Elucidation of the composition structure and physicochemical stability of flaxseed oil bodies recovered from neutral...

Flaxseed oil bodies (OBs) are considered a naturally occurring delivery carrier of bioactive α-linolenic acid (ALA). This study aimed to explore the effects of water imbibition and recovery pH values on the physicochemical stability, focused on the changes in composition structure of flaxseed OBs. The results showed that flaxseed still exhibited suppressed water migration efficiency upon 24 h of hydration due to the stiff seed coat and compacted endosperm. The water imbibition led to slow swelling of cotyledon cells and intracellular OBs in flaxseed. Following aqueous extraction, the particle sizes of flaxseed OBs recovered at pH 9.0 significantly decreased, whereas the zeta potential values evidently increased (-48.81 %, +39.09 %; p < 0.05) compared with those collected at pH 7.0. Flaxseed OBs exhibited more desirable anti-aggregation and flocculation ability as evidenced by the excellently dispersed lipid droplets in both nano- and micron-sizes upon the collective pH values shifted from 7.0 to 9.0. Flaxseed OBs recovered at pH 9.0 exhibited higher elasticity, lower apparent viscosity and surface activities than those obtained at pH 7.0, concomitant with mild remodeling of the monolayer structure of phospholipids (PLs), lower retention of peripheral proteins and phenolic compounds, and weaker antioxidant activities. However, the lipolysis of PL-protein membrane and triacylglycerol cores greatly decreased for flaxseed OBs recovered at pH 9.0 during storage, which was mainly attributed to the inhibition of lipase and phospholipase A₂ activities (-59.91 %, -24.65 %; p < 0.05). Collectively, the physicochemical stability of flaxseed OBs preparations could be improved through tailoring the interface composition of OBs upon suitable seed water imbibition and recovery pHs value.