Application of small angle X-ray scattering in exploring the effect of edible oils with different unsaturation FAs on bioaccessibility of stigmasterol oleate

BACKGROUND Phytosterol can improve its lipid solubility, lipophilic/hydrophilic balance and bioaccessibility by esterification with fatty acids, which increases its practical application range in the food industry. In the present study, small angle X-ray scattering combined with the pH-stat in vitro digestion model was applied to continuously monitor the molecular structure evolution of mixed micelles during digestion and investigate the effect of three edible oils (olive oil with 72.41 ± 0.57% oleic, sunflower seed oil with 63.45 ± 0.78% linoleic, refined linseed oil with 51.74 ± 0.34% linolenic) on bioaccessibility of stigmasterol oleate in vitro . RESULTS The release degree and rate of fatty acids in the three edible oil systems ( k OO+ST-OA = 0.0501, k SO+ ST−OA = 0.0357, k LO+ST-OA = 0.0323) was compared. The three different edible oils had similar impact on the formation of dietary mixed micelles during the simulated in vitro digestion of stigmasterol oleate, although there were significant differences in molecular morphology and composition of mixed micelles. The results showed that the vesicles formed by linoleic oil (SO system) or linolenic oil (LO system) were easy to dissociate. The largest average number and diameter of vesicles (5.55 × 10 16 cm −3 and 2230.75 Å), the most stable vesicle structure and the fastest fatty acid release rate were observed in the OO system. CONCLUSION Compared to linoleic (SO system) or linolenic (LO system), the oleic (OO system) could facilitate the transformation of micelles to vesicles and maintain the stability of its membrane, significantly promotin the dissolution of stigmasterol and improving bioaccessibility. © 2023 Society of Chemical Industry.