An increase in the frequency of wildfires in California, Oregon and Washington in recent years has exposed wine grapes in some areas to high levels of smoke. Smoke from wildfires contains a number of different volatile compounds that can be transferred to grapes and potentially released during wine making.
When present at certain concentrations, these volatile compounds can impart a “smoky,” “ashtray” or “campfire” flavor that consumers may find objectionable. Unfortunately, an understanding of the effect of smoke exposure on wine is limited, making it challenging to develop strategies to prevent exposure or mitigate its effects.
In response, the Oregon Wine Research Institute (OWRI) in the College of Agricultural Sciences at Oregon State University formed a multi-disciplinary study team to seek information and develop solutions to this growing concern. The team includes OSU Extension viticulturists Patty Skinkis and Alex Levin, Extension enologist James Osborne, sensory scientist Elizabeth Tomasino, flavor chemist Michael Qian, and applied economist James Sterns. All are OSU faculty and OWRI core faculty members.
The group initially met in the fall of 2018 to define the problem, evaluate resources and current research, and begin to formulate a science-based approach to acquiring the necessary knowledge upon which recommendations can be based. This led to the development and submission of a number of grants to various funding agencies at the federal and state level.
OWRI faculty have secured grants from the American Vineyard Foundation and the Northwest Center for Small Fruit Research for smoke exposure research and a large federal grant will be submitted to US. Department of Agriculture’s National Institute for Food and Agriculture Specialty Crops Research Initiative in early 2021.
An Extension publication, “Impact of Smoke Exposure on Wine” was developed that summarizes the current knowledge regarding smoke exposure and wine. This document will be continually updated in response to the latest research findings from the OWRI smoke exposure team. Currently, best practices to reduce risk of smoke characteristics in wine include:
- Identifying and separating grape lots that are at risk of developing smoky wine characteristics.
- Preventing material other than grapes from getting into the fermenter, minimizing skin contact early in the process.
- Whole cluster pressing whites, using oak or oak chips to reduce the perception of smoky wine characteristics.
- Using yeast strains that may enhance fruity characteristics.
- Reverse osmosis and spinning cone treatment of wine can reduce the concentration of the free forms of the smoke aroma compounds, but smoky characteristics may reappear over time.