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Wine can be classified by..
Color(red, white, rose, blush)
Grape variety
Place of origin
Table wine
less than 14% alcohol
dessert or fortified wine
14 to 24% alcohol
Co2 + Alcohol
most important legal criteria for classifying wine
tax rate for table wine
tax rate for dessert wine
tax rate for sparkling wine
table wine in Europe
quality classfication
Flavor of wine comes from three sources:
grapes, fermentation, processing/aging of wine
grapes ideally suited for wine because...
high sugar concentration, and contain nitrogen and other nutrients required by yeast.
When did the vinifera domestication occur
4000 BC.
Ideal climate for vitis vinifera
mild winters and warm, dry summers.
Pierce's disease
affects grapes vascular system.
Cabernet Sauvignon
Major red wine of the Bordeaux region. Very important in Cali.
Major red Bordeaux. Widely known in Cali and has become one of the most important international varities for varietally labeled wine.
Pinot noir
Red grape of the Burgundy region. Important component of Champagne. Grows in coolest regions of Cali.
Red wine that is used to make both red and blush wines. Came from Croatia. Grown in warmer regions of Cali and southern Italy (primitivo).
Main grape of the white wines of Burgundy. Widely grown in Cali and many other wine regions of the world.
Sauvignon blanc
White wine grape that is important in both Bordeaux and the Loire Valley of France and also in Cali. Sometimes called Fume blanc.
classic white wine grape of Germany. Not widely grown in Cali but is more important in New York, Oregon, and Washington.
Vitis labrusca
Includes the familiar Concord grape from which grape juice and jelly are made.
Muscandinia rotundifolia
Immune to pierce's disease. Used for fresh fruit and jelly.
Vitis aestivalis
variety: Norton or cynthiana. Important in Missouri and Arkansas
Vitis riparia and vitis rupestris:
important because of their resistance to the root phylloxera and their consequent value as rootstocks.
vitis californica
found along streams in the coast range and foothills. Not been used as a rootstock or for any other ag. purpose.
aphid like insect that attacks the roots of the grapevine.
hybrid direct producers
created by crossing European wine grapes w/ various American grapes. Achieved phylloxera resistance but mediocre wine.
physically attaching a vinifera top (scion) to a roostock from
American species.
Powdery mildew
affects the leaves and fruit. Controlled by dusting vines w/ sulfur or fungicide.
infects the fruit cluster and causes bunch rot. also knwn as noble rot because it punctures skin and contributes its own flavor thus producing rich, sweet wine.
foudn int he seeds and skins. contribute to bitterness and astringency.
Brix scale
used to express sugar concentration. = %sugar by weight.
mostly responsible for decrease in acid (berry is increasing in size and water content).
malic acid + respiration
malic acid gets converted to CO2. Another reason why acid decreases.
Global Wine Production
Global Wine Consumption
US Production
90% comes from CAli.
Sources of Wine Consumed in 2005
Cali - 67%
Other US 8%
Imports - 25%
bonded winery
an enterprise that produces and stores wine under a bond that guarantees payment of the federal excise tax.
top 5 US producers
Wine Group
70% of all wine sold in US
Top 6 - 10 us producers
Brown Forman
Kendall Jackson
St. Michelle
10% of all sales
Alcohol calories
cooler places
Less sugar, lower yields, later maturity, more acid, more color, more flavor, better quality
Hotter Places
More sugar, more tons per acre, ripen earlier, lower acid, less color, less flavor
very cold
winter kill, spring frost (important in Cali), poor fruit set, won't ripen.
wine yield
160 gallons per ton
5 bottles per gallon
7 tons per acre
a framework of stakes and wires used to train and arrange the vine growth in the most advantageous manner
What is saccharomyces cervisiae?
It is a "sugar fungus." It is yeast used for winemaking. Found naturally on grape skins along w/ wild yeasts. Most wineries use selected strains which are purchased from commerical suppliers. SO2 is added to inhibit wild yeast. Major advantage of S cervisiae over wild yeast is that it's alcohol tolerant and insensitive to SO2.
What is the definition of must?
The unfermented or fermenting juice expressed from fruit, especially grapes.
Describe natural fermentations:
Some winemakers do not innoculate their must w/ commerical yeast strains. Instead, they prefero to allow natural fermentations or wild fermentations to take place. These fermentations are probably carried out by resident strains of S. cervisiae that have become established in the vineyard or winery.
What are some disadvantages to wild yeast?
-Produce compounds that result in off flavors.
-Alcohol intolerant. Tolerate only about 4 - 6% alcohol.
