Oleogel-based emulsions as proanthocyanidin delivery systems: Impact of fatty acid saturation and oil/water ratio on molecular packing, rheology, and bioaccessibility.

Abstract

This study investigated oil-type-dependent variations in molecular packing, crystallization behavior, interfacial properties, rheology, and oxidative stability of oleogel-based emulsions (OGEs), with a focus on correlated gradients of fatty acid saturation, and developed a delivery system to encapsulate the hydrophilic bioactive substance (proanthocyanidins, PAs). Results showed that the fatty acid saturation was associated with molecular stacking and crystal arrangement, further modulating gel strength and thermal stability. Among the tested oils, medium-chain triglyceride (MCT) based OGEs exhibited the highest oxidative stability. Varying the oil/water ratio affected thermal stability and antioxidant properties. OGEs with 60% oil phase achieved the highest encapsulation efficiency of PAs. Following simulated digestion, MCT-based OGEs with 70% - 80% oil phase exhibited enhanced free fatty acids (FFAs) release and PAs bioaccessibility. This study demonstrated that fatty acid saturation and oil/water ratio can be rationally tuned to construct a stable and efficient lipid delivery system, providing a theoretical foundation for the design of delivery systems for functional bioactive substances.