Common Defects in Wine Presented by Jef L. Stebben Stebben Wine Consultants

Formed in 2002 to provide quality winemaking to small producers Formed in 2002 to provide quality winemaking to small producers Consistent focus on quality and improvement at low cost to clients Consistent focus on quality and improvement at low cost to clients Now working with wineries from 9,000 cases to home winemakers Now working with wineries from 9,000 cases to home winemakers

Jef L. Stebben Phone (707) Phone (707) (Notes from this presentation will be posted on the website.)

Overview Reduction in Wine – Sulfides Reduction in Wine – Sulfides Oxidation in Wine – Volatile Acidity Oxidation in Wine – Volatile Acidity Brettanomyces / Dekkera Brettanomyces / Dekkera

Sulfides In wine H 2 S – The most common in wine H 2 S – The most common in wine –Can form during fermentation –Forms in stressed fermentations –Low nitrogen musts –Utilizes vineyard Sulfur (Residue on skins) –Low levels of Vitamins in musts –High levels of Cysteine –Yeast strain –Too much SO 2

Mercaptans / Disulfide Mercaptans are stable molecules forming from large amounts of H 2 S and Ethanol and/or reduction of Amino Acids during storage. Mercaptans are stable molecules forming from large amounts of H 2 S and Ethanol and/or reduction of Amino Acids during storage. Dimethyl Disulfide and Diethyl Disulfide can form from mercaptans and need to be reduced before they will can be removed from wine. Dimethyl Disulfide and Diethyl Disulfide can form from mercaptans and need to be reduced before they will can be removed from wine.

Prevention of Sulfides Vineyard Practices – No Sulfur post veraison Vineyard Practices – No Sulfur post veraison Harvest sound balanced fruit Harvest sound balanced fruit Add VITAMINS to fermentations Add VITAMINS to fermentations Add NUTRIENTS to fermentations Add NUTRIENTS to fermentations Do not add Cu prior to fermentation Do not add Cu prior to fermentation Rack whites after settling Rack whites after settling Do not ferment in the presence of Bentonite Do not ferment in the presence of Bentonite

Removal of Sulfides H 2 S can be removed by contact with Copper. (CuSO 4 or other method) H 2 S can be removed by contact with Copper. (CuSO 4 or other method) Often the addition of nutrients during fermentation will remove H 2 S Often the addition of nutrients during fermentation will remove H 2 S Often racking or splashing the fermentation will remove H 2 S Often racking or splashing the fermentation will remove H 2 S

Removal of Disulfides Perform a test to determine the presence of Disulfides (Cd ++, Cu ++, and Ascorbic Acid) Perform a test to determine the presence of Disulfides (Cd ++, Cu ++, and Ascorbic Acid) Use SO 2 to reduce Disulfides to Mercaptans Use SO 2 to reduce Disulfides to Mercaptans Treat with CuSO 4 to remove H 2 S and Mercaptans Treat with CuSO 4 to remove H 2 S and Mercaptans

Samples Hydrogen Sulfide Hydrogen Sulfide Mercaptan / Disulfide Mercaptan / Disulfide

Volatile Acidity Defined as those acids which may be removed from solution by steam distillation Defined as those acids which may be removed from solution by steam distillation Generally taken to mean Acetic Acid Generally taken to mean Acetic Acid May include Carbonic, Sulfurous, Sorbic, Lactic, Formic, Butyric, and Propionic Acids May include Carbonic, Sulfurous, Sorbic, Lactic, Formic, Butyric, and Propionic Acids

Sources of Volatile Acidity Yeast Yeast Lactic Acid Bacteria Lactic Acid Bacteria Acetic Acid Bacteria Acetic Acid Bacteria

Conditions that promote VA Wines with residual sugar Wines with residual sugar Wines made from Botrytis infected fruit Wines made from Botrytis infected fruit Wines with Brettanomyces Wines with Brettanomyces Stuck Fermentations Stuck Fermentations ML fermentation in the presence of sugar ML fermentation in the presence of sugar High sugar fermentations High sugar fermentations

Conditions that promote VA High temperature fermentations High temperature fermentations Wines stored with headspace Wines stored with headspace “Cold Soaking” without SO 2 “Cold Soaking” without SO 2 “Cold Soaking” without gassing tank “Cold Soaking” without gassing tank And many more… And many more…