-Unpredictable: Cannot anticipate the progress of the fermentation.
-SO2 sensitive:
What are characterisitcs of a good wine yeast strain?
-Reproducible and predictable
Vigorous fermentation (to outcompete spoilage organisms)
Complete fermentation (no sugar is left for spoilage organisms)
-Good alcohol tolerance (most commercial yeast will tolerate up to 17 - 18%)
High temp. tolerance
Minimal off flavors
SO2 tolerance.
True or false. Yeast strains are usually chosen for flavor.
False. The small flavor difference in wine are not very significant. Some aroma differences may be evident right after fermentation, but these generally disappear before wine is bottled.
What are the requirements for good fermentation?
-Sugar: Yeast uses glucose and fructose
-Vitamins: Yeast can make all the vitamins it needs excpet biotin. Obtains from grape.
-Minerals: especially phosphorous.
-low pH.
-Temp between 50 - 100F. yeast can survive around 110 F but this tolerance drops towards the end of fermentation due to the high alcohol.
-Ehthnol below 16%
What are the products of fermentation?
glucose is converted into 2 ethanol molecutles and 2 carbon dioxide molecules.
What is the relationship between Brix and Fahrenheit?
A reduction in sugar of 1 degree brix results in a temperature rise of 2.3F or 1.3C. This is important because it can result in a fermenting must that reaches a temperature high enough to kill the yeast.
How much energy is produced from fermention 1 mole of glucose?
56 kcal. Less than half ot that energy is stored as ATP for use by the yeast in other biochemical reactions. The rest is lost as heat.
What is the approximate ethanol yield by volume?
55%. So juiice that is 20% sugar (20 brix) will produce a wine that is bout 11% ethanol.
What is the most important determinant of fermentation time?
Temperature. Fermentation proceeds faster at higher temperatures. Because white wines are fermented at a lower temperature, they typically require longer time to complete.
What is stuck fermentation?
If some nutrients becomes limiting or the environment becomes inhospitable before all sugar is fermented, fermentation will stop, leaving unfermented risidual sugar. These are usually due to a nitrogen or phosphorus dificiency in the grape juice. White fermentations are more likely to stick than red. Excessively low or high temps can also cause a fermentation to stick.
What is malolachtic fermentation? Why is it important?
The coversion of malic acid to lactic acid. ML fermentation reduceds the acidity of the wine, generates CO2 and contributes a buttery flavor (imparted by diacetyl). It increases the stability of the wine because once it has been completed it cannot occur again after bottling. If ML fermentation occurs after bottling, the wine will be fizzy and the growth of the mL bacterial will cause the wine to be cloudy.
What is acetbacter?
The bacterium responsible for the production of vinegar. Usually present in all winieries. Coverts ethnol to acetic acid and ehtyl acetate. This can be prevented by excluding air. Inhibited by alcohol concentrations above 14% and by SO2.
What is brettanomyces?
A wild yeast that contributes a sweaty, leathery smell to wine. It is hard to control because it is ethanol tolerant and grows under much the same conditions as wine yeast. Can be controlled by SO2.
How is sugar measured before harvest?
Fruit samples usually brought into winery lab. Sugar is measured by its refraction to light (with a refractometer) or by the density of the juice (hydrometer). Acid is measured by titration and measurement of pH.
What is the upper limit for US table wine? Lower limit?
14%, 7%.
What is the alcohol range for most US wines? What about titratable acidity?
11 - 13% alcohol. .6 to .8 grams per 100 ml.
What sugar are grapes harvested for sparkling wine? White wine? Red wine?
Sparkling: 18 - 20 brix
White: 19 - 23 brix
Red: 20 - 24 brix
What is the product of crushing?
Must. Consistis approximately of 80% juice, 16% skins, 4% seeds.
Where does the pigment for red wines come from?
Pigment for red wines comes from the skins.
Where are most of the tannins found?
Why add SO2 to wine?
to inhibit oxidation (causes browning) and other deleterious changes. Also inhibits undeseriable microorganims. Wine in US must carry phrase "contains sulfites" if the conentration is above 10 parts per million (whether or not SO2 was added). Sulfites also occur naturally during fermentation.
What is organic wine?
wine that is made without added SO2 but will still contain naturally produced SO2.
What happens if the potential alochol of the must is too low?
May be enriched by the addition of concentrated grape juice or the addition of sugar (called chaptalization). Chaptalization is prohibitedin Cali as well as in souther Europe and in some other countries. Acidity can also be adjusted. In cali, acidity is more often too low and is adjusted by addition of tartaric acid to the juice.
Why is pressing necessary?
