Abstract
Dried leaf powders of red beetroot and broad bean, prepared with different particle sizes (<500 μm and ∼1000 μm), were investigated with respect to their thermal properties using differential scanning calorimetry and thermogravimetric analysis. Kinetic parameters of thermal degradation were derived from the thermogravimetric analysis data by applying the isoconversional Friedman method. Although the samples exhibited comparable thermal behavior, kinetic analysis revealed that powders with smaller particle sizes were less susceptible to thermal deterioration, as indicated by lower rate constants (kp). Further characterization of the red beetroot and broad bean leaf powders was performed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, and Fourier-transform infrared spectroscopy. The presence of a crystalline structure was detected in the samples of fava bean leaves powder. The findings provide useful structural and compositional insights for further usage of food industry waste material, which represents a valuable source of functional food ingredients.