What Is a Phytochrome?

Plant pigments include fat-soluble chloroplast pigments and water-soluble cytosol pigments. The former is present in chloroplasts and is related to photosynthesis, such as chlorophyll; the latter is present in vacuoles, especially related to the color of flowers, such as anthocyanins, which are flavonoids . Understanding their properties helps to understand their physiological functions.

The flowers, leaves, fruits, and skins of plants often show a variety of colors.

Plant pigments (Phytochromes) are widely distributed in Chinese herbal medicines.

The main production processes for extracting pigments from plants are as follows:

Solvent extraction

The final product is obtained by leaching with an organic solvent, and then filtering, concentration under reduced pressure, vacuum drying and refining. The solvent used to extract the pigment has different choices according to the nature of the pigment and the raw materials used. Commonly used are water, acid-base solution, organic solution, such as ethanol, acetone, alkene, benzene, etc., oils and carbon dioxide. The method is simple, but the product quality is not ideal. It often has the disadvantages of poor pigment solubility, large color change, etc., and the use of a large amount of solvent (usually such as ethanol) in the extraction process, the recovery is difficult, resulting in high product production costs. It is often used in experimental research and is a relatively common method. ^[1]

Supercritical fluid extraction

It is an emerging extraction and separation technology in the food industry. It is an extraction process that uses fluids above the critical temperature and critical pressure as solvents. The fluid near the critical point not only has a very high dissolving capacity for the substance, but also the solubility of the substance changes with the pressure or temperature of the system. CO2 is commonly used as the extractant. ^[1] The main advantages are: (1) CO2 is non-toxic, flame retardant, non-explosive, non-corrosive, and does not pollute products; (2) The critical temperature of CO2 (Tc = 31 ) is close to normal temperature and the critical pressure is low ( (Pc = 7. 8MPa), which can prevent the decomposition and loss of heat-sensitive substances, and keep the original aroma of the aromatic substances; (3) After the supercritical CO2 is separated from the solute, it can be reused as long as it is compressed again, without the need for liquid-liquid Extraction requires distillation treatment to recover the solvent, so the production efficiency is high, which can save a lot of energy, but the one-time investment in supercritical equipment is large, and the process of extracting natural pigments is not mature, so it has not been widely used.

Adsorption purification

Macroporous resin adsorption is adopted. Macroporous resin is a kind of high molecular polymer which is characterized by adsorption and has the function of concentrating and separating organic matter. It has a wide range of applications in organic matter separation, preparation and purification. The adsorption effect of the adsorption resin on the substance is not only related to the physical and chemical properties of the resin, but also to the nature of the adsorbed substance, the nature of the medium, and the operation method. It is mostly used to extract anthocyanins. It extracts plants with an acidic solution and filters them. The filtrate is adsorbed with a macroporous adsorption resin and then eluted with a suitable solvent. The eluate is concentrated or spray-dried to obtain the final product. After treatment with macroporous adsorption resin, the pigment was purified. ^[1] Its process is more complicated than the solvent method, but the quality of the product is good and the recovery rate is high.