Red pigment of celosia cristata L.

Abstract

For the development of new natural red pigments as food colorant, the studies on the red pigment of Celosia cristata L. which has very attractive large sized red flowers have been undertaken. By the 1.2\% preparative agarose slab gel electrophoresis, the pigments of Celosia cristata L. were separated into 5 distinct bands with high resolution. Using this method, the major red pigment was purely purified by a simple steps. With the comparison of the known betacyanin of red beet, Beta Vulgaricus, the characteristics of this purified red pigment were fully investigated like as following chemical and instrumental analyses. The absorption spectra of the crude pigment of Celosia cristata L. represented two absorption peak, one at 537 nm which is typical of betacyanin, the other at 480 nm characteristic of betaxanthins. However, the purified red pigment showed only one maximal absorption spectrum at 537 nm. The fact that the major functional groups in the red pigment of Celosia cristata L. were the same with those of red beet could be confirmed from the absorption peaks of infrared spectra. The sugar attached to color backbone was hydrolyzed with 2N-HCl by heating at 80$^\circ$C for 1 hr. Using a technique of thin layer chromatography, the sugar component was identified as glucose. Also, from the result of the $\beta$-glucosidase enzyme treatment at pH 5.0 for 24 hrs, it was found that the glucose was linkaged to its aglycone with $\beta$-glycosidic bond. The organic acids which were usually bound to sugar portion were cleaved with a treatment of the pigment by 2N-NaOH at room temperature in the absence of oxygen. Analysis of organic acids by gas liquid chromatography revealed that p-coumaric acid an ferulic acid were the components of the red pigment. Using the high performance liquid chromatography, we detected four components of betacyanin of red beet; betanin, isobetanin, betanidin, and isobetanidin with retention time of 21, 39, 54, 76 min, respectively. The same...