The effect of pH on the formation of coloured compounds in model solutions containing anthocyanins, catechin and acetaldehyde

Authors

  • Christina García-Viguera
  • P. Bridle
  • J. Bakker

DOI:

https://doi.org/10.5073/vitis.1994.33.37-40

Keywords:

model vines, anthocyanins, catechin, acetaldehyde, pH, HPLC

Abstract

The qualitative and quantitative effect of pH on the formation of new coloured compounds from the interaction between malvidin 3-glucoside, (+) catechin and acetaldehyde was studied. Five different solutions were prepared at pH 2, 3, 3.7, 4 and 5, and the concentration of the reactants and newly formed compounds was monitored by HPLC. In all mixtures there was a decrease in the concentration of malvidin 3-glucoside and catechin, coupled with the formation of two principal new compounds thought to be dimers (labelled A and B), linked at different positions, and several minor compounds. The rate of loss of the reactants and the longevity and concentrations of A and B varied according to pH, with the greatest amounts and most rapid formation of these compounds occurring at pH 2. The catechin concentration still decreased when there was no malvidin 3-glucoside remaining. This observation indicated that further polymerisation reactions were occurring, involving catechin molecules only, or catechin and coloured polymers.

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Published

2015-08-19

Issue

Vol. 33 No. 1 (1994): Vitis

Section

Article

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