Plant pigments include a variety of different kinds of molecule, porphyrins, carotenoids, anthocyanins and betalains.

The traditional method of extracting plant pigment is:

First, crude extract is carried out in organic solvent, then refined with resin or other processes, and then evaporated and concentrated at a low temperature .The process

is complex, difficult to control, has large amount of organic solvents and resin dosage, consumption of acid and alkali, high operating costs, polluted environment, unstalbe pigment quality , low color value.

Application of membrane separation and purification process can simplify whole process, save organic solvents. Ultrafiltration process can remove protein, starch and other impurities, and then desalinated by nanofiltration to remove small molecules, while concentrated.Automatic control can be achieved, greatly reducing extraction costs, pigment quality and stability and high color value can be satisfied.The entire process does not add any additives, is the real green technology.