Winemaking/vinification Flashcards
How long have people been making wine?
at least 8,000 years
Who discovered Malolactic fermentation, when was it first introduced in winemaking?
Late 1950s
Émile Peynaud in France, Brad Webb in California, and others in Portugal—all simultaneously isolated the first malolactic bacteria culture
What year did Louis Pasteur discover yeast was responsible for fermentation?
1857
Who postulated in 1891 that bacteria was responsible for acid reduction in wine?
Hermann Müller (Thurgau)
in 1913 with Osterwalder, he demonstrated this principle successfully
In this year Tschellitscheff demonstrateed cold fermentation, and the Vaslin horizontal plate press was popularized
1945
When were the first active dry yeast cultures produced commercially?
1965
in what year did Château Haut Brion install temperature controlled stainless fermenters
1965
What is Flash Détente, and when was it introduced to the wine industry?
introduced 1993
thermovinification process consists of a fast heat treatment, with the grapes brought up to high temperature, followed by immediate cooling by pressure reduction.
significantly increases the quantity of extracted dyes, the polyphenols and the polysaccharides. The wines have more colour, and are fruitier and rounder, but with the same tannic structure.
heated rapidly to near-boiling temperatures (185 degrees Fahrenheit), then cooled rapidly using a vacuum.
what year were rotary fermenters introduced
1980, create juicier more extracted wines more easily
Who invented micro ox, what year was it implemented?
1991
Du Corneau
What year were Smith Patents introduced for Reverse Osmosis, for what reason?
1992, to remove volatile acidity
What is MOG
Material other than grapes
What is a primary aroma
Flavors and aromas present in the fruit
What is a secondary aroma
aromas arising from fermentation
what is a tertiary aroma
Aromas arising from aging and oxidation
aroma, color, and flavor compounds represent this % of a wines composition
only 3% of wine by weight.
Compounds other than Water and ethyl alcohol in wine
glycerol (a “sugar alcohol”), organic acids, unfermentable sugars, proteins, fusel alcohols (larger alcohols), phenolic compounds such as pigment and tannins, and aroma compounds like esters, terpenes, and thiols.
The compositional makeup of a bottle of wine
Rootstock other than vinifera
Vitis rupestris, Vitis riparia, Vitis berlandieri, Vitis labrusca, Vitis aestivalis, Muscardinia rotundifolia, and Vitis amurensis.
How many grape varieties are known?
over 10,000 grape varieties are known, with roughly 1,400 in commercial production.
What are unfermentable sugars called?
Most unfermentable sugars are pentoses, which means that their chemical structure includes five-carbon atoms, while glucose and fructose are hexoses (six-carbon sugars).
18-27 brix translates to this g/l of rs
180 to 270 grams per liter sugar before fermentation
What is the tool used on fermenting must to measure density
densiometers
In the field, this tool is used to measure sugar
in the winery, this tool is used to measure sugar
refractometer, which infers sugar concentration by measuring the refractive index of a liquid. In the winery, sugar content is measured with a hydrometer
In the EU, this is how potential alcohol is measured
In the EU, potential alcohol is estimated using the official conversion ratio of 16.83 grams per liter sugar yielding 1% ABV.
Primary organic acid that occurs in grapes
Tartaric
What does TA mean?
titratable acidity
What is the range of the PH scale
0 (very acidic) to 14 (very basic)
PH is technically this
Technically, pH is a measure of the concentration of hydrogen ions (or protons) in a solution
Examples of Phenolics in wine
Tannins and anthocyanins
What are Catechins?
Catechins are small polyphenols that are extracted mostly from seeds and stems (though also from skins) and are largely responsible for bitterness in wine
Flavors and aromas in wine come from these
esters, terpenes, pyrazines, norisoprenoids, and thiols.
What is encuvage
After harvest, new wines go to barrel to age
Why would a winemaker use hyper ox
the juice turns brown initially but clarifies throughout fermentation. This allows the most susceptible compounds to be oxidized and discarded as lees, resulting in a finished wine that is potentially less fruity but more resilient against post-fermentation oxidation.
What is the enzyme created from Botrytis?
Laccase
causes rapid oxidation that is not deterred by sulfur dioxide or alcohol, unlike other enzymes. Botrytis imparts a specific flavor profile (ginger and saffron, accompanied by oxidation)
Why would white and rosé winemakers use whole cluster press
Whole-cluster pressing minimizes skin contact, resulting in clearer juice with fewer skin-derived compounds, including phenolics that may cause bitterness. The stems act as a press aid, improving juice yields and clarification.
