Preparation Of Lauric Acid Esterified Starch Granules And Analysis Of Their Pickering Emulsion Properties

Pickering emulsion has attracted wide attention because of its good biocompatibility,stability and safety in the fields of food,medicine and cosmetics.Starch,as a kind of polysaccharide with abundant resources,environmental friendliness and biodegradability,is an ideal natural polymer material for preparing "green" granular emulsifier,but its hydrophilicity and low emulsifying ability limit its direct use.Therefore,in this paper,different kinds of starch granules were selected,ethanol solvothermal method was used to prepare esterified starch with lauric acid(LA)in a closed environment higher than gelatinization temperature.A new method for the preparation of esterified starch and the stability of Pickering emulsion were studied.A stable Pickering emulsion under acidic condition was constructed by esterifying high amylose maize starch(LA-HAMS)granules with methylcellulose(MC),and esterified tapioca starch(LA-TS)granules were used to prepare high internal phase Pickering emulsions(HIPPEs).The main research contents are as follows:(1)Influence of starch composition and structure on esterification effect: Waxy maize starch(WMS),normal maize starch(NMS),high amylose maize starch(HAMS),tapioca starch(TS)and potato starch(PS)were selected as raw materials.Starch granules were modified by solvothermal esterification to prepare LA-starch granules and O/W Pickering emulsion.The results show that the solvothermal process has no effect on the morphology of granules,but it changes the crystal structure,and the crystal shape of all starches tends to be V-shaped.LA-HAMS had the best esterification,and the contact angle was 80°.Starch granules swell into dense molecular chains in the emulsion,the viscosity increases,and the emulsion is stable.After 30 days,there was no oil analysis or demulsification.(2)MC collaborates with LA-HAMS particles to construct stable Pickering emulsion under acidic condition: MC with p H insensitivity and gel properties was selected to construct emulsion with LA-HAMS to solve the instability of Pickering emulsion under acidic conditions.The results show that,compared with Pickering emulsion prepared by pure LA-HAMS or MC,the emulsion constructed by MC-LA-HAMS can still reach more than 70% after 30 days of p H 3-6,showing good stability.(3)Preparation HIPPEs from LA-TS granules: The reaction conditions were further optimized to prepare LA-TS granules with higher degree of esterification.The results showed that gel HIPPEs with oil phase volume fraction of 75% were successfully prepared at 4.0 wt% LA-TS granules.When the oil phase volume fraction is 90% or p H is 5-9,the emulsion is still stable.After 30 days of storage,the emulsions did not appear oil out and demulsification,and all were pseudoplastic non-Newtonian fluids.With the increase of LATS granule concentration,φ and p H,the viscosity of HIPPEs increased and the system structure was stable.