溶膠－凝膠法製備含檸檬烯抑菌粒子的檸檬烯含量及其抑菌效果之探討

Preparation of Limonene-Containing Particles with Antibacterial Property Using the Sol-Gel Method

近年來，人們對食品安全的議題非常關注，常在食品中使用天然精油作為抑菌成分來抑制食品中微生物生長，以滿足消費者對食品品質及安全性的期望，來達到延長食品保存期限之目的。本研究目的是使用溶膠-凝膠法（Sol-Gel）製備出具有揮發性檸檬烯（Limonene）之抑菌粒子，在製備過程中探討此抑菌粒子的檸檬烯含量及對Escherichia coli的抑菌效果。試驗使用聚乙烯醇（Polyvinyl alcohol, PVA）和四乙氧基矽烷（Tetraethoxysilane, TEOS）進行溶膠-凝膠法，來製備具有揮發性物質檸檬烯之抑菌粒子，用氣相層析儀（Gas chromatography, GC）分析抑菌粒子中檸檬烯的含量，並使用變異數分析（Analysis of variance, ANOVA）及多元迴歸分析（Multiple regression analysis）來探討參數對檸檬烯含量之關係，再將檸檬烯抑菌粒子以揮發擴散方式得到抑菌圈大小及抑制率來評估Escherichia coli的抑菌效果。試驗結果將檸檬烯含量用多元迴歸分析PVA／TEOS比例、反應溫度及檸檬烯添加濃度三變量試驗而得到最好的製備條件，亦即是PVA／TEOS比例1：6.24、反應溫度60℃及檸檬烯添加濃度100％（v／v），依迴歸方程式預測此條件抑菌粒子中最多有0.94％的檸檬烯含量，經試驗驗證後得到檸檬烯含量為0.90％與預估值的相對偏差為2.17％。抑菌試驗方面：試驗證明利用溶膠-凝膠法製備出來的檸檬烯抑菌粒子對Escherichia coli可以有效達到抑菌效果，期望未來能應用在食品包裝上並延長食品的保存期限。

In contemporary times, many people are concerned about food safety issues. Natural essential oils are widely used as antibacterial ingredients to inhibit microbial growth in foods and fulfil consumer expectations regarding food quality and safety and to extend the shelf life of food. In this study, the objective was to prepare antibacterial particles containing volatile limonene by using the sol-gel method and to investigate their antibacterial effect on Escherichia coli. Polyvinyl alcohol (PVA) and tetraethoxysilane (TEOS) were used in the sol-gel process to form a gel network structure to prepare limonene particles. Limonene and gas chromatography were used to analyze volatilization of the particles. Analysis of variance and multiple regression analysis were used to investigate the solubility and volatilization properties of limonene and to determine the optimal conditions for preparing antibacterial particles. The antibacterial effect of limonene against Escherichia coli was determined by measuring the inhibition zones of limonene particles. Multiple regression analysis of the three variables revealed an optimized condition when the particles were prepared using PVA and TEOS in the ratio 1:6.24, a reaction temperature of 60°C, and limonene concentration of 100% (v/v). According to the regression equation, nearly 0.94% of limonene was released from the particles, and after verification, the amount of limonene released was nearly 0.90%. In summary, the limonene-containing particles prepared using the sol-gel method exhibit effective antibacterial properties against Escherichia coli. The results of this study can be applied to food packaging and to extend the shelf life of food.