Week 3 Notes VEN 003
Week 3 Notes VEN 003 Ven 3
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This 19 page Class Notes was uploaded by AlexandraRita Notetaker on Thursday April 14, 2016. The Class Notes belongs to Ven 3 at University of California - Davis taught by Jean-Jacques Lambart in Spring 2016. Since its upload, it has received 52 views. For similar materials see Intro to wine making in Art History at University of California - Davis.
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Date Created: 04/14/16
th Day 5 (April 12 ) Making Table Wine THE DECISION TO HARVEST • Is the fruit ready? • Vineyard sampling – Sugar • Refractometer, hydrometer – Acidity • TitraPon – Flavor • Human being REFRACTOMETER • For measuring sugar in grape juice Hydrometer • For measuring sugar in grape juice THE DECISION TO HARVEST • Style of wine? • Alcohol concentration? • FORMULA: 0.55 x °Brix • 16 -‐ 25.5°Brix • 9 -‐ 14% alcohol (Legal lower limit is 7%: Legal but yucky) BERRY RIPENING: • Sugar increases, Acid decreases THE DECISION TO HARVEST • Sugar must be high enough • Acid must not be too low • Varietal flavor should be optimal àTaste the fruit! THE DECISION TO HARVEST Red wines 20 -‐ 24°Brix White wines 19-‐23 Blush wines 19-‐23 Sparkling wines 18-‐20 SORTING • WHY? – To remove all “MOG” (Maner Other than Grapes) – To remove over-‐ripe or unripe berries • HOW? – Sorting Tables (whole clusters) – Optical sorting of individual berries CRUSHING • WHY? – To break the berries open – To let the yeast get at the juice • HOW? – Crusher / De-‐Stemmer – Crush produces “MUST” CRUSHING CHOICES • Crushing and destemming • Destemming only -‐Ferment whole berries • Whole clusters -‐Direct to press (whites) -‐Carbonic maceraPon (reds) • MUST = product of crushing -‐ 80% juice, 16% skins, 4% seeds WINEMAKING DECISIONS • DESTEM? • WHOLE BERRIES OR CLUSTERS? 2 • MIXTURE? SO2 ADDITION Why? • Antimicrobial – Kills wild yeast and other contaminants • Antioxidant – Prevents browning caused by polyphenol oxidase (PPO) • “Contains sulfites” • Required on the label by law if -‐SO2 >10 ppm • Wine still contains sulfites even if SO2 is not added • SO2 is also a natural product of fermentation ORGANIC WINES AND SO2 • USA RULES: SO2 allowed in wine labeled “made with organic grapes” if total sulfite concentration does not exceed 100 ppm • EUROPEAN RULES: White & Rosé Wine labeled ORGANIC: 150 ppm (Conventional: 200 ppm) Red Wine labeled ORGANIC: 100 ppm (Conventional: 150 ppm) MUST ADJUSTMENTS • Sugar Enrichment -‐Chaptalization • Sugar addition to raise potential alcohol of wine -‐ Not Legal in California • Juice Concentrate Is Legal in California • Acid Adjustment -‐Common in California and other warm areas where acid is low at harvest • Add Tartaric acid 3 • When? • Before fermentation (whites or rosés) • After or during fermentation (reds or ports) • Why? • To SEPARATE juice or wine from skins and seeds • How? • Squeezing in various ways PRESSING Squeeze in stages: 1. Free Run – just gravity • Highest quality • Lowest in tannins » Less bitter » Less astringent PRESSING Squeeze in stages: 1. Free Run – just gravity 2. Press Fractions » Increasingly tannic 3. Hard Press » Very tannic » (quality will drop) PRESSING • Juice/wine yield: • 140 -‐ 190 gallons/ton – More for reds than whites because: • Reds are pressed after fermentation • It’s OK for reds to be more tannic, so they can be pressed harder 4 TYPES OF PRESSES 1. CONTINUOUS PRESS • Fast, high volume fruit presses MEMBRANE PRESS • Lower quality – Higher tannins • Low priced wines • Large wineries 2. BASKET PRESS • Oldest, traditional presses • Uses a piston and basket 3. MEMBRANE PRESS • Also called Bladder Press • Widely used àGentler, so lower tannins àPremium wineries SETTLING • Allow solids to settle to bottom of tank • Then separate juice from solids – Pumping (“racking”) – Filtration } Large – Centrifugation } Wineries Large Centrifuge: An Alternative to Settling and Racking SOME TERMS • RACKING – Transfer of juice or wine away from settled solid material • LEES – Solid material in juice/wine -‐Grape solids -‐Yeast solids -‐Chemical precipitates 5 FERMENTATION • Inoculate? • CULTURED DRY YEAST at 1 to 2% by volume • OR USE MUST from an active fermentation • “Natural” fermentation? -‐ More common in small wineries FERMENTATION VESSELS – Wooden tanks – Lined concrete tanks – Plastic boxes – Stainless steel▯ – Usually closed containers, but sometimes open top for reds Heat from Fermentation Example: 