Modified Chitosan Films with CPH-based additives for Food Packing Applications

Abstract

Chitosan films designed with the addition of fillers have been widely studied for their potential application in numerous fields. In this project, chitosan nanocomposite films were prepared using additives extracted from cocoa pod husk (CPH). High molecular weight chitosan was used as the matrix, and cellulose nanocrystals (CNC), dialdehyde nanocellulose (DANC), and phenolic extracts (PCPH), as the functional additives. These additives were used to improve the chitosan's mechanical and barrier properties. The focus of this thesis was the extraction of CPH-additives for the processing and characterization of films for food packing applications. Cellulose was extracted via alkaline treatment combined with bleaching and enzymatic hydrolysis. FTIR analysis and X-ray diffraction studies revealed alkaline treatment derivatives in high crystalline cellulose, while the enzymatic one results in holocellulose. The three additives were blended separately with chitosan as a matrix and glycerol as a plasticizer at different ratios to obtain homogeneous films except for the DANC formulation. The microscopy study showed no CNC aggregations but did it for DANC on a micro-scale. Crosslinking was efficiently performed on DANC films by forming a Shiff base. Mechanical testing revealed decreased chitosan's tensile strength by adding 0.5% glycerol and additives, showing better performance at the addition of 3% CNC. All formulations can be UV-blockers. Moreover, barrier properties slightly improved by adding CNC and DANC, while PCPH formulated films reveal inhibition of moho growth. Chitosan-based films have the potential to be used in the food industry as bio packaging materials, with the chance to be improved to act as active packing.