Comparative Acid Hydrolysis and Physicochemical Characterization of Agro-Food Processing Residues for Glucose-Rich Extract Production

Agro-food processing residues represent an abundant yet underutilized source of lignocellulosic carbohydrates for biorefinery applications. In this study, wheat husk, sweet lime peel, and carrot pomace were comparatively evaluated as potential feedstocks for glucose-rich extract production via dilute acid hydrolysis. The structural and compositional changes induced by hydrolysis were systematically investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), and proton nuclear magnetic resonance (¹H NMR). All three residues showed evidence of lignocellulosic disruption and saccharide release after hydrolysis, with clear feedstock-dependent differences in hydrolysis behavior and extract composition. Among the tested residues, carrot pomace exhibited the most favorable overall performance, showing stronger glucose-related spectral features, reduced structural recalcitrance after treatment, and a mineral composition supportive of downstream bioprocessing potential. Sweet lime peel also demonstrated effective hydrolysis and selective glucose-associated signals, whereas wheat husk showed comparatively lower hydrolysis efficiency, consistent with its more rigid lignocellulosic structure. These findings provide a comparative physicochemical basis for selecting agro-food residues as carbohydrate-rich feedstocks and highlight carrot pomace as a promising candidate for glucose-oriented biomass valorization and future bioprocessing applications.