Anthocyanin condensation reactions under high hydrostatic pressure

The effects of temperature and/or high hydrostatic pressure on anthocyanin condensation reactions were studied. For this purpose, model solutions containing cyanidin-3-O-glucoside (Cy3gl) and pyruvate, in excess, were subjected to different combined temperature/pressure treatments. After a high hydrostatic pressure treatment of 600 MPa, at 70 degrees C during 30 min, about 25% of Cy3gl was degraded. Parallel to this decrease, a vitisin A-type derivative was formed. By contrast, the rate of condensation was only 5% when samples were heated (70 degrees C, 30 min). In both cases, the degradation kinetics fitted well to a first order reaction (R-2 = 0.99). The decrease in Cy3gl was correlated with a decrease in the antioxidant activity. Moreover, the chemical stability of wine subjected to a temperature/pressure treatment of 600 MPa, at 70 degrees C during I h was investigated. After this treatment, a decrease in the concentration of malvidin-3-O-glucoside (Mv3glu) was found. As a consequence, an increase in the concentration of several products of high molecular weight at 370 nm was observed. When wine was subjected to pasteurization conditions (600 MPa, 70 degrees C, 10 min), no significant changes in the chemical composition were found (P < 0.05). (C) 2008 Elsevier Ltd. All rights reserved.