Free Guaiacol and 4-Methylguaiacol as Markers of Smoke Taint in Grapes and Wines: Observations from the 2008 Vintage in California
By E. Herve, S. Price and G. Burns
Read it here

UC Davis white paper, “Successful management and mitigation of smoke exposed grapes: a needs assessment of the Pacific Coast grape and wine industry:”
Read it here

Australian Wine Research Institute’s factsheet, “Smoke taint: entry into grapes and vineyard risk factors:”
Read it here

Australian Wine Research Institute’s factsheet: “Smoke taint: practical management options for grapegrowers and winemakers,’

 

UC Davis

From: Karen L Block <klblock@ucdavis.edu>
Subject: Smoke Exposure Resources and a Zoom Question and Answer Session
Date: September 13, 2020 at 4:26:50 PM PDT

The UC Davis Department of Viticulture and Enology would like to provide as much useful information as possible about the potential risk of smoke impact, from recent events on the West Coast, to grape growers and winemakers.  To that end, we are providing the following resources:

1. The West Coast Smoke Exposure Task Force Grape Sampling protocol:WCSETF Grape Sampling Protocol
2. The WCSETF Small-Scale Fermentation Protocol: WCSETF Small-Scale Fermentation Protocol
3. A Video of Dr. Anita Oberholster (UC Cooperative Extension Specialist in Enology) processing 10 lbs. of grapes (~3.3L of juice) through the Small-Scale Fermentation Protocol, explaining the process step-by-step (How to do small-scale fermentations for the evaluation of grape smoke exposure risk).
4. A Frequently Asked Questions (FAQ) sheet that will be updated on a regular basis: Frequently Asked Questions (FAQ) sheet

———————————————–

How smoke compounds interact with grapes in the vineyard and the potential risks for smoke damaged grapes and their effects on wine quality are not well understood. Laboratory analysis of smoke exposed grapes can reveal useful information, but often such analysis alone is insufficient to reliably predict the risk of smoke affected wines. Consequently, researchers recommend the use of laboratory analysis and sensory analysis of wine made from a small-scale fermentation of smoke exposed grapes.

Fermenting a grape field sample is one of the best tools currently available to predict smoke exposure markers (both free and bound volatile phenols) that may be present in a wine post-fermentation. A winemaker or grape grower can use the finished small-scale fermentation to evaluate the presence of off-aromas and ashy flavors (through sensory evaluation) and should also submit a wine sample to a certified laboratory for volatile phenol and glycoside analysis to understand the potential risk of smoke damage.

If you have questions about any portion of the above information, please email klblock@ucdavis.edu

 

NapaLife, September 14, 2020

Will smoke doom this year’s wines?

There are a lot of questions about how the smoke from ongoing fires will affect grapes and wine made this year. I asked some respected winemakers for their views.

First, consumers need not be concerned, as winemakers are going to be very careful to make sure that any wine they release will be fine. Esther Mobley wrote a nice piece on that in the Chronicle. Nevertheless, wines from this year may be “tainted” by critics even if the wines released are fine.

For growers and winemakers, however, many questions remain. Some of my sources said that many grapes, like those picked early, from Carneros where the smoke hasn’t been as intense, and white (and pink) wines that see little skin contact seem little affected.

One big problem is that the testing labs seem very busy testing grapes; it’s better to offer microfermented samples than grapes or must.

A winemaker and grower who preferred to stay anonymous suggested that growers who are insured take the money if there’s any question.

Some winemakers will take the grapes “on consignment” and bulk it out for the grower if necessary.

There are processes to reduce smoke taint (from VA Filtration, for example) from finished wines but most winemakers aren’t anxious to use it on expensive wine.

Grape and wine prices are already soft with dropping demand due to recent large crops, disappearing restaurant and bar sales and moderating sales overall.

Anyway, halfway through my reporting, I received a release from the experts at Davis, so I’ll turn the dialog over to them but I’ve edited the release for length (mostly):

How smoke compounds interact with grapes in the vineyard and the potential risks for smoke-damaged grapes and their effects on wine quality are not well understood.

Laboratory analysis of smoke-exposed grapes can reveal useful information, but often such analysis alone is insufficient to reliably predict the risk of smoke-affected wines.

Consequently, researchers recommend the use of laboratory analysis and sensory analysis of wine made from a small-scale fermentation of smoke-exposed grapes.

Fermenting a grape field sample is one of the best tools available to predict smoke exposure markers (both free and bound volatile phenols) that may be present in a wine post-fermentation.

A winemaker or grape grower can use the finished small-scale fermentation to evaluate the presence of off-aromas and ashy flavors (through sensory evaluation) and should also submit a wine sample to a certified laboratory for volatile phenol and glycoside analysis to understand the potential risk of smoke damage.

Not surpassingly, the UC Davis Department of Viticulture and Enology provides useful information about the potential risk of smoke on grapes and wine to grape growers and winemakers. Here are some of its aids:

•The West Coast Smoke Exposure Task Force grape sampling protocol

WCSETF Small-Scale Fermentation Protocol
Read it here

Micro-Fermentation Protocol – Read it here

A video of Dr. Anita Oberholster (UC Cooperative Extension specialist in enology) processing 10 lbs. of grapes (~3.3 L of juice). How to do small-scale fermentations for the evaluation of grape smoke exposure risk.

