Newsletters are written as topics arise, not on a regular schedule. They are distributed through an email list, and are also posted below. If you wish to receive newsletters by email, contact Joy at VaWREx@gmail.com and ask to be added to the list. Generally, newsletters are posted here within a few days of email distribution.
Varietal Thiols in Wine: Interventions in the vineyard and winery
Several WRE experiments in the 2018-2019 season focused on increasing varietal thiols in aromatic white and rosé wines. These volatile compounds contribute to the varietal character of Virginia wines such as Sauvignon Blanc, Petit Manseng, and Riesling as well as varieties used to produce red and rosé wines. There are several steps in the winemaking process from vineyard to bottle that affect the production, protection and perception of thiols in the finished wine, and therefore several points of intervention for winemakers to consider if they want to increase the impact of these compounds.
For some background on thiols, including their chemistry, origins, transformations, and many different ways to increase thiols in your wine, here is a review.
Four experiments were done in the 2018-2019 season exploring the optimization of thiols in aromatic wines:
Scott Dwyer of Chemeketa Community College investigated The effect of early leaf pulling on thiol production in an Oregon Sauvignon Blanc (2018)
Rachel Stinson Vrooman from Stinson Vineyards explored The effect of Stimula Sauv Blanc (Scottlabs) fermentation nutrients on Thiol Production in Sauvignon Blanc (2018)
Emily Pelton from Veritas Vineyards and Winery undertook a Comparison of protocols for thiol production in Sauvignon Blanc (Scottlabs vs. Veritas)(2018)
Tim Gorman from Cardinal Point turned his efforts to Developing a protocol for rosé stabulation using Laffazyme THIOLS (Laffort) and Fermoplus Tropical (AEB)
Virginia Viticulture Association Winter Technical Meeting 2019
The VVA included a great lineup of presentations by Virginia Tech faculty and students as well as invited speakers from Michigan and New Jersey. We were also able to welcome the new Extension Enologist Beth Chang. Several of our WRE participating winemakers served on a panel presenting research results from previous years as well as a tasting of an experiment from 2018. Many thanks to the VVA for the opportunity to share our results, and to the winemakers for serving on the panel. Following are some links to the material presented during the WRE Panel.
Here are some links to the studies featured during this presentation:
Despite our best efforts in the vineyard and good decision making in the winery, many winemakers still face a few lots from 2018 with higher VA than desired. As we learn the lessons of this vintage, and consider our options going forward, here are a few notes on VA:
Volatile Acidity: Definition, legal limits, sensory thresholds
Where did it come from: Causes of Volatile Acidity
What to do now? Using filtration to remove Volatile Acidity
Several winemakers have asked about ways to make the most of the wines that came in, protect them during aging and manage elevage to make the best wines possible. Concerns included thin mid-palate, lack of structure, and high VA. This edition of the newsletter includes background information on topics including:
Analyses to do now
Cellar practices to protect your wines and limit VA accumulation
Body, Structure, Weight and Balance
The role of mannoproteins in the body of wine and the addition of yeast products
The types of tannin and their addition to wine
There is also a section with specific manufacturer’s recommendations and contact information.
This season has included many challenges in the vineyard that are now translating to the winery. Many of the red grapes being picked are less ripe than desired.
Overall, a winemaking philosophy of maximizing fruitiness and minimizing astringency may be a good focus when working with underripe grapes. There is no magic bullet to make underripe grapes taste ripe. However, there are a few things to think about when planning your winemaking to respond to this vintage. This newsletter gives some background chemistry and winemaking suggestions for this season’s fruit.
Though this season has been a challenge in the vineyard, the grapes are still ripening and it is time to start picking! So far people have reported higher than normal pH, lower brix, and watery fruit. Not a surprise given the weather. But today the sun is out and the forecast (at least for a few days) looks pretty good. Lets hope this weather holds.
This newsletter includes sections addressing: Vineyard Sampling, Sample Preparation and testing, Rot Protocols, and High pH
This updated protocol from Scottlabs was added after first publication of the pre-harvest newsletter.