Guide for Preparing the Winery for Fire Season

Last year was the worst fire season on record for the west coast of the US. Fires in California, Oregon and Washington led to lost vintages, burned vineyards and smoke tainted wine. One estimate puts the loss at $3.7 billion for last year alone. But the real loss may not be seen for years as wineries rebuild, replant and the smoke tainted wine ages and is released to the public. This year is forecasted to be another bad fire season. So, how does a winery prepare? Here is my guide to preparing the winery for this years fire season.

What is smoke taint?

Before I delve into preparations, it’s important to know a little bit about smoke taint. Not everyone has a phd in chemistry, including me. So, I have tried to distill the science and research down to basics.

Smoke taint molecules guaiacol and 4-methyl guaiacol
Smoke Taint Molecules

Smoke taint is the smokey, ashy and cigar/cigarette butt aromas and flavors in wine that are caused by smoke in the vineyard. The exact combination of molecules that make up smoke taint in any one wine will vary. It is based on what was burning and how far away the fire was from the vineyard. While smoke taint is made up of many molecules, researchers have narrowed the most relevant, for wines, to guaiacol and 4-methyl guaiacol. These are the two molecules in their free form. 

The grape vine considers these, and other molecules in the smoke, to be dangerous. So, when smoke from wildfires comes into contact with the plant, the plant binds them to sugars, primarily in the grapes, to form several different compounds. 

What you end up with, in the winery, is juice that has both free and bound smoke compounds. The free compounds in the juice can be smelled and tasted, but the bound chemicals cannot. Massive amounts of research at UC Davis, OSU and Washington State in the last few years have given us a better understanding of what is happening within the vine and in the wine, but there is a lot we still don’t know.

Some of what we know:
  • Fermentation and hydrolysis (during aging) release (free) the bound forms of the smoke taint molecules.
  • Increased skin contact releases these chemicals into the wine.
  • 80% of the volatile phenols we associate with smoke taint are released into the wine in the first 5 days of skin contact as both free and bound chemicals.
  • Roughly 25% of the bound molecules are released after ML fermentation.
  • A small amount of these molecules, and their bond forms, are found naturally in different grape varieties.

How to Prepare

Preparing the vineyard for fire season

One of the most important things a vineyard can do is to remove as much fire fuel as possible around and inside the vineyard. This means:

  • Mow between the rows as closely as possible.
  • Clear brush in the wooded areas around the vineyard.
  • Clear brush around your roads.

Train your team to deal with small spot fires so that you can deal with small fires before they become a problem. If you have an insurance policy, it is important that you understand what tests and information you need for a claim. If you don’t have one, you should consider getting one if possible.

Contracted fruit

If your fruit is contracted to a winery, it is important that you know and understand any contract language regarding smoke taint. If there is no specific language in the contract regarding smoke taint, the provisions: “no defects” and “suitable for producing quality wine” have been applied to smoke taint. Check with the winery about what tests they require before harvest. Many wineries, and insurance companies, are requiring micro fermentation with a sensory analysis by the winery to determine acceptability of the grapes. This would be accompanied by a lab analysis of free and bound smoke markers.

Know where the nearest lab is, check what tests they offer and the requirements for each. For example, the ETS Labs Smoke Volatile Markers – Basic Panel for wine needs 60 mL of wine for testing. Freezing both grapes and wine samples for testing at a later date is a good way to make sure you can get your material tested when labs are backed up.

Micro fermentations should start as soon as the grapes are ripe enough to pick and at least two weeks before your target picking date. The West Coast Smoke Exposure Task Force created a micro fermentation protocol to help vineyards and wineries who want a wine that can be reliably tested within 3 days. Grapes have some amount of the molecules that cause smoke taint so, micro fermentations should happen regardless of a fire/smoke event. This will give you a baseline number for the future. The California Association of Wine Grape Growers has more information on their website.

Preparing the Winery for Fire Season

Like in the vineyard, it is important to reduce fire fuel and create a defensible space around your winery buildings. Now is a good time to increase the defensible space around your facility. Clear brush and keep the vegetation around your roads cleaned and mowed. Check the vents into the eaves of buildings to make sure that embers can’t be pulled into the building. Maintain your fire suppression system. If you don’t have one, this is a good time to see what you can do to your facility for fire suppression. Install a generator to keep your tanks functioning during a power outage or if the power goes down.

Be prepared for a fire emergency. Create an evacuation plan, if you don’t have one, for employees and guests. Know how to get to a safe place based on the different locations that fires can come from. Make sure that you can verify that all of your employees got to safety. Be sure to distribute and practice the plan before you need it. There are many ways to stay informed through the internet and apps on your phone. Know which ones will give you information about fires, smoke and evacuation orders.

Preparing to Dealing with Smoke Taint

Pre-harvest plan

Part of your planning is knowing what types of wines you can make from each block and the minimum sugar that you need. I talk in another blog posting about how you can minimize smoke taint by reducing skin contact, like making a rosé. But, it’s equally important to know if that type of wine matches your brand and, if so, how much you can sell. If a different style of wine will not match the expectations of your customers, you are better to not make it than to have the cost of a wine that you can’t sell. And, selling a wine that is not up to your normal standards will have a long term negative impact.

A pre harvest plan becomes critical when there is a fire event, but then it’s too late. So, create the plan now.

The plan should cover:
  • The minimum ripeness for each vineyard block.
  • Testing each vineyard block with micro or bucket fermentations as soon as fruit is ripe enough to pick.
  • Sensory panels and lab testing.
  • What happens if a block fails the sensory testing?
  • Fruit handling procedures for smoke affected vineyards.
  • Winemaking procedures for smoke affected fruit.

Sensory testing the micro or bucket fermentations is the best step for assessing wine for smoke taint. A lab test is a good additional measurement, but can be difficult to get when there is a large fire event. OSU has a very good guide to sensory testing your wines.

Once you’ve done all of this the next question is: What do you do with smoke tainted grapes? I will cover that in another posting dedicated to the winemaking side of dealing with smoke taint. Be sure to signup for my blog feed or my newsletter so that you don’t miss it.

Success! You're on the list.

Published by Genevieve Rodgers

I'm an engineer turned, winemaker, turned winery consultant.

Leave a Reply