EFFECT OF PLANT FILLERS DERIVED FROM FRUIT PITS ON THE PROPERTIES OF CORN STARCH-BASED COMPOSITES

The growth of fruit processing is accompanied by the generation of large amounts of waste, which can have adverse environmental effects. Pits from different fruits have distinctive chemical compositions, ranging from a high content of rigid lignocellulosic fibers in date and cherry pits to significant amounts of lipids (in particular, punicic acid) and antioxidants in pomegranate seeds. The incorporation of such powdered fillers can not only improve the physicomechanical properties of the starch matrix through reinforcement or plasticization effects but also impart new functional properties to biocomposites. The addition of 20% date and cherry pit powders increased the elastic modulus of the corn starch-based biopolymer by 10% and 30%, respectively. Impact strength increased from 17 kJ/m² for the unfilled sample to 28 and 23 kJ/m² for samples containing date and cherry pit powders, respectively. The pomegranate seed filler reduced these properties and exhibited a plasticizing effect. The increased water absorption observed for all samples limits the potential applications of the resulting bioplastics and indicates the need for additional modification, such as the incorporation of cross-linking agents or hydrophobic agents. At the same time, increased water absorption may contribute to enhanced biodegradability, which is advantageous from an environmental perspective.