Why would a winemaker use Pectolytic enzymes
break down pectin, may be added to speed up the extraction process
How long is juice left with skins in red wine production
10 to 21 days average
In thermovinification, must is heated to this temp for this long
between 140 to 180 degrees Fahrenheit for a period of 30 minutes to 24 hours,
most common type of press
Pneumatic presses
Different kinds of presses
A bladder press has an inflatable cylindrical bladder in the center of the press that expands radially, compressing the grapes symmetrically against the tank’s sides.
A membrane press is similar, but the inflatable bladder is located along one side of the tank and grapes are compressed against the other side.
A tank press is a fully enclosed membrane press that allows the winemaker to exclude oxygen for very reductive winemaking. This may be preferred for bright and clean white wine styles with delicate aromas, like popular styles of Sauvignon Blanc.
Ways to prevent oxidation during winemaking
dry ice and, with juice, sulfur dioxide
Methods of clarifications (fining or collage) in winemaking
débourbage, or settling overnight at cold temperature, followed by racking or decanting the juice off of the solids that have settled to the bottom of the tank.
filtration or centrifugation.
Another method of clarification is flotation, in which gas is pulsed through the juice, and the solids float to the top of the liquid.
Bentonite
The most common method for reducing potential alcohol
adding water to the must
Can also irrigate right before harvest
Ways of deacidifying wine all involve this
all involving adding salts that react with tartaric acid to form tartrate salts that settle out of the wine
The bacteria responsible for Malolactic fermentation
Oenococcus oeni
Do pathogens exist in wine?
NO
What is yeast?
single-celled eukaryotic fungi.
They require a carbon source, like sugar, for energy and a nitrogen source, like ammonia or amino acids, for growth and metabolism.
If a winemaker inocculates, it will be with one of these strains of yeast
Saccharomyces cerevisiae or, less often, Saccharomyces bayanus
Like 6 carbon sugars like glucose and fructose
Saccharomyces cerevisiae can withstand alcohol % of this, a unique characteristic
16% to 17%
Indigenous yeast varieties
Cryptococcus and Rhodotorula
genera Hanseniaspora (Kloeckera), Candida (Metschnikowia), and Torulaspora
more sensitive to sulfur dioxide (SO2) and alcohol
Spoilage yeast example
Pichia, which produces large levels of volatile acidity (vinegar)
Dominant yeast species at beginning of fermentation
Kloeckera apiculata
Kloeckera produces ethyl acetate
Spoilage yeasts that enter the picture after fermentation
Zygosaccharomyces, Saccharomycodes, and the notorious Brettanomyces bruxellensis (Dekkera bruxellensis).
Brettanomyces can metabolize sugars that Saccharomyces is not able to
compounds associated with medicinal, barnyard, and smoky aromas.
4-ethylphenol and 4-ethylguaiacol
What is Acrolein taint
What causes it
Sensory Impact: Extremely bitter
Compound(s): Acrolein
Source: Lactic acid bacteria
Biogenic amines
What causes them
Sensory Impact: Nauseating
Compound(s): Histamine, tyramine, putrescine, other amines
Source: Lactic acid bacteria, especially Pediococcus
Ropiness
What causes it
Sensory Impact: Slimy texture, similar to egg white
Compound(s): Polysaccharides
Source: Lactic acid bacteria
Acetic acid bacteria
(AAB) convert alcohol to acetic acid (vinegar)
Types of AAB
Acetobacter, Gluconobacter, and Gluconacetobacter reside on grapes
only alcohol-tolerant Acetobacter persists in wine.
This compound is required for AAB (Acetic acid bacteria) to thrive
Oxygen is required for the growth and activity of acetic acid bacteria
What is pied de cuve
a portion of yeast-rich, already fermenting grape must, may be used to inoculate a fermentation—as with using a sourdough starter for baking
The first ten of the 12 steps of fermentation are called this
glycolysis, the process whereby yeast converts sugar into energy.
During fermentation this amount of CO2 is “evolved” or given off
equivalent to 60 times the volume of the must
Three distinct Phases of yeast during fermentation
lag phase, exponential phase, and stationary phase.
Low levels of nitrogen in the must are associated with this
yeast’s production of hydrogen sulfide (H2S), a reductive thiol that smells like rotten eggs, and stuck fermentations
What is YAN? How is it measured?
yeast-assimable nitrogen
the sum of ammonia and amino acids present in the juice, to assess whether the natural levels are sufficient for the yeast. The recommended levels have changed over the years, but YANs of 200 or more are generally considered ideal for yeast health.
