Marigold is a kind of wild plant rich in carotenoid and sepiapterin and is widely grown in northeastern, northwestern and northern parts in China. It is green renewable resource and can be used as important pharmaceutical intermediates and functional natural food additives. The color shade of marigold yellow pigment is better than that of carotenoid and does not change with the influence of ph value. However, marigold yellow pigment is not soluble in water and is sensitive to light and oxygen, which has limited its direct application in pharmaceuticals, food, etc.

The research group for chemical components of medicines at the CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences (CAS), has developed a method for preparing water-soluble marigold yellow pigment microcapsules. The technique has received a Chinese invention patent in May 8. The patent number is ZL200910117742.1.

Using marigold yellow pigment as raw materials, the inventors have prepared water-soluble marigold yellow pigment microcapsules through ultrasonic cell crushing technique in combination with emulsion technique. The microcapsules obtained this way are 100% water soluble and their average grain size is about 190nm. They can be directly used in medicine, baking food, refrigerated food, drink, jelly, jam and so on. They can maintain chemical and physical stability during processing and storing process. And they have good nutrition strengthening function and colouring function.