Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 22, 1996
Publication Date: N/A
Interpretive Summary: The yearly processing of oranges for orange juice generates approximately 3.3 million tons of peel as by-product. Much of this is processed into cattle feed which generates very little profit to the citrus juice processing industry. However, orange peel by-products are a rich source of plant natural products which could be converted to a number of value-added products. The flavonoids is one of these classes of natural products that occurs in high concentrations in orange peel by-products and shows the most promise in the development into value-added products. Flavonoids are biologically active compounds, many of which have been studied for medicinal applications. This publication reports on the concentrations of the flavonoids in different citrus-by products. The results show that the levels of these compounds exist in high concentrations and that different by-products are selectively enriched in different classes of the flavonoids. This work is important in the development of flavonoids into value-added products for American agriculture.
Technical 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 by-products 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 molasses. Yet, hesperidin occurred at very hig levels in dimethylsulfoxide extractions of unfiltered molasses (5718 ppm), and in the centrifuged solids of orange peel molasses (65642 ppm). The polymethoxylated flavone aglycones were the only flavonoids cold-pressed orange peel oil. These compounds also occurred in high concentrations in light-density solids, and commercial wax isolated from the cold-pressed peel oil. Thus, the different citrus peel by-products are selectively enriched with high concentrations of different groups of flavonoid compounds.