Winemakers can augment nitrogen-deficient musts with high levels of H2S by adding this
adding diammonium phosphate (DAP), an easy-to-metabolize form of nitrogen
A happy mercaptan ;)
3-mercaptohexanol, a compound which commonly lends grapefruit and passionfruit aromas to Sauvignon Blanc.
mercaptans likee methane and ethane thiol, with aromas described as putrefaction and as skunk, onion, and rubber, respectively are created by this
H2s (Hydrogen sulfides) not managed properly
Yeast requires this temperature
45 to 95 degrees Fahrenheit, below which they will be inactive, and above which they will die
White wine fermentation temp range
40s to mid-60s degrees Fahrenheit
Fermentation temps for red wines
70s to the low 90s
Lactic acid bacteria for Malolactic fermentation are inhibited by this:
low pH (below 3.2), high alcohol (above 14.5%), low temperature, and sulfites; as a result, some wines struggle to complete malolactic fermentation
Lactic acid bacteria is very sensitive to this
Bacteria are sensitive to SO2, and even a small amount can inhibit their activity.
Temperature ideal for Malolactic to occur
70 F
Why Sulfur immediately after malolactic fermentation?
results in more retention of diacetyl and other aromas derived from malolactic fermentation
Why do winemakers wait for primary fermentation to finish before starting malolactic fermentation?
The reason for this is two-fold: it avoids competition between yeast and bacteria, which could lead to a stuck fermentation, and it reduces the risk of high volatile acidity, since some lactic acid bacteria convert sugar to VA.
Why delay malolactic fermentation in red wine?
For light-colored varieties such as Pinot Noir, delaying malolactic fermentation can help to maximize a finished wine’s color intensity.
Wine storage temperature in a cuve, after fermentation
45 to 65 degrees Fahrenheit.
oxygen is consumed more quickly in reds than in whites. True or False?
True, Because red wine contains more phenolic compounds
How do sulfites and phenolics “Protect” a wine from oxidation
Sulfites and phenolics “protect” the wine since they are easily oxidized, which prevents the oxidation of aroma and flavor compounds.
Where was Micro Ox first practiced?
Micro-ox was originally devised in Madiran to hasten the aging of ultra-tannic wines
Difference between Micro Ox and Cliquage
Micro Ox: Mimics barrel aging
red-winemaking technique that introduces a slow dose of oxygen to a wine over time. For wines aged in tank, this technique mimics the oxidative benefits of barrel aging and is seen as a more economical alternative.
Cliquage: Mimics racking
similar technique in which a larger dose of oxygen is added to the wine to mimic the oxygen pickup that would be expected during racking, which is a labor-intensive process.
oak tannins are called:
Oak tannins are called hydrolysable tannins or ellagitannins
French oak has more than twice the tannin content of American oak: True or false
TRUE
What is the whisky lactone?
Cis- and trans-oak lactone
They offer oaky, vanilla, coconut, sweet, and cocoa aromas to the wine
Difference between Free and Bound SO2
Free SO2 is the portion of SO2 that has been added and is available to protect the wine from oxidation and microbial spoilage
two forms of free sulfur exist in wine:
molecular and bisulfite (most is bisulfite)
The legal limit (in most countries) for total SO2 allowed in dry wine is between
150 to 350 parts per million
Stages of production that may require racking
In white winemaking, just after pressing and prior to fermentation to remove solids. If solids are desired, a portion may be added back to increase turbidity, or the wine may be racked “dirty,” with some solids included during racking.
After primary fermentation to remove the gross lees, or the large volume of lees generated during fermentation.
After malolactic fermentation to remove lees prior to the addition of SO2.
Periodically throughout aging for clarification and aeration.
During blending.
After fining to remove fining agents and/or prior to filtration.
After cold stabilization to remove tartrate crystals.
What is soutirage à l’esquives?
Traditional method of racking in France
involves draining the wine through a valve on the face of the barrel. Then, a winch inverts the barrel, decanting the wine off the lees until sediment appears. A small, shallow cup called a tastevin was traditionally used to taste and assess the clarity of the wine during racking. This technique is said to result in slower, more precise racking but appears to be more oxidative than its modern counterpart.
Vegan fining agents
PVPP and nylon
Bentonite is a naturally occurring, negatively charged Montmorillonite clay used to remove large, positively charged compounds, including proteins and polysaccharides, in juice and wine
Where is fining most prevalent?