Step-by-Step: How to do small-scale fermentations for the evaluation of grape smoke exposure risk – Watch it here

Frequently Asked Questions Sheet – Read it here

 

Napa Valley Grapegrowers

From: nvg@napagrowers.org
Sent: 9/11/2020 4:35:12 PM Pacific Standard Time
Subject: Smoke, Ash Exposure 7 Steps to Take Now
Grower Bulletin | September 11

Smoke, Ash Exposure 7 Steps to Take Now

We recommend taking these 7 steps NOW to mitigate risks related to smoke and ash exposure in the vineyard.

1. Communicate early and often with wineries/purchasing partners to work out vineyard and winery mitigation strategies and a unified approach to reducing risk and losses
2. Visit NVG’s Mitigating Losses with Winery Partners webpage
3. Understand approved winery standards for 2020 fruit
4. Despite testing delays, submit fruit or micro-ferment samples for testing NOW and consider freezing samples for future testing
5. Review your insurance policy – many will not cover loss of grape sales without test results indicating taint
6. If you do not have crop insurance, continue to check NVG Grower Bulletins for disaster assistance updates
7. Visit NVG’s Tools for Grape Sales webpage for contract language pertaining to smoke exposure
8. Continue to protect the health and safety of vineyard workers – pick up free N95 masks at the NVG office
9. Take care of your vineyard; vines are resilient to heat and smoke exposure when properly cared for

Mitigating Losses

Visit NVG’s Smoke Exposure webpage for detailed information on these 7 steps and for additional resources including:

1. The latest research on grapes and smoke exposure
2. Vineyard and winery mitigation strategies
3. Lab contact information

Smoke Exposure

NVG has developed the following additional website pages with dedicated wildfire response resources:

Disaster Assistance
Health & Safety
PSPS
Fire Preparedness

Login for access or contact info@napagrowers.org to set up a member login online

 

Napa Valley Vintners

https://napavintners.org/downloads/2020/Available_Labs.pdf

https://napavintners.org/downloads/2020/WCSETGrapeSamplingProtocol.pdf

https://napavintners.org/downloads/2020/WCSETMicroFermentProtocol.pdf

https://napavintners.org/meetings/videos.asp#zsM3Uiu75to

https://napavintners.org/downloads/2020/Smoke_Impact_Database.pdf

https://napavintners.org/Downloads/2020/smoke_impact_082020F2.pdf

https://napavintners.org/downloads/2020/CA_Wildfire_Smoke_Protection_Law.pdf

Grape Sampling Protocol and Micro-Fermentation Protocol: https://www.cawg.org/Shared_Content/Resources/Wildfire_Smoke/Wildfire_and_Smoke_Exposure.aspx

https://www.cawg.org/Shared_Content/Resources/Wildfire_Smoke/Wildfire_and_Smoke_Exposure.aspx

Wine Institute wildfire webinar:  https://mailchi.mp/wineinstitute/cwm-toolkit-7991841?e=f74f0ecdf7

 

Wine Institute

Sept. 3, 2020

California Wildfires – Wine Industry Talking Points

• Lightning storms during an unusual late summer weather pattern of extreme heat created wildfires in several regions of California first reported mid-August. The fires started in remote areas of Northern California’s coastal regions including the counties of Napa, Sonoma, Santa Clara, Santa Cruz and Monterey. Cooler weather and morning fog aided efforts and most of the fires are 80 percent or more contained.
• Fire damage to wineries and vineyards has been minimal. Of the 4,200 wineries in California, two have been reported as lost by fire, one in Vacaville in Solano County and one in the Santa Cruz Mountains. Several areas had precautionary evacuations and residents in those areas are returning home as orders are lifted.
• Wineries that temporarily closed are reopening for outdoor tastings.
• It is too early to predict the impact of the fires on the 2020 vintage from smoke exposure. Multiple considerations determine the impacts of smoke exposure. 
• The smoke must be fresh, dense and in close proximity to the grapes (vs. smoke being in the upper atmosphere) to have an impact. The latest research has found that “old” smoke, older than 24 hours, has no impact on grapes. Air quality in wine communities, which is usually late-stage smoke from remote fires, also does not correlate to impacts on grapes. Other factors include wind direction, grapevine growth stage, grape variety and the length of smoke exposure.
• California wine country is vast with winegrapes grown in 49 of the California’s 58 counties. Most of the state’s wineries and vineyards were not affected by the fires. Wildfires near winegrowing regions were in remote areas and only impacted a small percentage of those regions.
• Despite the wildfires, California vintners and growers are excited about the quality of the 2020 vintage. As harvest continues, vintners are making decisions to ensure that their wines meet or exceed the quality standards that consumers have come to expect.
• The 2020 growing season was cool and mild and the heat spell in early August accelerated ripening. The start of harvest was earlier than normal and is expected to be completed early if it stays on the current track. The size of the 2020 vintage was anticipated to be smaller than average, however, wine inventories are well stocked and there will be no issue with supplying wines for markets.
• We are deeply saddened by the friends, neighbors and winery colleagues who have been impacted by the fires and our thoughts go out to individuals who have experienced losses. It is heartening to see our wine community come together to help one another and we appreciate the brave firefighters and first responders.
• Several organizations are raising funds to support displaced winery and vineyard workers and support local winegrowing communities, such as the one at: https://www.gofundme.com/f/2020-wine-country-fire-relief-fund