Study On The Preparation Of Ultra-high Oil Load Powdered Oil By Spray Drying Pickering Emulsion

In addition to maintaining the inherent properties of oil,powdered oil has the extra functions of alleviating oil droplet oxidation,extending shelf life,masking the offflavor,and improving the transportation and storage of oils.Powdered oil has been widely used in the food industry and spray drying is the most commonly used production method.However,the oil load of powdered oils based on conventional emulsions is generally lower than 60%,which cannot meet the demand on powdered oil with high oil loads.Solid particles have excellent emulsifying ability and the Pickering emulsions stabilized by them are potential in the production of high oil load powdered oils by spray drying.Polyelectrolyte complexes formed by the electrostatic interaction between proteins and polysaccharides are considered the most promising Pickering stabilizer in the food industry.In preliminary works,we found that the polyelectrolyte complex formed by ovalbumin(OVA)and gum Arabic(GA)has strong emulsion stabilization ability and the resultant Pickering emulsion could be spray dried to produce powdered oil with ultra-high oil content.Hence,the production of oil powder with ultra-high oil content based on the Pickering emulsion stabilized by the OVA-GA polyelectrolyte complex was studied in the current work.The conditions for preparing Pickering emulsion using the OVA-GA complex as the stabilizer were optimized by selecting perilla seed oil as the core material,and the spray drying process as well as the measure to improving oil powder quality were explored to obtain oil powder with oil load 80%,low surface oil content,and excellent fluidity.The conclusions of this paper are as follows:(1)OVA could complex with GA and the interaction was affected by mixing ratio,p H,ionic strength,and temperature.The optimal conditions for the interaction between OVA and GA were OVA to GA mixing ratio 3:2 and p H 3.5 in the absence of Na Cl,and the optimum conditions for OVA-GA complex with the highest emulsifying activity were OVA to GA mixing ratio 1:1,p H 3.5,and total biopolymer concentration 0.1% in the absence of Na Cl.(2)The total biopolymer concentration greatly affected the interaction between OVA and GA as well as the composition,emulsifying ability,rheological properties,and secondary structure of the resultant complex.The interaction between OVA and GA was inhibited in total biopolymer concentration of 3% or higher.The OVA-GA complex was spherical in morphology and total biopolymer concentration 4% conferred the best dispersion and Pickering emulsion stabilizer ability to the OVA-GA complex.(3)The conditions for preparing perilla seed oil Pickering emulsion with %,4%and 6% OVA-GA polyelectrolyte complex were optimized.Compared with the conventional emulsion,the Pickering emulsions were more stable against storage,freeze-thaw cycling,and oxidation,but its viscosity was more sensitive to total solid concentration variation.(4)The Pickering emulsion stabilized by OVA-GA polyelectrolyte complex could be spray dried to produce perilla seed oil powder and the optimum conditions were inlet air temperature 160 °C,feeding speed 5 m L/min,and total solid concentration of the emulsion 10%.Under such conditions,the surface oil of the oil powder was 18.96%,the oil load was 76.73%,the embedding efficiency was 75.29%,and the powder yield was 67.90%.Compared with the oil powder derived from the conventional emulsion,the Pickering emulsion-based oil powder was more effective in protecting the core oil and more uniform in size distribution and had better rehydration and fluidity.(5)Measures to reduce the surface oil content of the perilla seed oil were concerned.Replacement of partial OVA-GA complex with gelatin could effectively reduce the parameter to 9.41%.(6)Addition of gelatin before the homogenization of the primary emulsion could effectively reduce the viscosity of the perilla seed oil emulsion and increase the total solid concentration of the emulsion to 20%.Under the optimized conditions,the resultant perilla seed oil microcapsule had an oil content of 77.84%,surface oil content of 9.90%,powder yield of 76.08%,and oil content less than 4% with good rehydration and fluidity.In conclusion,the spray dried Pickering emulsion stabilized by OVA-GA polyelectrolyte complex could produce perilla seed powder with oil content of up to77.84% with surface oil content 9.90%.The process conferred a total solid concentration of 20% to the emulsion and powder yield of up to 76.08%.Hence,the process had a good industrial application prospect.This work enriches the theory of protein-polysaccharide polyelectrolytes interaction,expands the application scope of Pickering emulsions stabilized by protein-polysaccharide polyelectrolyte complex in the food industry,and provides a new choice for the production of high oil content powder oils and fats.