Polyphenolic composition of raisins.

TitlePolyphenolic composition of raisins.
Publication TypeJournal Article
Year of Publication2000
AuthorsKaradeniz, F, Durst, RW, Wrolstad, RE
JournalJ Agric Food Chem
Date Published2000 Nov
KeywordsChromatography, High Pressure Liquid, Flavonoids, Food Preservation, Frozen Foods, Molecular Structure, Phenols, Polymers, Polyphenols, Rosales

The polyphenolics of raisins were extracted, separated by HPLC, and characterized by their UV-vis spectra, and their concentrations measured. Color measurements and browning indices were also determined. Samples (n = 20) included sun-dried, dipped, and golden raisins. Comparisons were also made with fresh and frozen Thompson Seedless grapes. Golden raisins (which are treated with SO(2)) had the highest amount of hydroxycinnamic acids and the highest lightness values. In comparison with fresh grapes, percent losses of the two major hydroxycinnamics (caftaric and coutaric acids) in sun-dried, dipped, and golden raisins were on the order of 90%. Flavonols were not influenced by processing as much as hydroxycinnamics, while procyanidins and flavan-3-ols were completely degraded in all raisin samples. Formation of hydroxymethylfurfural and loss of amino acids in sun-dried and dipped raisins are ascribed to Maillard browning reactions.

Alternate JournalJ. Agric. Food Chem.
PubMed ID11087484