Effect of citron peel waste on thermal properties of carboxymethyl cellulase/sodium alginate edible films

Food packaging is typically manufactured from non-biodegradable plastics that possess superior characteristics, including impermeability, flexibility and cost-effectiveness. However, the lack of biodegradability of synthetic polymers has the potential to result in environmental contamination and pose a risk to human health. Consequently, to address the issue of plastic pollution, there has been a notable rise in the utilization of packaging materials with high biodegradability properties. Edible packaging is composed of substances that demonstrate greater solubility and biodegradability than conventional plastic films. Moreover, as with conventional plastics, they serve to safeguard foodstuffs from contamination and pathogens [1]. Carboxymethyl cellulose (CMC) and sodium alginate (SA) are biopolymers of particular interest. CMC is a biocompatible and non-toxic anionic polysaccharide derived from cellulose with excellent film-forming properties and is widely used in the preparation of edible films for the food industry. SA is a water-soluble and non-toxic polymer with an electronegative nature due to the presence of carboxyl groups in its structure. The combination of both with natural antioxidants and antimicrobial compounds, such as essential oils and natural agents, obtained from plants or agro-industrial residues, enhances the technical and functional properties of biofilms. Citron processing waste is considered a suitable raw material for this purpose. In particular, citron peels contain a number of bioactive components, including polyphenols and essential oils, which possess excellent antioxidant and antimicrobial properties capable of modifying the physical and thermal properties of films. The aim of this study is to evaluate the impact of incorporating varying concentrations (100 and 200 mg/100 g) of citron peel on the thermal properties of CMC and SA films.The biofilms were prepared using the casting method. The samples were subjected to DSC, TGA and FT-IR analysis. It has been observed that the thermal stability of films containing citron peels increases in proportion to the quantity of citron peel incorporated into the film. In particular, there is a shift in the maximum decomposition rate to higher temperatures (with an increase of about 8 °C for SA and 13 °C for CMC). In the ATR-FT-IR spectra, an increase in signal intensity and no noticeable change in adsorption wavenumbers have been observed, indicating that the addition of citron peels did not result in any alteration to the molecular structure. The use of citron peels as an active biocomponent in the edible films has been demonstrated to be an effective method of maintaining structural integrity of the films and enhancing resistance to degradation. This allows for its use in a multitude of environmental and temperature conditions.