| Marigold is rich in carotenoids, especially lutein most abundant. Studies havefound that lutein has a lot of function which includes antioxidant, anti-cancer,cardiovascular disease prevention and the protection of eyesight, etc. Lutein inmarigold has been studied in this paper, conducted a more comprehensive study of itsextraction process, saponification,dynamic analysis and stability.The main researches are as follows:Marigold flowers is used as raw material,and xanthophylls has been extracted byusing the method of ultrasound—a mixed solvent, the content of xanthophylls hasbeen tested by UV spectrophotometry; on the basis of single factor researches,theyield of the lutein served as the response value, selecting the ultrasonic power (X1),ultrasonic time (X2) and temperature (X3) three factors,and conducting theoptimization by the response surface, then quadratic regression equation has beenobtained:Y=22.51+1.94×X1-0.85×X2-0.037×X3-0.35×X1×X2-0.25×X1×X3+0.59×X2×X3+1.48×X12+0.27×X22-4.34×X32. The optimum extraction conditions were obtained:the extraction solvent is ethyl acetate and petroleum ether (v/v=3:2), solid-liquid ratioof Marigold: extraction agent equal to1:20(g/ml), ultrasonic power is450w,ultrasonic time is35min, temperature is39.5℃, the predictive yield of lutein is27.45mg/g. Validating the optimization scheme by experiments, the actual yield oflutein was26.78mg/g. This value is close to the predictive value and indicating thatthe regression model is reliable.(2) In order to obtain the free state of lutein, lutein which is extracted byultrasound—mixed solvent has been used as raw material for the research ofsaponification process of lutein ester, the saponification reaction rate of lutein esterwas measured by thin layer chromatography (TLC). Combined with single factorresults and the response surface method of saponification value of lutein esters, thethree factors including the consumption amount of C2H5OH (X1), saponification temperature (X2) and the consumption amount of the solid of KOH (X3) was selectedto the analysis and optimization of response surface based on the saponificationreaction rate of lutein ester, then the quadratic regression equation was gained:Y=78.24+0.99×X1+1.05×X2+1.16×X3-0.48×X1×X2+0.35×X1×X3-0.13×X2×X3-1.17×X12+0.41×X22-2.92×X32. The optimal conditions of the saponification were obtainedby this equation: the consumption amount of C2H5OH (X1) is31.3ml, thesaponification temperature (X2) is60℃, the consumption amount of KOH (X3) is2.1g,and the saponification time is4h. Under this condition, the saponification reaction rateof lutein ester can be reached up to78.4%, the deviation is only minus1.8%compared with the theoretical prediction, which indicates that the analysis of responsesurface through the conditions is simple and feasible.(3) The kinetics studies of the saponification reaction of lutein ester has indicatedthat the reaction kinetics satisfy the secondary reaction, the rate constants increasewith the increased temperature, and the activation energy Ea=36.8kJ/mol.(4) The results based on the studies of the stability of lutein in marigold haveshown that the effect of light on lutein is destructive; temperature changes in a shorttime has little effect on lutein, and with the extended time, its preservation rateemerge negatively correlated tend with temperature; compared with acid/alkalinesolution, lutein under neutral condition is stable;Na+, Mg2+and Ca2+have no impacton lutein, Fe3+and Cu2+have greater damaging effects on stability, Fe2+has initiallyprotective effects on lutein, after a certain time, then becomes damaged; oxidants havesignificantly destructive effect on stability; reducers have well protective effects onthe stability of lutein; sucrose has no effect on the stability of lutein, but salad andMSG have a certain destructive effect. |
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