Concentrations of Hesperidin and Other Orange Peel Flavonoids in Citrus Processing Byproducts

Abstract

The concentrations of flavonoids were measured in the peel of different orange (Citrus sinensis L.) varieties and compared to the distributions of flavonoids in the byproducts of orange processing. While the flavanone glycoside hesperidin was the main flavonoid in peel, precipitation of this compound during processing resulted in dramatic losses in hesperidin in filtered peel juice and filtered molasses. Yet, hesperidin occurred at very high levels in dimethyl sulfoxide extracts of unfiltered molasses (5718 ppm) and in the centrifuged insoluble solids of orange peel molasses (65 642 ppm). The polymethoxylated flavone aglycons were the only flavonoids in cold-pressed orange peel oil. These compounds also occurred in high concentrations in light-density oil solids and in commercial wax isolated from the cold-pressed peel oil. Thus, the different citrus peel byproducts are selectively enriched with high concentrations of different groups of flavonoid compounds. Keywords: Citrus sinensis; bioflavonoids; orange peel molasses; peel oil; polymethoxylated flavone