Eco-friendly development of biocomposite films from Durio zibethinus Murr. seeds reinforced with nanocellulose and functional carrageenan additives

BACKGROUND AND OBJECTIVES: The increasing concern over plastic pollution has driven the search for biodegradable and sustainable alternatives derived from renewable polysaccharides. However, films made from starch generally exhibit poor mechanical strength, high water sensitivity, and low thermal resistance. Durian seed starch, is an underutilized agricultural by-product that holds great potential as a film-forming matrix but has rarely been explored. To address its limitations, the study objectives were to develop and optimize composite films from durian seed.METHODS: A statistical optimization approach based on Box–Behnken design under response surface methodology was employed to investigate the effects of starch, carrageenan, and nanocrystalline cellulose on film performance. Mechanical properties were evaluated (tensile strength and elongation at break) as the main response variables. Seventeen experimental runs were conducted, and the model was statistically validated to identify significant effects and interactions among the variables. The optimum film was selected and further characterized using Fourier-transform infrared spectroscopy to evaluate functional groups, X-ray diffraction to assess crystallinity, scanning electron microscopy to examine morphology, and thermogravimetric analysis to determine thermal stability. Thickness and swelling behavior were also measured to evaluate dimensional stability.FINDINGS: Run 9 was identified as the optimum formulation, achieving a tensile strength of 2.32 mega pascal, an elongation at break of 44.94 percent, and the lowest swelling ratio of 142.39 percent. Carrageenan stabilized the starch suspension, enabling smooth film formation, while nanocrystalline cellulose reinforced the composite network by improving compactness, crystallinity, and interfacial hydrogen bonding. X-ray diffraction revealed an increase in crystallinity index from 48.14 to 55.42 percent, surface morhology showed a denser and more homogeneous morphology with fewer voids, and thermogravimetric analysis demonstrated improved thermal resistance due to restricted chain mobility and enhanced char formation.CONCLUSION: This study represents the first systematic attempt to valorize durian seed into functional biocomposite films reinforced with carrageenan and nanocrystalline cellulose. The synergistic roles of carrageenan and nanocrystalline cellulose effectively tailored structural integrity and functional properties, overcoming the common drawbacks of starch-based films. The findings highlight the potential of transforming underutilized durian seed biomass into biodegradable packaging materials, thereby contributing to sustainable strategies for reducing plastic waste.