Based On The Re-assembly And Emulsification Of Casein To Improve The Stability And Bioavailability Of β-carotene

β-carotene is one of carotenoids, which is orange and found in natural foods, such as green vegetables, sweet potatoes, carrots, spinach, papaya and mango. β-carotene is an antioxidant with detoxification, It is an indispensable nutrient to protect human health and has many significant functions in prevention of cardiovascular disease, anti-cancer, anti-oxidation. However, β-carotene is very unstable and easily biodegradable under the conditions of light, heat, oxygen and so on. β-carotene has poor solubility in water at room temperature, not soluble in saliva, intestinal and other water-soluble solvents, therefore, β-carotene has low bioavailability, it is hard to mix in food formulations, all these factors limited its application in the food industry. Casein has a special supramolecular structures, can be used to delivery lipophilic biological active substances, this structure not only connect lipophilic molecules but also can effectively protect the lipophilic molecule free from degrading under the condition of heat, light, oxygen and so on. Sodium caseinate and other protein foods can be more easily adsorbed at the oil-water interface, through electrostatic repulsion and steric stabilization; it can create a more stable dispersion system, so it is a common emulsifier.β- carotene and CN can form β-CE/CN nanocomplex by self-assembly. It found that the optimum conditions to form β-CE/CN nanocomplex as follows: temperature at 40 ℃, the mass ratio of β-carotene to casein sodium protein is 1: 300, pH 7. Compared with casein, the average particle diameter of β-CE/CN nanocomplex significantly reduced, the water-soluble improved significantly. The study showed that β-CE/CN nanocomplex can be largely protected β-CE from degradation at high temperatures and ultraviolet irradiation conditions. SDS-PAGE and HPLC analysis were used to evaluate the β-CE/CN nanocomplex hydrolysates, it found that β-CE / CN nanocomplex is easily digested and β-CE gradually released, thereby it can enhance the bioavailability of β-CE.By using β-carotene and sodium caseinate to make β-CE / CN nanoemulsion, it found that the optimum conditions to form β-CE/CN nanoemulsion as follows: oil type is corn oil, homogenizing pressure at 120 MPa, the mass ratio of oil to water is 25%, and the concentration of β-CE is 0.04%. The effect of various factors on β-CE / CN nanoemulsion stability was studied, the results showed that β-CE/CN nanoemulsion has good thermal stability, storage after 15 days, the nanoemulsion particle diameter slightly increased but no significance, and the pH and ionic strength had little effect on its stability. By simulating human gastrointestinal tract digestive system, including mouth, stomach and small intestinal, the ζ potential value and the particle size of β-CE/CN nanoemulsion were analyzed, and morphology confocal microscope of each digestion period was observed, it found that β-CE/CN nanoemulsion mainly digested in the stomach phase, during the digestive process, due to the presence of protease and lipase, the free fatty acids and β-CE was gradually released. Therefore, the bioavailability of β-CE improved.In order to produce yogurt riched in β-CE, the β-CE/ CN nanocomplex and β-CE/CN nanoemulsion was added to milk, respectively. The water holding capacity, hardness and rheological properties were analyzed. The results showed that β-CE/ CN nanocomplex has little effect on yogurt, the hardness and water holding capacity increased with the concentration increase of β-CE/CN nanomulsion, the water holding capacity, hardness and flexibility of nanoemulsion of yogurt also increased with the concentration increase of β-CE/CN nanemulsion, and the clotting time became short.