Sulfur is wine's friend and enemy at the same time. It has been used for centuries to control fungal diseases. Growers occasionally spray sulfur compound on grapes in the vineyards to combat ubiquitous powdery mildew, but excessive sulfur residue on the grapes can result in an unpleasant aroma of rotten eggs, a common defect in wines.
“The problem is, if elemental sulfur gets into the grapes that are harvested, it gets converted into hydrogen sulfide,” says Gavin Sacks, professor of enology and food science at Cornell. “And hydrogen sulfide smells like rotten eggs.”
"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 working for Cornell.
However, differences in weather and spraying conditions make it difficult to make any blanket recommendation. 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 the use of sulphur.
Therefore, Wilcox teamed up with Gavin Sacks, assistant professor of food science who specializes in the chemistry of grape and wine aromas at Cornell New York State Agricultural Experiment Station, to develop a way to easily measure elemental sulfur so winemakers and growers could test grapes themselves.
A new, inexpensive method developed by them may give the wine industry a way to protect both vines and fermentations by monitoring residues -- using Alka-Seltzer tablets to make a winery-friendly protocol. Dropping an Alka-Seltzer tablet into the grape juice helps release hydrogen sulfide, which can then be measured.
Interestingly, the same protocol may be useful for such industries as construction, wastewater management, petrochemicals and forensic analysis, say the researchers.
Testing kit developed at Cornell is currently being distributed for trials, according to a report. |