Beverage Emulsions Stabilized With Regenerated Cellulose:Preparation,Characterization And Stability

Stabilizing beverage emulsions against gravitational separation is usually achieved by adding weighting agents to match the densities between the oil phase and aqueous phase.However,the maximum amounts of weighing agents allowed are rather limited.Native cellulose has a highly crystalline structure stabilized by a strong intra-and intermolecular hydrogen-bond network,and its solubility in water and common solvents is poor,which limits the application of native cellulose in the food industry.By dissolving in phosphoric acid and regeneration in water,the resulting cellulose has a significantly decreased crystallinity and better property of dispersibility.In this study,we applied the cellulose regenerated from phosphoric acid in the formulation of beverage emulsions.By utilizing the Pickering mechanism and the gel nature of the regenerated cellulose,we successfully prepared beverage emulsions without the use of weight agents.The effects of preparation methods on the characteristic and the stability of the resulting emulsions were also further studied.At cellulose concentrations of 0.6 to 0.8%w/v and droplet concentrations of 1.0 to 2.0%w/v,stable citrus oil in water emulsions were prepared by ultrasound and shear homogenization.The emulsions prepared by ultrasound had smaller droplet diameter.Creaming was not observed within 1 month.Confocal laser scanning microscopy(CLSM)and scanning electron microscopy(SEM)clearly demonstrated the absorption of cellulose on the droplet surface.Thus Pickering mechanism might play an important role in stabilizing emulsion.The viscosity profile demonstrated a three-region characteristic:shear thinning-plateau or shear thickening-shear thinning,in which ionic strength and pH displayed little influence.Viscoelasticity analysis confirmed the gel nature of the resulting emulsion was not affected by temperature,ionic strength and pH value.Such a gel characteristic might play an important role in emulsion stabilization as well.The peroxide value of beverage emulsions determined by spectrophotometer was almost independent of the pH and ionic strength,but increased with the increase of storage temperature,which might be caused by the accelerated oxidation at higher temperature.The content of added linolenic acid determined by high performance liquid chromatography(HPLC)was not affected by pH and ionic strength,but decreased significantly at higher temperature.This indicated the three double bonds in linolenic acid were prone to oxidation at high temperature.Our research discovery offered a new solution in stabilizing beverage emmulsions without the use of weighting agents,especially at relative higher droplet concentrations.Additionally,the stability of resulting emulsion was not affected by pH and ionic strength,which may find intensive applications in the formulation of functional beverage emulsions.