百里香精油在果胶甲酯酶响应型抗菌薄膜中的扩散性能及其迁移行为

Diffusion and Migration Behavior of Thyme Essential Oil in Pectin Esterase⁃responsive Antibacterial Films

抗菌薄膜因其优异的保鲜性能在果蔬保鲜中应用广泛。然而果蔬储藏过程中内源果胶甲酯酶活性的升高及外源微生物的侵染会干扰抗菌薄膜中抗菌剂的迁移扩散,但抗菌剂在薄膜中的传质迁移决定了抗菌薄膜是否能够发挥预期作用。因此,该文对百里香精油在纳米复合抗菌薄膜中的酶响应迁移行为进行研究,建立释放动力学模型。纳米复合抗菌薄膜溶胀率和扫描电镜结果表明,抗菌薄膜在果胶甲酯酶活为0~2.5 U/mL的食品模拟液中均具有明显的溶胀行为,随着酶活的增强,薄膜横截面微观结构由致密逐渐变为疏松,甚至出现孔洞或缝隙;百里香精油释放动力学结果显示,当释放初期扩散比率Mt/M∞<2/3时,精油释放曲线趋于线性,利用短时释放模型和幂律模型对其进行模拟分析,发现随着酶活的升高,百里香精油的释放机制呈现出由不规则扩散向Fick定律转变的趋势;百里香精油扩散释放的全过程属于扩散⁃溶胀叠加机制,符合自拟的负指数生长回归模型(R2>0.95)。

Antimicrobial films are widely used in fruit and vegetable preservation due to their excellent preser⁃vation performance.However,the elevation of endogenous pectin methylesterase activity and the infestation of exogenous microorganisms during the storage process of fruits and vegetables can interfere with the migration and diffusion of antimicrobial agents in antimicrobial films.The mass transfer and migration of antimicrobial agents in the films determine whether the antimicrobial films can perform their expected roles.Therefore,in this work,the enzyme⁃responsive migration behavior of thyme essential oil in nanocomposite antimicrobial films was investigated,and a release kinetic model was developed.The swelling rate and scanning electron mi⁃croscopy(SEM)results of nanocomposite antimicrobial films showed that the antimicrobial films exhibited no⁃ticeable swelling behavior in the food simulation solution with pectin methyl esterase activity of 0-2.5 U/mL.As the enzyme activity increased,the microstructure of the film cross⁃section gradually changed from dense to loose,and even holes or slits appeared.The results of the release kinetics of thyme essential oil showed that the essential oil release curve tended to be linear when the diffusion ratio of the early stage of the release,Mt/M∞<2/3.Simulation analysis using the short⁃time release model and power law model revealed that the release mechanism of thyme essential oil shifted from irregular diffusion to Fick's law with the increase of enzyme ac⁃tivity.The entire process of the diffusive release of thyme essential oil followed the diffusion⁃solubilization su⁃perposition mechanism,which was consistent with the self⁃fitted negative exponential growth regression model(R2>0.95).