Transcript Slide 1
Management of Sulfides Formation
Linda F. Bisson
Department of Viticulture and Enology
UCD
Management of S-Taints
Diagnosis
of Taint
Taint Prevention
Taint Mitigation
DIAGNOSIS OF SULFUR TAINTS
Correct Diagnosis of Fault Is Important
Is
it an S-containing compound?
When did taint first appear?
What factors are associated with
appearance of the taint?
Is It a sulfur-containing compound?
Be
familiar with the characteristic off-odors
of sulfur compounds
Other classes of off-odors can be
reminiscent of S-compounds
Thresholds of detection are so low
compound may be difficult to detect
chemically
When did taint first appear?
Provides
important clues as to the reason
taint is occurring
If know why it is being made can take
steps to prevent formation
What factors are associated with
appearance of the taint?
Always
found with a specific vineyard?
Associated with unsound fruit?
Associated with specific processing?
– Inert gas blanketing
– Type of vessel
Associated
conditions?
with specific fermentation
TAINT PREVENTION
Preventing S-Taint Formation
Vineyard
Wine
chemistry
Yeast strain selection
Fermentation management
Preventing S-Taint Formation
Vineyard
– Judicious use of elemental sulfur
– Eliminate reliance on S-containing pesticides
– Address excesses of metal ions
– Address vine stress: nutritional or otherwise
Wine
chemistry
Yeast strain selection
Fermentation management
Preventing S-Taint Formation
Vineyard
Wine
chemistry
– Minimize use of ‘enabling’ practices
» Temperature
» Solids content
» “Reductive” aging conditions
» Role of the ‘lie’ in ‘sur lie’
Yeast
strain selection
Fermentation management
Preventing S-Taint Formation
Vineyard
Wine
chemistry
Yeast strain selection
– Match strain to winemaking conditions
– Meet the nutritional needs of the specific strain
Fermentation
management
Preventing S-Taint Formation
Vineyard
Wine
chemistry
Yeast strain selection
Fermentation management
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Provide adequate nutrition
Keep cells suspended
Mix to prevent reductive stratification of tanks
Remove from lees/yeast residue at first sign of
trouble post-fermentation
TAINT MITIGATION
Elimination of Hydrogen Sulfide
•
Rely on volatility and fermentation gas or
inert gas sparging to remove
– Need to make sure it is gone and not just
converted to a non-volatile form
•
•
Use of volatiles stripping technologies
Precipitation via copper
– Emerging issue: health and environmental
concerns about copper
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•
Use of fining agents
Use of strains not producing sulfides
Treatments for Higher Sulfides
Removal
by reduction of disulfide bond
with ascorbate and copper binding
Sulfide trapping by quinones
O
OH
O + RSH
OH
SR
Removal by charcoal fining
Conclusions
Sulfur
taints can be controlled
Need to use correct strain
Need to minimize use of compounds in
vineyard and winemaking techniques that
amplify S-compound formation
Many factors leading to S-taint appearance
are still not well understood