评价指标,在单因素试验基础上,通过响应面法优化了香蕉皮单宁提取工艺;滤纸片法测定了单宁对细菌、霉菌和酵母菌的抑菌性能;通过对O-2·和·OH的清除能力,确定了香蕉皮单宁的抗氧化能力。结果表明:香蕉皮单宁微波提取的最优工艺条件为,乙醇体积分数75%、提取时间为80 s、微波功率375 W、料液比1∶30(g∶m L),在此条件下单宁的提取率为87.04%;抑菌试验结果显示,香蕉皮单宁对大肠杆菌、金黄色葡萄球菌、根霉、青霉及酵母菌都有一定的抑菌效果,对大肠杆菌的最低抑菌浓度为0.78 mg/m L,金黄色葡萄球菌和酵母菌为6.25 mg/m L,霉菌为1.56 mg/m L;香蕉皮单宁对超氧阴离子自由基和羟自由基具有较好的清除能力,并在低浓度时(<1.0 mg/m L)抗氧化性要高于Vc,在浓度为1.8mg/m L时,香蕉皮单宁对超氧阴离子和羟自由基的清除率可达(66.04±3.926)%和(73.14±4.128)%。

In order to obtain a higher extraction efficiency of tannin and discuss its antibacterial and antioxidant activities,the tannins were extracted from banana peel by microwave. With the extraction rate of tannin as evaluation index,on the basis of single factor experiments,the response surface methodology( RSM) was chosen to optimize the extraction process of tannins. In addition,the antibacterial activity was determined by filtering paper method,also the antioxidant activity was measured through the capacity of scavenging the hydroxyl radical and superoxide anion radical. The results showed that the optimum extraction conditions by RSM were : ethanol concentration 75%,extraction time 80 s,microwave power 375 W,solid-liquid ratio 1 ∶ 30( mg∶ m L). Under the above conditions,the extraction yield of tannin reached at 87. 04%. In addition,bacteriostatic experiment results showed that the tannin in banana peel had certain antibacterial activity on the microorganisms,such as Escherichia coli,Staphylococcus,Rhizopus sporangia,Penicillium and Saccharomycetes. The minimum bacteriostatic concentrations( MIC) of tannin in banana peel for various microbes were as follows: Escherichia coli 0. 78 mg / m L,Staphylococcus and Saccharomycetes 6. 25 mg / m L and molds 1. 56 mg / m L. Tannin in banana peel had better antioxidant activity than Vc when the concentrations were lower than 1. 0 mg / m L,also the scavenging rate of hydroxyl radical and superoxide anion radical could reach at( 66. 04 ± 3. 926) % and( 73. 14 ± 4. 128) % when the concentration of tannin in banana peel was 1. 8 mg /m L.