Fining is more prevalent in cooler regions, where fruit is harvested less ripe and tannins may be underripe or rustic.
Legal limit for copper
0.5 and 1 milligrams per liter in the United States and EU, respectively
What is copper casse?
Excess copper can increase the rate of oxidation and reduce varietal thiols, and high levels can cause a haze or red-brown precipitate in bottled white wines
What is sterile filtration
clarifies wine or prevents microbial spoilage by physically removing yeast and bacteria
Why are Most wines with residual sugar or malic acid sterile-filtered
prevent refermentation in bottle.
Difference between depth and surface filtration methods.
Depth filtration:
the wine is passed through a relatively thick filter media often made of diatomaceous earth (DE or Kieselguhr) and/or cellulose (paper). The filter media forms a sort of maze, and as the wine passes through, larger particles are trapped. less prone to clogging than surface filtration methods. NOMINAL method, which means that the filter rating describes the filter’s average pore size. Some larger particles will also make their way through
Surface filtration:
wine is passed through a perforated plastic membrane with a uniform pore size. Surface filtration techniques are considered ABSOLUTE, which means that they filter out absolutely all of the particles larger than the filter rating. Usually depth filtration occurs first
0.2 to 10 microns is the range of filter for both methods
This depth filtration method is typically used by large wineries
Plate and frame: A support screen is coated with DE, and wine that has been mixed with DE is passed through the screen. Because the filter media is constantly replenished, this is a good technique for wines with a large amount of solids. The initial setup is expensive, and it is messy to operate. This method is typically used by large wineries.
This size of filter pore is used to ensure all bacteria and yeast is removed in sterile filtration
A pore size of 0.45 microns or smaller
most technical and expensive of the filtration techniques
Crossflow
surface filtration in which the flow of the wine runs parallel to the filter surface, making it less likely to clog. That said, the wine is still often pre-filtered to avoid clogging.
Methods of cold stabilization (removing tartrates or calcium bitartrate)
refrigeration, which involves holding the wine at very low temperature for several weeks. Afterward, the wine is racked, leaving the tartrates behind.
Potassium bitartrate crystals may be added to “seed” or hasten the crystallization process. (Crystals form more quickly on a crystalline surface.)
ion exchange and electrodialysis, which remove potassium and tartrate salts, respectively, from the wine. T
wine additives (including gum arabic, metatartaric acid, and mannoproteins) aimed at inhibiting crystallization.
How does cold stabilization affect acidity of wine
The removal of tartrate salts necessarily decreases a wine’s titratable acidity. The effect on pH depends on the starting value: for wines with an initial pH above 3.8, the pH increases, and vice versa for wine with pH below 3.8.
Ways of creating microbial stability before bottling
Lysozyme is an enzyme derived from egg whites that can be added to wine to prevent malolactic fermentation or to destroy lactic acid bacteria. Lysozyme will not protect against yeast or acetic acid bacteria.
Chitosan (No Brett Inside) is a positively charged fining agent derived from the exoskeleton of crustaceans that is used to remove yeast, including Brettanomyces.
Sorbic acid inhibits the growth of yeast, but lactic acid bacteria can convert it to a floral-scented compound responsible for so-called geranium taint.
Dimethyl decarbonate (DMDC), commonly known as Velcorin, kills yeasts and bacteria very effectively and can be added to wine on the bottling line as an alternative to filtration or higher levels of SO2. DMDC is very toxic to humans, but once it has been added to wine, it breaks down rapidly into harmless compounds. DMDC is used in sports drinks, juices, and other packaged beverages, but its use is controversial within the wine industry.
Pasteurization, or heating to high temperature, is another option for wine sterilization, but high heat has other deleterious impacts on wine and is not suitable for use in quality wine production. Pasteurization and other high heat methods occur at bottling.
What is OTR?
OTR, or oxygen transmission rate) helps determine how a wine will age in bottle, where cork is the standard for aging expectations.
This person first discovered yeast and bacteria in the 1680s
Antonie va Leeuwenhoek
What is another name for KMW scale
Babo
Used in Austria, Italy and Eastern Europe
Assumes 15% of the solids in Brix are Non sugar, since Brix technically measures all solids in wine
The Baumé scale used in France, Spain and Australia uses this, as opposed to sugar, as the reference
Salt, sodium chloride
phenolic compounds are divided into these three groups
Flavonoids (three ring chemical structure)
non-flavonoids
Polyphenols
Hydrolysable tannins are derived from this, and comprised of non flavonoids
Oak
What are norisoprenoids
aromatic compounds that produce trimethyl-1,2-dihydronapthalene (TDN) and damascenone
Machine harvested fruit has already been destemmed. T/F
True
Champagne is whole cluster pressed. T/F
True
This is added during fruit processing and storage to prevent oxidation
sulfur dioxide
These esters contribute bubblegum, kirsch, banana and strawberry in carbonic maceration
Ethyl cinnamate
Isoamyl acetate
Why add pectolytic enzymes during winemaking?
