Biodegradation, water sorption isotherms and thermodynamic properties of extruded packaging composed of Cassava starch with tomato peel

Abstract

In this study, we examined biodegradable packaging made from cassava starch and tomato peel and seed. We evaluated biodegradation using fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and visual analysis. Water sorption isotherms and thermodynamic properties were analyzed at various temperatures (5 °C, 15 °C and 25 °C) and humidity levels until reaching constant weight. These packages biodegrade rapidly, typically within about 18 days, in contrast to conventional fossil-based polymer packaging. During degradation, we observed visible surface changes, including roughness, hole formation, fragmentation and color alterations, confirmed by FTIR, TG and Scanning Electron Microscopy analyses. Water solubility decreased with the addition of tomato peel. The Guggenheim-Anderson-de Boer model provided the best fit for the water sorption isotherm data. Monolayer moisture content (Xm) ranged from 11.02 to 7.54 g of H2O/100 g of solids at 5 °C, from 12.99 to 8.89 g of H2O/100 g of solids at 15 °C, and from 34.93 to 16.68 g of H2O/100 g of solids at 25 °C. Thermodynamic properties revealed that lower moisture content led to higher ∆Hdiff values, indicating more active sorption sites, and higher − ∆Sdiff values, suggesting greater order in sorbed water molecules. In conclusion, our results highlight the viability of these active biodegradable packages, which degrade rapidly and exhibit adsorption behavior primarily influenced by entropy, as an environmentally friendly alternative.