The Development of Food Polymer-Based Nanocomposites as Novel Antimicrobial Agents and Sustainable Packaging Materials
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Nanocomposites developed from food polymers are an emerging technology, which has shown plenty of promising applications in worldwide food related markets. The dissertation first investigated how protein modification determined structural and functional properties of nanocomposites. The study then developed simple preparation methods for food polymer nanocomposites with two potential novel applications, including low toxic antimicrobial agent and high performance sustainable packaging material. First, the study investigated the effects of chemical modification on protein structures and properties. The glutamine rich protein, zein, was selected to study how deamidation via acid and base may affect structural, mechanical, and antioxidant properties of zein. High cysteine protein, alpha-lactalbumin (ALA), was then used to investigate how redox modification of cysteine groups may determine the functional property of ALA. The first potential application of food polymer nanocomposites is to lower the toxicity of silver-based antimicrobial agent. Although silver has renowned broad-spectrum antimicrobial activities, the use was still restricted by its toxicity from low biocompatibility and argyria (skin discoloration). In this study, silver-zein and silver-ALA nanocomposite showed promising capability to substantially reduce the toxicity of silver. The silver/protein nanocomposites may find a solution for the current challenge of silver-based antiseptics. Another potential application of food polymer nanocomposites is to modify sustainable film made of food polymers to develop biodegradable plastic materials with improved mechanical and barrier properties. Theoretical studies have proven that a well-ordered nanocomposite structure could provide maximum functionality improvement, but such structure was largely unachieved. A simple and cost effective method was developed in this study using ferromagnetic nanoplatelet as nanofiller materials to achieve highly-arranged structure. Thus prepared zein/Fe3O4 nanocomposite had improved mechanical and gas barrier properties.