Wine and Wildfires: A Journalistic Essay of Climate Change, Grapes, and Engineering a Solution
Wine and Wildfires: A Journalistic Essay of Climate Change, Grapes, and Engineering a Solution
Fire
It was Summer 2020, and the world was on fire. Southern California was
on fire. Napa was burning down. Oregon was on fire. And it seemed like fire was
the only one on the loose. Because the rest of us were on pandemic
lockdown.
I remember bits and pieces of that apocalyptic season, when I was
working on my Master's research at Cal Poly Pomona amid lockdown and social distancing.
This is what I remember of the 2020 wildfire season that would go down in history. At the time, Oregon wasn't yet on my radar, other than
daily news headlines about the fires. I actually wouldn't step into the picture
of Oregon fires until 2023, when I began my PhD at Oregon State University. That is also when I learned about
the grapes. The Pacific Northwest grape and wine industries were to suffer losses of over one billion dollars, thousands of jobs, and one-third of
wine grape yield, with ripples projected through 2023 (1). I would have a
very small part to play in helping a very big industry save one of the most
vulnerable agricultural crops: wine grapes.
Nurture
The first grape bunches looked like tiny green snowflakes; stiff green
stems topped with tiny beads. Viticulturists assign specific numbers to the stages of grape
growth (2). At stage 31, berries are pea sized. At stage 33, bunches have closed,
but berries are still hard and green. It was at about this stage that we
applied the first layer of the coating.
I, however, called the young berries "baby grapes." For myself
as their student, and for the viticulturists as their parents, this term is
perhaps apropos. I strolled through rows of vines inspecting the miniature
green grapes I was about to spray with a smoke-protective coating. Outfitted
with a backpack sprayer containing five gallons of liquid sloshing around, I
slowly moved amongst the vines, pushing away blankets of foliar leaves with my
hands to douse the tight clusters of pea-sized grapes underneath.
This liquid was unlike any other chemical spray used on crops, typically
fungicides. It was a carefully crafted formula, appearing like a thick milk,
but zooming in, was a powerful web of naturally abundant fibers cellulose and
chitosan, chemically networking and entangling with each other, holding
remarkable properties, being the superheroes of their own story. We envisioned
that the polymer matrix the spray imparted would expand with berry growth
(thanks to cellulose). We did not invent these fibers; Earth did. But, we
believe we can harness them to solve one of the most perplexing problems
agriculture is currently facing.
The more time I spent in the vineyard, the more I wanted to protect it.
Not just for the sake of the vines, but for the people who nurtured them,
starting with budburst in May.
Two
weeks after the inaugural spray application, I visited the vineyard
for a second coating in late July. This time, the grapes flashed
bright purple against dark green foliage. Stems were like a maze with no
solution, leading to entangled masses of fruit. I was pleased to see remnants
of the first spray coating still on the grapes. Coated grapes appeared to have silky
or papery surfaces, differentiating the formulations we were testing.
As the thick, milky mixture dripped slowly from bunches, I wondered if it would
be robust enough – or even still intact on the grapes – upon vine smoking in a
couple of weeks. It was Earth protecting Earth's harvest. Often, Earth holds
all the answers we need; we just need to understand. And the first step of
understanding is to listen. And that was this experiment.
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| Coated grapes appeared to have silky or papery surfaces, differentiating the different formulations we were testing |
[Enter: Smoke]
In the past ten years, the Pacific Northwest has faced increasingly more intense
wildfires. Years are cyclic, but trend up; every few years, another monster
firestorm hits (3). In past years, smoke from these wildfires has encroached on the
home of Oregon wine, especially Oregon Pinot noir.
So how does the smoke affect grapes? When woody material is burned, the
large, complex structural molecules are disintegrated into individual, cyclic
molecules we call volatile phenols. It is like cutting up the multi-ringed
plastic casing on a case of sodas into individual plastic rings. These consist
of a hexagonal-shaped ring, with a couple arms of varying complexity. These
volatile molecules are the Spidermans of the chemical world. They can go
anywhere. And one of their sneaky moves is to land on grape surfaces and
weasel their way through the outer waxy protective layers and skin of the
grape. The grape, identifying the intruder, activates its chemical defense
system. Where the grape resolves these invading species and rubs its hands in
satisfaction, the winemakers reel. The grape's innate solution is to attach
sugar molecules (of which there are many!) to the volatile phenols,
transforming them into a water soluble, chemically stable form. During
fermentation, aging, or during contact in human saliva, however, the sugar
molecules are cleaved, re-releasing the volatile phenols. These volatile
phenols carry ashy, medicinal, burnt, or rubbery flavors and aromas, imparted
to the wine in an unpredictable way.
