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Impact of a Water‐Soluble Gallic Acid‐Based Dendrimer on the Color‐Stabilizing Mechanisms of Anthocyanins
Author(s) -
Cruz Luís,
Basílio Nuno,
Mendoza Johan,
Mateus Nuno,
de Freitas Victor,
Tawara Maun H.,
Correa Juan,
FernandezMegia Eduardo
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901912
Subject(s) - chemistry , dendrimer , anthocyanin , gallic acid , malvidin , organic chemistry , photochemistry , cyanidin , food science , antioxidant
The interaction of two anthocyanins with a water‐soluble polyanionic dendrimer was studied through UV/Vis, stopped‐flow, and NMR spectroscopy. Cyanidin‐3‐glucoside (cy3glc) revealed a stronger interaction than malvidin‐3‐glucoside (mv3glc) at pH 1 according to their apparent association constants. A higher color increased was also obtained for cy3glc at pH 3.5 as a result of this stronger interaction. A high‐frequency chemical shift of the cy3glc aromatic protons suggest the formation of ionic pairs. The interaction parameters ( K≈ 700 m −1 , n ≈295) indicated the binding of approximately two anthocyanin molecules by each sulfate group. The equilibrium and rate constants of cy3glc in the presence of dendrimer showed an increased stability of the flavylium cation and a higher protection of this species from hydration (p K ′ a and p K h increased almost one pH unit). The tuning and color stabilization of anthocyanins by using this dendrimer allow novel applications as colorimetric sensors for food packaging.