The vinification starts when the grapes
arrive to the cellar. During the harvest bad bunches or grapes have to be
discarded but the pickers may overlook them in the hurry of picking. Therefore
a new sorting often takes place at a sorting table in the cellar.
It's important that the fermentation can
be started as quickly as possible after the harvest to avoid any wild
fermentation to start in an uncontrolled way.
To start primary fermentation yeast may
be added to the must for red wine or may occur naturally as ambient yeast on
the grapes or in the air. Yeast may be added to the juice for white wine.
FERMENTATION
The biochemical process that transforms
fresh grape juice into wine is called fermentation. Yeast cells excrete enzymes
that convert natural fruit sugars into almost equal quantities of alcohol and
carbonic gas. This process ceases when the supply of sugar is exhausted or when
the alcoholic level reaches a point that is toxic for the yeast enzymes
(usually 15 to 16 percent, although certain strains can survive at 20 to 22
percent). Traditionally, winemakers racked their wine from cask to cask until they were sure that fermentation had stopped, but there are now
many other methods that halt fermentation artificially. These can involve the use
of heat, sulfur dioxide, centrifugal filtration, alcohol, pressure,
or carbonic gas.
• Heat There are various forms of pasteurization
(for table wines), flash-pasteurization (for finer wines), and chilling
operations that are used to stabilize wine. These operate on the basis that
yeast cells are incapacitated at temperatures above 36°C, or below -3°C, and
that yeast enzymes are destroyed above 65°C. Flash-pasteurization subjects
wines to a temperature of about 80°C for between 30 seconds and one minute, whereas
fully fledged pasteurization involves lower temperatures of 50 to 60°C for a
longer period.
• Addition of sulfur dioxide or sorbic
acid Dosing with one or more aseptic substances will kill off the yeasts.
• Centrifugal filtration or filtration
Modern equipment is now capable of physically removing all the yeasts from a
wine, either by filtration (simply pouring the wine through a medium that
prevents certain substances from passing through) or by centrifugal filtration (a
process that separates unwanted matter from wine—or grape juice, if used at an
earlier stage—by so-called “centrifugal force”).
• Addition of alcohol Fortification
raises the alcohol content to a level toxic to yeast.
• Pressure Yeast cells are destroyed by
pressure in excess of eight atmospheres (the pressure inside a Champagne bottle
is around six atmospheres).
• Addition of carbonic gas (CO2 ) Yeast
cells are killed in the presence of 15 g per l or more of carbonic gas.
Yeast
The primary role of yeast is to convert
the sugars present (namely glucose) in the grape must into alcohol. The yeast
accomplishes this by utilizing glucose through a series of metabolic pathways
that, in the presence of oxygen, produces not only large amounts of energy for
the cell but also many different intermediates that the cell needs to function.
In the absence of oxygen (and sometimes even in the presence oxygen), the cell
will continue some metabolic functions (such as glycolysis) but will rely on
other pathways such as reduction of acetaldehyde into ethanol (fermentation) to
"recharge" the co-enzymes needed to keep metabolism going. It is
through this process of fermentation that ethanol is released by the yeast
cells as a waste product. Eventually, if the yeast cells are healthy and
fermentation is allowed to run to the completion, all fermentable sugars will
be used up by the yeast with only the unfermentable pentose leaving behind a
negligible amount of residual sugar.
The most common yeast associated with
winemaking is Saccharomyces cerevisiae which has been favored due to its
predictable and vigorous fermentation capabilities, tolerance of relatively
high levels of alcohol and sulfur dioxide as well as its ability to thrive in
normal wine pH between 2.8 and 4. Despite its widespread use which often
includes deliberate inoculation from cultured stock, S.cerevisiae is rarely the
only yeast species involved in a fermentation. Grapes brought in from harvest
are usually teeming with a variety of "wild yeast" from the Kloeckera
and Candida genera. These yeasts often begin the fermentation process almost as
soon as the grapes are picked when the weight of the clusters in the harvest
bins begin to crush the grapes, releasing the sugar-rich must. While additions
of sulfur dioxide (often added at the crusher) may limit some of the wild yeast
activities, these yeasts will usually die out once the alcohol level reaches
about 5% due to the toxicity of alcohol on the yeast cells physiology while the
more alcohol tolerant Saccharomyces species take over. In addition to S.
cerevisiae, Saccharomyces bayanus is a species of yeast that can tolerate
alcohol levels of 17–20% and is often used in fortified wine production such as
ports and varieties such as Zinfandel and Syrah harvested at high Brix sugar
levels. Another common yeast involved in wine production is Brettanomyces whose
presence in a wine may be viewed by different winemakers as either a wine fault
or in limited quantities as an added note of complexity.