Tracking smoke exposure in grapes is complex and serpentine. When a
smoke volatile phenol enters a grape, it is like putting a quarter into a
gumball machine. The grape can convert the volatile phenol into a variety of
chemical products, making compounds difficult to trace. It is like receiving a
randomly colored gumball from a gumball machine and trying to figure out which
quarter it came from. Additionally, it is almost impossible to predict how and
if this kaleidoscope of chemical reactions will influence the final wine. The
ongoing discovery of conversion compounds makes decision making difficult and
business decisions blurry. We are working to prevent the quarter from entering
the gumball machine in the first place; our coating is a buffer between smoke
and the grape.
The complexity inside grapes, and unknown outcomes as to ashy
aftertastes, is one factor which makes winemaking decisions murky. The other is
that not all smoke is equal. We still do not fully understand how to determine
if smoke poses a risk for grapes. If the smoke is higher in the air, like a
high cloud layer, it may not impact grapes as much as smoke that is close to
the ground and dense (4). Variation of smoke impact in grapes is highly dependent
on the smoke density and duration of exposure, as well as land topography, wind
direction, and wind speed (5). These compounding factors make decision making in
the vineyard very difficult. Not only is the smoke risk a compounding factor,
but it is nearly impossible to definitively say if produced wine will be affected
or not. Often, nanoferments of wine are recommended to the industry, when are
then sent off for analysis. Even then, each bottle poses a risk. A nebulous
collaboration of multiple disciplines, including environmental engineering,
viticulture, chemistry, is required to converse with Nature.
Smoke is stealthy. The chain of chemical reactions it produces in grapes
are not completely understood. Sometimes it strikes, sometimes it’s as if it
was never there. If the smoke is there, can we prevent the chain reactions in
grapes? Researchers have been trying for years. Every year, a variety of sprays
are applied to grapes for anti-sunburn or antifungal protection. Some studies have
piloted applying these same sprays to grapes during artificial smoking to see
if a simple outer layer coating would deflect the smoke chemicals or prevent
them from reacting (6). A simple bandaid has not worked. We must instead understand
how to work with the grape-- how to reinforce the grape’s natural defenses. We
are using two of the most abundant structural biopolymers on the planet--chitosan and cellulose--to do this.
Cellulose is responsible for about a third of all vegetable
matter on earth. From trees, to pulp, to pits, cellulose is structurally strong
when part of wood. But on its own, it is flexible and wettable, meaning it will
stick to the grapes' surfaces. It forms a flexible surface film on the grape surface, the scaffolding to
the defense we are designing. This scaffold is interwoven with the dense fibers
of chitosan. Chitosan, from shellfish or fungi, is one of the most unique biopolymers
on earth. It is the only biopolymer that can chemically complex with cellulose,
forming dense, yet flexible, networks of strong fibers, like weaving strands of
string into a thick rope. Under a microscope, the grape surface is an intricate
terrain composed of jagged ridges of hairlike and platelet shaped waxes (7). Our coating adheres to and connects between these wax platelets. If our spray
coating is designed to integrate into this surface structure, will it stop
the volatile phenols?
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| Uncoated (top) and Coated (bottom) grape surfaces under Scanning Electron Microscope |
Terroir
Oregon wine is rooted deep within place. It takes 3 years for a new
grape vine to establish its roots and be ready to bear fruit. Perhaps this deep
connection with the soil is why grape growing holds a mystique. Of
respect for the vines, many of which are reborn through generations. Of
appreciation for traditional wine making. Of the sanctity of the grapes.
 |
Hale, J. (2018, November 22). The 18 wine regions of Oregon, from Green Valleys to the High Desert. oregonlive. https://www.oregonlive.com/life-and-culture/erry-2018/11/40a837e3663598/the-18-wine-regions-of-oregon.html
Oregon's 5 American Viticultural Areas (AVA’s) in Oregon arch from the west coast to the north border. These 5 AVAs represent over 610
wineries, updated annually by an Oregon Vineyard and Winery census (20). Of these,
the Pinot noir grape is royalty. European royalty. It originated as a ‘vieille vigne Francois’ that could be translocated to Oregon by early
settlers. It had a rough start in Oregon, due to “temperamental”
conditions resulting in browning and volatile off flavors that led to it losing
popularity in the 1960’s (8). “Quixotic,” “capricious,” and “petulant” were the first impressions. In the 1970s,
California and Oregon wineries began to experiment with Pinot, leading to 1985
Rochioli Vineyard Pinot Noir being named top wine at the 1987 California State
Fair. Since then, Pinot crescendo back to the headlines. Pinot contains fewer
tannins and anthocyanins than other options such as Cabernet and Zinfandel and
was increasingly sensitive to cross adaptations of winemaking technology in
America. Today, Pinot is synonymous with “Willamette Valley.”
