Soy Protein Isolate-β-Cyclodextrin Microencapsulation Boosts Stability and Intestinal Delivery of α-Linolenic...

The previous study found that a structured lipid rich in α-linolenic acid (ALA-SL) is prone to oxidative rancidity due to its high degree of unsaturation. To improve its oxidative stability and targeted slow-release behavior during gastrointestinal digestion, ALA-SL microcapsules (ALA-SLMs) were prepared by freeze-drying in this study. Under optimal conditions, ALA-SLMs exhibited an excellent embedding efficiency of 98.00% ± 0.46%, with an approximately spherical structure, particle size concentrated between 1 and 10 µm, and good uniformity verified by a span value of 1.92. After 60 days of storage at 4°C, 25°C, 40°C, and 60°C, the peroxide value (PV) of unencapsulated ALA-SL was 1.02-, 1.06-, 1.01-, and 1.11-fold higher than that of ALA-SLMs, respectively. In vitro simulated digestion demonstrated its characteristic intestinal sustained-release behavior, which provides preliminary in vitro evidence that may favor enhanced intestinal absorption of α-linolenic acid (ALA); however, further cellular or animal trials are required to quantitatively validate its actual in vivo bioavailability improvement. Molecular docking predicted that β-cyclodextrin (β-CD) only forms weak shallow non-covalent complexes with ALA via cavity-mouth hydrogen bonds, which offers limited molecular-level protection for unsaturated fatty acids.