Preparation Of Millet Starch Octenyl Succinate Pickering Emulsion And Study On Curcumin Loading

Millet contains 51% and 79% starch,which is rich in starch,and the raw material is easy to obtain and renewable.The millet starch particle size is small,about 7 ～ 12 μm,which can be used as a particle emulsifier to construct Pickering emulsion.But at present,there are few studies on millet starch.In this paper,millet starch was esterified with octenyl succinate on the basis of ultrasonic pretreatment,and a new type of Pickering emulsifierOSA modified millet starch was constructed.Pickering emulsion was prepared and the effects of starch particle concentration and oil-water phase ratio on the stability of the emulsion were investigated.Then it was applied to the entrapment of curcumin to explore the protective delivery characteristics of curcumin in OSA millet starch-based Pickering emulsion.The main results are as follows:(1)The effects of different ultrasonic power on the structure and properties of millet starch and OSA millet starch were studied.Ultrasonic treatment had an effect on the structure and morphology of millet starch.the crystallinity of millet starch decreased and the surface morphology of millet starch was damaged,especially under the condition of high power ultrasound.Ultrasonic pretreatment improved the degree of substitution and substitution efficiency of OSA millet starch,the degree of substitution increased from0.0165 to 0.0184,and the substitution efficiency increased by 8.21%.In addition,the threephase contact angle of the original starch was 35.07°.After OSA modification,it was amphiphilic due to the introduction of hydrophilic carboxylic acid group and lipophilic alkenyl long chain.The three-phase contact angle of OSA millet starch was 50.18°.Ultrasonic pretreatment further increased the three-phase contact angle of OSA millet starch from 50.18°to 59.01°.(2)The effects of starch concentration and oil-water phase ratio on the stability of OSA millet starch-based Pickering emulsion were investigated.With the increase of starch particle concentration,the emulsion particle size decreased from 2051.67 nm to 720.83 nm,the emulsion index increased,the apparent viscosity increased,and the emulsion stability was enhanced,and the emulsion was basically stable when the particle concentration reached 5%;with the increase of oil phase ratio,the emulsion particle size increased,from638.11 nm to 2967.35 nm,the emulsion index increased,the apparent viscosity increased,and the emulsion stability enhanced.(3)The protective and delivery properties of curcumin by millet starch and OSA millet starch Pickering emulsion were studied.The release effect of curcumin in oral,gastric and s mall intestinal digestion stages was studied by in vitro digestion simulation test.Compared with the original starch,OSA millet starch improved the loading rate and bioaccessibility of curcumin,the loading rate increased from 43.86% to 90.38%,and the bioaccessibility increa sed from 9.52% to 23.49%.At the same time,OSA millet starch-based Pickering emulsion has higher free fatty acid release and higher storage stability,indicating that OSA millet star ch-based Pickering emulsion has great potential for the entrapment and delivery of bioactive substance curcumin.