Enhanced stability and controlled release of mandarin peel bioactives formulation for sustainable nutrition and next generation food system

Abstract

This study explored the microencapsulation of mandarin (Citrus reticulata) peel extract using ionic gelation and freeze-drying to improve the stability and bioavailability of citrus bioactives. Encapsulation involved sodium alginate, maltodextrin (MD), gum arabic (GA), and Aloe vera gel powder (0.3%), with a 20:80 core-to-wall ratio. Different formulations with varying MD and GA concentrations (total 2%) were tested for their effects on encapsulation efficiency, physicochemical properties, release behavior, and storage stability. Ionic gelation produced calcium-alginate beads with good biocompatibility but lower encapsulation efficiency; IG4 (1.5% MD, 0.5% GA) showed the best results in this group. Freeze-drying with ultrasonic homogenization significantly improved encapsulation efficiency, polyphenol retention, and antioxidant activity, with FD4 showing preferred formulation. Release studies revealed a biphasic, pH-dependent release profile, and MD-GA blends enabled controlled release, especially in FD4. Simulated gastrointestinal conditions showed higher release in the gastric phase, while FD4 and FD5 provided better protection and bioavailability. Storage stability followed first-order kinetics, with FD4 exhibiting the highest stability and longest shelf life. Overall, freeze-drying was more effective, thereby supporting the valorization of citrus waste to develop functional, antioxidant-rich food ingredients.