百里香精油纳米乳液的制备及添加植物油对其理化性质及抑菌效果的影响

Preparation of Thymus vulgaris essential oil nanoemulsions and the effects of adding vegetable oils on its physicochemical and antibacterial properties

目的优化确定百里香精油纳米乳液的制备工艺,探究植物油对百里香精油(Thymusvulgaris essential oil,TEO)纳米乳液理化性质及抑菌效果的影响。方法以乳液液滴粒径为目标,采用单因素和响应面实验优化TEO纳米乳液制备工艺参数;并考察玉米油、大豆油、菜籽油、花生油、葵花籽油、橄榄油、亚麻籽油7种不同植物油添加对TEO纳米乳液粒径、黏度、物理稳定性等理化性质及抑菌效果的影响。结果TEO纳米乳液最佳制备工艺为:柠檬酸缓冲液pH 3.5,吐温80添加量2.0%,剪切转速10000 r/min,剪切时间2.5 min,超声时间20 min;在最优工艺条件下,TEO纳米乳液粒径最小为(96.30±0.53)nm。相对于纯TEO纳米乳液,当花生油添加量为40%时,TEO纳米乳液的粒径显著减小(P<0.05),最小为(45.73±1.83)nm,不稳定性指数为0.200±0.001,具有良好的物理稳定性;且对于添加其他植物油,当花生油添加量为40%时,TEO纳米乳液对大肠杆菌、金黄色葡萄球菌和青霉具有良好的抑菌效果,其中对青霉的抑菌效果最好,最小抑菌浓度和最低杀菌浓度分别为78.1μg/mL和156.3μg/mL。结论适量添加花生油有利于TEO纳米乳液的物理稳定性和抑菌作用。该研究可为拓展辛香精油的应用提供理论和技术支撑。

Objective To optimize the preparation process of Thymus vulgaris essential oil(TEO)nanoemulsion,investigate the effects of different vegetable oils on the physicochemical and antibacterial properties of TEO nanoemulsions.Methods Taking the droplet size of nanoemulsions as the goal,the preparation process parameters of TEO nanoemulsion were optimized by single-factor and response surface methodology experiments.The effects of 7 kinds of different vegetable oils,including corn oil,soybean oil,rapeseed oil,peanut oil,sunflower oil,olive oil and flaxseed oil,on the physicochemical properties such as droplet size,viscosity and physical stability as well as antibacterial activities of TEO namoemulsions were also investigated.Results The optimal preparation process of TEO nanoemulsion was as follows:Citric acid buffer pH 3.5,Tween 80 addition amount 2.0%,shear speed 10000 r/min,shear time 2.5 min,and ultrasonic time 20 min.Under the optimal process conditions,the minimum droplet size of TEO namoemulsion was obtain to be(96.30±0.53)nm.Compared with pure TEO nanoemulsion,when 40%peanut oil was added,the particle size of TEO nanoemulsion was significantly reduced(P<0.05)with the smallest droplet size of(45.73±1.83)nm and the instability index was 0.200±0.001,showing a good physical stability.Besides,compared to other vegetable oils added TEO nanoemulsions,the 40%peanut oil added TEO nanoemulsion showed better antibacterial effect against Escherichia coli,Staphylococcus aureus and Penicillium,among which the activity of Penicillium was inhibited best with the minimum inhibitory concentration and minimum bactericidal concentration of 78.1μg/mL and 156.3μg/mL,respectively.Conclusion Moderate addition of peanut oil is conducive to the physical stability and antibacterial effect of TEO nanoemulsion.This study may provide theoretical and technical support for expanding the application of spicy essential oil.