VWT 272 Class 11 Quiz 10 Number of quizzes taken 20 Min 25 Max 30 Mean 29.8 Median 30 Mode 30
Lecture 11 Other (Smelly) Sulfur Compounds He that lives upon hope will die farting. Benjamin Franklin (1706-1790)
Plan of Study Vineyard Sulfur Additions S vs. Bordeaux Mixture Amino Acids & Proteins Structures Hydrogen Sulfide Causes Vineyard S, yeast nutrition, or??? Prevention Removal CuSO 4 vs. wishing Thiols & Disulfides
Where does Sulfur come from? Java, Indonesia
Where does Sulfur come from? Alberta Oil Sands, Canada
Vineyard Sulfur
Vineyard Sulfur Useful against Powdery Mildew (Uncinula necator) Used since 1890 s Spray intervals between 7 to 21 days Extremely good models of PM growth based upon temperatures between 70 and 85 F
Mutiple forms Vineyard Sulfur Dust S with average particle size of 20 to 45 microns applied dry Wettable S plus dispersants and surfactants applied wet or dry Micronized S with average particle size of 5 to 25 microns applied wet or dry Often discontinued when grapes reach 12 Brix Problem if residue in must > 1 to 10 mg/l
Powdery vs. Downy Powdery Mildew on Grapes Found everywhere in California Controlled by Sulfur and other fungicides Downy Mildew on Grapes From Plasmopara viticola Found in areas with spring & summer rainfall at temperatures above 50 F Controlled with Bordeaux Mixture Copper Sulfate (CuSO 4 ) & Slacked Lime (Ca(OH) 2 )
Bordeaux Mixture
Hydrogen Sulfide (H 2 S) AKA: Reduced
Recipe to make something smelly replace an O with an S Hydrogen Sulfide fart/rotten egg 1 ppb 1,3-hexanediol odorless 3-mercaptohexanol Passion fruit 60 ppt
Where does H 2 S come from? Vineyard based Elemental S residue More S leads to more H 2 S in the wine Mechanism not well understood S S 2- (sulfide) Highly yeast strain dependant Takes place on cell wall of yeast Younger yeast cells produce more S 2- Higher alcohol produces more S 2- Amino acid Cysteine may be important
A Brief Detour into Amino Acids A class of compounds that have a specific spine and various side chains
A Brief Detour into Amino Acids
A Brief Detour into Amino Acids Amino acids link together with Peptide Bonds to form Peptides Peptides link to form polypeptides
A Brief Detour into Amino Acids Polypeptides link to form the Primary Structure of proteins The Primary Structure folds and packs into complex forms like helices and pleated sheets
From Amino Acids to Proteins
From Proteins to the Nobel Prize
Where does H 2 S come from? Inappropriate Yeast nutrition Yeast leak H 2 S when they make 2 amino acids Methionine and Cysteine Yeast make all organic S containing compounds from the S containing amino acids
Where does H 2 S come from? Inappropriate Yeast nutrition Yeast release H 2 S when they use S containing amino acids to make other necessary building blocks Vitamin deficiency Biotin deficiency Yeast need ~ 1 μg/l Pantothenate deficiency Yeast need ~ 50 μg/l
Where (else) does H 2 S come from? High solids fermentations High temperature fermentations Lees contact Release from S containing compounds in yeast Loosely Bound to compounds in wine Poorly understood mechanism???
Removing H 2 S The Smart Way Copper Sulfate (CuSO 4 ) addition CuSO 4 Cu 2+ + SO 2-4 Cu 2+ + SO 2-4 + H 2 S CuS (s) + 2H + + SO 2-4 What matters is the Cu 2+ CuSO 4 available as: CuSO 4 (anhydrus) white powder CuSO 4 5(H 2 O) copper sulfate pentahydrate blue power 10% & 1% (as? (usually CuSO 4 )) Confirm with supplier
Removing H 2 S The Smart Way According to the TTB (27 CFR Ch 1 24.246) The quantity of copper sulfate added (calculated as copper) (Cu 2+ ) must not exceed 6 parts copper per million parts of wine (6.0 mg/l). The residual level of copper in the finished wine must not exceed 0.5 parts per million (0.5 mg/l). Atomic Mass of Cu 2+ = 63.5 Molar Mass of CuSO 4 5(H 2 O) = 249.7 So 25.4% of CuSO 4 5(H 2 O) is Cu 2+ 100 mg CuSO 4 5(H 2 O) / 25.4 mg Cu 2+
Removing H 2 S The Smart Way The secret about Cu 2+ If there any yeast present, especially live yeast, they will capture large amounts of any remaining Cu 2+ left in the wine after addition
Calculation with Cu 2+ 1500 gal of Grenache with a serious H 2 S problem. Bench trials suggest that you need to add 0.5 mg/l Cu 2+. How much CuSO 4 5(H 2 O) do you add? 1500 gal x 3.785 L/1 gal x 0.5 mg Cu 2+ /L x 100 mg CuSO 4 5(H 2 O) / 25.4 mg Cu 2+ x 1 g CuSO 4 5(H 2 O)/ 1000 mg CuSO 4 5(H 2 O) = 11.2 g CuSO 4 5(H 2 O) 225 L of Chenin Blanc with slight reduction. Bench trials suggest that you need to add 0.2 mg/l Cu 2+. How much 1% Cu 2+ solution do you add? First confirm that the 1% is as 1% Cu 2+ (not 1% CuSO 4 5(H 2 O) 225L x 0.2 mg Cu 2+ /L x 100 ml Cu 2+ solution / 1 g Cu 2+ x 1 g Cu 2+ / 1000 mg Cu 2+ = 4.5 ml Cu 2+ solution
Removing H 2 S The Dumb Way Splash or run Oxygen through the wine Splashing will force the volatile H 2 S out of the wine O 2 will displace the S in the H 2 S 2H 2 S + O 2 2H 2 O + 2 S Run the risk of forming thiols/mercaptans from the H 2 S reacting with acetaldehyde.
Acetaldehyde Formation
Removing H 2 S The Dumb Way 2H 2 S + CH 3 CHO HSCH 2 CH 2 SH + H 2 O Ethanedithiol Highly reactive Degrades into other thiols Smells like durian
Your New BSF - Durian
Removing H 2 S The Dumb Way Ethanedithiol can degrade into: Compound Methanethiol (Methyl mercaptan) Chemical Formula CH 3 SH Aroma Description Cooked cabbage, rotten eggs Concentration in Wine (µg/l) Odor Threshold (µg/l) 0 to 16 2 Ethanethiol (Ethyl mercaptan) CH 3 CH 2 SH Onion, rubber, natural gas, fecal 0 to 12 1.1 None of the above compounds are easily removed from wine SOME react with Cu 2+ slowly (months)
Removing H 2 S The Dumb Way Thiols can form an equilibrium with disulfides Compound Dimethyl disulfide Chemical Formula CH 3 SSCH 3 Diethyl disulfide CH 3 CH 2 SSCH 2 CH 3 Aroma Description Cooked vegetable, strong onion Cabbage Strong onion, burnt rubber Concentration in Wine (µg/l) Odor Threshold (µg/l) 0 to 22 29 0 to 80 4.3 Disulfides do not react with Cu 2+
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