VEN 003 Intro to wine making: Notes week 2
VEN 003 Intro to wine making: Notes week 2 Ven 3
Popular in Intro to wine making
Popular in Art History
verified elite notetaker
This 20 page Class Notes was uploaded by AlexandraRita Notetaker on Thursday April 7, 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 58 views. For similar materials see Intro to wine making in Art History at University of California - Davis.
Reviews for VEN 003 Intro to wine making: Notes week 2
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 04/07/16
Intro To Wine Making th Class Day 3 (April 5 )-‐ “It’s All in the Vine!” Annual Cycle Typical Dates in California • Spring – Bud break, April 1 – Flowering, May 15 • Summer ripening – Veraison, July 15 • Fall Harvest, September 15 • Winter Dormancy, November-‐March The Significance of Dormant Buds • The number of buds left after pruning determines the number of fruit clusters – Affects the amount of crop! • This year’s events affect next year’s crop The Shoot Tendril Leaf Cluster Bud Cane Start of Bloom 2 Fruit Set Pea Size Berries • Hard and green • Seed development Berry Structure Skin Pulp No Pigment Seeds Tannins Tannins à bitterness à astringency Veraison • Softening • Color Change 3 Grape Berry Components • Water • Sugar – Glucose & Fructose, 20-‐25% • Acids – Malic, tartaric, 0.5-‐1% – Essenfal to taste of wine • Pigments • Tannins • Aroma compounds – Trace quanffes, but key to high quality Sugar Increases, Acid Decreases 4 The Decision To Harvest • Sugar must be high enough • Acid must not be too low • Varietal flavor optimal – Taste the fruit! • Many berries must be sampled so that the analysis represents the whole vineyard – Each berry ripens at a slightly different rate Importance Of The Environment • Temperature • Water • Soil Vineyard Heat Index • “Degree days” – Developed in 1940’s at UCD – Cumulative measure of heat • Uses daily average temp – Add up each day during the season for which average temperature is >50F between April 1 and October 31. – i.e. if max 90, min 60: average 75ààadd 25 for this day – i.e. if max 110, min 80: average 95ààadd 45 for this day – i.e. if max 60, min 40, average 50ààadd zero for this day – Take the sum of all days throughout the growing season • California Has Five Regions: – RegionI<2,500degreedays; Region V>4000degreedays • Useful in new plantings – Varieties are adapted to particular heat levels 5 Different Grape Varieties Have Different Heat Requirements • Some need more heat to ripen – e.g. Cabernet Sauvignon, Zinfandel (warmer origins) • Some need less heat to ripen – e.g. Chardonnay, Pinot noir, Riesling (cooler origins) Hotter Places • More sugar – More tons per acre – Ripe earlier • Lower acid – Malic acid is respired • Less color • Less flavor Very Hot • Shriveled fruit • Sunburn • Sugar accumulation stops Cooler Places • Less sugar – Sugar addition may be necessary • More acid – Wine will be more tart or sour tasting • More color and more flavor • Overall, better quality areas (CA) Very Cold • Winter kill • Spring frost – Important in California • Poor fruit set • Fruit won’t ripen 6 Effects of Different Climates (California) Warmer Cooler SUGAR Higher lower ACID lower higher COLOR lower higher FLAVOR lower higher YIELD higher lower VALUE lower higher Effects of Water Availability • When? – Winter rain ideal (deep roots) – Summer rainàrot • How much? – Too littleàlow production – Too muchàpoor quality IRRIGATION PRACTICES • Europe – NOT permitted for many traditional wines • New world – widely used Soil Effects on Wine • Wine differences that are attributed to soil are probably due more to differences in the water holding capacity of the soil than to any other factor A New Vineyard • Not from seeds • Plant a piece of cane – a piece of wood cut off in pruning • Field budding OR • Bench grafts 7 PLANTING A NEW VINEYARD • 3 to 4 years to get first crop • Very expensive – Vines, trellising and training, irrigation system • Typical life: 20 -‐ 25 years • Cost: $10,000-‐50,000+ per acre VINEYARD YIELD • Range in California – 2-‐20 tons per acre • Typical high quality area – 4-‐7 tons per acre • Typical moderate quality – 8-‐12 tons per acre • Typical low quality – 15+ tons per acre WINE YIELD • 160 gallons per ton (80% of weight) • 5 bobles per gallon (750 mL) • 20 acre vineyard, 7 tons per acre – 20 x 7 x 160 x 5 = 112,000 bottles = 9133.33 cases VINE MANAGEMENT • Training • Trellising • Pruning àControl size and shape of vine ▯ à Influence wine flavor 8 Pruning • Removes most of last year’s shoot • Determines number of dormant buds Pruning Controls Amount of Crop • Number of buds – Number of clusters • Number of clusters – Maximum amount of fruit 9 PRUNING • Too few buds àexcessive vegetation àpoor flavor • Too many buds àover cropped àwon’t ripen CANOPY MANAGEMENT • Optimizing – Ratio of fruit to foliage – Amount