UNRIPE

This study explores the extraction and characterization of starch composites derived from unripe banana (Musa spp.) reinforced with okra (Abelmoschus esculentus) fibre, with a focus on their structural, chemical, and mechanical properties. The starch was extracted from unripe bananas sourced from Evbuotubu, Benin City, while okra fibres were obtained from Oluku Market. Composite formulations were prepared by blending 10 g of banana starch with 3 g of okra fibre and plasticized using 5mL of glycerol. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed enhanced hydrogen bonding interactions in the fibre-reinforced composite, evidenced by a stronger and slightly shifted O-H stretching peak (3300–3400 cm⁻¹) and the emergence of carboxyl (C=O) functionalities around 1700–1750 cm⁻¹. Elemental analysis revealed a decrease in carbon content from 70.02% (0G fibre) to 66.88% (3G fibre) and an increase in nitrogen from 23.40% to 29.56%, suggesting the introduction of nitrogen-rich organic components from okra fibre. The presence of calcium (0.48%) in the 3G fibre composite, absent in the 0G fibre sample, indicates mineral incorporation. Scanning Electron Microscopy (SEM) images showed a denser microstructure in the 0G fibre composite, whereas the 3G fibre composite exhibited a rougher and more porous texture, indicative of improved fibre-starch interfacial adhesion. Thermogravimetric Analysis (TGA) demonstrated enhanced thermal stability in the fibre-reinforced composite, with a higher degradation onset temperature and increased residual char content, confirming its resistance to thermal decomposition. X-ray Diffraction (XRD) patterns indicated a reduction in crystallinity upon fibre incorporation, as evidenced by broader and less intense diffraction peaks, suggesting a transition to a more amorphous structure. These findings demonstrate that okra fibre reinforcement significantly enhances the mechanical strength, thermal stability, and flexibility of starch composites, making them suitable for biodegradable applications in packaging and sustainable material development.