| Phytosterol is a special functional lipid adjoint.Its poor water solubility and lipid solubility limit its application.Dietary oils have an important effect on the absorption and utilization of phytosterol and phytosterol esters,and the difference in the composition of fatty acids and triglycerides significantly affects theirbioaccessibility.At present,there are relatively few studies on the effects of fatty acids in dietary oils and phytosterol esters on the digestion and absorption characteristics of phytostigol and phytosterol esters.In order to explore the effect mechanism of dietary oils on bioaccessibility of phytosterols,this study focused on the effects of fatty acid types on the digestion characteristics of phytosterols and the colloidal structure formed during digestion,the specific contents are as follows:Firstly,in order to investigate the effects of different fatty acids bound to phytosterol esters on theirbioaccessibility,stigmasterol oleate,stigmasterol linoleate and stigmasterol linolenic esters were prepared and separated,respectively.Among them,the best reaction conditions are alkyd molar ratio 1:2,7.5% lipase(w/w,enzyme/substrate)and 45? for 15 h.Secondly,in order to investigate the digestion rule of stigmasterol esters,the in vitro simulated digestion model was optimized,and the effects of different saturated fatty acids on simulated digestion characteristics of stigmasterol esters in vitro and the bioaccessibility of stigmasterol were analyzed.The results showed that there was little difference in the digestion of stigmasterol esters with different saturation.However,in the experimental group of stigmasterol oleate(14.01%),the dissolved stigmasterol in the dietary mixture formed after simulated digestion in vitro was significantly higher than that of stigmasterol linoleate(11.11%)and stigmasterol linolenic ester(10.19%).In the study on the effect of dietary oils on the bioaccessibility of sterol esters,in the experimental group rich in olive oil(39.08%%),the content of dietary mixture of gelatina after simulated digestion in vitro was higher than that of flaxseed oil(23.64%)and sunflower seed oil(25.78%),respectively.Compared with the bound fatty acids in stigmasterol esters,the effect of dietary fat on bioaccessibility of stigmasterol was more obvious.Finally,in order to explore the molecular mechanism of the effect of different fatty acids on bioaccessibility of plant sterol esters during simulated digestion in vitro,SAXS coupled p Hstat model was used to simulate digestion in vitro,and the evolution of molecular structure of dietary mixed micelles during digestion was continuously monitored.The results showed that the three kinds of dietary oils had similar effects on the formation of dietary mixed micelles during the simulated digestion of stigmasterol oleate in vitro,but the effects on the molecular morphology and composition of dietary mixed micelles were significantly different.During digestion,the fat in the simulated digestive fluid is rapidly transformed into emulsion droplets,and then the hydrolysates assemble and accumulate on the periphery of the droplets into lamellar structures and micelles,which then further assemble into vesicles.In this paper,using the shape factor and structural factor related characteristic function model for the morphology of micelles and vesicles and number density system is analyzed,the results found that three different dietary oil system,the number of vesicles in vitro digestive juices density were higher than micelle.But mainly linoleic acid and linolenic acid dietary fat formation of vesicles easy to disintegrate,and olive oil system number of vesicles and diameter were the largest,and the structure was stable.These results suggest that dietary oleic acid contributes to the transformation of micelles into vesicles and the stability of their membranes during digestion,and can significantly promote the dissolution of stigmasterol and improve theirbioaccessibility. |
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