Done in order to separate the juice or wine from the skins and seeds. May take place before fermentation (white wines) or after fermentation (red wines).
What is free run?
A type of pressing (or lack thereof). Juice or wine drains away from the skins and seeds by gravity alone, without added pressure. Thypically about 80 - 90% of the juice wine volume. Additional press fractions can be obtained by applying increasing pressure in successive stages.
What is the hard pres?
Juice or wine that is obtained in the last stage of the press. Sometimes it gets sold off for bulk wine or distillation.
What is pomace?
The residue of skins and seeds that remains after pressing.
How much grape juice does one ton of grapes yield?
140 - 190 gallons of juice or wine. Red grapes yield more because red grapes are pressed after fermentation when liquid can be more fully extracted. Also, red wines can be pressed harder since tannins are not undeseriable in red wines.
What are the different types of presses?
Basket: basically a piston that pushes the fruit down (oldest).
Other presses include moving hea d press and screw press.
True of false? Free run is considered to have the highest quality.
What is the most widely used kind of press in premium wineries?
Membrane press: rubber bladder lining the inside of the press is forced against the fruit by air pressure. The pressure is so gentle that very efficient extraction of juice or wine can be obtained without excessive skin and seed brekage (which would increase tannin concentration).
What is settling?
Juice or wine from the press contains some suspended solid material that is allowed to settle to the bottom of a tank.
What is racking?
Process in which the wine is separated from the 'lees' (sediment formed by the dead yeast cells)
What is lees?
the solid material that the juice or wine contains after pressing. Consisits of fruid solids, dead yeast, or chemical precipitates.
What can be used as fermentor vessels?
Wooden tanks, plastic boxes, concrete tanks lined w/ epoxy, stainless steel tanks. Fermentation vessels for white wine should always hafe a top in order to exclude air and contaminants.
How do wineries manage temperature?
Heat is most commonly removed by the use of stainless steel tanks that have refrigeration jackets or by heat exchangers to cool the fermentaiton.
How do you allow excess CO2 pressure to be released?
Through a fermentation lock. Allows CO2 to escape while preventing entry of air.
What does barrel aging do?
adds vanilla and spicy flavors and sometimes smoky flavors if the barrel has been heavily toasted. Most premium red wines are aged 6 months to 2 years.
What barrels are usually used? How long does each barrel last?
French oak barrels have been the most popular w/ California premium winemakers, but American oak is being used in increasing amounts. Barrel typically lasts 5 - 10 years.
What is a fining agent?
Wine may still be hazy after racking due to protein, polysaccharide or microbial residue. These can be removed by treating the wine w/ a fining agent that reacts with or absorbs the subastance, percipitates out and falls to the bottom.
What are some good fining agents?
Egg white, geltain, and casein (milk protein). Bentonite removes protein hazes.
What is potassium acid tartarate?
Ove time, and especially when wine is refrigerated, the potassium and tartaric acid in wine can form a crystalline percipitate (KHT). This can alarm consumers (some can even mistake it for broken glass). Can be prevented by cold stabilization, chilling the wine below 32F for several weeks to cause the KHT to precipitate in the winery, where it can then be removed by racking or filtration before the wine is bottled. Also, ion exchange can be used to replace the potassium ions w/ sodium or hydrogen ions resulting in more soluble form of tartrate.
What is diatomaceous earth?
Common filtration agent used to remove particular matter.
What is sterile filtration?
Any microbes that may lead to microbial instability problems in the bottle can be removed by sterile filtration. It is especially important in wine containing residual sugar that could serve as a substrate for remaining yeast cells. Also important for wine that has not undergone malolactic fermentation.
When does fermentation take place in red wines?
Before pressing, in the presence of the skins and seeds.
What is the ferment. temperature for red wines?
70 - 90F. Insures good color and tannin extraction, both of which are desirable in red wines.
How much does a red feremntation last?
Much faster than white fermentation. 4 - 12 days. This is due to a higher temp. and the better supply of yeast nutrients provided by skins and seeds.
True or false? Air contact is a great concern for red fermentations.
False. Browning is not apparent in red wines. Red juices also contain some natural antioxidants and the vigorous fermentation produces a dense surface layer of CO2 that prevents the entry of air into the must.
How do you increase color and tannin extraction?
Both are increased by higher temp., by alcohol concentration and by the amount of time before pressing.
Extraction is lowest in..?
Blush wines, which are pressed immediately after crushing. Rose wines are pressed after 24 - 36 hours of skin contact. Red wines are usually pressed after about 4 days.
High priced red wines usually have skin contact for how long?