The Willamette Valley was the perfect cradle for the first Pinot noir
vines, red soils rich in iron (9). It is a
sacred place for Oregon Pinot noir. It is where generations of vines are reborn
year after year, heralding in new vintages. This has drawn small, artisanal
wineries, about 70% of total wineries in Oregon. In homage to the Willamette
Valley, wines are crafted, starting with the grape, to reflect the land. A love
for the land may explain why nearly half of Oregon vineyard acres hold
Biodynamic, LIVE, or other sustainability certifications (10). This certification
follows National Organic Program protocol, but is additionally a pact
between the grower and the land; to preserve and protect the air, soil, and
water. The state and the regions are beautiful and people are working to
product the best quality products while being stewards of the land, explains
Greg Jones, grower, winemaker, and owner of Abacela Winery (11).
But then smoke drifted over this idyllic vineyard. Several methods are used to calculate smoke, including particulate matter, AQI, and USG (12). Particulate matter, PM, tells us about the density of the
smoke. For instance, PM2.5 is a value that describes the density of particles
that are smaller than 2.5 microns able to be inhaled into the lungs. PM2.5 can
then be converted into AQI values, which describe how harmful the air is to
human health from National Ambient Air Quality Standards. From 2013-2022, the
number of days of unhealthy or hazardous AQI has increased by about 10-fold,
especially near Southern Oregon and the Willamette Valley (12). USG is a measure of
human health, how “unhealthy” the air is for “sensitive groups,” such as
children, the elderly, or those with health conditions. In the last ten
years, the number of days with AQI levels above USG has increased by about 59
times in the Willamette Valley, and about 8.5 times higher in Medford/Southern Oregon (12). The Willamette Valley is seeing the
most dramatic increase in smoky days annually.
Granted, wildfires are not new. So why are we suddenly talking about
wine and wildfires? Greg Jones offered perspective from his multi-generational
family vineyards. A multi-generational wine making family, Jones’ father didn’t
have to think much about fires in the 1990’s-2000’s. It wasn’t until 2016-2018
that they have become more of a forefront issue. Jones’ observations are in
accordance with data showing acres burned in Oregon, Washington, and Northern
California from 2010 to 2022. Years are cyclic, but trend up; every few years,
another monster firestorm hits.
Granted Smoke is not mother nature’s first stab at wine grapes. Dick
Erath was one of the early pioneers of Oregon wine. “Mother nature rolls the
dice,” Dick described of his early days of the Erath vineyard, later the Knudsen Erath Winery (9). In November 1969, delicate buds were
petrified in a thin layer of ice, causing them to break. A black and white
photo of the first buds of Erath’s first vineyard shows the budling sleaved in
thin, dripping ice (9). And the vines snapped off. Another four acres succumbed to
a late frost in 1970.
Over the years, the climate has turned warmer and dryer, with less frost
and a longer growing season. In fact, in some ways climate change has been
favorable for the Oregon grape industry. Greg Jones explains how in the 50’s, you just couldn’t grow
grapes in Oregon (11). The climate was prohibitive, with risk of cold in winter and
spring. Varieties that previously could not tolerate the cold, such as the
Italian Barbera, now thrive. However growers still face climate extremes and
speak of triple-digit heat shriveling their grapes, grape shoot tips burning
off, or flash hailstorms flattening sections of vines (13,14). Some problematic pests,
such as a wine mealy bug, are also flourishing in the heat (4). These
challenges can be devastating, losing crops, but they can also be identified
and have a more concrete outcome. However, smoke has brought something much
more sinister. A phantom chemical reaction. The pretense of normalcy.
