Linda Seppanen Garvin Heights Vineyards 2255 Garvin Heights Road Winona, MN
Overview of winemaking
Quality fruit Grapes are fermented by yeast and converted into wine. Winemaking procedure(s) differs at winemaker, winery, region, and country level. Many different techniques, recipes, outcomes. Desired wine style dictates much of winemaking techniques employed. Money, time and workers also important. Why we bother! Evaluating Wine –Objective Qualities Varietal character How well a wine presents the aromas and flavors inherent to the grapes from which it was made Integration How well all the components of wine are balanced and complementary to each other Expressiveness Well‐defined and clearly projected aromas and flavors Complexity That indescribable something that makes wine more art than beverage Connectedness The cultural connection a wine has to the place it was grown Components of Wine Alcohol Comes from fermentation; affects body, texture, aroma, & flavor May be sensed as a “hot” smell or burning sensation in the nose Acidity Comes from natural acid in the grape; may be sensed as tartness Wines lacking acidity taste dull, flat or flabby and do not age well Tannin Comes from seeds, skins and stems; adds “backbone” and “character” to the wine; is a natural preservative In overabundance, wine tastes harsh or bitter Fruitiness Propensity of wine to display fruity aromas and flavors Sugar (sweetness/dryness) Depends on how much of the grape’s original sugar content was converted to alcohol Not the same as fruitiness! Evaluating Wine
Smell Taste Sight Evaluating Wine ‐ Smell Much of taste is smell, so getting a good whiff is important Aerate the wine by swirling it in the glass Stick your nose in the glass and inhale
Called the nose, aroma, or bouquet Aroma traditionally refers to grape‐associated smells Bouquet refers to other smells (e.g. oak, vanilla, nutty or buttery) Aroma Wheel Evaluating Wine ‐ Taste
Initial taste The first impression of a wine on your tongue Take a sip, don’t swallow yet Taste Swirl the wine around in your mouth, draw in some air Evaluate body & texture as well as flavor and balance Aftertaste The flavors and aromas that last after swallowing the wine Evaluate length of finish (the longer the better) as well as flavor
Spit or Swallow…? Evaluating Wine Body Light, medium, or full? (think about the difference between skim milk, whole milk, and cream) Texture How does the wine feel in your mouth (e.g. soft, sharp, smooth)? If you had to describe the wine as a fabric, what would it be? Flavor What specific components can you taste? It may help to run through lists of choices. Balance Is the wine overwhelmed by any components (alcohol, acidity, tannin, fruitiness, sugar)? Length How long do the flavors and aromas linger after swallowing? Evaluating Wine ‐ Sight Color Hold glass down & at 45 degree angle against a white backdrop Is a clue to age (whites darken, reds lighten w/ age) Is not a clue to flavor intensity For white wines, also look for clarity Legs Swirl the wine in the glass & note viscosity of droplets which form & run down glass Indicates body & possibly alcohol content and/or sweetness
Definitions USA: definition for taxation Table wine: 7 –14% alcohol Fortified wine: up to 24% alcohol Sparkling wine: effervescent wine with certain level of carbonation Europe Table wine: lowest quality wine produced No appellation or much distribution From the vineyard to the glass ‐ Terroir, the taste of place The qualities in a wine determined by its point of origin or appellation The combined effect of sun exposure, soil conditions, climate, water quality The sense of history In all agricultural products, but most talked about in wine and maybe cheese Upper Mississippi River Valley Viticulture Area
Winery Operations
Harvest Crush Must Additions Pressing Settling/Racking Fermentation(s) Aging/Blending Filtering/Cold Stabilization Bottling Harvest Harvest decisions
• How do we determine ripeness? • Vineyard Sampling • Berry Growth • Sugar concentration (Brix) • Titratable Acidity and pH
Portable refractometer for Brix Vineyard Sampling Sample must represent entire vineyard (changes in topography, soil, etc.) Everything must be chosen randomly i.e.. different areas of cluster, canopy location, row orientation Berry Sample (100‐200 berries) Most Robust but must be meticulous and unbiased Cluster Sample (20‐50) Removes bias in berry sampling but requires more fruit Vine Sample (all clusters from 1 vine) Only useful in vineyards where topography is uniform Most robust is Berry sampling Berry Expansion During Ripening
Berry Growth goes through 3 stages Stage 1 Rapid Growth Stage 2 Lag Phase Stage 3 Resumed Growth and Maturation Growth pattern follows a double sigmoid During ripening the berry is expanding 3 to 4 cell number cell volume 300 fold. Veraison (softening and coloration) begins at stage 3 Sugar and Organic Acids
Primary compounds of interest are sugar and organic acids (sweet and sour). As grape ripens it accumulates sugar Rapid sugar accumulation starts at veraison Organic Acids decline during ripening Decline is due to dilution and respiration. Climatic Variation changes sugars and organic acids Hot Climate: High sugar Low Acid Cool Climate: Low sugar High Acid Sugar and Organic Acids during Ripening Sugar Measurement Sugar (glucose and fructose) is the most abundant compound(s) found in berry. Other berry constituents are synthesized from it. Abundance allows indirect methodology for measurement. (Unit Brix=% or g/100 mL) Hydrometer used in winery to monitor fermentation Refractometer used in vineyard. (Uses refractive index of sugars) Sugar and Ripeness Typically grapes will accumulate up to 25‐26 Brix and after that increases are apparent and occur from dehydration. Winemakers often will allow crop to hang on vine and dehydrate waiting for flavors to develop. During this hang time the berries tend to shrivel and lose weight. Negotiation for grape prices can be based on tonnage and this reduces weight of clusters. Winemakers who like to develop flavors should negotiate an acreage contract to maintain grower relationship. Ethanol Predictions
Ethanol can be predicted from initial Brix in crusher.
