College of Agriculture & Natural Resources
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Item DEVELOPMENT OF CHITIN NANOCRYSTALS AND THEIR APPLICATIONS IN FOOD AND AGRICULTURAL AREAS(2024) Jia, Xiaoxue; Wang, Qin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Seafood industry generates millions of tons of waste annually, with crustacean shells being a significant component. Discarding these shells not only exacerbates environmental pollution but also represents a missed opportunity for resource recovery. This dissertation research aims to address these environmental challenges by repurposing crustacean shell waste into high-value nanomaterials, specifically chitin nanocrystals (ChNCs), and exploring their applications in the food, agricultural, and environmental sectors. The primary objective of this study is to investigate the fabrication, functionalization, and potential industrial applications of ChNCs, thereby offering a sustainable alternative to conventional synthetic materials.Traditional chitin nanocrystals ChNCs obtaining methods rely on strong acids, posing environmental risks. This research introduces a more sustainable phosphoric acid (PA) hydrolysis method, which uses significantly lower acid quantities, reduces environmental impact, and avoids corrosive waste. Moreover, the novel PA hydrolysis occurs in the solid state and can be handled by hand, simplifying operation. This method efficiently yields uniform ChNCs with positive surface charges (~+27 mV), suitable for scalable industrial applications. Additionally, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidation was employed to produce oxidized chitin nanocrystals (O-ChNCs) with negative surface charges (~ −56 mV). ChNCs and O-ChNCs were investigated as stabilizers in Pickering emulsions. Both were able to significantly enhance the stability of oil-in-water (O/W) emulsions, particularly when pH > 9. O-ChNCs further demonstrated encapsulation efficiencies of up to 80% for bioactive compounds like quercetin, highlighting their potential in food and nutraceutical delivery systems. Additionally, ChNCs and O-ChNCs were incorporated into a colorimetric sensor array (CSA) to monitor beef freshness. The negative charged O-ChNC-based sensor exhibited sensitivity to spoilage gases, achieving 99.3% accuracy in beef freshness detection with the aid of deep learning algorithms. This innovation provides a non-invasive cost-effective method to food quality and safety monitoring. Furthermore, ChNCs were deacetylated to form chitosan nanocrystals (ChsNCs), and subsequently modified with zinc to create a ChsNCs@Zn composite for the removal of per- and polyfluoroalkyl substances (PFASs) from water. The composite achieved 50% PFAS removal within 5 minutes and ultimately achieved 68% removal, showcasing strong adsorption capabilities and offering a potential sustainable solution for PFAS remediation in contaminated water sources. In summary, this research is driven by the need to solve the environmental problem of seafood waste, while also tackling challenges in food stability and safety, as well as water purification. The findings contribute to advancing sustainable materials and practices in response to pressing environmental challenges.