Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 2004
Publication Date: November 12, 2004
Citation: Manthey, J.A. 2004. Fractionation of orange peel phenols in ultrafiltered molasses and mass balance studies of their antioxidant levels. Journal of Agricultural and Food Chemistry. 52:7586-7592. Interpretive Summary: Orange peel byproducts contain large amounts of different classes of antioxidant phenolic compounds which might be useful as healthful food ingredients. The different classes of phenolic compounds were separated and quantified. The antioxidant actions of each class were then measured using two distinct assays. The results show that certain classes of phenolic compounds containing many similar minor-occurring compounds constitute important parts of the total phenolic content and antioxidant strength of orange peel. These findings will help in identifing useful phenolic fractions as potential food ingredients.
Technical Abstract: The flavonoids in orange peel molasses was fractionated by adsorption, ion-exchange, and size-exclusion chromatography. Size-exclusion chromatography effectively separated the different classes of flavonoids in ultrafiltered molasses, including the polymethoxylated flavones, flavanone-O-trisaccharides, flavanone- and flavone-O-disaccharides, and finally, flavone-C-glycosides. Mass spectral analysis of fractions off the size-exclusion column revealed a broad collection of minor-occurring flavone glycosides, which included in part, glycosides of limocitrin, limocitrol, and chrysoeriol. Most hydroxycinnamates in the molasses were recovered by ion-exchange chromatography, which also facilitated the recovery of fractions containing many other miscellaneous phenols. Total antioxidant levels were measured for the separate categories of phenols in the molasses, as well as for purified standards. A significant amount of the total antioxidant activity in orange peel molasses was attributable to minor-occurring flavones. The miscellaneous phenolic-containing fractions also constituted a major portion of the total antioxidants in ultrafiltered molasses.