of light reaching fruit • By -‐trellising -‐training -‐pruning Summary • Annual cycle=bud break, flowering, veraison, harvest, dormancy; this year’s events affect next year’s crop • Harvest occurs when composition (sugar, pH, color, flavor) is optimal for winemaking • Climate/environmental factors influence varieties planted, vineyard management practices • Grazing (rootstock and scion) used to establish vineyard • Vine management practices used to optimize yield and flavor End of Day 3 Notes 10 Notes Day 4 (April 7 ) Wine Microorganisms and Fermentation Wines were made by 4000 BC A Cave near Areni, Armenia BRIEF HISTORY OF THE KNOWLEDGE OF FERMENTATION • Many different cultures used a system of trial, error and careful observation to produce fermented beverages • Production of mead, using honey by the Vedic cultures, the Greeks, Celts, Saxons, Vikings • Produc1on of wine from grapes and beer from malted barley in Babyl on, Egypt, China, Greece • Produc1on of Chicha (Peru) from grain (corn) or fruit, and oc1 (aka pulque) from agave in America DISCOVERY OF FERMENTATION • For a long time, no one understood why leaving fruit or grain in a closed container for some 1me produced wine or beer. • The Romans used the la1n term “fervere” (i.e. to boil) to describe the bubbles produced by crushed grapes or fruit in a container. • They learned empirically that exposure to air and temperature were essential to the process of producing alcohol. • No one knew that the agents responsible were micro-‐organisms. The Discovery of Micro-‐Organisms Was Very Slow! • 17th century: a Dutchman, van Leeuwenhoek, making high quality lenses, mistakes yeasts for starch particles. • 1755: Samuel Johnson describes yeast as an organic chemical agent used for fermenting beverages and bread, not a living organism. • 18th and 19th century: Lavoisier understands the structure of sugars (O, C, H) and the fact that cane sugar is transformed into alco hol and carbon dioxide during fermenta1on. 11 French Chemist Louis Pasteur Explains Fermenta1on (1876) • Demonstrated experimentally that fermented beverages result from the action of living yeast transforming glucose into ethanol. • Showed that only microorganisms are capable of converting sugars into alcohol from grape juice; and that the process occurs in the absence of oxygen. • He concluded that fermenta1on is a biological process, not a chemical process. • Pasteur identified yeasts and a smaller microbe (likely Acetobacter). Important Terms Alcohol Ethyl alcohol, EtOH, ethanol Must Crushed grapes and/or juice Brix % sugar Pomace Seeds and skin after pressing Fermentation Grapes à Yeast à Fermentation à Processing and Aging à Wine Yeast: the other organism required to make wine • Kingdoms of living things: – Animals; Plants; Fungi • Yeast: Mainly unicellular fungus – About 1500 yeast species currently identified (there may be more than 1 million species of fungi not yet identified) Wild Yeast • Live on the surface of the grape berry • BUT not ideal for wine produc1on • Do not confuse with “feral” wine yeast (“escapees”) !! 12 Characteristics of Wild Yeast • Produce strong flavors during fermentation • Alcohol intolerant -‐Residual sugar means wine is microbiologically unstable • Unpredictable • SO2 sensi1ve • Examples -‐Kloeckera, Pichia, Dekkera, Brelanomyces, Candida The Wine Yeast Saccharomyces cerevisiae • Used for making: • Wine • Beer • Bread • Distilled beverages • Also found on the surface of grape berries as ‘FERAL’ wine yeasts • BUT in much lower numbers than wild yeast • Can become established on winery equipment • Can build up in vineyards if pomace is deposited • Out-‐competes wild yeast in a mixed fermentation • The Must is usually inoculated with a commercial strain of wine yeast What is a “Natural” Fermentation? • A fermentation that is NOT inoculated • Sometimes called “wild” or “na1ve” fermentations (but the yeast is not truly wild) • Usually a resident “house strain” of Saccharomyces on equipment conducts the fermenta1on What are the ADVANTAGES of Saccharomyces Over Wild Yeast? • Most important:▯ àMore alcohol tolerant àVigorous fermentor àLess sensitive to SO2 13 Characteristics of a Commercial Yeast • Reproducible and predictable • Vigorous • Ferments to dryness • Alcohol tolerant Characteris1cs of a Commercial Yeast • High temperature tolerant • Minimal off flavors • SO2 tolerant Choosing A Strain • Flavor differences between strains are not very significant except in very young wines due to ester formation – Exceptions: New Zealand Style Sauvignon blanc (formation of positive thiols) • A Yeast strain is not usually chosen for flavor – Except for sparkling wines where LACK of flavor is desired What Yeast Needs • Sugar (carbon source) – Glucose, fructose (from grape) – Sucrose (if permiled) • Nitrogen – Add diammonium phosphate (DAP) if needed • Vitamins – Makes all except bio1n 14 What Yeast Needs • Sugar • Nitrogen • Vitamins • Minerals, especially Phosphorus • Low pH (acidic) – Between 3 and 4 – Too acidic for most other microorganisms – Too acidic for ALL toxic spoilage organisms • Temperature 50 to 100° F – Fermenta1on is fastest at 80-‐85° F • Ethanol below 16% – But most table wines are between 10-‐14% ethanol Yeast Budding • Wine yeast reproduce by budding WHAT IS FERMENTATION? • The conversion of sugar into alcohol and carbon dioxide • With the resulting release of ENERGY • The yeast uses the energy that is generated in order to grow and ca rry out essential metabolic functions Yeast Cells Can Metabolize Glucose Through Respiration or Fermentation 15 RESPIRATION: • Another way yeast (and people) can get ENERGY from SUGAR -‐C6H12O6 +6O2 6CO2 +6H2O -‐glucose oxygen carbon water • Provides 680 kcal energy/mole of sugar • Lots of Energy, BUT Requires Oxygen! Fermentation -‐C6H12O6 2 CH3CH2OH + 2 CO2 -‐glucose 2 ethanol 2 carbon dioxide • Provides only 56 kcal energy/mole of sugar • Provides much less energy than Respiration, BUT no oxygen is needed! Fermentation • The oxygen in grape juice is rapidly depleted by respiration after yeast is added • Fermentation provides a way for yeast to keep getting energy in order to live after oxygen is depleted. • Ethanol is just a byproduct • Ethanol is toxic to yeast Where Does The Energy From Fermenta1on Go? Of the 56 kcal produced... • Some stored as ATP (22 kcal) • Most (34 kcal) lost as HEAT • 1° Brix dropè▯2.3°F rise (1.3°C) • Final temp of a wine if: – starting must 55°F, 22° Brix (assume no heat loss) – 55 + (22 x 2.3) = 105°F final temp – Unlikely that temp will exceed 100°F by much due to death of yeast 16 Managing This Heat is Very Important in the Winery! • The heat produced in a fermenting must can get high enough to inhibit the yeast and stop the fermentation. • Heat is crucial to warming red must, to ensure adequate color and t annin extrac1ons • It must be removed for low temperature fermenta1ons – Cooling systems are needed for white fermentations (and sometimes red wines – climate dependent) Calculating Ethanol Yield • Assume approximately 55% by volume • Multiply initial sugar concentra1on x 0.55= final alcohol % • Example: If you start with grapes at 20° Brix (20% sugar), then you get about 11% EtOH by volume in the wine -‐20 x 0.55 = 11 Fermentation Time • A few days to a few weeks • Temperature is the most important factor – Red wines: 70 -‐ 90°F, Faster • Good for extrac1on of color and tannin – White wines: 55 -‐ 70°F, Slower • Good for better fruity aromas Fermentation Nutrition vs. Wine Type • Red wines ferment faster – Skins and seeds provide more nutrients for yeast • White wines ferment more slowly – No skins and seeds, so less nutrients for yeast 17 “Stuck” Fermentation • UNPLANNED: Fermentation stops before sugar is used up – Lille or no change in Brix readings • Caused by: – Depletion of an essential factor, e.g. N, P – Overheating • More common with white wines – Lower level of nutrients Lac1c Acid Bacteria • Also important in sauerkraut, yogurt, cheese, pickles, etc. • Wine relevant species – Lactobacillus – Pediococcus – Leuconostoc • Leuconostoc oenos – ML-‐34 strain – PSU-‐1 strain • Reduces the acidity of wine • Eliminates malic acid for stability 18 • Contributes “buttery flavor” – Caused by the compound diacetyl • Generates CO2, bubbles • You don’t want this to happen in the bottle! Oenococcus oeni • A type of bacteria that converts Malic acid to Lac1c acid and CO2 (Malolac1c fermenta1on) Malolactic Fermentation (MLF) • Occurs naturally in some wines (with low ini1al acid) – Almost always occurs in wooden containers • Occurs in most red wines and ~20% of white wines – Especially barrel fermented Chardonnay • Can inoculate with ML bacteria to encourage • Can prevent MLF with SO2 or sterile filtrati on • High acid wines tend to be the excep1on Acetic Acid Bacteria • Acetobacter species – “Vinegar Bacteria” – Alcoholàace1c acid à ethyl acetate Acetic Acid Bacteria • Usually present in all wineries • Requires O2 • Control by excluding air • Inhibited above 14% EtOH • SO2 sensi1ve 19 Brettanomyces -‐ a Wild Yeast • –“Horsey”, “sweaty” or “leathery smell, “barnyard”... – Hard to control because EtOH tolerant, just like wine yeast – More SO2 sensi1ve than wine yeast – Can be controlled by SO2 or filtra1on • Characteristic of some wines -‐“Burgundian terroir character” -‐ Common in organic wines SUMMARY • You Should Know About: – Differences between Wild Yeast and Commercial Yeast – Requirements for good fermenta1on – Yeast growth and the differences between respiration and fermentation – Heat and Ethanol generated in fermentation – Malolactic Fermenta1on – Other important (good or bad) microorganisms such as O enococcus, Acetobacter, and Brettanomyces End of notes Day 4 20