What Is the Structure of Carotenoids?

Carotenoids (carotenoids) is a general term for an important class of natural pigments that are commonly found in yellow, orange-red, or red pigments in animals, higher plants, fungi, and algae. Carotenoids are the main source of vitamin A in the body, and they also have anti-oxidant, immunomodulatory, anti-cancer, and anti-aging effects.

So far, more than 700 natural carotenoids have been discovered, which can be divided into two types according to different chemical structures. One is carotene (containing only two elements of hydrocarbons and no oxygen, such as B2 carrots). Lycopene and lycopene), and the other is lutein (with hydroxyl, keto, carboxyl, methoxy and other oxygen-containing functional groups, such as lutein and astaxanthin). ^[1]

Green vegetables and fruits

The green tissue of a plant includes, in addition to leaves and stems, green fruits, pods and seeds of beans (such as peas). The reason these tissues appear green is that the chloroplasts in these plant tissues contain chlorophyll. Both the light in the chloroplast and the protein complexes of systems I and II contain carotenoids, whose role is to quench excess light energy. The types of carotenoids in the chloroplast are constant, and the larger amounts of carotenoids include -carotene (accounting for 25% to 30% of the total carotenoid mass),

I. Naming

When discovering new carotenoids, discoverers of new carotenoids generally choose names that reflect their source or characteristics (such as maximum absorption wavelength). Therefore, people call the pigments from carrots carotenoids and the ones from violets "

Carotenoids are the main source of vitamin A in the body, and they also have anti-oxidant, immunomodulatory, anti-cancer, and anti-aging effects. For example, lutein has antioxidant and light filtering effects, can protect vision to a certain extent, prevent vision decline, and prevent eye diseases such as cataracts ^[6]

There are three ways to prepare carotenoids, namely chemical synthesis, biosynthesis, and natural extraction.

Carotenoid chemical synthesis

Chemical synthesis is the main method for the mass production of carotenoids. The synthesis of carotenoids can be traced back to 1950, Karrer and Eugster developed a method to synthesize B2 carotene and lycopene. At the same time, another scientist Inhoffen proposed a better method for synthesizing B2 carotene, thereby realizing the industrial synthesis and commercialization of B2 carotene. So far, eight natural carotenoids have been industrially synthesized. However, in the food industry, synthetic compounds have brought many negative effects, and the safety of synthetic foods has attracted more and more attention from the society. Therefore, it has forced people to seek greener preparation methods. ^[1]

Carotenoid biosynthesis

Carotenoid biosynthetic pathway

Biosynthesis is a method for synthesizing carotenoids from fungi or plants. This method originated in the 1950s, but its application was once limited due to technical reasons. The advent of modern molecular genetic technology has promoted gene separation, achieved functional complementation in vivo, optimized properties of recombinases and the creation of transgenic plants, and promoted the progress of carotenoid biosynthesis. Carotenoids produced by bacteria, fungi, and algae have become good substitutes for industrially synthesized carotenoids. The research on the method of carotenoid synthesis from higher plants has also made great breakthroughs. ^[1]

Natural carotenoid extraction method

In today's society, people have higher and higher requirements for green food. Extracting carotenoids directly from natural raw materials is undoubtedly the best and most trusted method. The natural extraction of carotenoids has been extensively studied, but is mainly limited to lycopene and B2 carotene. The existing extraction and purification methods are: solvent extraction, supercritical fluid extraction, distillation, membrane separation, chromatography and crystallization. From an industrial point of view, solvent extraction is the first choice for natural extraction because of its simplicity and low cost. However, today's food production technology is minimizing the use of organic solvents, so the development of solvent extraction methods is also limited. ^[1]

Supercritical fluid extraction of carotenoids is a new technology developed in recent years. The principle of this method is: under certain temperature and pressure conditions, supercritical fluid (usually CO2) has the dual properties of gas (fluidity) and liquid (solubility), which can effectively extract carotenoids from the mixture Then, under another temperature and pressure parameter, the ability of the supercritical fluid to dissolve carotenoids is reduced, and the carotenoid crystals are separated from the analytical column, and the supercritical fluid can be reused by compression by a compression pump. This method has many advantages, such as high extraction efficiency, low cost, high yield, environmentally friendly, etc., and maintains the pure naturalness of the product. ^[1]