Preparation and properties of fucoxanthin-loaded emulsion gel microspheres

Fucoxanthin, a marine carotenoid, suffers from poor stability under light and heat, limiting its use in functional foods. To address this, we developed a multilayer emulsion-based gel microsphere system for enhanced protection and controlled intestinal delivery. Microspheres were fabricated using whey protein, corn oil with 5% fucoxanthin, and chitosan-sodium alginate shells, followed by Ca²⁺ cross-linking. Using Box-Behnken design, optimal conditions were determined: whey protein 2.3%, oil/water ratio 4:16, chitosan 2.0%, alginate 2.6%, and Ca²⁺ 4%, achieving 77.37% encapsulation efficiency. The system achieved targeted release: only 38.9% fucoxanthin was released during 12-h simulated intestinal digestion, versus 13.25% passive degradation of free fucoxanthin. Microspheres also improved photostability (73.89% vs. 46.55% retention) and preserved antioxidant activity (75.84% scavenging retention). These findings demonstrate that the multilayer microsphere system effectively overcomes fucoxanthin's stability limitations, offering a platform for site-specific delivery of hydrophobic bioactives.