Application Of Protein Materials In The Preparation Of Microencapsulation

In this thesis, protein and its derivatives were chosen as key materials to investigate their value in microencapsulation process. In order to protect unstable nutrients, we developed three kinds of new microencapsulations with extrusion dripping, spray drying and complex coacervation, respectively. After optimized the preparation conditions, the embedding effect of these microencapsulations were significantly increased. In addition, the functionality and stability of these microencapsulations were also evaluated by different characterization methods. The conclusions were drawn as follows:Alginate-casein microspheres as bioactive vehicles for riboflavin:The aim of this chapter was to develop an alginate-casein composite microsphere as a bioactive vehicle for oral administration of nutrients by a simple extrusion dripping method. Riboflavin was selected as a model drug, and the microencapsulation efficiency was raised to 97.94% after optimizing the preparation conditions by response surface methodology. Since casein was introduced, the surface became smooth and compact, and the spherical shape was more plump. In vitro release studies showed that riboflavin released completely from alginate-casein microspheres in simulated intestinal fluids, and casein matrix was hydrolyzed into bioactive peptides by trypsin.Preparation of flaxseed oil microencapsulations using spirulina as the main wall material:A new type of spirulina microencapsulations was prepared by spray drying using flaxseed oil as the core material and spirulina as the main wall material. The optimum technological parameters of spirulina microencapsulation by spray drying were as follows:air pressure was 3 bar, fan speed was 4.3 m/s, inter temperature was 190℃, feed speed was 900 ml/h, feed concentration was 10%, and the weight ratio of core material to wall material was 1:3. The microencapsulation efficiency could be up to 48.85% under these conditions. Gelatin and maltodextrin were selected as the supplement wall materials, and the microencapsulation efficiency was over 75%. Compared with commercially available spirulina powder, the oxidation resistance of spirulina microencapsulations was increased by 47.7%. Microencapsulations of flaxseed oil with compound wall material of spirulina, gelatin and maltodextrin had good thermal stability and storage stability. When the temperature increased from 40℃ to 200℃, the quality retention of the microencapsulation reached to 82.96%. Stored at room temperature for 30 days, the core material retention rate of this microencapsulation was still more than 80%.The preparation and characterization of chitosan-TPP-KGM coated CPP-Ca2+ compounds:Combining the CPP-Ca2+ compounds with complex coacervation method, the chitosan-TPP-KGM nanocapsules coated CPP-Ca2+ compounds was obtained. Simplified the fabrication process of core material, the calcium-binding ability of CPPs reached 96.98 mg calcium (Ca2+)/g (CPPs-Ca2+). The optimal preparation conditions of nanocapsules were as follows:The mass concentration of chitosan was 0.2%; the mass ratio of chitosan, TPP and KGM was 6:1:1.2; the best cross-linking time was 15 min and the temperature was 30℃. The results showed that the CPP-Ca2+ loading rate of nanocapsules was as high as 62.59% and the diameter was about 416 nm. This nanocapsules could be used in food processing with good dispersibility.