Cristina Medina-Plaza and Anita Oberholster*
*University of California, Davis, 595 Hilgard Ln, Davis, CA, 95616 (aoberholster@ucdavis.edu)

Aging wines, especially red wines, in wood barrels improves their complexity and organoleptic characteristics. Barrel-maturated wines are enriched in aromatic compounds, the color is more stable, and mouthfeel complexity is improved. The ex­traction of oak phenolics has been shown to be governed by diffusion kinetics, follow­ing a curve in which the rate of extraction is initially high, decreasing as the concen­tration in the wine approaches that on the surface of the wood. Additionally, oxygen plays an important role in wine aging, facilitating polymerization reactions and more. Thus, the use of techniques such as microoxygenation (MOX) have become popular during red winemaking. MOX in combination with barrel aging could accelerate aging, reducing the time that wine needs to be in barrel while still obtaining the benefit of oak aromas. In this project, a red wine blend was aged in barrel and stainless steel vessels using different rates of oxygen dosing (0, 1 and 2 mg/L/month). Dissolved oxygen (DO), volatile acidity, and free and total SO2 levels were measured weekly showing that, although DO wasn’t significantly different between treatments, a larger decrease in free SO2 was found in those vessels with MOX treatments, with a greater decrease in the oak barrels. Acetaldehyde-adducts and phenolics were determined by RP-HPLC. Using spectral data and tasting, the 2 mg/L/month treatment was stopped after three months, while the 1 mg/L/month treatment was applied for six months. The barrel treatments without MOX continued for 12 months. Results indicate that, for the red wine blend studied, the 2 mg/L/month oxygen dose was excessive and the wine showed browning after three months of treatment. However, the six months oxygen treatment at 1 mg/L/month showed comparable aging to the barrel treatment without MOX after 12 months. Wine controls in stainless steel barrels showed the least amount of aging, but lacked the positive oak aromas.

Funding Support: Lyon-Cisneros Family Research Fund