Fabrication And Regulation Of Astaxanthin-based Delivery Systems

Astaxanthin,a nutrient of the carotenoid family,its special chemical structure makes it possess strong physiological activity,such as antioxidant,anti-diabete,anti-cancer.However,the particular structure of astaxanthin also makes it have defects,for instance,weak stability,inferior solubility and poor biological accessibility.Therefore,its application in cosmetics,health products or food fields has been greatly limited.Encapsulated delivery systems are used to protect nutrients,this technology can promote the solubility of nutrients,optimize its stability,and promote its ability to be absorbed and utilized by the human body.Thus,the encapsulated delivery system is used to protect astaxanthin,which can broaden the application of astaxanthin in variety fields.Meanwhile,this study could provide the theoretical basis for encapsulation of other fat-soluble nutrients.The main research contents and results were indicated as follows:1.At first,the preparation of astaxanthin microcapsules was optimized using emulsion solvent evaporation and spray drying methods methodologies.The encapsulation efficiency,moisture content,bulk density,repose angle,antioxidant and cytotoxicity of microcapsules were also measured.The results showed that the sizes and Zeta potentials of dispersions and microcapsules were lowest at 1 wt% polylactic acid content.The highest encapsulation efficiency of the microcapsules was 70.82%at polylactic acid concentration of 2.5 wt%.The moisture content values,flowability,and bulk density of the obtained microcapsules decreased with increasing polylactic acid content.Furthermore,the cell culture experiment indicated that the obtained microcapsules had no cytotoxicity in specific dose and possessed excellent antioxidant activity.2.The hydrophobic deep eutectic solvent based on thymol and lauric acid was used as solvent to dissolve astaxanthin.The oil-in-water(O/W)emulsions were prepared by using astaxanthin-hydrophobic deep eutectic solvent solution as oil phase and gelatin/gum Arabia mixture as water phase.Meanwhile,the morphology,stability,rheological property and bioaccessibility of obtained emulsions had been considered.The results revealed that the particle size of the emulsion was small and homogeneous when the gelatin/gum Arabic mass ratio was 5:1(w:w)and emulsifier mass fraction was 1.5 wt%.The rheological study showed that the emulsions had a shear thinning behavior and gel-like properties.Moreover,the astaxanthin retention rate of obtained emulsions was maintained 83% during 20 d storage which was better than the reported studies(50.4%-79.25%),and the astaxanthin retention rate of control group was 78%.The astaxanthin bioaccessibility of encapsulated group was increased to37% than that of control group.3.This work used hydrophobic deep eutectic solvent-astaxanthin mixing solution as oil phase,gelatin/gum Arabic mixture as water phase.Using complex coacervation and spray drying to fabricate astaxanthin-loaded microcapsules.The optimizing p H for complex coacervation and the effect of different core/wall ratios on the prepared complex coacervate and microcapsule were explored.The morphology and rheological properties of complex coacervate were studied.In addition,the morphology,physical properties,encapsulation efficiency,bioaccessibility,and thermal stability of microcapsules were considered.The results showed that the best complex coacervation was fabricated by gelatin/gum Arabic at ratio of 1:1 with p H of4.1.The encapsulation efficiency,water content,flowability,and bulk density of microcapsules increased with the decreasing core/wall ratio.The bioaccessibility of microcapsules was improved after encapsulation.