Sulfur dioxide
Sulfur dioxide has two primary actions,
firstly it is an anti microbial agent and secondly an anti oxidant. In the
making of white wine it can be added prior to fermentation and immediately
after alcoholic fermentation is complete. If added after alcoholic ferment it
will have the effect of preventing or stopping malolactic fermentation,
bacterial spoilage and help protect against the damaging effects of oxygen.
Additions of up to 100 mg per liter (of sulfur dioxide) can be added, but the
available or free sulfur dioxide should be measured by the aspiration method
and adjusted to 30 mg per liter. Available sulfur dioxide should be maintained
at this level until bottling. For rose wines smaller additions should be made
and the available level should be no more than 30 mg per liter.
In the making of red wine, sulfur
dioxide may be used at high levels (100 mg per liter) prior to ferment to
assist in color stabilization. Otherwise, it is used at the end of malolactic
ferment and performs the same functions as in white wine. However, small
additions (say 20 mg per liter) should be used to avoid bleaching red pigments
and the maintenance level should be about 20 mg per liter. Furthermore, small
additions (say 20 mg per liter) may be made to red wine after alcoholic ferment
and before malolactic ferment to overcome minor oxidation and prevent the
growth of acetic acid bacteria.
Without the use of sulfur dioxide, wines
can readily suffer bacterial spoilage no matter how hygienic the winemaking
practice.
Potassium sorbate
Potassium sorbate is effective for the
control of fungal growth, including yeast, especially for sweet wines in
bottle. However, one potential hazard is the metabolism of sorbate to geraniol
which is a potent and unpleasant by-product. The production of geraniol occurs
only if sorbic acid is present during malo-lactic fermentation. To avoid this,
either the wine must be sterile bottled or contain enough sulfur dioxide to
inhibit the growth of bacteria. Sterile bottling includes the use of
filtration.
Some winemakers practice natural wine
making where no preservative is added. Once the wine is bottled and corked, the
bottles are put into refrigeration with temperatures near 5°C.
MALOLACTIC FERMENTATION
Malolactic fermentation is sometimes
known as the secondary fermentation.
Occurs when lactic acid bacteria
metabolize malic acid and produce lactic acid and carbon dioxide. This is
carried out either as an intentional procedure in which specially cultivated
strains of such bacteria are introduced into the maturing wine, or it can
happen by chance if uncultivated lactic acid bacteria are present.
Malolactic fermentation can improve the
taste of wine that has high levels of malic acid, because malic acid, in higher
concentration, generally causes an unpleasant harsh and bitter taste sensation,
whereas lactic acid is more gentle and less sour. Lactic acid is an acid found
in dairy products. Malolactic fermentation usually results in an increase on
the pH of the wine. This should be monitored and not allowed to rise above a pH
of 3.55 for whites or a pH of 3.80 for reds. pH can be reduced roughly at a
rate of 0.1 units per 1 gram/litre of tartaric acid addition.
The use of lactic acid bacteria is the
reason why some chardonnays can taste "buttery" due to the production
of diacetyl by the bacteria. All red wines go through complete malolactic
fermentation, both to lessen the acid of the wine and to remove the possibility
that malolactic fermentation will occur in the bottle. White wines vary in the
use of malolactic fermentation during their making. Lighter aromatic wines such
as Riesling, generally do not go through malolactic fermentation. The fuller
white wines such as barrel fermented chardonnay, are more commonly put through
malolactic fermentation. Sometimes a partial fermentation, for example,
somewhere less than 50% might be employed.
POST-FERMENTATION PROCEDURES
Racking
Racking, often referred to as Soutirage
or Soutirage traditionnel (in French), also filtering or fining, is a method in
wine production of moving wine from one barrel to another using gravity rather
than a pump, which can be disruptive to a wine. The process is also known as
Abstich in German and travaso in Italian Draining the clear wine off its lees,
or sediment, into another vat or cask is known as “racking” because of the
different levels, or racks, on which the wine is run from one container into
another. In modern vinification, this operation is usually conducted several times
during vat or cask maturation. The wine gradually throws off less and less of a
deposit. Some wines, such as Muscadet sur lie, are never racked.
