Sustainable Recovery and Stabilization of Coconut Residues (Cocos nucifera L.) Phytochemicals via Hydrothermal Extraction and Chitosan–Alginate Encapsulation

Abstract

This study aimed to evaluate pressurized hydrothermal extraction as a sustainable strategy for recovering bioactive compounds from coconut residues. The methodology involved a continuous-flow system at varying temperatures (60, 90, and 120 °C) to optimize phytochemical recovery, followed by stabilization via chitosan–alginate encapsulation, and a comprehensive sustainability assessment using EcoScale and Path2Green metrics. The study demonstrated that pressurized hydrothermal extraction at 120 °C is the most effective condition for recovering bioactive compounds from coconut residues, yielding the highest levels of total phenolic content (41.57 mg GAE g^–1), total flavonoid content (57.52 mg CE g^–1), and total tannin content (15.37 mg TAE g^–1), along with the maximum antioxidant activity (69.74 μmol TEAC g^–1). The encapsulation process using chitosan–alginate matrices achieved encapsulation efficiencies of up to 65.47%, with dry microcapsules showing enhanced phenolic retention (26.73 mg GAE g^–1 capsules) compared to wet capsules (24.41 mg GAE g^–1 capsules). The release kinetics of phenolic compounds followed a diffusion-controlled mechanism, with lyophilized microcapsules exhibiting a higher initial release (45% within 15 min) and greater long-term stability, retaining 86.79% of phenolic content after 30 days of refrigerated storage. The environmental assessment revealed favorable sustainability metrics, with an EcoScale score of 88.10 and a Path2Green global score of 0.320, highlighting the process’s alignment with green chemistry principles and its potential for industrial applications in food, cosmetics, and pharmaceuticals.