Preparation Of Octenyl Succinic Corn Starch Ester By Semi-dry Method And Its Emulsification In Pickering Emulsion

Octenyl succinic starch ester,as a kind of chemically modified starch,has good emulsify character and thickening properties.It is used in food,medicine and industry fields widely.However,the study in preparation methods,performance index and applications of octenyl succinic starch ester still needs to be further improved.In this paper,corn starch was taken as the research object,the preparation method and structural characterization of octenyl succinic corn starch ester were studied.Then,the starch ester was nanocrystallization by alcohol precipitation method and used as emulgator to explore the influence of starch ester nanoparticles on the emulsifying property of Pickering emulsion.The specific research contents are as follows:1.Octenyl succinic corn starch ester was prepared by semi-dry process with corn starch as raw material,Na₂CO₃as catalyst and octenyl succinic anhydride as esterification agent.The influence of different factors on esterification reaction was studied,on the basis of single factor experiment,response surface methodology was used to optimize the preparation process conditions,and obtained the optimal process parameters:Na₂CO₃dosage of 1.6%,dilution ratio of 2.65:1,reaction temperature of139°C,reaction time of 99.5 min,and the degree of substitution of octenyl succinic corn starch ester at 6.1755×10^-3±2.87×10^-5.2.The structure of the octenyl succinic corn starch ester was analyzed by Braband viscosity（Braband）analysis,fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）,H-nmr spectroscopy（¹H-NMR）,scanning electron microscope（SEM）and contact angle.Braband viscosity analysis showed that the introduction of octenyl succinic anhydride group had some influence on the gelatinization properties of octenyl succinic corn starch ester.FT-IR showed that octenyl succinic anhydride group was successfully introduced into corn starch molecules.X-ray diffraction confirmed that the esterification mainly occurred in the amorphous region of corn starch.SEM indicated that esterification occurred on the surface of corn starch particles.The¹H-NMR spectra of octenyl succinic corn starch ester showed that the introduction of octenyl succinic anhydride group resulted in the formation of a new small peak at about1.06 ppm.Contact angle analysis showed that the introduction of octenyl succinic anhydride group enhanced starch ester hydrophobicity.3.Octenyl succinic corn starch ester were used as raw materials,octenyl succinic corn starch ester nanoparticles were prepared by alcohol-deposition,and the appropriate emulsifier were selected from corn starch,corn starch nanoparticles,octenyl succinic corn starch ester and octenyl succinic corn starch ester nanoparticles according to the emulsion layer height and emulsification property of Pickering emulsion.The results showed that the octenyl succinic corn starch ester nanoparticles were the best emulsifiers.When the degree of substitution of octenyl succinic starch ester nanoparticles was 6.1416×10^-3,the oil-water ratio of the system was 1:1,and the particle concentration was 3%,the Pickering emulsion with strong stability could be prepared.The microstructure showed that the droplets of Pickering emulsion were complete and It was regular sphericity,the changed trend of the emulsion droplet size was consistent with the particle size.