Alcohol % = about ½ Brix
Table wine (USA definition) = 7 –14% alcohol Organic Acids
Principal organic acids are tartaric acid and malic acid. Tartaric acid (most abundant) Stereochemistry was elucidated by Louis Pasteur in 1849. Stable to microbial fermentation but forms insoluble salts with potassium (K2Tar found on the bottom of the cork or bottle in aged wines, KHTar is cream of tartar) Malic acid (second abundant) can be metabolized by yeast and bacteria (discussed later). Organic Acid Measurement
Measured by titrating with a base of known concentration in the presence of a chemical indicator with a known pH end point. This measurement called titratable acidity (TA) pH is measured either with a meter or litmus paper. Concentrations range from 8.0 g/L to 6.5 g/L pH ranges from 2.8 to 4.0. White wine 3.0‐3.3 Red wine 3.2‐3.4 Other Parameters?
Anthocyanin and tannin content in red grapes Total phenols in white grapes. Grape and wine relationship not well established for either because of processing effects. Aroma compounds in grape difficult to measure. Methodology(s) for measurement tedious and not ready for production scale. Tasting Grapes
Contrary to myth no one can accurately estimate sugars and acid by taste. Tasting by panel (including winemaker and grower) with examination of sugar, acid, color, and flavor. Experience will provide perspective on varietal aroma, color and balance. Building a historical database with subjective and objective descriptions can help. Harvesting Practices
Primary objectives: Pick all of the grapes as fast as possible with minimum damage, inexpensively. Sounds impossible? Condition of fruit at crush largely determines wine quality. Competition with birds (good ripeness indicator). Early morning harvest are good because it is easier to process cool fruit. Manual vs. Machine Harvesting Manual harvesting can be quick, selective, thorough, with minimal damage but not cheap. Machine harvesting is cheaper but usually damages vines and reduces yield slightly. Vineyard topography and trellis design largely determine type of harvesting style. Hilly vineyards are difficult to machine harvest. Trellis design must be able to withstand machine damage and make fruit easily accessible to machine mechanism. Good manual labor is hard to find. Crush Making White Wine Grapes are picked Grapes are crushed (stems may or may not be removed) Grapes are pressed, skins removed, and placed in tank Yeast may be added, and fermentation begins Making White Wine (cont.)