Yeast Kloeckara apiculata / Hanseniaspora uvarum will produce large amounts of Ethyl Acetate Kloeckara apiculata / Hanseniaspora uvarum will produce large amounts of Ethyl Acetate Brettanomyces will produce acetic acid Brettanomyces will produce acetic acid Sacharomyces will produce VA in a normal fermentation (about 0.4 g/L) Sacharomyces will produce VA in a normal fermentation (about 0.4 g/L) VA production is higher in the presence of Botrytis cineria VA production is higher in the presence of Botrytis cineria

Bacteria Lactic Acid Bacteria will utilize sugars during fermentation to make VA. They can out-compete yeast and stop a fermentation. Lactic Acid Bacteria will utilize sugars during fermentation to make VA. They can out-compete yeast and stop a fermentation. Acetic Acid Bacteria can utilize sugars and oxidize ethanol to make VA. They are more common after fermentation. Acetic Acid Bacteria can utilize sugars and oxidize ethanol to make VA. They are more common after fermentation.

Prevention of VA Cleanliness and good cellar technique Cleanliness and good cellar technique Good, clean, and sound fruit Good, clean, and sound fruit Keep up with topping in barrels Keep up with topping in barrels Overflow barrels when topping, combined with direct addition of SO 2 Overflow barrels when topping, combined with direct addition of SO 2 Minimize headspace in tanks Minimize headspace in tanks Keep up with monthly SO 2 additions Keep up with monthly SO 2 additions

Removal of VA Mechanical separation of VA from wine Mechanical separation of VA from wine –Reverse osmosis, followed by ion exchange Blending Blending Re-fermentation of contaminated wine is not very effective and may spread the contamination Re-fermentation of contaminated wine is not very effective and may spread the contamination Tannin and/or Yeast lees may reduce perception of oxidation in wine Tannin and/or Yeast lees may reduce perception of oxidation in wine

Samples Elevated VA in wine Elevated VA in wine Oxidation in wine Oxidation in wine

Brettanomyces/Dekkera One of the most common spoilage yeasts One of the most common spoilage yeasts Present in every wine region Present in every wine region It has never been isolated in the vineyard It has never been isolated in the vineyard Contributes unwanted phenols in wine Contributes unwanted phenols in wine –4-ethylguaiacol (4EG) –4-ethylphenol (4EP)

Brettanomyces/Dekkera It can survive on minute amounts of sugars It can survive on minute amounts of sugars It can metabolize cellobiose (from cooperage) It can metabolize cellobiose (from cooperage) Thrives in wines with RS and low SO 2 Thrives in wines with RS and low SO 2

Prevention of Brett Cleanliness Cleanliness Maintain SO 2 and Topping Maintain SO 2 and Topping Fermentation Management Fermentation Management Control Vectors Control Vectors –Used cooperage –Purchased wine –Pumice and winery waste

Brettanomyces Notes SO 2 levels over 25 ppm will inhibit enzymes which allow production of 4EP and 4EG SO 2 levels over 25 ppm will inhibit enzymes which allow production of 4EP and 4EG SO 2 will degrade thiamine required for Brettanomyces growth SO 2 will degrade thiamine required for Brettanomyces growth

Removal of Brett Taint Blending of wine is not effective (sensory threshold for taint is 1.6 ppb) Blending of wine is not effective (sensory threshold for taint is 1.6 ppb) Mechanical removal Mechanical removal –Reverse Osmosis combined with Ion Exchange

Samples 2005 Cabernet Sauvignon 2005 Cabernet Sauvignon 2006 Petite Syrah 2006 Petite Syrah

References Concepts in Wine Technology, Yair Margalit, PhD., The Wine Appreciation Guild, 2004 Concepts in Wine Technology, Yair Margalit, PhD., The Wine Appreciation Guild, 2004 Production Wine Analysis, Bruce Zoecklein, Kenneth C. Fugelsang, Barry H. Gump, & Fred S. Nury, Van Nostrand Reinhold, 1990 Production Wine Analysis, Bruce Zoecklein, Kenneth C. Fugelsang, Barry H. Gump, & Fred S. Nury, Van Nostrand Reinhold, 1990 Wine Analysis and Production, Bruce Zoecklein, Kenneth C. Fugelsang, Barry H. Gump, & Fred S. Nury, Aspen Publishers, 1999 Wine Analysis and Production, Bruce Zoecklein, Kenneth C. Fugelsang, Barry H. Gump, & Fred S. Nury, Aspen Publishers, 1999 Wine Microbiology, Kenneth C. Fugelsang, Chapman and Hall, 1997 Wine Microbiology, Kenneth C. Fugelsang, Chapman and Hall, 1997