Optimization and Stability Evaluation of Simulating Milk Fat Globule Membrane Delivery Systems for DHA-rich Algal Oil

Objective: To enhance the bioavailability of functional substances and the stability of reprocessed products, the development of different algal oil product forms and the application of simulated milk fat globule membrane (MFGM) embedding systems in food research and development were investigated. Methods: Algal oil containing no less than 74% docosahexaenoic acid (DHA) was utilized as the main embedding component. Two types of simulated MFGM emulsification systems for algal oil were optimized through single-factor experimental design and response surface methodology. The physical and oxidative stability of these systems were evaluated using indicators including mean particle size, clarification index, and peroxide value. In vitro simulated digestion was subsequently conducted to assess sample digestion characteristics. Results: The optimal formulation process was determined to involve 10% algal oil, 0.04% vitamin E, 1.10% soybean lecithin, and 1.32% concentrated whey protein. Through sequential addition of the oil phase to the aqueous phase followed by 10000 r/min shearing for 5 minutes and 62000 kPa homogenization (5 passes), an emulsion with mean particle size of 241.3 nm was obtained. Significant improvements in physical and oxidative stability were achieved through 121 ℃ high-temperature pressure sterilization (12 minutes) and 4 ℃ low-temperature storage (P<0.05). When resistant starch was employed as the single wall material for DHA algal oil microencapsulation under spray-drying conditions (wall-to-core ratio 1.5:1.0, inlet air temperature 180 ℃), an encapsulation efficiency of 56.74% was attained for the digestion-resistant algal oil powder. In vitro digestion simulations revealed that the mean particle size of both algal oil emulsion and powder initially increased then decreased under digestive conditions. Particle size distribution analysis at different digestive stages indicated that emulsification and microencapsulation could effectively reduce gastric breakdown and digestion of algal oil, thereby facilitating increased DHA delivery to the small intestine. Free fatty acid release rate analysis during intestinal digestion demonstrated that both techniques effectively delayed oil release, with the powder form exhibiting superior sustained-release properties. Conclusion: It was demonstrated that the construction of an algal oil emulsification embedding system through MFGM simulation was feasible for improving DHA algal oil bioavailability. The developed product forms were shown to potentially enhance algal oil applications in seafood processing, nutritional fortification, and functional food development.