Study On Stabilizing Pickering Emulsion With Hydrophobic Wheat Bran Cellulose And Its Rheological Properties

In recent years,the use of solid particles instead of traditional emulsifiers to stabilize emulsions has received extensive attention.In this paper,the effect of wettability of nanocellulose on the stability and rheological behavior of Pickering emulsions was studied.Biomass-based and environmentally friendly wheat bran cellulose(WBC)was esterified with stearic acid to reduce its hydrophilicity,and the resulting hydrophobilized wheat bran cellulose(SA-WBC)was used as emulsifier to stabilize Pickering emulsions.The particle size of hydrophobilized wheat cellulose increased with the degree of hydroxyl substitution,while the Zeta potential decreased with the degree of hydroxyl substitution.The higher the degree of substitution was,the greater the surface contact angle of cellulose became.All Pickering emulsions stabilized by hydrophobilized wheat bran cellulose were oil-in-water type.The stability of Pickering emulsions could be improved by hydrophobic treatment of wheat bran cellulose.In this paper,the emulsion stabilized by hydrophobilized wheat bran cellulose with the degree of substitution of 0.0105 showed the best stability.The stability of Pickering emulsions was significantly enhanced with the increase of cellulose concentration.When the cellulose concentration was 1.00 wt%,the stability of the emulsion was the best.Pickering emulsions were stored at room temperature for 6 months,and the emulsions remained stable enough.The selection of oil phase had some influence on the stability of emulsion.Pickering emulsions stabilized by wheat bran cellulose and hydrophobilized wheat bran cellulose were pseudoplastic fluid and the shear viscosity decreased with the increase of shear rate.Wheat bran cellulose with moderate hydrophobility was used as Pickering emulsion stabilizer;the resultant emulsions had a three-dimensional network structure and better viscoelasticity.Cellulose concentration had a great influence on the viscoelasticity of the emulsions.The emulsion prepared by hydrophobilized cellulose with a concentration of 1.00 wt%had the largest viscoelasticity.When a certain concentration of electrolyte was applied to the emulsion,with the NaCl concentration of 17 mM,the storage modulus of the emulsion increased the most,and the emulsion had the best viscoelasticity.The emulsions prepared with oil/water ratio of 5:5 and 3:7 had a large elastic modulus and a stable three-dimensional network structure,and resultant good viscoelasticity.In summary,stable Pickering emulsions were prepared by hydrophobilized cellulose.The viscoelasticity of emulsions relates closely to its stability.The viscoelasticity of emulsions can be regulated by adjusting the concentration of cellulose,hydrophobicity,electrolyte concentration and O/W ratio.The safe and biomass-based hydrophobilized wheat bran cellulose is expected to be used as an emulsifier in cosmetics,food and medicine products.