| Compared with synthetic pigment, natural pigment is not only safe, natural-colored, but most of them have biological activity and pharmacological function. It has already become the focal point that world has competitively developed,and is a main trend of the development of food additives.With strong growth and reproduction capability, long flowering period, bright colors, rich materials easy to obtain, The extraction of pigment from Mirabilis jalapa L. has good social and economic significance,and broad prospects. In this paper, using the red flowers of Mirabilis jalapa L. as material, the optimum conditions of extracting pigment by lixiviating and ultrasonic was researched,the method of purifying pigment was explored,the structure of pigment was qualitatively identified,the interrelated physical and chemical property of the pigment was studied.After choosing the preferred solvent for extracting red pigment of Mirabilis jalapa L., it determines to use 30% ethanol solution as the extracting solvent.The maximum absorption wavelength of the pigment extracted with ethanol solution is 536nm. Through the orthogonal test for leaching pigment, it showed that the size of the effect four factors on the extraction was:A (temperature)> C (ethanol concentration)＞B (ratio of material to liquid)> D (time). In addition, the effect of temperature and ethanol concentration on the extraction was extremely significant,and the ratio (material to liquid) and time was general significant. The best extracting conditions were A1C2B3D2:temperature was 30℃; ethanol concentration was 30%; ratio of material to liquid was 1:60 g/ml; time was 1.5h. On the best extraction conditions, the extraction effect represented by absorbance A was 0.403. After doing the orthogonal test of ultrasonic extraction, it could get the affecting size order of four factors:B (ratio of material to liquid)> D (time)> A (temperature)> C (ethanol concentration). Compared with the lixiviating experiments, the sequence is different and the effect of four factors on ultrasonic extraction were all extremely significant.The optimal extraction conditions were B3D2A2C2:ratio (material to liquid)-1:60g/ml, time-30min, temperature-50℃, ethanol-30%. On the best ultrasonic extraction conditions,the extraction effect represented by absorbance A was 0.457,which showed that the ultrasonic extraction was much better than the lixiviation because the extraction percentage was not only higher but it also saved more time.The color value of the pigment's crude products was only E1cm1% (536nm)=0.6,after using ethanol solvent to gradientily precipitate and remove the proteins, polysaccharides, starch and other impurities,the color value got E1cm1% (536nm)=2.6. Then used amberlyst of AB-8, HPD-450 HPD-600 to adsorb and remove the impurities in solution of the pigment, filtered it and then used the ADS-7 adsorb again,finally desorbed it with 30% ethanol solution, the color value reach E1cm1% (536nm)=10.8 which increased 18 times compared with the crude product..After the identification of the pigment by its characteristic and the UV and IR spectra analysis, it could conclude that:the red pigment of the Mirabilis jalapa L. belongs to anthocyanin; its molecule has acyl structure which make the molecule structure stability; it is a single anthocyanin 3-substituted, without methoxy, so it can not be Malvidin, Peonidin and Petunidin.The physical and chemical properties of red pigment from Mirabilis jalapa L. has been studied,the result shows that:The Mirabilis jalapa red pigment can be dissolved in polar solvents and is water-soluble;It is purple-red when acidic.blue-green when alkaline,and it is better to be preserved in about PH5 and 6;The higher the temperature is.the faster the pigment degrade,so it is better to be kept at low temperature; It is greatly affected by UV light and outdoor sunlight, slightly affected by indoor natural light,so it is better to be protected from light; These common food additives,sorbic acid potassium, sodium benzoate, sucrose and glucose etc., have little effect on pigment; The destructiveness of Na2SO3 and sodium D-erythorbate to the red pigment of Mirabilis jalapa L, is very great,so it should refrain to add it to them while producing and applying,H2O2 does not affect its stability large; Na+, Ca2+,Mg2+Al3+,Zn2+and K+have little effect on the stability of the red pigment except Pb2+,so it had better not to use lead container keeping it,while avoiding contact with the chemical reagent and something else carrying much lead. |
