Preparation and Characterization of New Biodegradable Packaging Materials Based on Gelatin Extracted from <i>Tenualosa ilisha</i> Fish Scales with Cellulose Nanocrystals

Food packaging industries generally use petroleum-based packaging materials that are non-biodegradable and harmful to the environment. Eco-friendly polymers such as chitosan (CH), gelatin (GE), and cellulose nanocrystals (CNCs) are leading viable alternatives to plastics traditionally used in packaging because of their higher functionality and biodegradability. In this study, an innovative approach has been disclosed to prepare new packaging materials by utilizing chitosan, gelatin, and cellulose nanocrystals (CNCs) through a simple solution casting method. GE and CNCs have been isolated from prawn shells and jute fiber, respectively. Utilization of Hilsa <i>Tenualosa ilisha</i> fish scale biowaste was a new and first approach for gelatin extraction. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis spectroscopy, and scanning electron microscopy (SEM) were used to examine the functional and morphological features of fish scale gelatin, chitosan, CNCs, and the resulting composite films. The synthesized film materials were analyzed for their mechanical strength, solubility, apparent density, swelling behavior, biodegradability, light transmittance, and transparency. The impregnation of CNCs into the polymer amalgam milieu effectively enhanced their physicochemical and biological properties. The degree of swelling in composite matrices was found to be increased gradually, whereas the solubility was decreased due to the cross-linking effect of CNCs. Elongation at break in the gelatin-chitosan (GC) film was observed as 48%. However, the incorporation of CNCs into the GC matrix potentially enhanced the elongation at break property to 64.05%, 62.86%, and 59.21% in GC1, GC2, and GC3 bioplastic films, respectively. The purified chitosan-gelatin films showed a tensile strength of 12.24 N/mm², which was increased to 13.93 N/mm² with the addition of 1.00% CNCs. The composite films were found to be highly transparent and stable in an ambient atmosphere. However, 49-60% deformation occurred in the composite materials after 7 days, whereas 71-84% biodegradation was realized after 21 days, when the respective composite films were subjected to a natural soil environment. These novel composite films possess all essential interesting features, such as biocompatibility, transparency, smoothness of surfaces, and biodegradability, making them suitable for use as packaging materials in different industries.