Tailoring the Properties of Arabinoxylan-Based Films from Corn Fiber

Corn fiber, an abundant agro-industrial residue from the starch industry, is a rich source of arabinoxylan (Ax), a polysaccharide with inherent film-forming capabilities and prebiotic potential. Films produced directly from arabinoxylan extracts already possess interesting functional properties, including inherent antioxidant activity and a natural UV/visible light barrier. However, for broader application in areas like food packaging, two key characteristics were targeted for improvement: the intense brown color of the extracts, which may not be appealing to consumers, and the high water-sensitivity of the films. This thesis presents a comprehensive strategy to valorize corn fiber by developing arabinoxylan-based films with enhanced aesthetic appeal and water resistance. Initially, arabinoxylan was extracted from corn fiber using an alkaline solution and purified, yielding a polymer primarily composed of xylose (50–52%) and arabinose (37–39%) with an arabinose to xylose (A/X) ratio of 0.72–0.77. During the purification, the smaller compounds (including some phenolic compounds) were partially removed, and this significantly enhanced the extract's antiproliferative effect against the HT29 cell line (EC50 = 0.12 ± 0.02 mg/mL) without cytotoxicity to Caco-2 cells. To create a more neutral-colored film and broaden its consumer appeal, a novel decolorization strategy was developed using the macroporous resin MN102. The adsorption process was systematically optimized, demonstrating high color removal efficiency (initial removal of 63.3%) and excellent reusability of the resin over multiple cycles. The adsorption mechanism was best described by the Freundlich isotherm model, and fixed-bed column breakthrough curves were successfully fitted with the Yan and log-Gompertz models, providing a robust framework for scalable decolorization. To overcome the polymer's inherent hydrophilicity, Ax was chemically modified via acetylation, substituting hydroxyl groups by acetyl groups. This modification, confirmed by infrared analysis (FT-IR), resulted in a polymer and corresponding film with improved thermal properties and enhanced the film's water resistance. Acetylated Ax films plasticized with triacetin exhibited a reduction in water solubility (from 96% to 4%), and a significantly lower water vapor permeability ((0.65±0.07) ×10⁻¹¹ mol·m·m⁻²·s⁻¹·Pa⁻¹) compared to unmodified AX films ((2.89±0.35) ×10⁻¹¹ mol·m·m⁻²·s⁻¹·Pa⁻¹). The acetylation process also resulted in light-colored films (ΔE*ab = 31.09) and maintained their mechanical integrity. In conclusion, this research successfully integrates extraction and purification, resin adsorption, and chemical modification to enhance the functional properties of arabinoxylan. By systematically addressing the challenges of consumer appeal and water sensitivity, this work transforms a low-value by-product into a high-performance biomaterial, yielding light-colored, hydrophobic films with significant potential for sustainable food packaging applications.