Vineyard at Dusk
It was time to understand if our barrier coating formulated from natural
fibers cellulose and chitosan would shield the Pinot noir grapes from simulated wildfire smoke. The moon had
risen over the small vineyard at the Southern Oregon Research and Extension
Center (SOREC; Medford, OR), reflecting some light over the vineyard otherwise
blanketed in darkness between hills. Faint moonlight intermingled with two
electric lights to cast the vines into
chiaroscuro, as they were seemingly more foreboding than earlier in the hot,
sunny day. I arrived wearing shorts, shivering slightly as the
temperature dropped and with excitement. As night fell, the team at SOREC
swiftly began assembling tent enclosures and smoking equipment. First, we built
plastic tents around rows of 6 vines. Several of us would stand on one
side, and using a wooden pole, throw a pile of plastic tarp to the opposite
side of the vines. Then, we would pull it taut over both sides, bunch up the
edges, untangle the ends of the vines, and duct tape the apparatus closed. The
bottom of the tent was anchored with lines of sandbags. Entering under the base
of each tent was a flexible PVC pipe, like one for a ventilation system, which
was connected to a main barbeque. Finally, we activated AQI sensors under each enclosure to monitor and control smoke particulate matter levels. Then, the barbeques were
ignited. Douglass fir chips were smoldered, and smoke was directed into each
enclosure while the team monitored air particulate matter. While most of the
smoke was being directed by piping into the tents, area lights illuminated
residual smoke, morphing in the hazy light.
Some of the grapes were coated with our barrier coating, but was it
enough to withstand this treatment of direct smoke? The coating was intended to
resist exposure to atmospheric smoke, which may be blown in from miles away. It
was not designed to resist an intense inundation of smoke. At this point, my
job was over. Now it was up to the grapes. My job was to be their student, to
observe how they reacted to the smoke to better understand this mysterious
process.
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| lights cast the vines into chiaroscuro |
Grey Zone
Regardless of these efforts, the effects of smoke on grapes and wine are
only our current understanding. Thus, scientific preventive measures or
treatments are only our best attempts.
So, in a way, we are trying to trap a ghost with the coating. We cannot
see it working. We cannot see what it is blocking. All we can do is measure the
damage that occurred. Surely, the grapes look better without the coating,
without a thin layer of white residue. However, without the coating they are
being harmed by the invisible.
While we are working on the science, the industry is keenly watching.
Wine makers and viticulturists know their grapes inside and out. Smoke, though,
is different. You can send grape samples off to state-of-the-art labs to get
tested, but it’s still unknown exactly what to look for. Originally, guaiacol
was the main indicator, what contract decisions between winegrower and
winemaker were based on. If the grape contained more than a certain amount of
guaiacol, it could jeopardize wine quality and, thus, grape value. However, as
described by Jason Cole, owner of Pacific Crest Vineyard Services, the science
is not yet complete (14). It is reasonable but flawed. There are still new analyses
and new compounds being discovered. As someone who manages labor and operation
for vineyards, Jason explains that growers and buyers need to figure out how
they will handle smoke levels; the fruit is either good to be purchased or not
good at all. The grey in-between complicates this decision making. Where the
science becomes exciting, the business decisions become difficult. Necessitated due
to the chance of smoke exposure, grape growers now have the option to purchase
crop insurance. While crop insurance helps growers to recoup some of their
expenses, growers may be required to harvest and drop their fruit to compost in
place.
Right now, a standard test of smoke impact in grapes or wine is a set of
about seven volatile phenols. These are the ‘quarters,’ the volatile chemicals
carried in smoke. However, some of these volatile phenols will have been
converted by the grape into their bound counterparts, the multicolored
‘gumballs’. The most prevalent bound phenols can also be tested for. Using
these arrays of data, we can try to approximate smoke impact on the final wine,
but the conclusions are not explicit. A recent study measured
chemical markers of smoke in both wine samples and grapes from California and
Oregon (15). Additionally, trained panelists tasted all wine samples and rated them
for “ashy” tastes. The results? It was impossible to attribute the ashy taste
to any one chemical compound in either grapes or wine. Rather, a plethora of
chemicals, in either grapes or wine, floated in a hazy “grey zone,” where all
contributed something to the identification of ashy tastes, but none was
entirely responsible. In fact, in grapes, many of these chemicals were poorly
associated with perceived smoke taint in wine. What happens in the grapes, then, really
is mysterious, uncertain, and capricious. Only after fermenting the grapes into
wine, do the cards fall into place. And even then, it is a random hand.
Academia quickly adapted the word ‘smoke taint,’ first appearing out of
the Australian Wine Research Institute in 2023, to address the inherent damage
of grapes exposed to wildfire smoke (16). In 2007-2008, smoke taint was further
associated with specific chemical markers, initially guaiacol (17).
However, the industry cautiously tiptoes around this term. This term, they
argue, is not representative of the broad spectrum of smoke impact, with plenty
of opportunities for little to no noticeable impact. Only the most affected
wines may bear an unpalatable ashy aftertaste. Also, consumers may accept
smoke-exposed wine if wineries use marketing to feature smoke as a feature of
the growing season, rather than as a detriment (18). Furthermore, not all
smoke is equal, and the density, location, and height of smoke, composition of
smoke, timing of smoke, and duration of smoke factor into outcomes with
particular vines of grapes.