22°B juice at 70°F 22°B x 2.3 = 50.6°F rise 50.6°F + 70°F = 120°F TOO HOT! HAVE TO KEEP IT UNDER 100°F !!!! REALITY: SOME HEAT IS LOST • Calculation assumes all heat stays inside fermention, none lost • But some heat IS lost • HOW MUCH is lost depends on: à Size and shape of fermentation vessel AND à Artificial cooling 6 MANAGING TEMPERATURE – Why? • Keep yeast healthy • Control wine flavor – How? • Small fermentation vessels • Refrigeration jackets • Heat exchangers • Small fermentation vessels – Barrel fermentation – Not practical for large volume production • Small fermentation vessels • Refrigeration jackets – Common in warm places like California, Chile, Australia, Southern France, etc. • Heat exchangers – Common in cool places like Northern Europe – Used for heating must – But also used to cool WHERE DOES THE CO2 GO? C6H12O6 à 2 CH3CH2OH + 2CO2 – Must let CO2 OUT without letting AIR IN – How? Fermentation Lock FERMENTATION TIME • WHITES 10 to 30 days – Cooler temperature – Less nutrients • REDS 4 to 12 days – Warmer temperature – More nutrients for yeast from skins and seeds 7 FERMENTATION TIME • Some varieties ferment faster – Better source of nutrients for yeast? STUCK FERMENTATIONS • Stops before sugar is used up • Undesirable because wine will be: – Sweet – Microbiologically unstable Normal Fermentation Stuck Fermentation Fermentation Restarted 8 MALOLACTIC FERMENTATION (MLF) • Loss of malic acid and creation of lactic acid and CO2 • Often spontaneous in wood – Barrel fermented Chardonnay – Red wines aged in wood • But usually inoculated with ML bacteria – Either along with the yeast, or later MALOLACTIC FERMENTATION • BENEFITS • Buttery flavor (diacetyl) • Microbiological stability • Lower acidity (not so important in California) End of Notes Day 5 9 th Day 6 (April 14 ) Making Table Wine Part 2 Invention of the Barrel nd • 2 Century AD -‐ Gallo-‐Roman relief depicting a river boat transporting wine barrels, an invention of the Gauls that came into widespread use during the 2nd century. BARREL AGING • Adds flavors: – Vanilla – Spicy – Smoky (if toasted*) • Usually oak but sometimes chestnut • Traditional for red wines • 6 months to 2 years • Not for wines intended to have fruity flavors • Not for inexpensive wines • Flavor contribution from barrel declines with repeated use • A barrel is typically used for 5 years • Wineries typically use a mixture of old and new barrels Barrel Parts 10 BARREL AGING IS EXPENSIVE • Barrels are expensive • French oak ∼$800 each • American oak ∼$200 each • Space for barrel storage is expensive • Handling barrels is expensive – A medium sized winery may spend several million dollars each year on new barrels! OAK ALTERNATIVES • Oak chips • Inner staves • Inexpensive • Allow oak influence in large tanks TOPPING BARRELS • Some wine is lost due to evaporation • High humidity will minimize loss • Wine replaced to minimize head space • Top barrels periodically DURING BARREL AGING • Topping • Racking from barrel to barrel • SO2 addition FINING • Why? – To improve clarity of wine • Helps to know cause of cloudiness (e.g., proteins, polysaccharides, metals) – To remove some tannins • How? – Add something that reacts with or adsorbs substance to be removed – Falls to bottom as precipitate 11 Finning • What? – Bentonite (a clay) – Removes proteins – Enzymes – Remove polysaccharides – Egg white, gelatin, casein, isinglass – Remove tannins • Downside • May remove “complexity” • May remove or change flavors • Minimize fining if you don’t care about absolute clarity or you are willing to rack barrels more TARTRATE STABILIZATION • Why? – To prevent formation of KHT crystals in bottle – KHT = Potassium acid tartrate (or potassium bitartrate, ‘cream of ta rtar’) – For appearance only (the crystals look like broken glass) • KHT is very insoluble in alcohol • Precipitates out when wine is chilled in refrigerator (whites) • So accelerate by chilling in winery: COLD STABILIZATION • Below 32° for several weeks • Then filter out crystals AFTER COLD STABILIZATION, KHT CRYSTALS ARE EASILY REMOVED BY FILTRATION • Ion exchange – Alternative to cold stabilization • K ions replaced by Na or H – Tartrate then more soluble • Favored by larger wineries • Faster, cheaper • But adds Na or increases acidity 12 WINE FILTRATION • Why? -‐Clarification -‐Stabilization • How? -‐Diatomaceous earth -‐Sterile membrane filter FILTRATION • Diatomaceous earth – Removes particulate matter • Sterile membrane filter – Removes microbes • Important if » Residual sugar » Wine has not undergone malolactic fermentati on (MLF) • Excessive filtration can reduce complexity • Can avoid if: -‐Completely dry -‐Completed MLF -‐Racked enough to be clear -‐Large producers always filter BLENDING • Combine wine lots from -‐Different vineyards -‐Different varieties -‐Different maturities -‐Different treatments • Usually tested on small scale first • The ultimate winemaking decision! 