Research On The Microencapsulated Mandarin Oil Preparation Technology And The Physicochemical Property Of The Microcapsule

In view of the characteristics of mandarin oil that is highly volatile,oxidized,and degraded,this paper uses microcapsule technology to encapsulate mandarin oil by spray-drying method and freeze-drying method respectively.The encapsulation efficiency of mandarin oil microcapsule is the core investigation index.In this paper,mandarin oil is used as the core material,and the compound wall material are gum arabic and maltodextrin（DE 10-15）.The compounding ratio is 1:1.8,the core wall ratio is 1:4,and the shear emulsification speed of 10000 rpm（10 min）.The mandarin oil emulsion was prepared under the above conditions,which was allowed to stand at room temperature for 24 h without delamination.Therefore,the mandarin oil emulsion has good stability.The mandarin oil microcapsules were prepared by spray-drying method,first the mechanism of the influence of the core wall ratio,the inlet air temperature,the feeding speed and the emulsion solid content on the encapsulation efficiency of the microcapsules was studied through a single factor experiment.Then based on the single factor experiment,construct and analyze the response surface model.The p-value of the model is less than 0.0001,indicating that the constructed model is significant to the response value.The R²_adj of the model is 0.9704,indicating that the constructed model can explain 97.04%of the response value.The best process parameters through response surface experiment are:inlet air temperature 194℃,feed rate 90.2 mL/min and solid content 34.7%,predicted encapsulation efficiency 89.7868%.Under this process parameter,the actual encapsulation efficiency was 90.17%,was basically consistent with the theoretical prediction.The mandarin oil microcapsules were prepared by freeze-drying method,first using resistance method to determine the eutectic point temperature of mandarin oil emulsion is-11.6℃,determining the pre-frozen temperature to-30℃.And then,according to the saturated vapor pressure curve of ice,the chamber pressure was select to 0.300 mbar.Under this process parameter,the encapsulation efficiency was 82.48%.The physicochemical property（sensory properties,fluidity,moisture content,microstructure,encapsulation efficiency,glass transition temperature and thermal stability）of mandarin oil microcapsule products prepared by spray-drying method and freeze-drying method were evaluated and compared.Both spray-drying product and freeze-drying product are light yellow,with a light mandarin aroma.The spray-drying product is more regular spherical,delicate,dense capsule wall and resulting in a high encapsulation efficiency;The freeze-drying product is irregular and thin,loose and rough,the original emulsified structure destroyed in pre-frozen,resulting in a low encapsulation efficiency.Compared with spray drying,freeze drying takes a long time and consumes a lot of energy.The freeze-drying product only has a slight advantage in moisture content and fluidity.There is no obvious difference in glass transition temperature and thermal stability between spray-drying product and freeze-drying product.Both products have certain heat resistance,which can reduce the heat loss of core materials in processing applications.