In natural products the most common carotenoid is the yellow-orange pigment of the carrot (Daucus carota), the β-carotene. It was isolated together with additional carotenes in crystalline form as early as 1831 by Wackenroder. Later, it gave the name to the entire class of these compounds.
Different total syntheses of β-carotene were published independently in 1950 by Karrer & Eugster, Inhoffen and Milas. Just four years later β-carotene was produced commercially and used as pigment in food and feed. The capacity for the production by industrial synthesis is several hundred tons of β-carotene per year.
Because of its pro-vitamin A activity β-carotene is one of the most important carotenoids. The first step in biosynthesis is the cleavage of the central double bond of the β-carotene molecule which results in two molecules of retinal. This reaction is catalyzed by the enzyme β-carotene -15,15′-oxygenase. Afterwards, retinal is reduced to vitamin A (retinol).
The chart below shows the content of β-carotene in various fresh fruits and vegetables
β-carotene content in mg per 100g edible material
The values indicated can only serve as an approximation since:
- the β-carotene content can vary depending on the variety, the season and the degree of ripening;
- the bioavailability of β-carotene from fruits and vegetables depends on the method of preparation before ingestion
β-Carotene is one of six individual carotenoids produced industrially by chemical synthesis by DSM and BASF AG companies. These are namely canthaxanthin, astaxanthin and the apo-carotenoids 8′-apo-β-caroten-8′-al, ethyl 8′-apo-β-caroten-8′-oate and citranaxanthin.