Hydrolyzed Karaya Gum–Chitosan Complex Coacervates for Controlled Release of Ginger Essential Oil

This study aimed to develop a pH-responsive microencapsulation system using complex coacervation with chitosan (CS) and hydrolyzed karaya gum (HKG) as natural wall materials to encapsulate ginger essential oil (GEO) as a core material. Key parameters influencing coacervate formation and encapsulation efficiency were studied and optimized. The results indicated that the maximum complexation yield (77.3%) was achieved at a pH of 4.6 with a CS:HKG mass ratio of 1:2. Under these optimal conditions, microcapsules were fabricated at various wall-to-core ratios, with the 3:1 ratio demonstrating the highest encapsulation efficiency (65.73%) and process yield (75.7%). Physicochemical characterization revealed that the microcapsules possessed low hygroscopicity and a pH-dependent solubility profile. Scanning electron microscopy (SEM) showed that freeze-dried microcapsules had a more porous, amorphous structure compared to the denser, irregular particles produced by oven-drying. Crucially, in vitro release studies demonstrated a pronounced pH-responsive behavior: GEO release was significantly faster and more extensive in simulated gastric fluid (pH 2.0) than in neutral or simulated intestinal fluid (pH 7.4). These findings highlight the successful fabrication of a stable CS-HKG micro-delivery system that effectively protects GEO and facilitates its controlled, targeted release in acidic environments, indicating strong potential for applications in gastric targeted functional food and pharmaceutical products.