The factor that most greatly influences the extraction of phenolics during wine fermentation has been shown to be the temperature at which the fermentation is performed. Previous research has shown that fermentation temperatures approaching 30 °C produce finished wines that are more highly colored and have greater concentrations of pigmented polymers. A second fermentation factor that is also likely to have a significant effect is the production of ethanol during fermentation. Based on these findings it is likely that the fundamental mechanisms and kinetics of phenolic extraction during red wine fermentation will be greatly affected by both temperature and ethanol. The effects of temperature and ethanol concentration on the kinetics of phenolic adsorption and desorption interactions with five different types of cell wall materials (CWM) were investigated. Independent variables include temperatures of 15°C 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 small, bench-top solutions that mimic a single berry fermentation environment. The desorption experiments were carried out immediately after the completion of the adsorption experiments to minimize changes to the cell walls that may affect the kinetics. Results indicate that more than 90% of the adsorption occurs within the first 60 minutes of exposure to CWM, with desorption occurring even faster. At 15°C different concentrations of anthocyanins produced only small variations in the percentage of adsorption and desorption. At 30°C, higher anthocyanin concentration (2 mg/mL) showed significantly higher adsorption rates compared to lower anthocyanin concentrations (1 and 1.5 mg/mL). In both temperature conditions, increasing ethanol concentration resulted in lower adsorption rates. The extent of both adsorption and desorption was shown to be dependent not only on temperature and ethanol concentration but also on the components of the CWM. This suggest that anthocyanin solubility in the fermenting must and binding affinity of the CWM are driving forces of the anthocyanin extraction mechanism.

Mechanism of anthocyanin extraction during red wine fermentation

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.