Patterns of carotenoid pigments extracted from two orange peel wastes (valencia and navel var.)

The peel waste from two orange varieties (Valencia and Navel) was analyzed. The saponified extract was analyzed for the carotenoid content by thin-layer chromatography and high-performance liquid chromatography. Identification was made by ultraviolet-Vis spectrometry. Our studies revealed that the waste of Valencia orange peels is rich in apocarotenoids like 10′-apo-β-caroten-10′-ol, 10′-apo-β-caroten-10′-al, 8′-apo-β-caroten-8′-ol, 8′-apo-β-caroten-8′-al and 6′-apo-β-caroten-6′-ol representing more than 60% of the total carotenoids. Also identified were β-chryptoxanthin and, in minor quantities, dihydroxycarotenoids (zeaxanthin and its epoxides). β-Cryptoxanthin, which exhibits provitamin A activity, was the main compound in Navel variety extract. ζ-Carotene as well as some dihydroxy derivatives were also present. The amount of apocarotenoids in this variety is very low. The data reveal important differences of carotenoid composition depending on orange variety: Valencia variety was richer in short-chain apocarotenoids while Navel variety in nonpolar carotenoids. The citrus fruit residues, remaining after juice extraction, represent approximately half of the wet mass of the whole fruit, including the peel (flavedo and albedo) and almost one-fourth of the whole fruit mass. Such a waste can be used as a good source for extracting bioactive molecules like carotenoid pigments, pectins and terpenes (essential oils). The technological applications given by the carotenoid composition of the orange peels may help the industrial processors to find new ways of increasing the profit by recuperating important bioactive molecules and also reducing the considerable problem of waste disposal. Such extracts can be very useful as functional additives for food matrices. The presence of ζ-carotene proves the fact that there is a great amount of phytoene in Navel variety, which is a compound commercially desirable, so the orange peel waste from Navel variety oranges can be taken as a commercial source of phytoene. β-Cryptoxanthin, which exhibits provitamin A activity, was also present. Its capacity to quench single oxygen and to be used as dairy product additive (e.g., butter colorant) is very useful in practice (medicine and food industry).