Basically, the effect of smoke on wine depends on a juggernaut of
factors. Without chemical testing, it is impossible to say how particular
grapes have been impacted. Winemaking techniques can also reduce the risk of a
smoky wine. It is easy to shrug off smoke, dismissing 2020 as a one-off, just
like the Pandemic. A one-off that couldn't possibly occur again. Or perhaps
with 2024 being a good year for smoke and for grapes, we have moved on from the
devastation caused in 2020 and before. Either way, we must learn from these
past experiences, and steer science and engineering forwards to develop the
agricultural technology of the future. Counting on luck for smoke, wind, and
smoke taint is like building a foundation in quicksand.
Planted
To many, the word "beautiful" describes Oregon, describes
multi-generational vineyards, and describes the craft of winegrowing and
winemaking. One thing is for sure: Oregon wine is planted. And assuredly the
same can be said for vineyards around the world.
Necessarily, the hazy meeting between grapes and smoke will be an annual
occurrence. Where and when this occurs, we cannot say for sure. While our
spray-on coating is not the only solution in development, it allows a window
into the world of the grape, an opportunity to address one of the most pressing
agricultural needs of our time. The results of our field study were recently
published in the Journal of Food Science (19). Like any good study, it raised a
multitude of further questions. We found some positive effects against smoke,
but perhaps more importantly, we saw the coatings interact differently with the
grapes. Now we hypothesize that we don't need to cover the grape with a
secondary layer, we instead need to reinforce the grape's surface. And if we
can find the best way to do this, this could lead to breakthroughs in
using natural polymers to defend grapes against sunburn, pests, and other
environmental threats. Our results also reaffirm the power of building with
cellulose and chitosan. We are engineering a scaffold to hold up the miniest of
miniature cities: the grape's surface.
Oregon wine has been etched and molded in the last 50 years of nurturing
and learning, warming climates and changing soils, extreme heat, and extreme
cold. The result is a product so inseparable from the Earth in which it grew,
and from the people who crafted it. As climate extremes manifest in years of
extreme smoke, Oregon grapes also face these conditions. Smoke poses new
challenges but also new possibilities. And with the help of engineers,
scientists, winegrowers, and winemakers, Oregon wine will prove resilient.
References:
1. Economic Forensics and Analytics. (2021). The Economic Impact of the Wine and Wine Grape Industries on the Oregon Economy 2019 and 2020 Estimated.
2. Coombe B.G. and Dry P.R. eds. 2006. Viticulture Volume 1-Resources. 2nd ed., Vol.1. Winetitles.
3. National Interagency Coordination Center Wildland Fire Summary and Statistics Annual Report 2020.
4. Private Communication, John Pratt, Owner and founder of Celestina Valley Vineyards, May 27, 2024.16. Høj, P., Pretorius, I., & Blair, R. (2003). The Australian wine research institute annual report. The Australian Wine Research Institute: Urrbrae, SA, Australia, 37-39.
17. Kennison, K. R., Wilkinson, K. L., Williams, H. G., Smith, J.
H., & Gibberd, M. R. (2007). Smoke-derived Taint in Wine: Effect of
Postharvest Smoke Exposure of Grapes on the Chemical Composition and Sensory
Characteristics of Wine. Journal of Agricultural and Food Chemistry, 55(26),
10897–10901. https://doi.org/10.1021/jf072509k.
18. Fryer, J. A., Dupas de Matos, A., Hort, J., & Tomasino, E. (2025). Consumer responses to smoke-impacted pinot noir wine and the influence of label concepts on perception. Food Research International, 203, Article 115881. https://doi.org/10.1016/j.foodres.2025.115881
19. Caballero, S., Levin, A., Deshields, J., Cerrato, C., Zhao, Y., & Jung, J. (2025). Preharvest Cellulose–Chitosan Spray for Mitigating Smoke Impact in Wine Grapes: Enhanced Blocking m‐Cresol, Validation in Model Table Grapes, and Vineyard Field Evaluation. Journal of Food Science, 90(9), e70515-n/a. https://doi.org/10.1111/1750-3841.70515
20. Oregon Wine Industry. (2025). 2024 Oregon Vineyard and Winery Census. University of Oregon Institute for Policy Research and Engagement. https://industry.oregonwine.org/resources/reports-studies/2024-oregon-vineyard-and-winery-report/
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