Antimicrobial Edible Coating Composed of Chitosan Polyvinyl Alcohol and Zinc-Coated Halloysite Nanotubes
Date of Award
Master of Science (MS)
Molecular Science and Nanotechnology
David K. Mills
Changes in everyday activities like food packaging are required due to the global shift from a linear to a circular economy. Therefore, industrial, and institutional research centers are interested in using biodegradable materials like polyvinyl alcohol and natural raw materials like chitosan to develop novel food packaging films. Edible coating materials have been extensively researched to extend the shelf life of fruits and vegetables and reduce the risk of ingesting chemical reagents. Chitosan (CH) is widely used as a natural preservative for fruits and vegetables, but its poor mechanical, and water resistance limits its use. To improve the properties of chitosan, we prepared chitosan composite films by incorporating polyvinyl alcohol (PVA) with varying amounts of halloysite nanotubes (HNTs) and zinc oxide coated HNTs (ZnHNTs) into a 1% chitosan solution. The effects of PVA/CH blended films with varying concentrations of HNTs and ZnHNTs were assessed using SEM/FESEM, FTIR, and XRD. FTIR and XRD confirmed the presence of zinc on the HNT surface. SEM showed a rough surface that increased roughness with HNT/ZnHNTs addition. Adding ZnHNTs and HNTs improved the chitosan/PVA film's tensile strength (TS) and elongation at break (EAB) with a decrease in light transmittance. We tested the films' antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The CS/PVA/ ZnHNTs films were significantly antimicrobial over two weeks. Coatings made of PVA and chitosan (80/20 ratio) with concentrations (0, 0.2%, 0.4%, and 0.6%) of HNTs and ZnHNTs were selected for further study. The results indicated that the bio‐based films can extend food shelf life and could be used as novel active food packaging materials. Among them, the most promising film was 0.6% ZnHNTs, showing a good preservation effect.
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