Development And Characterization Of An Antimicrobial Packaging Film For Preservation Of Minimally Processed Fruits And Vegetables

Polylactic acid(PLA)is the most extensively researched and utilized biodegradable polyester;biodegradable and renewably derived polymers have attracted much attention due to the environmental concerns.Minimally processed fruits and vegetables require preparatory steps,such as washing,peeling,shredding,and cutting.These steps result cuts,bruises and injuries to internal tissues and fasten the respiration rate.Although the conventional packing material can reduce the loss of water to some extent,having no effect on inhibition for the growth of microorganisms.In this paper,the optimal essential oil was screened by comparing the inhibitory effect of carvacrol and AITC on the pathogen fungi in vitro which were isolated and identified from decayed cherry tomatoes during the storage.PLA composites containing AITC and TBC were prepared via cast blending.The crystallization,morphology,and mechanical properties of PLA composites were studied.The effect of the antimicrobial packing film which containing AITC on storage quality of cherry tomatoes and greengrocery were also investigated.The main conclusions of this study were as follows:1.Three kinds of pathogen fungi causing postharvest disease and rot of cherry tomatoes were isolated and identified:Geotrichum candidum,Fusarium oxysporum,and Phytophthora spp..The minimal inhibitory concentration(MIC)of carvacrol and AITC against the test strains was studied.The MIC values indicate that the carvacrol was more efficient than AITC.Due to the different release of AITC and cavacrol in.antimicrobial packing film,the effectiveness of antimicrobial packing film containing carvacrol was higher than which containing AITC against the pathogen fungi in vitro.So AITC was selected for the following experiments.2.TBC enhanced the tensile strength,ductility,flexibility and morphological stability,and decreased the glass transition temperature,permeability to water vapor and oxygen of PLA.The sample containing 7.5 wt%TBC obtained the film with higher mechanical properties and the best barrier properties.3.PLA was blended with 5 wt%AITC and 7.5 wt%TBC for the antimicrobial packing film.The effect of the antimicrobial packing film and 4? storage temperature on the quality of minimally processed greengrocery was investigated.The treatment significantly reduced the etiolation,degrading rate of chlorophyll and vitamin C,the growth of bacteria and maintained the nutrient.The antibacterial rate was 33%and 26%,respectively,storing at 4? and 10?.4.The antimicrobial packing film and 4? storage temperature inhibited the growth of the test strains:Escherichia coli,Geotrichum candidum,Fusarium oxysporum and Phytophthora spp.,the antibacterial rate was 17%,13%,8%and 7%,respectively,after stored 21 days.The treatment maintained better firmness,TSS,TA of cherry tomatoes,and decreased degradation of vitamin C.