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Title: PHENOLS IN CITRUS PEEL BYPRODUCTS. CONCENTRATION OF HYDROXYCINNAMATES AND POLYMETHOXYLATED FLAVONES IN CITRUS PEEL MOLASSES

Author
item Manthey, John
item Grohmann, Karel

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2001
Publication Date: 7/19/2001
Citation: N/A

Interpretive Summary: Orange fruit processing produces enormous amounts of peel byproducts, one of which is a highly concentrated liquid peel extract, termed molasses. In this molasses are many chemicals that occur in the peel, and are known to have potential health-promoting properties. Included in these chemicals are compounds called flavonoids and hydroxycinnamates, many of which are found exclusively in citrus. This study provides measurements of the concentrations of these flavonoids and hydroxycinnamates in the molasses byproduct.

Technical Abstract: In addition to the main flavanone glycosides (i.e. hesperidin and naringin) in citrus peel, polymethoxylated flavones and numerous hydroxycinnamates also occur in citrus peel and are major phenolic constituents of the molasses byproduct generated from fruit processing. While a small number of hydroxycinnamates in citrus occur as amides, most occur as esters and are susceptible to alkaline hydrolysis. This susceptibility of most of the citrus hydroxycinnamates to alkaline hydrolysis was used in measuring the levels of the hydroxycinnamates in citrus peel molasses. The highest concentrations of hydroxycinnamates occurred in molasses of several varieties of orange (C. sinensis L.) and tangerine (C. reticulata L.) compared to grapefruit (C. paradisi Macf.) and lemon (C. limon L.). Concentrations of two phenolic glucosides, phlorin (phoroglucinol-B-O-glucoside), and coniferin (coniferyl alcohol- 4-B-O-glucoside) were also measured. Measurements of the polymethoxylated flavones in molasses from several tangerine and orange varieties showed that these compounds occurred in the highest amounts in Dancy tangerine, while two other tangerine molasses contained significantly lower levels, similar to those levels in late- and early/mid-season orange molasses.