Harnessing plum (Prunus domestica L.) processing wastes for the fabrication of bio-composite edible films: An attempt towards a food circular bioeconomy

This study investigated the effects of different biopolymer matrices on the quality characteristics of edible films produced from plum kernel protein isolate (PKPI), arrowroot starch (ARS), and plum kernel oil (PKO). All eight film-forming matrices produced a self-supporting and peelable film. Among the formulations tested, a composite film containing 50% PKPI, 50% ARS, and 1% PKO (P50S50O) exhibited favourable features, including the highest glass transition temperature and tensile strength, which were 2.05 and 1.59-folds higher than PKPI film, respectively. The composite film (P50S50O) showed a reduced water vapour transmission rate (WVTR), permeance, and water vapour permeability (WVP) indicating a decreased affinity for moisture and an improved tortuosity of the vapour diffusion path. XRD analysis revealed a 55.75% increase in crystallinity, and SEM micrographs showed smoother and more homogeneously entrapped PKO in P50S50O films. Peak shifting in FT-IR spectra confirmed the development of additional cross-linking among various film-forming matrices, which improved the barrier, mechanical, and thermal properties of the composite films, paving the way for the prospective application of plum processing waste in the development of edible films and curbing the environmental pollution of plastics films.