Fining
In winemaking, fining is the process
where a substance (fining agent) is added to the wine to create an adsorbent,
enzymatic or ionic bond with the suspended particles, producing larger
molecules and larger particles that will precipitate out of the wine more
readily and rapidly. Unlike filtration, which can only remove particulates
(such as dead yeast cells and grape fragments), fining can remove soluble
substances such as polymerized tannins, coloring phenols and proteins; some of
these proteins can cause haziness in wines exposed to high temperatures after
bottling. The reduction of tannin can reduce astringency in red wines intended
for early drinking. Many substances have historically been used as fining
agents, including dried blood powder, but today there are two general types of
fining agents — organic compounds and solid/mineral materials.
Organic compounds used as fining agents
are generally animal based, a possible cause of concern to vegans. The most
common organic compounds used include egg whites, casein derived from milk,
gelatin and isinglass obtained from the bladders of fish. Pulverized minerals
and solid materials can also be used, with bentonite clay being one of the most
common, thanks to its effectiveness in absorbing proteins and some bacteria.
Activated carbon from charcoal is used to remove some phenols that contribute
to browning as well as some particles that produce "off-odors" in the
wine. In a process known as blue fining, potassium ferrocyanide is sometimes
used to remove any copper and iron particles that have entered the wine from
bentonite, metal winery and vineyard equipment, or vineyard sprays such as
Bordeaux mixture. Because potassium ferrocyanide may form hydrogen cyanide its
use is highly regulated and, in many wine producing countries, illegal. Silica
and kaolin are also sometimes used.
Some countries, such as Australia and
New Zealand, have wine labeling laws that require the use of fining agents that
may be an allergenic substance to appear on the wine label.
There is the risk of valuable aromatic
molecules being precipitated out along with the less desirable matter. Some
producers of premium wine avoid fining, or delay it in order to leach more
flavor and aroma from the phenols before they are removed.
Cold stabilization
When wines are subjected to low
temperatures, a crystalline deposit of tartrates can form a deposit in the
bottle. Should the wine be dropped to a very low temperature for a few days
before bottling, this process can be precipitated, rendering the wine safe from
the threat of a tartrate deposit in the bottle. For the past 20 years, cold
stabilization has been almost obligatory for cheap commercial wines, and it is
now increasingly used for those of better quality as well. This recent trend is
a pity because the crystals are, in fact, entirely harmless and their presence
is a completely welcome indication of a considerably more natural,
rather than heavily processed, wine.
Filtration
While fining clarifies wine by binding
to suspended particles and precipitating out as larger particles, filtration
works by passing the wine through a filter medium that captures particles
larger than the medium's holes. Complete filtration may require a series of
filtering through progressively finer filters. Many white wines require the
removal of all potentially active yeast and/or lactic acid bacteria if they are
to remain reliably stable in bottle, and this is usually now achieved by fine
filtration.
Most filtration in a winery can be
classified as either the coarser depth filtration or the finer surface
filtration. In depth filtration, often done after fermentation, the wine is
pushed through a thick layer of pads made from cellulose fibers, diatomaceous
earth or perlite. In surface filtration the wine passes through a thin
membrane. Running the wine parallel to the filter surface, known as cross-flow
filtration, will minimize the filter clogging. The finest surface filtration,
microfiltration, can sterilize the wine by trapping all yeast and, optionally,
bacteria, and so is often done immediately prior to bottling. An absolute rated
filter of 0.45 µm is generally considered to result in a microbially stable
wine and is accomplished by the use of membrane cartridges, most commonly
polyvinylidene fluoride (PVDF). Certain red wines may be filtered to 0.65 µm,
to remove yeast, or to 1.0 µm to remove viable brettanomyces only.
Bottling
A final dose of sulfite is added to help
preserve the wine and prevent unwanted fermentation in the bottle. The wine
bottles then are traditionally sealed with a cork, although alternative wine
closures such as synthetic corks and screwcaps, which are less subject to cork
taint, are becoming increasingly popular. The final step is adding a capsule to
the top of the bottle which is then heated for a tight seal.