Break down pectin. Can speed up the extraction process.
Two categories of wine press
Batch and continuous
When and why would a winemaker use bentonite post pressing
prior to racking, to clarify juice.
Is chaptalization legal in California
NO, but adding grape concentrate to must is legal
Most common acid addition
Tartaric acid (it is stable)
Deacidifying wine involves the addition of this
Salts. They react with tartaric acid to form tartrate salts that settle out of wine.
What are exogenous tannins
Tannins that are added to wine, can come from many sources, even grapes
Oenococcus Oeni bacteria is responsible for this winemaking process
Malolactic Fermentation
These two yeasts refer to indigenous yeast and they are identical
Kloeckera Apiculata
Hanseniaspora Uvarum
Winemakers refer to yeasts in these three genus:
Saccharomyces
Brettanomyces
Kloeckera
Two different kinds of Saccharomyces strains
Cerevesiae
Bayanus
these compounds produced by Brett are associated with barnyard and smoky aromas
4-ethylphenol
4-ethylguaicol
When would a winemaker add DAP (diammonium phosphate) to must
When YAN is low, and Hydrogen sulfides are present, it addes nitrogen
Two methods of arresting fermentation
Temperature reduction and
sulfur addition
Filtration or centrifugation, removing yeast
methods of halting malolactic fermentation
Lysozyme
sulfur dioxide
filtration
Benefits of sulfuring immediately afer malo
preserved diacetyl aromas and flavors
one mature oak tree from over 80 year old trees creates this many barrels
between one and four
Which is more watertight: American or French oak
American
French oak must be split against the grain to prevent leakage, and only this % of the tree can be used
20%
French oak species
Quercus Robur
Quercus Petraea (Quercus Sessilis)
American oak is this species
Quercus Alba
French Oak from these forests is tighter grained
Jupilles
Allier
Troncais
French oak from these forests is medium grained
Nevers
Bertranges
French oak from this forest is looser grained
Vosges
Oak lactones are indefinitely released from wood in this kind of environment
Acidic
Components of oak
Cellulose
Hemicellulose
Lignin
Tannin (hydrolysable, or ellagitannins)
Oak tannin that imparts a green sawdust or cardboard aroma that decreases through seasoning and toasting
Trans-2-nonenol
These flavor compounds are created during the toasting process
Guaiacol and 4-methylguaiacol (smoke, spice)
Syringol (smoky)
Cresols (leather)
cellulose and hemicellulose break down in oak to create furfural and 5-methylfurfural, increasing perception of these flavors
Oakiness
Almond
Butterscotch
Caramel
Cost per bottle of wine made with 100% new oak
If wine is aged in a cave with relative humidity of higher than 70%, what happens to the alcohol?
It decreases through aging
If less than 70%, it increases
SO2 binds with this compound and masks the effect of oxidation
acetaldehyde (bruised apple)
Most sulfur in wine is this kind
Bisulfite, combats oxidation
(molecular bisulfite is antimicrobial)
molecular So2 of this range is recommended for red and white wines to protect against microbial spoilage
0.5-0.8 ppm
most adjust free sulfur levels to this ppm at bottling
25-50ppm
What is KMBS
Potassium Metabisulfite
releases SO2 when dissolved in water
Bentonite has this charge
Negative; used to remove large proteins and polysaccharides post fermentation. Also used prefermentation
Copper fining removes this unpleasant compound
thiols and mercaptans
What is DE in the context of filtration
Diatomaceous earth
What are tartrates
Calcium bitartrate
potassium bitartrate
Cold stabilization using refrigeration alters the acidity of a wine in this way
Removal of tartrate salts decreases a wines titratable acidity
What is the name of the test to detect Brettanomyces or spoilage activity
Scorpion
Stabilization agents
Lysozyme
Chitosan
Sorbic Acid
Dimethyl Decarbonate (DMDC, or velcorin)
Pasteurization
Technical Cork
Synthetic Cork
DIAM
Nomacorc
What is TCA
trichloroanisole
