摘要
The low density polyethylene(LDPE)film containing 5%zinc oxide nanoparticles(nano-ZnO)(LDPE/5%ZnO)and the LDPE film containing antifogging agent(often surfactants(SF))and 5%nano-ZnO(LDPE/SF/5%ZnO)were prepared.The retention rate of nano-ZnO,the release property,and the antibacterial activity against Pseudomonas fluorescens in lettuce of the films were investigated.The antibacterial effect of the films on Pseudomonas fluorescens was investigated by studying its cell wall,cell membrane,bacterial morphology,intracellular nucleic acids and proteins,and reactive oxygen species(ROS)levels.Compared with LDPE/5%ZnO film,the LDPE/SF/5%ZnO film showed higher retention rate of nano-ZnO in the film,higher release rate of nano-ZnO into the aqueous food simulant and stronger antibacterial activity against Pseudomonas fluorescens.The possible mechanism of the enhanced antibacterial activity of LDPE/SF/5%ZnO film was elucidated as follows:(1)LDPE/SF/5%ZnO film released more Zn^(2+)into the bacterial suspension to exert the antibacterial effect than LDPE/5%ZnO film,causing greater damage to the cell membrane;(2)Compared to LDPE/5%ZnO group,the quantity and area of direct contact between nano-ZnO and bacterial surfaces in LDPE/SF/5%ZnO group increased,leading to the increased damage to bacterial surface and the leakage of more intracellular substance;(3)The release of more nano-ZnO induced the production and accumulation of more ROS in cells of LDPE/SF/5%ZnO group,which increased oxidative attack on bacteria.This work revealed the enhanced antibacterial mechanism against Pseudomonas fluorescens of antifogging agent on polyethylene films containing nano-ZnO.It showed a promising prospect of antifogging and antibacterial polyethylene films in fruits and vegetables packaging.
基金
Shanghai Green Leafy Vegetables Agriculture Research System(postharvest preservation group),China Agriculture Research System of MOF and MARA(CARS-47)
Shanghai Municipal Science and Technology project to enhance the capabilities of the platform(20DZ2292200)for the financial support.
