Valorisation of Coffee Husk Fiber into High Performance PLA Biocomposites for Sustainable Food Packaging Applications

Agro-waste valorisation offers a sustainable route for developing environmentally responsible materials, particularly for packaging applications. In this study, coffee husk fiber (CHF), a lignocellulosic by-product of coffee processing, was chemically treated and utilised as a reinforcing agent in polylactic acid (PLA) to develop high-performance biocomposites. The CHF underwent alkaline treatment followed by benzoylation to enhance fiber–matrix compatibility by reducing its hydrophilicity. Composites were fabricated using compression moulding with varying CHF loadings (2.5%, 5%, and 7.5% by weight). The influence of fiber treatment on the mechanical, morphological, and water absorption properties of the composites was systematically investigated. Results showed a notable improvement in impact strength and flexural stiffness, particularly at 5% of CHF content treated. Water absorption was significantly reduced in treated composites, indicating enhanced durability. SEM revealed improved fiber dispersion and bonding, while FTIR confirmed successful chemical modifications. The findings demonstrate the feasibility of upcycling coffee processing waste into biodegradable packaging materials, supporting circular economy and waste reduction initiatives.