Bio-polyethylene Composites Reinforced with Tomato Pruning-Derived Cellulose Fibers for Sustainable Food Packaging Applications

Abstract

Tomato pruning residues were valorized as cellulose fibers using a mild and sustainable soda-pulping process. This approach achieved a high cellulose content exceeding 40% and fibers with a length of less than 0.55 mm. These cellulose fibers were incorporated into bio-based polyethylene (BioPE) to develop biocomposites that exhibited enhanced properties suitable for food packaging applications. The mechanical properties of the biocomposites were optimized by adjusting the concentration of the coupling agent (MAPE). A concentration of 9% MAPE yielded the highest tensile strength, attributed to improved interfacial adhesion, as confirmed by SEM analysis. Furthermore, the integration of tomato fiber (TF) demonstrated a positive impact on the mechanical properties, resulting in a 12% increase in tensile strength and a noteworthy 109% increase in flexural strength at a 40% TF loading in comparison to pure BioPE. The presence of TF significantly enhanced the water absorption capacity of the biocomposites, achieving a remarkable increase of 4000%, while maintaining the thermal stability of the polymer matrix. The lignin inherent in the fibers contributed to antioxidant properties and reduced bacterial adhesion, particularly against S. aureus and E. coli, with optimal results observed at intermediate fiber content levels of 20–30%. However, excessive fiber loading may lead to diminished heat seal resistance due to heterogeneity introduced in the polymer matrix. The findings indicate that TF-reinforced BioPE biocomposites represent a promising sustainable material for food packaging. These materials effectively combine improved mechanical performance, bioactivity, and environmental compatibility, positioning them as a viable alternative in the packaging industry.