College of Agriculture & Natural Resources
Permanent URI for this communityhttp://hdl.handle.net/1903/1598
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Recent Developments in Food Packaging Based on Nanomaterials(MDPI, 2018-10-13) Huang, Yukun; Mei, Lei; Chen, Xianggui; Wang, QinThe increasing demand for high food quality and safety, and concerns of environment sustainable development have been encouraging researchers in the food industry to exploit the robust and green biodegradable nanocomposites, which provide new opportunities and challenges for the development of nanomaterials in the food industry. This review paper aims at summarizing the recent three years of research findings on the new development of nanomaterials for food packaging. Two categories of nanomaterials (i.e., inorganic and organic) are included. The synthetic methods, physical and chemical properties, biological activity, and applications in food systems and safety assessments of each nanomaterial are presented. This review also highlights the possible mechanisms of antimicrobial activity against bacteria of certain active nanomaterials and their health concerns. It concludes with an outlook of the nanomaterials functionalized in food packaging.Item DEVELOPMENT OF NOVEL AG-BASED ANTIMICROBIAL MATERIALS: ANTIMICROBIAL EFFICACY AND POTENTIAL APPLICATIONS IN FOOD(2020) Mei, Lei; Wang, Qin QW; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Silver (Ag) and Ag-based compounds have been used as broad-spectrum antimicrobial agents for centuries for their great antimicrobial activities against many different strains of bacteria, fungi, and viruses. Though the development of Ag-based antimicrobial agents have made a great advancement in the past decades, many challenges remain to be addressed: 1) constructing sustained-release delivery system of antimicrobials to ensure prolonged antimicrobial efficacy; 2) reducing antimicrobial agents’ toxicity to human; 3) minimizing the risk of causing potential environmental pollution by incompletely degraded antimicrobial agents residues. To meet these challenges, two novel Ag-based antimicrobial agents have been developed: Ag nanoclusters (AgNCs) and alkynyl Ag modified CS (Ag-CS). Further studies were conducted to investigate their synthesis routes, chemical and physical properties, antimicrobial efficiencies, cytotoxicity, and potential applications. AgNCs with particle size of 2-4 nm were successfully synthesized and embedded into zein films to form a novel antimicrobial coating material. AgNCs endowed bright fluorescence with emissions between 620-650 nm and the synthesis conditions were optimized by adjusting the irradiation time, light sources, and concentrations of synthesis materials. The antimicrobial efficacy and cytotoxicity of AgNCs were then systematically evaluated and compared with those of AgNO3 as well as larger Ag nanoparticles (AgNPs) with diameters of 10 nm (AgNP10) and 60 nm (AgNP60). AgNCs presented a comparable dose-dependent antimicrobial efficacy to AgNO3, but had a significantly lower toxicity towards human cells than that of AgNO3. Further, AgNCs presented a much greater antimicrobial capacity than AgNP10 and AgNP60, which indicated that the administration dose of AgNCs for antimicrobial applications could be dramatically reduced compared to that of AgNPs. Ag-CS were prepared by modifying the alkynyl Ag group on the backbone of chitosan (CS) through chemical reactions. Experiment results indicated that Ag-CS exhibited a sustained release of Ag for over 5 days whereas Ag acetate (AgOAc) infused CS released 91.182.07 % of its Ag in 4 h. Ag-CS was proved to have potent bacteria inhibition and inactivation efficiencies that were stronger than AgOAc at the same equivalent Ag concentration. By coating on shrimps and strawberries, Ag-CS greatly extent their shelf lives under cold storage conditions.