Alka-Seltzer has been soothing human indigestion and heartburn for years. Now, it's helping out the wine industry.
Elemental sulfur is wine's "frenemy" - it effectively keeps the ubiquitous powdery mildew disease in vineyards at bay, but excessive residues carried over into wine can result in a rotten egg aroma.
Now a new, inexpensive method developed by Cornell scientists gives the wine industry a way to protect both vines and fermentations by monitoring residues -- using Alka-Seltzer tablets to make a winery-friendly protocol. The same protocol may be useful for such industries as construction, wastewater management, petrochemicals and forensic analysis, say the researchers.
Elemental sulfur has been used for centuries to control fungal diseases.
"Because it's cheap, effective and certified for organic production, sulfur is the material of choice to control powdery mildew in the summer," said project collaborator Wayne Wilcox, professor of plant pathology and plant-microbe biology based at Cornell's New York State Agricultural Experiment Station (NYSAES) in Geneva. "Growers want to know how close to harvest they can spray sulfur-based fungicides without affecting wine quality. With no real data on how long the residues persist, there is a tendency towards extreme conservatism in sulfur use."
Differences in weather and spraying conditions make providing blanket recommendations difficult, so Wilcox teamed up with Gavin Sacks, assistant professor of food science who specializes in the chemistry of grape and wine aromas at NYSAES, to develop a way to easily measure elemental sulfur so winemakers and growers could test grapes themselves.
Misha Kwasniewski, a doctoral student in the field of food science, was tasked with working out a method to convert elemental sulfur into the more easily measured hydrogen sulfide gas. The final hurdle was devising a way to remove all oxygen from the flask and flush the hydrogen sulfide into a detection tube. A research lab would use nitrogen from gas cylinders for this task, but finding a winery-friendly solution took Kwasniewski to the drug store.
"I recalled a water-testing kit that used Alka-Seltzer to generate carbon dioxide," Kwasniewski said. "When I tested it in our system, it actually solved three problems: It cleared the oxygen, it buffered the solution at the ideal pH for the reaction, and the carbon dioxide bubbles pushed the newly formed hydrogen sulfide gas into the detection tube."
The resulting protocol takes less than half an hour to perform, requires equipment that costs about $50, uses consumables that cost only about $5 per analysis and could save growers thousands of dollars, says Wilcox.
"Elemental sulfur generally costs $10-$20 per acre less than other powdery mildew controls," said Wilcox. "A grower with 50 acres of wine grapes who is able to use elemental sulfur in place of more expensive sprays five times during the growing season could realize savings of several thousands of dollars."
Kwasniewski found that the method works just as well on drywall, which can also be contaminated with elemental sulfur. Microbial digestion of sulfur has been suggested as a source of rotten egg smell and corroded pipes in homes afflicted by "Chinese drywall syndrome."
Sample sulfur detection kits have been distributed to interested growers and winemakers across New York and extension agents in Oregon, Ohio, Virginia and North Carolina for testing during the coming harvest.
The project was funded by the Canandaigua Wine Endowment Fund, federal formula funds provided to state land grant universities in support of agricultural research and the New York State Department of Agriculture and Markets.