Carotene refers to several related unsaturated hydrocarbons with the molecular formula C40H56. It is synthesized by plants and is an orange photosynthetic pigment. It is the main source of vitamin A, mainly including a and β. , γ three forms, the most important of which is β-carotene. Food sources are mainly dark vegetables and fruits. Carotene is one of the most common vitamin A supplements. Vitamin A is essential for human visual development. If the body lacks vitamin A, there will be vision problems and even night blindness.

Carotenoids are a class of compounds with a 040 tetraterpenoid structure and their derivatives, which have been widely studied as antioxidants. It is a pigment composed of 8 isoprenoid units and is yellow, orange-red or red. Carotenoids can be divided into 4 subgroups: carotenes, such as α-, β-, γ-carotene and lycopene; carotenols, such as lutein, jade, and astaxanthin; esters of carotenoids, Such as β-apo-carotene; carotene, such as crocin and annatto. All carotenoids can be derived from the degradation of lycopene through oxidation, hydrodehydrogenation, cyclization, and carbon skeleton rearrangement. When birds eat food containing these compounds, they tend to accumulate them in their egg yolks, so yolk pigments are primarily carotenoid compounds.

Carotenoids can also be divided into two categories: Carotene and Xanthophy. Lutein is an oxidized carotene, and the molecule contains one or more oxygen atoms. Form hydroxyl, carbonyl, methoxy or epoxide, several common carotenoid molecular structures, including lycopene (Lycopene), zeaxanthin (Zeaxanthin) all-trans beta carotene (AllTrans-Carotene), Antheraxanthin, α-Carotene, Violaxanthin, Canthaxanthin. People's diet contains 50 to 60 carotenoid compounds. More than 22 carotenoids and more than 8 metabolites have been found in human plasma. Among them, the main carotenoid compounds include β-carotene, α-carotene, lycopene, lutein, zeaxanthin and cryptoxanthin. There are certain synergistic effects between different carotenoid compounds. Utilizing the synergistic effect between carotenoids to develop some new carotenoid healthy or functional foods will be an important development direction of carotenoids.