10 - 30 days. This extended maceration does not increase the color of the wine, but it does increase the tannin concentration of the wine.
High tannin levels are an indicator of what?
associated w/ long aging, but make young wine less pleasant to drink.
what is a cap?
During red fermentations, the skins and some seeds form a cap taht floats at the top of the tank (thick, occupies 1/3 of total volume). Good extraction of color and tannins require good cap management.
What is cap management?
Mixing of the cap w/ the fermenting wine. Small tanks (punching down). Larger tanks: pumping over (pumping wine from the bottom of the tank and spraying it over the surface of the cap until the cap is mixed back in.
what is carbonic maceration?
a red wine variation in which whole berries are blanketed w/ CO2 and left for 8 - 10 days during which chemical changes take place inside the berries. Eventually, skins break open and the must is pressed, inoculated, and allowed to ferment normally. Produces very fruity, low tannin, light red wine.
How do you make blush wines?
produced exactly like fruity white wines but from red grapes. Pressed immediately after crushing to minimze color extraction. No wood contact, no agin.
Whem making white wines, what happens after crushing?
The must is sometimes allowed to settle in a drain tank to allow juice to dain away by gravity. Pectic enzymes may be added to help break down the fruit tissue and release ore juice.
For white wines, what happens to the juice?
The juice is kept cold and protected from air to prvent the browning that is caused by the oxidation of phenolic compounds.
How quickly is the must pressed after crushing (for white wines)?
Right away to minimze the extraction of phenolic compounds. These are the substrate for browning and contribute bitterness and astringency.
What are most white wines fermented in?
Temperature controlled tanks in which the temp. is kept relatively low to maximize the fruity flavors that are produced by yeast at low temps and to minimize the loss of volatile flavor compounds that can occur w/ rapid CO2 generation at higher temps.
Are some white wines barrel fermented?
Yes. Particulary high priced Chardonnays. Usually undergo ML at the same time. Barrel fermented Chardonnays have characteristic flavors of vanilla and butter. These barrels are not temp. controlled, but their small volume allows heat dissipation and keeps the fermentation temp. low.
What is sur lies aging?
Againg of the lees. Flavors are contributed by the dead and dying yeast and this may be enhanced by stirring the barrels regularly.
What is arresting the fermenation? Why is it used?
Expensive chardonnays and most sauvignon blancs are made dry. Less expensive chardonnays are often made w/ a little residual sugar. Sweetness may be produced by arresting the fermentation (chilling or sterile fermentation) before all the sugar is consumed or by fermenting to dryness and adding sterile juice concentrate.
When can the name "champagne" be used on a bottle of sparkling wine?
Only if the word is accompanied by US geogrpahic name such as California champagne or Napa Valley champagne.
What is the legal definition of sparkling wine?
Wine containing greater than .392 g CO2 per 100 ml (approx. 1 atm. of pressure). Sparkling wines usually have much more than this ( 5 - 6 atm).
What is sparkling wine taxed at?
3.70 per gallon as opposed to 1.27 for still wines in Cali.
What is the basis for sparkling wine production?
A second fermentation in a closed container such that the CO2 produced during the fermentation cannot escpae. If CO2 added artificially, it cannot be called sparkling wine.
What is the cuvee?
This is what the production of sparkling wine begins with, the base wine.
What are some characteristics of the cuvee?
Relatively low alcohol, moderatley high acidity, low SO2 and is usually completely dry. Grapes harvested early (low alcohol).
What are the traditional varieties used in Champagne?
Chardonnay, Pinot noir (red), and meunier (red). Less expensive wines are made from French Colombard or Chenin blanc.
What are blanc de blancs?
Sparkling wines made entirely from chardonnay. If made from red, they are called blanc de noirs.
What is the tirage?
The cuvee is mixed w/ a syrup containing the yeast and sugar and then dispensed into bottles.
How much sugar does it take to generate 1 atm?
4 g of sugar per liter.
How are yeast strains selected for sparkling wines?
Usually specially selected for their ability to tolerate high CO2 and low temp. and for their ability to flocculate(clump together to be easily removed later).
What happens after you have the tirage?
The bottles are capped and cellared to allow the second fermentation. After the fermentation has finished (1 - 3 months) the yeast die and form a sediment on the side of the bottle.
What is riddling?
A process that drives the yeast sediment into the neck. bottles are turned a little each day and gradually tilted from horizontal to vertical. Process takes about 2 months by hand. 8 days by machine.
What happens after riddling?
Neck of the bottle is dipped into a sub freezing solution. Freezes the sediment in the bottle neck into a solid plug. Bottle is opened and CO2 pressure forces the plug out.
