溶剂和微乳化的稀释效应对食用植物精油抗菌活性的影响

Dilution Effect of Solvent and Micro Emulsification on the Antibacterial Activity of Plant Essential Oils

通过溶剂、乳化两种稀释载体制备植物精油复合物溶液,对其质量进行评价,测定最低抑菌浓度、最小杀菌浓度,分析其抗菌活性。结果表明:无水乙醇为溶剂,可改善植物精油的水溶性,其整体增强抗菌的效果不如1,2-丙二醇;以Tween80为表面活性剂、无水乙醇为助表面活性剂、牛至-百里香复合物(1∶1)为油相构建拟三元相图,制备微乳液,其外观为淡黄色、澄清透明液体;当Tween80与无水乙醇比值为3∶1时获得微乳区域的最大面积(29.55%)、最小可稀释比(9∶1);对微乳液的粒径分布、多分散指数、黏度、Zeta电位进行评价,发现微乳配方(10∶1∶28)的粒径最小(13.0 nm±0.6 nm)、多分散指数最低(0.231±0.020)、Zeta电位适宜(-22.23 mV±0.24 mV);植物精油经乳化后具有良好的耐盐、耐酸碱、耐糖、耐贮藏性,而其抗菌活性大大减弱。本研究为食用植物精油应用于食品“高效、安全”的防腐保鲜提供了理论依据。

The compound solution of plant essential oils were prepared by solvent agent and emulsifying two kinds of diluent carrier,and its quality was evaluated.The antibacterial activity was studied by measuring the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC).Result showed that anhydrous ethanol as solvent agent can effectively improve the aqueous solubility of essential oils,but its overall antibacterial effect was less than 1,2-propylene glycol.The stable oil-in-water microemulsions could be fabricated using Tween-80 as a surfactant,anhydrous ethanol as a cosurfactant and oregano-thyme compound(1∶1)as an oil phase via construction of pseudo-ternary phase diagrams,which was a light yellow and transparent liquid.When the ratio of Tween 80 to anhydrous ethanol was equal to 3∶1,the system has the largest area of microemulsion region(29.55%)and the minimum dilution ratio(9∶1).Characterized for its droplet size distribution,polydispersity index(PDI),viscosity,Zeta potential,the microemulsion formula(10∶1∶28)was found to have the lowest droplet size(13.0nm±0.6nm),the lowest PDI(0.231±0.020)and optimal Zeta potential(-22.23mV±0.24mV).Essential oil by emulsion have better resistance to salt,glucose,acid and alkali,as well as good storage stability.However,the antibacterial effect of microemulsion were found to be greatly weaken against the tested microorganisms.The research results provide a theoretical basis for the edible plant essential oils applied to the field of food preservation with its characteristics of high efficiency and safety.