Wine Faults Prevention and Correction
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WINE FAULTS PREVENTION AND CORRECTION BERNARD CLEVE 20 NOVEMBER 204 V0LATILE ACID • Sharp Pungent Vinegar Aroma • Spoilage Threshold 700 mg/l • Causes – Yeast Fermentation by-product – Lactic Acid or Acetic Acid Bacteria – Damaged or Rotten Fruit – Dirty Equipment – High pH – Exposure to Air – Low SO2 • Appears as a Film or Haze Mainly on Surface Volatile Acid Prevention and Correction • Prevention – Clean Fruit • Avoid Rot • If High pH Lower With Tartaric Acid – Use SO2 at Crush 50 ppm – Use Commercial Yeast Strain – Good Winery Sanitation – Avoid Yeast Stress – Punch Down Cap 2-3 Times a Day for Reds – Add SO2 at End of Fermentation or After MLF – Monitor SO2 – Keep at 0.8ppm Molecular • Remedy – Vigorous Racking – Blending Desired Free SO2 in Wine Free SO2 for 0.8 Molecular 70 ppm Free SO2 Threshold for Taste Excessive SO2 • Pungent Smell • Caused by Winemaker Error • Rack • Test and Reduce Using H2O2 • 10 ml 3% H2O2 per 5 gallons Wine = 30ppm SO2 Reduction Oxidized • Causes – Sherry Like Nutty Acetaldehyde odor – White Wine Brownish Hues – Red Wine Orange Blush – Low Concentrations Decreased Varietal Character • Cause – Juice Air Exposure – Wine Air Exposure Oxidation Prevention/Remedy • Clean Grapes • Clarify Juice • Air Exclusion – Purge Carboys With SO2 Prior to Racking – Fill From Bottom When Racking – Minimum Headspace in Storage Containers – Purge Bottles With SO2 at Bottling – Proper Free SO2 - 0.8 ppm Molecular • Remedy - None Vegetative • Description - Green, Grassy, Herbaceous • Vineyard Prevention – Avoid Excessive Water and Over cropping – Increase Sun Exposure • Avoid Picking Unripe Fruit – For Picking Add Taste, Seed Color etc. to Numbers – Work With Supplier – Red Grapes Add 50 grams Oak Chips per 5 gal. • Search: Making Wine With Unripe Grapes Scott Labs Buttery • Buttery Aroma • Due to Diacetyl • Caused by MLF • Prevention – Suppress MLF with SO2 – Use Different ML Strain – Add SO2 Only After MLF has Concluded – Don’t Bottle Immediately After MLF Bad Lactic Acid • Sauerkraut Odor • Causes – Lactic Acid Bacteria – High pH, Warm Storage, Bad Malolatic Strains • Prevention – SO2 to Must – Control pH 3.5 or less – Proper SO2 Usage • Remedy – Early Detection Add SO2 and Filter – High Levels, No Cure, Drink with Sauerkraut Cork Taint • Wet Cardboard, Musty, Wet Dog • Prevention – Keep Bleach Out of Winery – Use Quality Corks – Use Synthetic Corks – Screw Caps • Remedy - None Ethyl Acetate • Acetone Odor • Causes – Reaction of Acetic Acid and Ethyl Alcohol – Poor Barrel Hygiene • Prevention – Clean Fruit, SO2 at Crush – Avoid Yeast Stress • Remedy - None Brett • Leather, Barnyard, Horsy • Caused by Brettanomyces • Prevention – Clean Winemaking Conditions – Add SO2 to Must/Juice – Maintain 0.8 ppm molecular SO2 – Keep Containers Topped – Keep Wine pH Low – Store Wine at Cool Temperature Chemical Contamination/ Juice Settling • Aromatic Chemical Caused by – Plastics – Use Only Food Grade – Cellar Mustiness – Detergents – Sterilizing Agents • Vegetal Character Reminiscent of Cigar Butts – Causes By Not Settling Juice Mousy Taint • Rises in Mouth After Spitting Sometimes