Stabilization Research On Microencapsulated DHA Of Algal Oil

DHA has been gradually become the investigative focus in recent years for its biological functions of improving cerebrum growth, protecting vision, dropping blood-fat and preventing arteria sclerosis. The short source of DHA and its unstability were two main concerns with the utilazation and promotion of DHA in food processing. The antioxidants and microcapsulation technology were investigated for improving their properities of DHA in algal oil and protecting thier denaturazation.The response-face model was applied to select antioxidants by using the content of TBHQ, VE and L-ascorbyl palmitate as independent variables, and the POV, acid values and DHA content as response value. The optimal combination of 0.125‰TBHQ, 0.25‰V_E and 0.175‰L-ascorbyl palmitate was showed in antioxidat ability. The effective order is VE> L-ascorbyl palmitate>TBHQ. The stability and shelflife of the DHA in algal oil were significantly improved while treated in optimized combination stored at 63±1℃for 24d.The wall-materials, emulsifiers, core-material and their concentrationes and emulsionized time were investigated for optimizing the technology of Microencasulation. The optimal microencasulation parameters were determined as following: maltodextrin+casein+β-CD being as the wall-materials, sucrose esters + monoglyceride esters + tweens-80, 35% core-material content, 1.5% emulsifier content, 30MPa homogen pressure and spray drying method.The physico-chemical of DHA microcapsule prepared with optimization was detected. It shows the product had fine dissolubility, the moisture content was 3.85%, it fit long-term storage; the microcapsule was ellipse, whose wall had relative integrity, the ultramicrostructure displayed the embedding effect well; the particle size distribution of the emulsifying liquid after homogen was 50～1000nm, the mean diameter was 246.5nm, the particle size distribution of the microcapsule was 50～1000nm, the mean diameter was 311.5nm, compared with infant formula milk-powder, its mean diameter was small and dissolved easily. The DSC curve demonstrated there was a small heat absorption hump close to 80℃and the enthalpy was only 88.2538J/g, but all the other three wall materials had heat absorption hump with higher peak area, it showed microencapsulation improved the character of raw material and the product was stable; TG and DTG curve had concordance with the same sample. TG curve showed the product loss in weight firstly at 90℃and the wall-material began degradation at 160℃.The physico-chemical property demonstrated self-made product embedded well. To certify the good stability of the product and reasonability of the optimized prescription and technic, we inspected the influence of illumination, oxygen, temperature and metal ion on the product stability and took a research on the stability self-made product beverages in chapter 5.