Thermodynamic and Kinetic Properties of a New Myrtillin-Vescalagin Hybrid Pigment

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Abstract

During red wine maturation in contact with oak wood, C-glucosidic ellagitannins can react with anthocyanins, leading to new pigments. In this work the thermodynamic and kinetic constants of the network pH-dependent equilibrium of a new myrtillin (delphinidin 3-O-glucoside)-vescalagin hybrid pigment (1-deoxyvescalagin-(1 beta -> 8)-myrtillin) have been determined by UV-visible absorption and stopped-flow experiments and compared to those determined for myrtillin. The vescalagin substitution at the C-8' center of myrtillin entails important variations in the pigment behavior upon pH changes. The hybrid pigment showed lower p(a)(K') and p(a)(K) values and a much higher value of K-t. As a consequence, at moderately acidic pH values (4 < pH < 6), the percentage of the hemiketal is much lower and the quinoidal base and the (E)-chalcone represent higher percentages relative to those for myrtillin. Therefore, the hybrid pigment can provide in slightly acidic or neutral solutions an exceptionally different color compared to that of myrtillin.
Original languageUnknown
Pages (from-to)11569-11578
JournalJournal of Agricultural and Food Chemistry
Volume61
Issue number47
DOIs
Publication statusPublished - 1 Jan 2013

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