Linked to Metallic Taste • Causes – Low SO2 – High pH Additive Overuse • Use of Potassium Sorbate – Chemical, Bubblegum Character – With MLF Wine Germanium • High SO2 Usage – Rack – Extreme Cases Add Hydrogen Peroxide (H2O2) • 5 Gallons of Wine • +10 ml H2O2 = 30 ppm Decrease Free SO2 • Increases Wine Acidity Maderized/Baked • Description – Cooked Baked Caramelized Odor • Cause by High Temperature – Of Grapes on Vine, Transit, Storage or Processing – During Fermentation • Prevention – Cold Ferment White Juice – Prevent Total Sun Exposure of White Grapes Light-struck • Description – Cooked Cauliflower, Wet Wool Aromas, Wet Cardboard • Caused by Excessive Exposure to Light • Prevention – Store Wine in Dark – Put Brown Bags Over Carboys – Bottle in Dark Glass – Keep Wine in White Bottles in Dark Hydrogen Sulfides • Wine Smells Like Rotten Eggs • Caused by – Certain Types of Wine Yeast – Too Little or to Much Nitrogen in Must – Most Likely in High Brix Grapes – Too Long on Lees • Test for Yeast Assailable Nitrogen (YAN) • Correct Must YAN • In Wine Rack or Treat With Copper – Legal Limit Cu in Wine 0.5 mg/l – 3.25 Drops 1% Cu Solution = 0.1 mg/l http://www.nanaimowinemakers.org/Steps/AddingNitrogen.htm for addition of Nitrogen YAN Test Materials Sodium hydroxide solution, 1N Sodium hydroxide solution, 0.10 N, standardized against potassium hydrogen phthalate or equivalent Formaldehyde, reagent grade, 37% (vol./vol. or 40% wt/vol.) neutralized to pH 8.0 with 1N sodium hydroxide pH meter sensitive to ± 0.05 pH Calibration buffers for the pH meter Whatman No. 1 filter paper Method 1. Pour 100 mL of sample into a 200-mL beaker. 2. Neutralize the sample to pH 8.0 using 1 N sodium hydroxide and pH meter. 3. Transfer the pH adjusted sample into a 200-mL volumetric flask. Bring to volume with deionizer water, and mix well. 4. Filter the solution through Whatman No. 1 filter paper. (DE addition will enhance filtration rate). 5. Transfer a 100-mL aliquot of the sample into a beaker, place calibrated pH/reference electrodes and a stir bar into the solution, mix, and readjust the pH to 8.0, if necessary. 6. Add 25 mL of the previously neutralized formaldehyde (pH 8.0) to the aliquot, mix, and titrate to pH 8.0 using 0.10 N sodium hydroxide. 7. The concentration of assimilable nitrogen is calculated as follows: mg/L of assimilable N = mL of 0.10N sodium hydroxide used to titrate x 28. Notes A different sample volume may be used. For example, if 25 mL of juice is analyzed add 6.25 mL of neutralized formaldehyde and titrate as previously described. mg/L assimilable N = mL of 0.10N sodium hydroxide used x 28 x 4. A new bottle of formaldehyde may have a pH as low as ~3.5. This will require about one-half milliliter of 1N sodium hydroxide to neutralize. If the formaldehyde is not neutralized, significant over titrations may result yielding high values for fermentable nitrogen. The pH of the formaldehyde will begin to drop with time and should be periodically readjusted to pH 8.0. Ideal Wine Yeast • Low Sulfur Dioxide Producer • Low Hydrogen Sulfide Producer • Not Sensitive to Nutrients • Provides Desirable Characteristics Desired Parameters Grapes Wine White Red White Red Sugar 21 to 