Designing microstructure for improved quality: Texture and stability optimization in galangin-loaded bigels

This study comprehensively investigates the structure-function relationship of bigels tailored by varying oleogel-to-hydrogel ratios (3O:7H, 5O:5H, and 7O:3H v/v) for the delivery of the model bioactive compound, galangin (GAL). Through microstructural, spectroscopic, rheological, and in vitro analyses, it was shown that the ratio of oleogel/hydrogel greatly influences the physicochemical, mechanical, digestive, and release properties. The 5O:5H bigels exhibited excellent structural stability, optimal swelling behavior, and IDDSI Level 5-6 compliance, making it suitable for dysphagia-friendly foods. FTIR and XRD analyses confirmed the role of monoglyceride in promoting β-sheet formation and crystalline network development, while LF-NMR and rheology revealed composition-dependent water distribution and viscoelastic behavior. During in vitro digestion, hydrogel-rich bigels exhibited faster lipid digestion and greater FFA release, with cumulative FFA release decreasing from 93.87% in 3O:7H to 56.32% in 5O:5H and 52.80% in 7O:3H. In contrast, oleogel-rich systems showed slower lipid digestion, suggesting improved potential for controlled release. Electronic nose results further highlighted temperature- and composition-dependent volatile release profiles. Overall, this work establishes that bigel composition can be precisely modulated to meet specific requirements in functional foods and pharmaceutical formulations. The 5O:5H bigel, conforming to IDDSI Level 5-6, is identified as the optimal formulation for dysphagia-friendly food due to its excellent structural stability and swallowing safety. The 7O:3H bigel exhibits superior sustained-release capacity and high bioavailability, making it the optimal candidate for controlled delivery of GAL. These findings provide a theoretical basis for the precise formulation design of bigels.