13 BOTTLING • Transfer wine to holding tank • Add SO2 • Bottling line -‐Bottles washed -‐May be flushed with N2 -‐Filled and corked quickly • Bottling line – Must be clean – May be separate room • Bottles labeled and cased • Bottle aged (and monitored) • OR aged before labeling Making Red Wine • About 9-‐18 Months Red Fermentation Issues • Extraction of phenols (tannins & color) – Requires alcohol • Warm fermentation (85°F) • Fast fermentation (4-‐7 days) • Vigorous carbon dioxide evolution – Protects wine from air 14 Maceration Extraction of Skins and Seed • Tannins and other phenols are extracted – Color (anthocyanins) – Seed and skin tannins – Fruit aromas (some) • Phenols are antioxidants – Necessary for preservation during aging – High levels needed for long aging • Astringency may be too high for immediate consumption – Levels decrease during aging Red Maceration Parameters Skin/Seed Contact Time • Rosé: 12-‐24 hours contact time • Light Reds (picnic wine): about 4 days maceration • High Priced Red Wines: 10-‐30 days • Extended maceration does not increase color (peaks after 3-‐5 days), but does increase tannins Cap Management Manipulation of skins and seeds (pomace) • Carbon dioxide bubbles lit the pomace to the top • “Punchdown” – Push down on the cap to re-‐mix it with the fermenting must • “Pumpover” – Pump liquid from bottom of tank and spray over cap – Some physical mixing if a heavy spray is used • Oxygen inclusion if needed ‘Pump Over’ SchemaLc • Must/Wine is pumped from racking valve • Sprayed over cap in tank 15 Carbonic Maceration Fruity Flavors • Grapes are not crushed first • Whole berries are sealed in a "Fermentor" for 8-‐10 days under CO2 • Grape enzymes convert some sugar to alcohol • THEN crush, press and ferment remaining sugar • Wine should be consumed soon – does not age well • Produces a fruity, low tannin, light red wine • Beaujolais nouveau is made this way – Made and released just a few weeks a fter harvest in fall Beaujolais Nouveau • Made from Gamay noir grape • Carbonic maceration • Produced in Beaujolais region of France • Released once a year, third Thursday in November • Promoted in US for Thanksgiving Making White Wine • About 4-‐9 months total 16 Making White Wines Prevent Tannin Extraction • Add pectic enzymes – break down fruit tissue and release more juice • Prevent browning – caused by oxidation of phenols – Keep juice cold, protect from air • Must is pressed right away – Minimize bitterness, astringency (phenolics) – “Direct to press” without crushing first • Cool fermentation temperature – Temp controlled (50-‐70°F) – Maximizes fruity flavors – Long fermentation, ~10-‐30 days Barrel Fermentation Oak Flavor Desirable in US • Some white wines (Chardonnay) are barrel fermented • Undergo Malolactic Fermentation (MLF) at same time • Characteristic Flavors: Vanilla (oak), Butter (ML bacteria) • Barrels are small, heat dissipates, keeps temperature low • After fermentation, leave in the barrels up to 6 months (“sur lees” or “sur lie” aging) • Only for expensive wines: barrels and labor are costly Sur Lees (Sur Lie) Aging • Lees (lies in French) = dead yeast • Allow barrel fermented wine to remain in barrels after fermentation is finished • Stir periodically • Contact with dead yeast cells gives flavor and texture differences 17 Making Blush or Rosé Wines Minimal color extraction • “White” wines made from red grapes – e.g., White Zinfandel • Produced exactly like fruity white wines (but from red grapes) • Fermented cool • No wood contact (barrels, chips), No aging • Some residual sugar; should be filtered to prevent fermentation in the bottle (BAD!) • Sometimes blend in red wine at end to adjust color Sweet White Wines • Inexpensive Chardonnay • Often Riesling, Gewürtztraminer, Chenin blanc • HOW? – Arrest fermentation with chilling or sterile filtration – Add sterile juice concentrate • Sauternes (Bordeaux) -‐ noble rot • Tokay (Hungary) -‐ noble rot • Vouvray (Loire) Less Vs. More Expensive Wines End of Notes day 6 18 19
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