正山小种精油大孔树脂吸附工艺优化及其抗氧化活性分析

A study on the preparation of essential oil of Lapsang Souchong with macroporous resins and its antioxidant activity

通过大孔树脂吸附法制备正山小种精油,优化制备工艺,并对其挥发性香气成分和抗氧化活性进行分析。试验结果表明,最佳的精油制备工艺为:以LX-8大孔树脂作为吸附树脂,按1∶350(树脂湿重∶香气水,g/mL)比例在恒温摇床振荡器(25℃,转速200 r/min)吸附正山小种香气水的香气成分,吸附时间为180 min,然后使用95%乙醇,按1∶5(树脂湿重∶乙醇,g/mL)比例在恒温摇床振荡器(25℃,转速200 r/min)中对大孔树脂进行解吸附,解吸附时间为150 min。该条件下获得最高浓度的正山小种精油,产品具备典型的正山小种的香气特征,其香气成分浓度是香气水的约35倍,回收率约51%。气相色谱—质谱联用(GC-MS)分析吸附过程各阶段香气水的成分发现,正山小种的特征香气成分可以被LX-8大孔树脂吸附。该精油具有一定的抗氧化活性,其DPPH自由基和ABTS自由基清除活力分别为4μg/mL抗坏血酸当量与3μg/mL抗坏血酸当量。

In the present study,the Lapsang Souchong essential oil was prepared by using macroporous resin,during which the preparation process was optimized.Furthermore,the volatile aroma components and antioxidant activity of the product were analyzed.The results showed that the optimal process was using LX-8 macroporous resin as the adsorption resin,and the aromatic components were absorbed in a constant temperature shaker(25℃,200 r/min)for 180 min.The ratio of resin wet weight and substrate was 1∶350(g/mL).Subsequently,macroporous resin was desorbed by using 95%ethanol in a constant temperature shaker(25℃,200 r/min)for 150 min.The ratio of resin wet weight to ethanol solution was 1∶5(g/mL).Under the control of this condition,the highest concentration of Lapsang Souchong essential oil was obtained.The aromatic components were concentrated 35 times,with the recovery rate approximate 51%.Gas chromatography-mass spectrometry(GC-MS)analysis indicated that most of the characteristic aroma components of Lapsang Souchong were adsorbed by LX-8 macroporous resin.Furthermore,the product was found to possess profound antioxidant activity.Its DPPH and ABTS free radical scavenging activity are 4 and 3μg/mL ascorbic acid equivalent,respectively.