Annegret Cantu, Andrew L. Waterhouse,* Mauri Anderson, Patricia A. Howe, and Nicolas Delchier
*UC Davis Department of Viticulture and Enology, One Shields Avenue, Davis, CA 95616 (alwaterhouse@ucdavis.edu)

Understanding the effect of various closures on wine aging is an ongoing research effort globally. Innovative technical closures avoid development of “cork taint” and offer a range of controlled oxygen transfer rates for postbottling storage of different wine styles. This five-year project aimed to compare various closures’ effects on aging characteristics of four wines. The wines were all high-quality and commercially available. These included a Sauvignon blanc, a barrel-aged Chardonnay, a Pinot noir, and a Cabernet Sauvignon. All wines came from wineries in Napa and Sonoma, California, and were aged under controlled temperature for five years. The four closures tested were three DIAM controlled-oxygen transfer rate (OTR) closures and a standard 49- mm natural cork. We measured free and total sulfur dioxide levels, color, and phenolic profiles. As expected, white wines were more susceptible to the effects of oxidation; thus, their aging profiles were more dependent on the level of oxygen allowed by the different closures we tested. Generally, we observed a difference in oxygen exposure on browning and rates of sulfur dioxide loss. The choice of closure impacted the wine composition over five years but had less impact on red wines than whites. Overall, red and white wines closed with the DIAM technical closures, especially those with lower OTRs, had significantly less variation in the final sampling for sulfur dioxide levels. Furthermore, from these results, we could conclude that red wines were more resilient to oxidation in the bottle and manufactured closures, like DIAM closures, provided a more uniform end product after some time in the bottle. The results also suggest that the choice of a low-OTR closure is more critical for storage and aging of white wines.

Funding Support: DIAM Bouchage