| Lycopene is a kind of natural pigment which has the functions of various healthcares, such as antioxidation, decreasing the risk of cancer, and increasing immunityetc. Therefore, lycopene has been widely used in food and pharmaceutical industriesin recent years. However, lycopene is unstable and vulnerable to light, oxygen andother environmental conditions because of lots of conjugated double bonds in it,which improves its oxidative degradation; therefore its applications are limited greatly.Microencapsulation can protect lycopene from the unfavorable conditions, improve itsstability and make it more convenient in its storage and applications.In this paper, lycopene microcapsules were prepared by a spray-drying methodusing a wall system consisting of soluble soybean polysaccharides. The preparationprocessing, physicochemical properties and storage stability of lycopenemicrocapsules were studied. Main experimental results are listed as follows:On the basis of single factor experiment, five independent variables of spray-dryingprocess were studied on lycopene microencapsulation, including the wall materialconcentration, ratio of core and wall material, contents of emulsifier, inlet temperature,and outlet temperature. The optimum process conditions determined by theorthogonal experiment with five factors and four levels were as follows: the wallmaterial concentration of0.28g/mL, ratio of core and wall material of1:7, contents ofemulsifier of2%, inlet temperature of160oC, and outlet temperature of88oC. Themicroencapsulation efficiency of products obtained under these conditions was91.8%by validation test.The physicochemical properties of lycopene microcapsules were investigated. Theresults were as follows: lycopene microcapsules products were dry, metalignitious andfinely disseminated. The moisture content, ash content, bulk density, repose angle,average particle size and solubility of the products were3.8%,0.38%,0.54g/cm3,36o,10μm and90.8%, respectively. The SEM showed that the appearance ofmicroencapsulated lycopene was uniform spherical without flaws of the majority, thesurface structure was smooth and compact.The storage stability of the microencapsulated lycopene was also tested bymeasuring the lycopene retention ratio under different conditions such as light, oxygen,temperature, humidity and storage under the normal condition, taking the lycopene oilresin as the control group. The experimental results showed that the lycopeneretention ratios were69.9%in lycopene oil resin and90.2%in lycopenemicrocapsules after10hours of storage in light. The lycopene retention ratios were52.4%in lycopene oil resin and82.3%in lycopene microcapsules after10hours ofstorage in oxygen. The lycopene retention ratios were16.9%in lycopene oil resin and79.2%in lycopene microcapsules after20days of storage at normal temperature. The lycopene retention ratios were17.5%in lycopene oil resin and81.7%in lycopenemicrocapsules after40hours of storage at80oC. At the30%and66%storagemoistures, the retention ratios of the two samples were not changed obviously, but thedegradation of lycopene was very significant after30d at the95%storage moisture.The results indicated that the stability of microencapsulated lycopene wassignificantly higher than that of lycopene oil resin under the same conditions.Based on classical isothermal experiment, the release kinetics of lycopene oil resinand lycopene microcapsules were investigated under different storage temperatures.The Arrhenius equation was employed to analyze the release kinetics of the twosamples and determine their periods of validity. The results indicated that thedegradation of lycopene oil resin and lycopene microcapsules both followed the firstorder reaction, and the periods of validity obtained by the t0.9law were35days and204days, respectively. |
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