Citrus Carotenoids. I. Comparison of Carotenoids of Mature‐Green and Yellow Lemons

SUMMARY —Lemons, both mature‐green and yellow, yield a complex mixture of carotenoids. The lighter color of the pulp and flavedo of yellow lemons may be attributed to much lower concentrations of carotenoids than in oranges. A comparison of the pigment mixtures shows that, as the lemons ripen and coincident with the disappearance of chlorophyll, alpha‐carotene disappears and zeta‐carotene and an eta‐carotene‐like compound appear in both the pulp and peel. The eta‐carotene‐like compound has not been previously reported in citrus. Furthermore, small but significant amounts of beta‐carotene 5,6‐monoepoxide and its isomeric 5,8‐epoxide, mutatochrome, are present in the pulp of yellow lemons.