Hierarchically Structured Gelatin Gels Incorporating Chitosan–Oleic Acid Complex Particles for Hydrophobic Nutrient Delivery

Abstract

This study developed a gelatin (GL) hydrogel incorporating fine particles of chitosan–oleic acid (CHI–OA) complex as a potential carrier material for the delivery of hydrophobic nutrients. The resulting system formed a composite gel with a hierarchical structure involving the association of oleic acid alkyl chains, particle formation through chitosan complexation, and dispersion within the GL matrix. The structural features were analyzed using particle size distribution, confocal laser scanning microscopy, and small-angle X-ray scattering. Gelation and melting behaviors were evaluated by viscosity measurements and differential scanning calorimetry, which indicated that the interactions between the CHI–OA particles and the GL matrix altered the gelation temperature and thermal properties. Compression tests further revealed that particle incorporation significantly affected the mechanical properties, including deformation and fracture behavior. As a model hydrophobic nutrient, α-tocopherol was encapsulated within CHI–OA particles and incorporated into the GL gel. The encapsulated α-tocopherol remained stable during 20 days of storage under cool and dark conditions. Our findings indicate that the developed composite hydrogel is a promising carrier platform for incorporating hydrophobic nutritional compounds into gelatin hydrogels.