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 °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 °C, 30 min). In both cases, the degradation kinetics fitted well to a first order reaction (R2 = 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 °C during 1 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 °C, 10 min), no significant changes in the chemical composition were found (P < 0.05).