Fruit and vegetable residues flours with different granulometry range as raw material for pectin-enriched...

The aim of this study was to develop biodegradable films using fruit and vegetable residue (FVR) flour with different granulometry range and pectin levels. The FVR flour was divided in three fractions, according to their granulometric distribution: A (425-500 μm), B (212-300 μm) and C (<150 μm). FVR presented heterogeneous particle size distribution and fibrous structure showing granular compounds adhered to the surface. The fiber contents decreased according to granulometry, whereas the protein content increased. The films obtained from FVR were malleable, homogeneous, yellowish, and presented high solubility (90%). The granulometry reduction and the pectin addition have significantly improved the viscosity and the yellow color of the film solutions (FS). There was decrease of solubility (50%) and improvement of the mechanical properties of the pectin-based films: decrease of elongation (16-30%) and increase of tensile strength (2.88 ± 0.79 MPa). The sorption isotherms of the pectin-FVR films evidenced the lower availability of polar groups able to work as water-sorption sites. Therefore, different residue fractions could have different applications depending on their particle size and composition, either as source of dietary fibers (the thickest fractions) or as raw material for film production.