Constructing a Novel Oleogel Based on Decrystallization: Enhancing the Loading Efficiency and Bioaccessibility of Curcumin

Curcumin is a lipophilic polyphenol with good anti-inflammatory, antioxidant, and anti-cancer physiological activities, but lower loading capacity and bioaccessibility limit its wide application in the functional food industry. The high loading (3 wt%) curcumin oleogel was prepared using hydroxylated lecithin (H-Lec) and mono- and diglycerides of fatty acids (MDFA) as oleogelators, with coconut oil (CO) as the dispersing medium, and a heat treatment process to induce decrystallization. The effects of the addition of H-Lec and MDFA and heat treatment on the crystal structure, rheological properties and texture of the samples, and the decrystallization and bioaccessibility of curcumin were investigated. Incorporating MDFA led to a pronounced needle-like crystal morphology within the oleogel. All samples demonstrated shear-thinning properties, with viscosity decreasing as shear rate increased. The oleogel with 30 wt% H-Lec and 15 wt% MDFA exhibited the greatest hardness. While heat treatment alone could diminish the presence of curcumin crystals, it could not prevent recrystallization. However, the combined application of H-Lec, MDFA, and heat treatment enabled the complete amorphization of high content curcumin within the oleogel, significantly enhancing its bioaccessibility. The high loading curcumin oleogel prepared in this study can lay a theoretical foundation for the wide application of curcumin in the functional food and nutritional food industry.