Study On The Extraction、Purification And Stability Of Red Pigment From Jujube Peal

Zyzypus Jujube dates is one of the fruits of China, as a medicinal and edible food, its unique nutritional and medicinal values are more and more attention. And its processing products are increasingly rich, but the Jujube peel which rich in red pigment as a by-product has not been fully utilized, extracted red pigment from Jujube peel not only comprehensive utilized the resources of Jujube dates, but also provided new products safely and non-toxic for food、medicine and the cosmetics industry.In this paper, Jujube peel of LingWu long Jujube was chosed as the raw material, the extraction, purification and stability of red pigment from Jujube peel were studied, the major components and sturcture of the pigment were indentified. The research provided a reference for the development and application of red pigment from Jujube peel. The main results are as follows:(1) The extraction of red pigment from Jujube peel was studied by using the Ultrasonic-assisted extraction and microwave-assisted extraction. The results showed that, the optimum conditions for Ultrasonic-assisted extraction were as follows:ultrasonic time was30min, ultrasonic power was80W, concentration of NaOH was0.5mol/L the ratio of raw material to liquid was1:10g/mL(w/v) and the temperature was75℃, extracted3times and the extraction yield reached95.77%; The optimum conditions for microwave-assisted extraction were as follows:the microwave power was540W, the concentration of NaOH was0.51mol/L, the extraction time was134s, the ratio of material to solvent was1:10g/mL, extracted3times and the extraction yield reached96.89%; There were no obvious difference in the extraction yield of two methods, but the extraction time of microwave-assisted extraction was less than7min, which is much smaller than Ultrasonic-assisted extraction and solvent extraction.(2) The results of purification were as follows:the purification ability of macroporous resin LX-60was much better than others. The optimum conditions showed that the pigment concentration was1.208(absorbence), absorption speed1.0mL/min at normal temperature, the eluant (alcohol) concentration50%, desorption speed1.0mL/min at normal temperature. After the purification, the red pigment yield was5.73%, the colourity was23.61, which was closed to10times before purification. The results of color reaction, ultraviolet-visible and infrared spectrum showed that the Jujube rind pigment maybe is flavanone compound and the structure included:C-OH、C-H、C=O、 aromatic ring or heterocyclic.(3) The stability of red pigment has been studied and the results showed that, the pigment was stable to weak acid, neutral and alkaline solution, the temperature and edulcorator. The sunlight and food acids such as citric acid and ascorbic acid had significant effects of the pigment. The pigment had definite antioxidant and reduction prosperities, it’s stable to Na2SO3and H2O2of low concentration. The pigment was stable to sodium benzoate which enhanced its stability. The pigment was very sensitive to the metal irons Fe3+、Fe2+、Cu2+、Al3+、Zn2+、Pb+、Ca2+, complexation and precipitation with these metal irons easily, so the pigment should try to avoid contact with these metal ions in the storage and use of the process. But the metal irons K+and Mg2+can enhanced its stability.