Written by ARCS Oregon Scholar Sarah Caballero
Hello, I’m Sarah, and I’m a 1st year PhD student in Food Science at Oregon State University and an ARCS Scholar. When I applied to OSU, I wanted to work on a project related to food engineering and agricultural sustainability. After admission, I found out that I would be taking the lead on the infamous “smoke and wine” project at the College of Agricultural Sciences.
While working on my master’s in 2020 at Cal Poly Pomona, my family received an evacuation order when hot, windy conditions led to fires in Southern California. Luckily, the winds shifted, and we were fine.
While vineyards and wineries suffered insurmountable physical and financial damage during the catastrophic 2020 fires, another silent assailant was just being uncovered. Small, airborne particles, ‘volatile phenols’ released when timber burns, were penetrating the waxy protective layer on grapes close to their harvest time. The grapes’ natural enzymes converted these phenols to phenol glycosides; essentially anchoring the volatile compounds into the grape by attaching them to a sugar molecule.
During grape fermentation, these volatiles are released from their glycoside anchors, causing off-flavors and aromas. Wines fermented from grapes exposed to smoke have been described as ‘ashy,’ ‘chemical/plastic,’ ‘tar’ or ‘musty’. Studies have shown that smoke-affected wines negatively impact consumer acceptance of the wine, making those ferments a financial and business risk for wineries. Smoke-exposed grapes may also be left unharvested, as during 2020, generating crop loss and food waste.
While the 2024 vintage in the Pacific West and Northwest has spectacular prospects, wildfires are now a regular threat. In the lab, we are working to innovate a protective barrier for wine grapes. Specifically, we are developing a pre-harvest spray coating made of natural fibers to act like an air purification filter. Ideally, smoke compounds will be blocked from being absorbed into the grape. Then, the coating would be removed during crushing and fermentation.
In the lab, I am studying various coating formulations by drying them into films. I hang the films in airtight jars containing smoke compounds (Figure 1). I measure the amount of smoke compound on the film pieces to determine their effectiveness in blocking the smoke phenols. I have also experimented with putting table grape bunches in these jars and exposing them to smoke (Figure 2). When I open the jars to remove the grapes, a repulsive odor is released. The best way I can describe it is burnt rubber. Due to the unpleasant volatiles, I do my experiments under the fume hood.
Wildfires can be scary, dangerous, and ominous. My food science research helps ensure that they pose less of a threat to agriculture, particularly the wine industry. I am excited about the future of this project and our research in sustainable agriculture.
Please do not hesitate to contact me: https://sites.google.com/view/sarahcaballero/home
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(Figure 1: Inspecting film pieces in the fume hood after exposure to smoke compounds)
Photo of Sarah in lab
Figure 2: Experimenting with dipping table grapes in different coating formulations.