What is disgorgement?
Removal of the plug of sediment (when making sparkling wines) after it has been frozen.
How much sugar do most sparkling wines contain?
.5 - 1.5% sugar. this does not taste sweet, so sugar is usually added to balance the acidity and flavor.
What are some highlights of the traditional method?
Expensive to produce due to the extra labor, space, and time required. Bottles labed "fermented in this bottle." Does not leave the bottle. Less than 20% of the sparklilng wine made in the US is made by this method.
How is the trasnfer process different from the traditional method?
Once the second fermentation is complete, the bottles are not riddled. Bottles are emptied into a large transfer tank (under pressure). Wine is filtered, dosage added, and the wine is returned to the bottles.
What are some highlights of the transfer process?
Wine is mixed. Cheaper method than the traditional method. No bottle aging on the yeast - complex flavors do not develop. Labeled "bottle fermented" or "fermented in the bottle" but not in "this bottle". Very little US sparkling wine is made this way.
How does the Charmat process work?
Also known as bulk process.
1. Base wine is mixed w/ yeast and sugar in a tank and held at about 55F for 1 to 2 weeks during which time the second ferementation occurs.
2. Wine is the cold stabilized and sterile filtered, all under pressure.
3. dosage is added and the wine is bottled.
What are some highlights of the charmat process?
Wine may be exposed to air and thus subject to oxidation and browning, thus SO2 may be added.
Rapid process (may take less than a month). No aged character or yeast flavors. About 75% of US sparkling wine is made this way.
In Spain, what is sparkling wine called if it is produced by the traditional method?
It is called cava.
What was the earliest culture in which wine was an important item?
In Egypt, whta was wine initially associated with?
Priests and royalty. It eventually diffused to loewr classes.
In Greece, wine was associated with what?
Worship of Dionysus.
Who had the greatest impact on the development of viticulture than any other ancient culture?
The Romans. virtually all of the major wine producing regions of western Europe today were established by the Romans.
After the fall of the Roman Empire, who preserved wine making technology?
The church.
What was England's inluence on certain European wine regions?
England controlled Bordeaux and was a major consumer of its wine, contirbuting greatly to the development and continuing prominence of this region. Also played a strong role in the sherry industry in So-Spain.
Who discovered that wine spoilage was caused by microorganisms?
How do you control powdery mildew?
How do you control Downy mildew?
Bordeaux mixture (copper sulfate and lime).
Why was the controlled appelation system reated?
Because of phylloxea, half of the vineyards in France were destroyed. The severe reduction in wine supply caused prices to increase and encouraged the production of fraudulent wines.
Who brought grapes to California?
the missions.
Why was the wine department developed at UC Davis?
In the late 1800s, the wine industry was beset w/ economic problems and soon after by tremeondous vineyard losses to phylloxera. department was created to help the industry overcome its problems.
What is absorption?
the movement of alcohol into the body which casues blood concentration to rise.
How much alcohol is absorbed in the stomach? In the small intestine?
20% in the stomach. 80% in the small intestine.
What is the equation for BAC?
.08(#of drinks)(ounces per drink)(% alcohol) / weight
What factors affect BAC?
Ethanol concentration (rate is higher for higher concentration)
Food (lower when consumed w/ food)
What is the first step in alcohol metabolism?
Ethyl alcohol gets convereted to acetaldehyde by the enzyme alcohol dehydrogensae.
Where is most of the alcohol metabolized?
In the liver (80%) by hepatic ADH. 20% in the stomach by gastric ADH.
What is alcohol metabolism in the stomach referred to as?
first pass metabolism
How fast is alcohol metabolized in the bloodstream?
.1 gram per kilogram of body weight per our.
What is the equation to estimate the amount of an alcohol beverate that a person will metabolize?
weight / 5*(% alcohol)
what is the equation for hours per drink?
250 / weight
What do the studies say about the health benefits of wine?
Moderate wine consumption is correlated with some health benefits, particulary reduced cardiovascular heart disease. Connection is clear but the cause is not proven.
what do the studies say about heart disease and wine?
Study by Rimmand Harvard clearly showed that moderate drinking reduced the risk of heart disease.
What did a study from Denmark by Groenbaek show?
REduction in death due to heart disease that can be attriburted to alcohol is solely due to wine. Klatsky and Armstrong showed that drinkers who consume predonimnantly wine have mortality rates 50 - 70% of those of spritis drinkers, but they were unwilling to attritubte this effect to wine, saying US wine consuemrs typically had lifestyle factors predisposing them to lower mortality.

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