Researchers from the University of California, Davis and the U.S. Department of Agriculture are testing whether a calcium spray can protect grapes from smoke exposure caused by wildfires, an issue that threatens California’s wine industry.
“Wildfire smoke exposure can lead to something called smoke taint in wines and this is an unfavorable sensory outcome in the wines themselves that relate to smoky, ashy flavors,” said Arran Rumbaugh, a USDA research chemist who collaborates with UC Davis’ Department of Viticulture and Enology. “We want to see how we can affect the absorption itself of smoke into the grapes by using a calcium spray.”
The experiment was conducted at the vineyard behind the Robert Mondavi Institute for Food and Wine Science at UC Davis. Researchers exposed 10 cabernet sauvignon and chardonnay vines to smoke generated from pellets made of oak, grass, pine and other materials under hoop houses with shade screens. A control group was not exposed.
Arpa Boghozian, a doctoral student in viticulture and enology at UC Davis who helped design and lead the study, explained that calcium supports disease resistance in grapes, prevents cracking, and strengthens skins and cell walls. The team applied calcium spray twice during grape development: once when berries began ripening (veraison) and again two weeks later.
“Our hypothesis was that by applying calcium we could further thicken the grape skin cell wall and decreasing absorption of smoke into the grapes,” Boghozian said.
After exposure, researchers collected both treated and untreated grape samples. Some were turned into wine for chemical analysis while others underwent puncture tests to assess changes in skin strength.
“We’re trying to understand with a puncture test did it actually strengthen the integrity,” Boghozian said.
This project continues work started by Anita Oberholster, a Cooperative Extension specialist known for developing early methods for detecting smoke taint in grapes. Both Rumbaugh and Boghozian previously worked in her lab.
“It’s been definitely really special to continue what Anita was passionate about and collaborate on research,” Boghozian said.
Analysis is ongoing; results are expected later this year or early 2027.
UC Agriculture and Natural Resources (UC ANR), which supports this type of research through science-based practices statewide (https://ucanr.edu/), maintains nine Research and Extension Centers across diverse ecosystems (https://ucanr.edu/). UC ANR operates offices in all 58 California counties along with these centers (https://ucanr.edu/), building collaborations focused on farming approaches, wildfire protection strategies, nutrition programs, food networks, youth education resources developed over more than a century (https://ucanr.edu/). Glenda Humiston serves as vice president of UC ANR (https://ucanr.edu/).
The article first appeared on the UC Davis News page.