柠檬草精油成分分析、抑菌性及对巨峰葡萄保鲜研究

采用中国西南地区的柠檬草,以水蒸气蒸馏法提取得到的柠檬草精油(lemongrass essential oil,LEO),通过气相色谱-质谱法(gas chromatography-mass spectrometry,GC-MS)分析柠檬草精油的成分和相对含量;通过测定抑菌圈直径和最低抑菌浓度研究对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌的抑菌效果;研究不同浓度的柠檬草精油对新鲜采摘的巨峰葡萄产品品质和生理的影响,确定其保鲜作用。结果表明:当料液比达到1∶15(g/mL)时,出油量与得率达到最大,平均得率为0.91%。利用GC-MS分析柠檬草精油成分,其中有21种组分,主要成分为柠檬醛,占比为70.11%。柠檬草精油对3种供试菌均有较好抑制作用,对枯草芽孢杆菌、金黄色葡萄球菌和大肠杆菌抑菌圈大小分别为23.8、22.5 mm以及11.2 mm。其中对金黄色葡萄球菌和枯草芽孢杆菌的抑制效果较好,对金黄色葡萄球菌和枯草芽孢杆菌的最低抑菌浓度为0.1μL/mL,大肠杆菌的最低抑菌浓度为0.2μL/mL;与对照组相比,柠檬草精油处理能有效缓解可滴定酸、可溶性固形物含量和硬度的降低,减少烂果率和失重率,其中0.50%柠檬草精油处理组的保鲜效果明显好于其他处理组。由此可见,柠檬草精油具有抑菌和水果保鲜的作用。

Analysis of Volatile Components,Antibacterial Activity and Perseveration on Kyoho Grapes of Lemongrass Essential Oil

The lemongrass essential oil(LEO)extracted from the leaves of lemongrass in Southwest China was obtained by steam distillation. The composition and relative content of LEO were analyzed by gas chromatography-mass spectrometry(GC-MS). The effect of antibacterial activity of LEO against Escherichia coli,Staphylococcus aureus,Bacillus subtilis were studied by bacteriostatic circle method and the minimum inhibitory concentration method. To studied the preservation effect of LEO with various treatments of LEO concentration on the quality and physiology of freshly picked Kyoho grape products. The results showed that maximum yield of 0.91 % at a ratio of 1 ∶ 15(g/mL). Using GC-MS to analyzied the components of LEO,of which there were 21 components and the main component was citral,accounting for 70.11 %. LEO had great antibacterial effects. The inhibitory zone diameters of LEO against B. subtilis,S.aureus and E. coli were23.8,22.5 mm and 11.2 mm,respectively. Minimum inhibitory concentration of LEO against E. coli,S.aureus and B. subtilis were 0.2,0.1 μL/mL and 0.1 μL/mL,respectively. It indicated that LEO against bacteria with S.aureus and B. subtilis had higher activity than E. coli. In addition,compared with the control group,the treatment of LEO effectively alleviated the decrease of titratable acid,soluble solid content and hardness,reduced the rate of rotten fruit and weight loss rate and the preservation effect of 0.50 % lemongrass essential oil treatment group was better than other treatment groups obviously. These findings clearly indicated that effects of antibacterial activities and fruit preservation of LEO were observed.