Cell Wall-Anthocyanin Interactions during Red Wine Fermentation-Like Conditions

The effects of temperature, ethanol and anthocyanin concentration on the adsorption and desorption processes of anthocyanin onto cell wall material were investigated. Independent variables included temperatures of 15 and 30°C, model wines with ethanol concentrations of 0 and 15%, and anthocyanin concentrations of 1, 1.5, and 2 mg/mL. These experiments were conducted in triplicate in bench-top solutions that mimic a single berry fermentation environment. Desorption experiments were carried out immediately after the completion of the adsorption experiments to minimize changes on the cell walls that may affect the kinetics of the process. Results indicate that more than 90% of anthocyanin adsorption occurs within the first 60 minutes of interaction with cell wall material. However, desorption appears to occur much faster; a maximum was reached after 30 minutes. Temperature, ethanol and anthocyanin concentration were found to have significant impact on both adsorption and desorption kinetics by means of analysis of variance (ANOVA). Results show that phenolic concentration in the final wine not only depends on the amount released from the grapes but also on its interactions with the solids in the fermentor. Additionally, these interactions are dependent on temperature and ethanol concentration.