Liquid chromatographic profiles of major carotenoid esters in commercially processed California Navel and Valencia orange juice concentrates.

A procedure for establishing profiles of major carotenoid esters in commercially processed Valencia and Navel orange juice concentrates by reversed-phase liquid chromatography (LC) using Sudan 1 as internal standard is described. The procedure involved conversion of 5,6-epoxides in heat concentrated citrus juices to more stable 5,8-epoxides by treatment of extracted carotenoids with hydrochloric acid followed by dual wavelength analyses at 400 and 465 nm using LC. The esters of 5,8-furanoids (auroxanthin and mutatoxanthin) were approximately quantitated at 400 nm without interference from other carotenoids. Cryptoxanthin esters and free cryptoxanthin, lutein esters, citraurin esters and carotenes were approximately quantitated at 465 nm without interference from auroxanthin esters. The furanoid esters varied from 60 to 75% of the total carotenoids in the concentrates. The cryptoxanthin esters varied from 5 to 10% of the total carotenoids in Valencia orange juice concentrates and from 10 to 15% of the total carotenoids in Navel orange juice concentrates. Citraurin esters were present only in Navel orange juice concentrates and beta-carotene content was less than 5% of the total carotenoids in both concentrates. The total carotenoids and individual carotenoids increased with the advance in season in Navel orange juice concentrates which had less than half the amount of total carotenoids of Valencia orange juice concentrates.