Tailoring natural polymer-based microcapsules for ascorbic acid delivery: An RSM approach

Ascorbic acid is a well-known antioxidant compound with significant potential for combating oxidative stress. However, its application is limited due to poor stability and susceptibility to degradation under environmental conditions. To address this limitation, microencapsulation was employed as a protective strategy to enhance the stability and functional delivery of ascorbic acid. This study aimed to optimize the microencapsulation conditions of ascorbic acid using gum arabic as a natural wall material, focusing on the influence of pH and stirring time. Optimization was conducted using Response Surface Methodology (RSM), with pH values ranging from 4 to 6 and stirring times from 20 to 60 min. Encapsulation efficiency was used as the primary response variable. The optimal conditions were identified at pH 5 and a stirring time of 40 min, resulting in an encapsulation efficiency of 91 %. The microcapsules produced under these conditions exhibited antioxidant activity, with an IC₅₀ value of 73.60 μg/mL. Structural characterization using Fourier-transform infrared spectroscopy (FTIR) confirmed the successful formation of microcapsules, indicated by the presence of characteristic carbonyl (1687.21 cm⁻¹) and carboxylic (1406.24 cm⁻¹) functional groups. Scanning electron microscopy (SEM) revealed predominantly spherical microcapsules with particle sizes ranging from 1.33 to 6.54 μm. These findings suggest that gum Arabic-based microencapsulation is an effective approach to improving the stability and antioxidant functionality of ascorbic acid for potential applications in functional food and pharmaceutical formulations. • This study utilizes Response Surface Methodology (RSM) to optimize the freeze-drying microencapsulation process of ascorbic acid. • Gum Arabic was used as encapsulating wall materials, with variables including pH, stirring time and polymer concentration. • The optimized conditions significantly improved encapsulation efficiency (EE) and retained antioxidant activity of ascorbic acid. • SEM confirmed that microcapsules had smooth and spherical morphology, ideal for stability and controlled release.