Microemulsion And Microencapsulation Of The Purple Sweet Potato Colorant

PSPC (purple sweet potato colorant) is a kind of anthocyanin pigment that is strongly hydrophilic. Thus, PSPC is not insoluble in oil and it can not be applied in fat class food. Therefore, the application field of PSPC in food industry is limited. In this study, Span80 and Tween80 are used as the the mixed surfactants to make the GTCC-Span80-Tween80 PSPC microemulsion and the corn oil-Span80-Tween80 PSPC microemulsion respectively. By drawing pseudo three component phase diagrams to confirm the mass of the GTCC、corn oil and the mixed surfactants.Based on these results, the effect of the cosurfactant species, the concentration of the cosurtactant, the mass of the PSPC and the pH value on the solubilization of water mass is also discussed. The values of the the conductivity and particle size are also tested to identify the type of the two kinds of microemulsions and measure the properties of the microemulsions respectively.To the GTCC-Span80-Tween80 PSPC microemulsion, the ratio of Span80 to Tween80: 5:5, the ratio of GTCC/the mixed surfactants:5:5, the concentration of the Glycerol:50%, the ratio of water to PSPC:10:2. The maximum solubilization water quality is 3.37g. The aqueous phase content, the PSPC content, the GTCC content and the the mixed surfactants content is 25.2%,2.1%,37.4% and 37.4% respectively. To the corn oil-Span80-Tween80 PSPC microemulsion, the ratio of Span80 to Tween80:7:3, the ratio of corn oil/the mixed surfactants:5:5, the concentration of the anhydrous ethanol:50%, the ratio of water to PSPC:10:2. The maximum solubilization water quality is 3.24g. The aqueous phase content, the PSPC content, the corn oil content and the the mixed surfactants content is 24.4%, 2.04%,37.8% and 37.8% respectively. The increase of the aqueous phase’s pH value has no significant influence on the maximum solubilization water quality. The resultsof the conductivity measurement show that when the aqueous phase quality reaches a certain value, the two kinds of W/O microemulsions will change into two kinds of B.C. microemulsions. The particle size values of the two microemulsions are less than 100nm, which declare that the two kinds of microemulsions meet the requirements.During the storage time, the particle size value of the GTCC-Span80-Tween80 PSPC microemulsion ranges from 22.6nm to 24.1nm, while the Poly value ranges from 0.351 to 0.374. The particle size value of the corn oil-Span80-Tween80 PSPC microemulsion ranges from 31.2nm to 32.8nm, while the Poly value ranges from 0.476 to 0.509. In the course of 28 days storage time, the particle size values and the Poly values of the two kinds of microemulsions don’t change significantly, so both the two kinds of microemulsions have good storage stability.Choose the malt dextrin as the wall-material to carry on the experiment of the PSPC microencapsulation. According to the single factor research, the embedding time, the embedding temperature and the ratio of the wall-material to core-material are selected to conduct the response surface research. The optimum conditions of microencapsulation are: embedding time 3.3h, the embedding temperature 28℃, the ratio of wall-material to core-material 3.06. Under these conditions, the microencapsulation efficiency is 93.46%. When opposed to light, oxygen and high temperature, the stability of PSPC is highly improved after the microencapsulation.