薄荷油纳米乳液的稳定机制及抑菌特性

The Stability Mechanism and Antimicrobial Property of Peppermint Oil Nanoemulsion

以大豆分离蛋白(SPI)、磷脂酰胆碱(PC)为乳化剂,研究高压均质机制备的薄荷油纳米乳液的微观结构、稳定机制及抑菌特性。采用冷冻扫描电镜观察纳米乳液液滴呈球状,表明大豆蛋白完整地吸附于纳米乳液的油-水界面处,呈核壳状结构。理化稳定性测定结果表明薄荷油纳米乳液具有较高的pH值和盐离子抵抗性,碱性条件更利于薄荷油纳米乳液保持理化稳定性。氯化钙浓度对薄荷油纳米乳液理化稳定性的影响大于氯化钠。薄荷油纳米乳液在4,25,55℃下贮藏30 d后,乳液粒径增加30~50 nm,薄荷油保留率高于85%,乳液无明显分层现象。薄荷油纳米乳液的抑菌特性研究结果表明薄荷油纳米乳液对单增李斯特菌和金黄色葡萄球菌的最小抑菌浓度均为0.5%,此结果与对照组薄荷油的抑菌效果相一致。两种微生物的36 h生长曲线表明,薄荷油纳米乳液具有时效更长的抑制微生物生长的特性。

Peppermint oil nanoemulsion was prepared by using the method of high pressure homogenizer with soybean protein and phosphatidylcholine as emulsifier.The microstructure,stability mechanism and antimicrobial property of peppermint oil nanoemulsion were studied.It was found that nanoemulsion droplet was in the spherical shape by using freezing cycle scanning electron microscopy to observe the microstructure of peppermint oil nanoemulsion,indicating that the soybean protein was completely adsorbed at the oil-water interface of the nanoemulsion and presented a core shell structure.The results of physical and chemical stability showed that the nanoemulsion of peppermint oil had higher pH value and salt ions resistance.The alkaline condition was more favorable for the maintenance of the physical and chemical stability of nanoemulsion.And the effect of CaCl2 concentration on it was greater than that of sodium chloride.After30 days of storage in 4,25 and 55 ℃,the size of emulsion increased by 30-50 nm and the retention rate of peppermint oil was higher than 85%.No obvious stratification occurred in the emulsion.It was found that that minimum bacteriostasis concentration of peppermint oil nanoemulsion to listeria monocytogenes and staphylococcus aureus were 0.5%,and the result was consistent with the bacteriostatic effect of the control group of peppermint oil.However,the results of the growth curve of the two microorganisms in 36 hours manifested that the nanoemulsion of peppermint oil had a longer time-effect depressant effect on microbial growth.