Structural and functional properties of chemically modified fibers from sweet corn cob bio-waste

The aim of this study was to investigate the chemical extraction and modification of bio-waste corn cob fiber. The process involved sequential alkali treatment, bleaching, and esterification using sodium hydroxide, hydrogen peroxide, and acetic anhydride, respectively. Results showed that increasing the alkalinity and hydrogen peroxide concentration enhanced the water-holding capacity (WHC) and water-swelling power (WSP) compared to the untreated fiber. In the acetylated samples, a higher concentration of acetic anhydride (AA) significantly increased WHC and WSP relative to the alkaline hydrogen peroxide (AHP)-treated fibers. Color measurements indicated that for AHP-treated fibers, the L* value increased, while a* and b* values decreased compared to the raw fiber, suggesting a decrease in chromophoric content due to lignin degradation. Fourier-transform infrared (FTIR) spectra exhibited a distinct peak at 1754.19 cm⁻¹ in the acetylated fibers, corresponding to the C=O stretching vibration of the acetyl group confirming successful acetylation. Scanning electron microscopy (SEM) revealed that AHP treatment disrupted the compact surface of the raw fiber, forming a more open and porous structure. With increasing AA concentration, the fiber surface exhibited greater separation and deeper cavities, which likely contributed to the higher WHC and WSP values observed. The TGA results revealed that the acetylated sample had an equal thermal stability compare to AHP-treated samples. Overall, the chemical modification of corn cob waste fibers substantially improved their structural and functional properties, providing a sustainable approach for valorizing agricultural waste and highlighting their potential as value-added ingredients for food formulation applications.