Fish oil–fish gelatin composite oleogels via emulsion templating for curcumin delivery

This study developed a curcumin-loaded oleogel system using an emulsion-templating method with fish oil as the oil phase and homologous fish gelatin (FG) from fish processing by-products as the gelling agent. The inherent compatibility between FG and fish oil enhanced interfacial stability and promoted the formation of a homogeneous three-dimensional network. The effects of FG concentration (0.1%–0.5%, w/v) on the microstructure, physicochemical properties, and in vitro digestibility of the oleogel were investigated. A stable emulsion template with uniform droplets was obtained at FG concentrations of 0.3%–0.5%. The optimal oleogel exhibited excellent oil-binding capacity (84.56 ± 4.56%) and hardness (182.95 ± 26.80 g). Under accelerated oxidation at 60 °C, the oleogel showed significantly lower peroxide value and thiobarbituric acid reactive substances levels (TBARS) than ungelled fish oil, indicating enhanced oxidative stability. The physically crosslinked, thermoreversible gel network acted as a barrier against lipid migration and oxygen diffusion, while the FG–fish oil interface improved network integrity. The oleogel also promoted curcumin protection and controlled release, achieving higher free fatty acid release (46.37%) and curcumin bioaccessibility (35.50 ± 1.90%) than conventional fish oil (38.93% and 24.00 ± 1.00%, respectively). These findings demonstrate that the oleogel is a promising delivery system for hydrophobic bioactive compounds in functional foods requiring improved stability and sustained release.