Kimberlee Marinelli, Ben Montpetit,* Ron Runnebaum, James Nelson, Gita Mallya, and Andre Knoesen
*University of California, Davis, 1136 Robert Mondavi Institute North, 595 Hilgard Lane, Davis, CA 95616 (benmontpetit@ucdavis.edu)

In the wine industry, tracking redox potential, or ORP, during fermentation is an emerging process parameter. ORP can offer a valuable, real-time indicator of yeast metabolism during fermentation and could be used to make decisions around aeration to prevent formation of unwanted compounds associated with reductive fermentation conditions. The goal of this study was to gain a better understanding of how oxygen introduction, at various times and amounts during the course of fermentation, affects redox status and how this is linked to overall fermentation outcomes. Using juice concentrate as a consistent fermentation medium, the impact of oxygenation on redox potential and fermentation kinetics was investigated at lab scale in triplicate, including experiments set out to evaluate when introduction of air during fermentation is required to improve fermentation performance. Total soluble solids, redox, and cell density were measured in all trials and compared against un-aerated ferments and across those subject to different oxygenation time regiments. Data collected to date shows that aerated ferments with higher redox values have faster fermentation kinetics and reach overall greater cell densities than those that were un-aerated. In addition, the timing of aeration was found to be important for this effect. Future work will investigate the amount of oxygen required, i.e., target ORP values and how these additions may alter wine chemistry.

Funding Support: N/A