Utilization of coffee silverskin in the production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biopolymer-based thermoplastic biocomposites for food contact applications

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the most attracting biopolymers, nevertheless, its expensiveness has hampered its uses in daily applications. In this framework, Coffee Silverskin (CS), an agricultural residue, has been embedded in variable amounts into a PHBV matrix plasticized by acetyl tributyl citrate (ATBC) to achieve a biocomposite system through melt extrusion technique. Thermal, morphological and mechanical properties have been investigated in order to validate whether these PHBV/CS-based biocomposites can be used to manufacture molded items. The increasing concentration of CS improves the crystallinity, stiffness and heat deflection temperature properties of the biocomposite. Using the optimized formulation, coffee capsules have been produced by injection molding and characterized in terms of migration properties in contact with simulants. The overall migration at 100 °C was below the limit (10 mg/dm2) required for plastic materials at food contact. These results demonstrated the feasibility of using CS to produce high efficient PHBV/CS based biocomposites.