Molecularly reconstructed walnut oil-linseed oil based structured lipids: High sn-2 α-linolenic acid content, balanced ω-3/ω-6 ratio, enhanced stability and industrial scalability

This study aimed to optimize the fatty acid composition and sn -2 positional distribution of α-linolenic acid (ALA, ω-3) via non-regiospecific lipase-catalyzed enzymatic interesterification, using ω-6-rich walnut oil and ALA-abundant linseed oil as co-substrates. Optimized by BBD-RSM, the structured lipids (SLs) achieved 36. 29% ± 0.87% total ALA incorporation, with 29.63% ± 0.52% ALA distributed at the sn -2 position (P < 0.05 vs. physical blend), optimizing the ω-3/ω-6 ratio to 1:1.3–1:1.4. Enzymatic modification enhanced fatty acid positional distribution and with the theoretical potential to enhance ALA bioavailability, with SLs exhibiting superior physicochemical quality and oxidative stability (OSI: 3.5 ± 0.2 h at 110°C) compared to raw oils. 5-fold scale-up and 9-cycle enzyme recovery (>82% residual activity) confirmed industrial feasibility, offering a promising strategy for nutritionally balanced functional lipid development.