【作者】 吕飞；

【导师】 梁浩；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2011， 硕士

【摘要】 本论文研究了植物单精油以及复配精油对四种食品微生物(大肠杆菌,金黄色葡萄球菌,枯草芽孢杆菌和酿酒酵母)的抑制活性。使用滤纸片法和试管梯度稀释法对十种植物精油的抑菌活性进行了初步筛选。结果显示,牛至精油对四种供试菌种均显示出了最强的抑制活性,罗勒精油和佛手柑精油对革兰氏阳性菌有很好的抑制效果,而紫苏精油则对酿酒酵母有很强的抑制专一性。采用棋盘稀释法,研究复配精油间可能存在的协同增效作用。以FIC指数作为参照依据,选定的复配精油组合及联合最小抑菌浓度如下：大肠杆菌(牛至精油-罗勒精油,MIC联合：0.313-0.313μL/mL)；金黄色葡萄球菌(罗勒精油-佛手柑精油,MIC联合：0.313-0.156μL/mL)；枯草芽孢杆菌(牛至精油-佛手柑精油,MIC联合：0.313-0.313μL/mL)；酿酒酵母(牛至精油-紫苏精油,MIC联合：0.313-0.156μL/mL)。采用气质联用技术(GC/MS),对所选植物精油的化学组成进行了分析鉴定：牛至精油和罗勒精油的主要化学成分是酚类和萜烯类物质,佛手柑精油中主要含有萜烯类、醇类和酯类物质,而酮类物质在紫苏精油中的含量相对较高。通过观察菌体的扫描电镜图片,测定菌体细胞培养液的电导率、细胞溶出物以及菌体细胞膜脂肪酸的变化,研究了复配精油的抑菌机理。结果表明,所有的复配精油均能够破坏菌体细胞膜的完整性,并使其通透性增加,最终达到抑制菌体生长的目的。最后,为了改善精油的溶解度以提高抑菌活性,本研究比较了九种增溶剂对精油的增溶效果,并对增溶体系的抑菌活性和抑菌机理进行了研究。结果发现,HP-β-CD对精油的增溶效果最为明显。随着HP-β-CD的加入,可以显著降低复配精油的用量,提高了复配精油对菌体的作用强度。更多还原

【Abstract】 The aim of this study was to evaluate the antimicrobial efficacy of selected essential oil (EO) and their combinations against four food-related microorganisms. Ten EOs were initially screened against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Saccharomyces cerevisiae using agar disc diffusion and broth dilution methods. The highest efficacy against all the tested strains was shown when testing the oregano EO. EOs of basil and bergamot were active against the Gram-positive bacteria, while perilla EO strongly inhibited the growth of S.cerevisiae. The checkerboard method was then used to investigate the antimicrobial efficacy of EO combinations by means of the fractional inhibitory concentration index (FICI). Based on an overall consideration of antimicrobial activity, organoleptic impact and cost, four EO combinations were selected and their MIC values were listed as follows:oregano-basil (0.313-0.313 [μL/mL) for E. coli, basil-bergamot (0.313-0.156μL/mL) for S. aureus, oregano-bergamot (0.313-0.313μL/mL) for B. subtilis and oregano-perilla (0.313-0.156μL/mL) for S. cerevisiae. The chemical components of selected EOs were then analyzed by GC/MS. Phenols and terpenes were the major antimicrobial compounds in oregano and basil EOs. The dominant active components of bergamot EO were alcohols, esters and terpenes. For perilla EO, the major active constituents were mainly ketones.Furthermore, the mechanisms of the antimicrobial action of EO combinations were studied by the measurement of conductivity and the release of cell constituents, the electronic microscopy observations of the cells and the changes in the percentage of principal fatty acids of cells. The results demonstrated that all EO combinations destroyed the integrity of cell membrane, resulting in the death of microorganisms.Finally, we test the ability of nine solubilizers to increase EOs solubility and the effect of selected solubilizer on the antimicrobial activity of EO combinations by checkerboard method. The results indicated that the effect of HP-β-CD on increasing EOs solubility was most obvious. The addition of HP-β-CD could not only decrease the usage of EO combinations significantly, but also enhance the effects of EO combinations on microorganisms.更多还原