When fermentation ends, wine may be left in contact with lees (spent yeast) Wine is racked Possibly cold stabilized Possibly put into barrels to age Possibly filtered Wine is bottled Making Red Wine
Grapes are picked Grapes are crushed (stems may or may not be removed) Grapes, juice, skins and seeds are put in a tank Yeast may be added, and fermentation begins Making Red Wines (cont.) “Cap” is pushed down Wine is drained (first run) and then pressed (first press) off skins after fermentation ends Wine is put in barrels to age Periodically racked Possibly filtered Wine is bottled Press Tanks for aging Bottling Fermentation Primary fermentation is conversion of sugar into EtOH and CO2 is carried out under anaerobic conditions. Anaerobic: Lacking oxygen
C6H12O6 2CH3CH2OH + 2CO2 Heat is a by‐product of reaction Yeast can be killed if temperature gets too high. Above 38C problems occur. Fermentation temperature can be regulated
CO2 is dangerous by‐product that needs to be managed Fermentation Temperature
Whites generally ferment at a lower temperature than reds. White fermentation temperatures Lower temp. to preserve volatile components Red fermentation temperatures Higher temp. for extracting phenolic components from skins and seeds Regulation of Fermentation Temperature
Metal tanks (excellent conductor) can use jacket filled with coolant (ethylene glycol, ammonia) Wooden tanks (poor conductor) can use heat exchangers (uses tubes filled with cooler liquid, that when moved past warmer liquid trades temperatures). Requires external pump. Barrel fermentation temperature not controlled CO2 Management Carbon dioxide is dangerous by‐product How much is produced? About 3 times the volume of liquid during one day of a slow fermentation. Fermentation rooms must have proper ventilation Cellar workers going into tanks should work in pairs
CO2 detectors should be used in winery (Workplace safety have an upper limit of 0.5%)
Evolved CO2 also will remove off odors and pleasant ones. CO2 Management II Tank fermentations Ventilation system with a fan or blower Ferment in an outside tank Barrel fermentations‐Inside Ventilation system required Air conditioning load to cool room is greatly effected by outside air.
About 10,000 liters of CO2 produced by one complete barrel fermentation. Yeast Selection
Basic Criteria for selecting a yeast Fermentation vigor (rate of fermentation) Finishes fermentation to dryness Reproducible fermentation characteristics Ethanol tolerance Temperature tolerance Produces no off‐flavors or aromas Sulfur dioxide tolerance Yeast Selection II
Dried yeast are produced healthy under aerobic conditions with plenty of survival factors (saturated fatty acids, sterols) Healthy cell membrane for EtOH tolerance. Dried packets will survive for one year if stored in cold. Before addition to must, re‐hydrate in a small volume of warm (40C) water. Add about 0.1‐0.2 g dry per L of must. Yeast by‐products
Aside from EtOH and CO2 Glycerol‐viscous by‐product Not enough to modify wine mouth feel
Elevated production in SO2 conditions Acetic Acid‐vinegar (volatile acid) Normal production (100 to 200 mg/L) can be made from nutrient deficient musts Also made by spoilage organisms (Acetobacter) Yeast by‐products II Higher Alcohols‐ higher MW higher BP Formation by breakdown of amino acids (removal of amino group at end of pathway). Excess amino acids does Also made from sugar breakdown Not enough to normally change aroma of wine. Isoamyl alcohol (banana) Active amyl alcohol (?) N‐propyl alcohol Phenyl ethanol (rose aroma) Yeast Selection III Don’t choose a yeast because it supposedly produces different aromas
CO2 blows of most yeast volatiles during fermentation. “Fermentation bouquet” are unstable volatiles that can be achieved through cool fermentation and protected from air contact it can be maintained for about a week. Research showed no detectable differences between strains with same initial juice after fermentation was complete. During fermentation all lots of odors are detected but not after fermentation is complete. Only exceptions to this are wild yeasts and different species of Saccharomyces Wild Yeasts
Examples: Kloeckera, Hansenula, Candida, Brettanomyces, Zygosaccharomyces Can produce off aromas (horse sweat, feces) Compete with Saccharomyces
Generally are SO2 and EtOH intolerant.
Can be reduced by early SO2 addition and inoculation with Saccharomyces. Are temperature intolerant, at 25C they are inhibited while Saccharomyces will survive up to 38C Stuck Fermentations
Two classes: Stuck and Stinky Some can be easily fixed, while others are more challenging. Causes: EtOH toxicity, nutrient limitations, substrate inhibition, toxic substances and temperature shock. Monitoring Fermentation is key to catching a stuck or sluggish ferment. Oak Oak Used in fermentation, aging, both, or neither Provides vanilla and oak(!) flavors Depends upon the amount of toast Barrels or spirals Advances in Winemaking Stainless steel tanks Screw top? St Croix Marquette Frontenac Sabrevois
Frontenac Gris La Crescent
Edelweiss St Pepin
Prairie Star Brianna
Summary Good vineyard practices Quality fruit Harvest Crush Pressing Fermentation(s) Settling/Racking Aging/Blending Filtering/Cold Stabilization Bottling Enjoyment Questions?
Thank you for your attention.
Come visit us at Garvin Heights Vineyards to enjoy a glass of local wine and the great views. Take some bottles home to share. 2225 Garvin Heights Road Winona, MN 55987 507‐474‐WINE (9463) www.ghvwine.com