The 2017 fire season saw unprecedented levels of destruction for the California wine industry. Eleven California vineyards were damaged or completely eradicated by wildfire. Despite 2018 being a calmer year for the wine industry, the total amount of wildfire across the western United States increased to record levels. The yearly risk of wildfire is a new reality for many winemakers, not only in the western United States, but around the world. Although wildfires have always been a risk, the frequency and magnitude of them are new challenges for winemakers. There is no indication that the trend will stop anytime soon either.

As the fire season for 2019 gets underway, winemakers and researchers are continuing to look at ways to mitigate some of the damage caused by wildfires. Aside from the obvious risks of physical damage to property, one of the big problems facing winemakers affected by wildfires is smoke taint.  Smoke taint is the corrupting of a wine’s flavor from smoke that has penetrated the skin of a grape from the surrounding environment. The result is, as you can guess by the name, a wine that has a burnt or ashy flavor. Smoke taint comes from the direct contact between grape leaves and grapes with smoke from wildfire or any other burning source.

When fires occur plays a large role in smoke taint. Should the fire happen early in the season, when budbreak is just beginning, the likelihood of smoke taint occurring is decreased, as there is less surface area for the smoke to penetrate. However, the closer a vineyard gets to harvest, and the more available surface area there is for the smoke to reach, the chance of smoke taint increases. The longer a fire season is then, the more risk there is of smoke taint. The National Academy of Science estimates that on average, an additional nine days of high fire potential per year were added between the years 2000 and 2015 across the entire western United States. This trend is only expected to continue, and so winemakers are being forced to adapt to the new conditions.

As of now, winemakers have two options when their wines are affected by smoke taint: one, discard the affected wine; or two, sell the wine on the bulk market where it is likely to become blended with other wines. Neither of these options are readily appealing, especially for winemakers who are attempting to create artisanal products. Winemakers often work to avoid revealing whether their wines have been affected by smoke taint, as it will cause the value of the wine to fall. However, researches are working towards finding ways to eliminate and reduce the smoke taint of affected wines.

The key to removing and reducing smoke taint is identifying and removing the chemical compounds in the wine responsible for smoke taint. One of the main culprits is the chemical compound guaiacol. This chemical compound can actually be found in wines aged in oak barrels. The barrels are typically flame or heat toasted before being filled with wine, which produces a small amount of guaiacol, which lends a subtle smoke flavor to the wine. However, when wildfires occur and vineyards become inundated with ash and smoke, the levels of guaiacol can skyrocket and produce wines that are corrupted by smoky, ashy flavor. Other chemical compounds identified as contributing to smoke taint include 4-methylguaiacol, and 4-ethylphenol.

Structural Formula of Guaiacol


To remove the chemical compounds responsible for smoke taint, researchers have a few options. One method involves the use of enzymes to remove the chemical compounds responsible for smoke taint. Another method is to pass the wine through tight filters designed to remove and dissolve those chemicals. Other methods include reverse osmosis. Researchers have also begun testing a new method of removing smoke taint by filtering wine through special membranes, although the work being done on this is still largely under wraps.

The end goal of each of these methods is to preserve a wine’s natural properties and flavors while removing the chemical compounds responsible for smoke taint. Unfortunately, none of the processes have been shown to eliminate smoke taint without removing other essentials properties of the wine. This is the dilemma that winemakers face when worried if their wines have been affected by smoke taint. They can either run the risk of producing wine that might be affected by smoke taint, or filter the wine and risk diluting it. Some companies and research labs offer testing for wines affected by smoke taint, but either way winemakers are stuck between a rock and a hard place.

Wineries in regions at risk of wildfire are now establishing “best practices” to reduce the chance of smoke taint. For example, the Australian Wine Research Institute (AWRI) has released guidelines for the handling of vines and grapes in order reduce the overall effects of smoke taint on wine. The AWRI was one of the first research institutes to begin looking at the effects of wildfire on wine following the 2003 fire season in Australia. Guidelines include hand harvesting to avoid rupturing grape skins, which contain the smoke taint chemical compounds, and excluding leaf material that might be contaminated as well. However, while the AWRI acknowledges that while these practices “help reduce the extraction and expression of smoke taint compounds,” they admit the methods are not foolproof. As of now, there is no guaranteed method to completely remove smoke taint from a wine.

Since a wine affected by smoke taint can become unsalvageable, some researchers are instead looking to identify grapes that are naturally resistant to smoke taint. ETS Labs in St. Helena, CA are currently working on analyzing grapes for smoke taint, hoping to find varietals or individual harvests that can be reproduced to resist smoke taint. The hope is that by finding these specific varieties, the wine industry can continue to produce in the same regions as before without having to worry about additional processing for their wines post-harvest.

However, with the possibility that smoke taint might become a permanent attribute to wines made in certain regions, some winemakers are taking a marketing-based approach. Instead of working to remove smoke taint, they are working to embrace it. By making the smoke and ash flavor part of the overall flavor of the wine, winemakers hope to market their products with a degree of authenticity, in the same way that some Burgundy wine use Brettanomyces contamination of their wines as a stamp of authenticity. The hope is that the smokey flavor caused by smoke taint will one day have the same appeal as the “barnyard” taste associated with those burgundy wines affected by Brettanomyces.

One way or another, winemakers are being forced to reckon with the fact that wildfires and smoke taint are becoming more prevalent in many traditional wine making regions. The regions affected by wildfires are starting to make progress towards figuring out how to get around the problem of smoke drifting through their vineyards, but there is still much work to be done. Hopefully 2019 will prove to be year of progress rather than destruction.


By Aldo Moreno