Study On The Preparation And Stability Of Ulva Polysaccharide β-carotene Emulsion

Ulva fasciata is a kind of marine macro alga,abundant in the costal seashore of south China.The polysaccharides extracted from Ulva fasciata are a group of sulfated heteropolysaccharide that features high viscosity and high content of hydroxyl.β-carotene has played an important role in food products as natural colorants and antioxidants.However,their applications in food formulations are currently limited because of their poor water-solubility and instability under heat,light,and oxygen.A primary goal of this study was to formulateβ-carotene(O/W)emulsions from food-grade ingredients.The next step was to research the influence of UFP on the physical and chemical stabilities ofβ-carotene(O/W)emulsions,to broaden the application of Ulva fasciata polysaccharide(UFP)in food.The main findings of this study as following:1.The effect of UFP on the physical characteristics ofβ-carotene oil-in-water(O/W)emulsions was investigated.The results showed that the emulsions stabilized with high concentration(>2%wt./wt.)of UFP had average droplet size(D[3,2])below1.0μm,and the average droplet size had a significant decrease until the polysaccharide concentration reached 3%.Images from light microscopy and zeta-potentials of emulsions demonstrated that 3%(wt./wt.)UFP was the optimum concentration added as the emulsifying agent.In comparison with other commercial polysaccharides,including gum Arabic and gum beet pectin,the UFP revealed better emulsifying properties and improved physical stabilities ofβ-carotene emulsions.2.The effects of high temperature,pH and metal chelating agent on the chemical stability of theβ-carotene emulsion were investigated.The results show that the acidic environment and high temperature can promote the degradation ofβ-carotene;α-tocopherol and EDTA can inhibit the degradation ofβ-carotene,maintain the stability of the emulsion.Compared with GA and BP,UFP could significantly inhibit the degradation ofβ-carotene i,and ensure the stability of the emulsion.3.The results of vitro simulated digestion show that theβ-carotene bioaccessibilities in three emulsions were 37.4%,27.9%,31.6%respectivle,which higher than control oil(4.44%).The results indicated that oil-in-water(O/W)emulsions can appreciably improve the bioaccessibility.4.The effect of pH value and ionic strength on the physical properties ofβ-carotene emulsions was studied.When pH=7,the addition of Na~+can promoted the slight flocculation,which had little effect on the stability of emulsion.pH=5,the addition of Na~+will lead to instability of the emulsion.With Na~+concentration increasing,emulsion particles inside the polymerization,the viscosity decreased,emulsion stability decreased.