DEVELOPING BIOPOLYMER-BASED FUNCTIONAL NANOCOMPOSITES FROM FOREST AND AGRICULTURAL RESIDUES FOR SMART FOOD PACKAGING APPLICATIONS

Smart food packaging is emerging as an effective solution to improve food quality and safety [1 - 6]. This technology integrates active and intelligent packaging processes in one system for food protection, containment, convenience, and communication. A smart food package consists of an intelligent layer and an active layer. The intelligent layer monitors and provides the user with information regarding the conditions of the food or its environment (e.g. temperature, pH, safety). The active layer protects the food from the outside environment and controls the amount of moisture, oxygen, carbon dioxide, or ethylene inside the package [4 - 7]. This packaging system can keep oxygen levels low and carbon dioxide levels high to impede cellular respiration or enzyme activity, preventing aerobic bacteria from multiplying in the foods. In addition to scavenging oxygen to reduce bacterial growth, the active layer can absorb ethylene to delay ripening of fresh fruits (e.g. apple, banana), thereby extending shelf life of the foods [5 - 7].The smart packaging market is currently driven by the increasing demand for improved health, safety, and authenticity in food & beverages, healthcare, personal care, and other industries [3 - 7]. However, one of the biggest challenges to implementation of smart packaging is lack of active and functional materials with effective mechanical, thermal, gas barrier, and other properties, yet are biodegradable and environmental friendly.The proposed project aims to develop an effective process to integrate biopolymer and nanotechnology to produce biopolymer-based functional nanocomposites (BFNs) from forest and agricultural residues for smart food packaging applications. The hypothesis is that appropriately dispersing specific nanoparticles in a biopolymer matrix could create a biodegradable functional nanocomposite. An innovative process will be developed to entrap specific nanoparticles (called nano-fillers) within a biopolymer-based matrix to form a new functional nanocomposite. Candidate nano-fillers molecules include inorganic nanoparticles (e.g. Ag TiO2, carbon fiber, or clay) and organic nanoparticles such as cellulose nanofiber (CNF) and cellulose nanocrystal (CNC). Candidate molecules for the biopolymer-based matrix are cellulose and/or lignin, which can be directly extract from forest and agricultural residues or recovered from the coproducts of biofuel, pulp, and paper industries. Wood sawdust and corn stover will be selected to extract biopolymers for BFN synthesis in this project. Three different nanocomposite synthesis processes, including solvent blending, thermal melting, or in-situ growth, will be tested for BFN fabrication. In the long-term, BFN materials can be tailored to specific applications including absorption and desorption of specific gases (e.g. O2, CO2, or C2H4), reduce oxygen and moisture permeability, increase mechanical strength and thermal stability, embedment of specific nanoparticles (e.g. Ag, TiO2) as antimicrobial agents or to signal undesirable levels of bacteria because of spoilage, (e.g. time-temperature labeling). The intent is to integrate BFNs into food packaging materials to develop new smart interaction packaging applications.The long-term goal of this project is to develop sustainable BNF materials from lignocellulosic biomass, such as woody biomass, perennial grasses, and agricultural residues, which are not only readily available, renewable, and inexpensive, but also environmental friendly, social acceptable, and economic feasible [7 - 12]. Therefore, production of BNF materials will be environmentally and economically sustainable. To achieve this long-term goal, five supporting objectives will be accomplished in this project.Extract biopolymers (cellulose and lignin) from corn stalks and sawdust for synthesis of BFNs;Determine the best performing nano-fillers that can fit into biopolymer-based matrices and form functional nanocomposites;Screen the best process of BFN fabrication from three nanocomposite synthesis technologies: solvent blending, in-situ growth, and thermal melting.Characterize physicochemical and functional properties of the BFNs produced and evaluate their potential for use in smart food packaging applications;Preliminarily estimate BFN production costs to evaluate the technical and economic feasibility of the best process of BFN fabrication. Optimize the BFN fabrication process to determine the best pathway for commercialization.Natural materials (e.g. wood, hemp, cotton, linen, etc.) have been used as food packaging materials for thousands of years and their use continues for some food products today. However, these materials lack the functionality, durability and uniformity required for modern smart food packaging. Currently, most materials used for food packaging are synthetic petroleum-based polymers (e.g. polyethylene, polyprolene), glass, and metal foils. These materials are non-degradable and can cause environmental problems. Attempts have been made to use biopolymers to create edible/inedible and biodegradable films to extend food shelf life and reduce food waste and packaging waste. Unfortunately due to poor performance characteristics (e.g., brittleness, inadequate gas and moisture barrier, low heat distortion temperature, and cost) such biopolymers have not achieved widespread commercial success [5 - 7, 10 - 12].These limitations of biopolymers can be addressed by integrating nano-fillers into the biopolymer matrix, thereby creating packaging materials with novel characteristics [5 - 7, 13 - 15]. Nano-fillers can improve the performance of the resulting nanocomposite materials because of their high surface area and ability to interact with the biopolymer-matrix. A uniform dispersion of nano-fillers added into a biopolymer can lead to a very large matrix/filler interfacial area, which changes the molecular mobility, the relaxation behavior and the consequent thermal and mechanical properties of the nanocomposites. In addition, nano-fillers can add new functional properties to the resulting nanocomposite, such as antimicrobial ability, enzyme immobilization, gas and moisture permeability reduction, oxygen scavengers, chemicals or bacterial sensing. These specific functional properties make nanocomposites possibly the best candidate used as smart food packaging materials [4 - 7, 9 - 13].Many efforts have been made to produce nanocomposites using cellulose nanocrystals or cellulose nanofibers [5 - 7, 11 - 14], but very few have reached commercial applications. There are currently no bio-based nanocomposites used in smart food packaging due to the lack of required properties and functionalities. Developing biopolymer-based and highly functional nanocomposite materials is necessary for smart food packaging. We are exploring effective processes to produce BFN materials for the needs of smart food packaging by integrating nano-fillers into biopolymer-based matrix. Our preliminary work has identified that cellulose or cellulose nanocrystal combined with metal ions (Ca2+ and Zn2+ ions) could generate a new biopolymer-based nanocomposite with significantly improved mechanical properties for applications in smart food packaging. If successfully developed, such a new biopolymer-based functional nanocomposite would represent a breakthrough in smart food packaging.