24% 23 to 25% 0 to 3% 0 to ? Acid 0.6 to 0.8% 0.5 to .8% 0.6 to 0.8% 0.5 to 0.7% pH 3.2 to 3.3 3.3 to 3.5 3.3 to 3.4 3.4 to 3.5 Taste Grapes No Vegetable Flavors Mild to No Acid Taste Very Sweet Seeds Brown and Crunchy Soft Berries Indicate Over ripe Grapes Vineyard Sampling Alternate Berry Sampling Location Select at Least 100 Grape Berries 400 Ideal Sample From Typical Vines – No End Vines Top of Clusters Front and Back of Clusters Bottom of Clusters Think hundreds as opposed to tens (or, heaven forbid, ones) of berries Vineyard Sample Processing • Place Grape Berries is a Plastic bag • Add Peptic Enzyme • Crush Berries • Store Overnight in Refrigerator • Strain Must • Let Settle or Filter • Check Acid, pH, Brix PHENOLS VOLUME / BODY TANNIN / SWEET ACIDS INTENSITY ASTRINGENCY BITTER DRY 10 5 10 3.8 3.1 0.3 ICV RELATIVE INTENSITY (Dominique Delteil) + + ETHANOL + - - - - - POLYSACCHARIDES (Grape, yeast, bacteria,oak, commercial products) - 0 0 SUGAR - + + + + + VSC (Soil Test, Irrigation, Test for nitrogen, Add suplements, Cu) GRAPE AND OAK TANNINS INCLUDING SEED (Vineyard, Cold Soak, VRSUPRA, Daysalage, Extended + + + + maturation, Adjust pH, Tannin +, Age) - RIPE SPICY AROMAS (Ripe Grapes) + + TANNIN INTENSITY (Ripe grapes, add Tannin, Oak Chips, Age in oak) + DRYNESS (Control) + BITTERNESS (Control) + + ACIDITY (Add, Sun, Ripe Grapes) + ACID, MAINLY MALIC AND ACETIC (Sun, Ripe Grapes, MLF, SO2) + ACID,SPECIFICALLY MALIC (Prunning, Trellis, ripe grapes, MLF) + VOLUME COMPOUNDS (Add, OptiRed, Emzymes) + + + YEAST IN SUNSPENSION (Wait or fine, filter) + + + HERBACEOUS COMPOUNDS (Ripe Grapes, Microoxygenation, Oak) + + - NON SOLUBLE SOLIDS(Bleed Wine, Adjust pH, fine, filter) - ALCHOL UP TO 13 % (Picking time, add sugar, add H20) + ALCHOL 13% AND ABOVE (keep below) - ALCHOL UP TO 14% ( Keep below) + ALCHOL 14% AND GREATER (keep below) Microoxygenation, reduces both tannin intensity and astringency, in part, due to reduction in red wine herbaceousness Also, a high concentrations of yeast and/or bacteria in wine can impact the perception wine structure/textural balance. The fact that dry tannins are not masked by sugar suggests that this common corrective approach is not very effective. The negative correlation between polysaccharides and bitterness is a reason for the use of high polysaccharide-producing yeast, and the use of agents such as gums, like Gum Arabic, and yeast fining. Compiled from a Presentation by Dominique DELTEIL of ICV Wine Corrections • High Acid – Add Sugar – Add Potassium Bicarbonate – Acid X • Wine Haze – Use Peptic Enzyme • Cloudy - Fine/Filter – SUPER-KLEER K.C. • Bitter Aftertaste – Fine With Gelerome • H2S – Treat With Copper Acid Decrease • Potassium Bicarbonate Most Common • 3.4 grams (1/2 tsp)/gallon = 0.1% reduction • Maximum Acid Decrease 0.4% • 0.1% acid Reduction = 0.1 pH Increase • Best Approach is to Bench Test • Can do Entire Batch but be Careful • Mixing is a Challenge • About 70% Reduction Before Cold Stabilization 27 Summary to Avoid Wine Faults • Fruit – Ripe – Rot Free • Practice Good Winery Sanitation • Use Commercial Yeast and ML Culture • Minimize Air and light Contact • Timely Racking • Maintain 0.8 Molecular SO2 THE END.