RED WINES
Fermentation
After the grapes are destemmed and
lightly crushed, they are pumped into a vat where fermentation may begin as
early as 12 hours or as late as several days later. Even wines that will be
caskfermented must start off in vats, whether they are old-fashioned oak
foudres or modern stainless-steel tanks. This is because they must be fermented
along with a manta, or cap, of grapeskins. To encourage fermentation, the juice
may be heated and selected yeast cultures or partially fermented wine from another
vat added. During fermentation, the juice is often pumped from the bottom of the
vat to the top and sprayed over the manta to keep the juice in contact with the
grapeskins. This ensures that the maximum color is extracted. Other methods
involve the manta being pushed under the fermenting juice with poles. Some vats
are equipped with crude but effective grids that prevent the manta from rising,
others rely on the carbonic gas given off during fermentation to build up
pressure, releasing periodically and pushing the manta under the surface;
another system keeps the manta submerged in a “vinimatic,” a sealed, rotating
stainless-steel tank, based on the cement-mixer principle. The higher the
temperature during fermentation, the more color and tannin will be extracted;
the lower the temperature, the better the bouquet, freshness, and fruit will
be. The optimum temperature for the fermentation of red wine is 29.4°C. If it
is too hot, the yeasts produce certain substances (decanoic acid, octanoic acids,
and corresponding esters) that inhibit their own ability to feed on nutrients
and cause the yeasts to die. It is, however, far better to ferment hot fresh
juice than to wait two weeks (which is normal in many cases) to ferment cooler
but stale juice. The fuller, darker, more tannic and potentially longer-lived
winesremain in contact with the skins for anything between 10 and 30days.
Lighter wines, on the other hand, are separated from the skins after only a few
days.
Vin de goutte and Vin de presse
The moment the skins are separated from
the juice, every wine is divided into two—free-run wine, or vin de goutte, and
press wine, or vin de presse.
For as long as presses have been used,
winemakers have been aware of the different color, body and aroma
characteristics of wine made from the "free-run" juice compared to
pressed juice. Free-run is the juice that has been extracted through the
process of crushing, the natural break down of the grape cell walls during
maceration and fermentation and by the own weight of the grape berries as they
are loaded on top of each other in a press. Even among press juice there are
compositional difference between the various "factions" of juice
produced from initial pressing through subsequent (and usually harsher)
pressing. Often winemakers will keep free-run and pressed juice separated for
most of the winemaking process including malolactic fermentation and barrel
aging with the options to later blend between them to make the most complete,
balanced wine, bottle separately under different labels and price tiers or to
discard/sell off the pressed fractions to another producer.
The main difference between free-run and
pressed juice is that pressed juice often has lower acidity levels, higher
potassium and pH level, more phenolic compounds such as tannins and more
suspended solids such as natural gum and proteins. Some of these attributes can
be positive influences on the wine with the increased phenolics offering more
body, aroma characteristics (such as the varietal aromas from terpenes) and
aging potential. Other attributes may have more negative influence such as
increased astringency and bitterness, precursor for browning pigments in white
wine, mouthfeel and balance issues (as well as potential microbial instability)
from the increased pH and the enhance need for fining agents to assist in the
clarification and stabilization of the wine with the increase in suspended solids.
The extent of these differences will be
magnified or minimized based on the initial condition of the fruit after
harvest (with moldy, damaged, sun-burnt or botryized grapes producing stark
differences between free-run and pressed juice), the type of press used, the
amount of pressure involve and the over amount of movement that the grapes are
subject to that could impact how much the skins and seeds are scoured and torn.
Carbonic maceration
Carbonic maceration is a winemaking
technique, often associated with the French wine region of Beaujolais, in which
whole grapes are fermented in a carbon dioxide rich environment prior to
crushing. Conventional alcoholic fermentation involves crushing the grapes to
free the juice and pulp from the skin with yeast serving to convert sugar into
ethanol. Carbonic maceration ferments most of the juice while it is still
inside the grape, although grapes at the bottom of the vessel are crushed by
gravity and undergo conventional fermentation. The resulting wine is fruity
with very low tannins. It is ready to drink quickly but lacks the structure for
long-term aging. In the most extreme case, such as with Beaujolais nouveau, the
period between picking and bottling can be less than six weeks.During carbonic
maceration, an anaerobic environment is created by pumping carbon dioxide into
a sealed container filled with whole grape clusters. The carbon dioxide gas
permeates through the grape skins and begins to stimulate fermentation at an
intracellular level. The entire process takes place inside each single, intact
berry. Ethanol is produced as a by-product of this process but studies have
shown that other unique chemical reactions take place that have a distinctive
effect on the wine.
The process of carbonic maceration
occurs naturally in a partial state without deliberate intervention and has
occurred in some form throughout history. If grapes are stored in a closed
container, the force of gravity will crush the grapes on the bottom, releasing
grape juice. Ambient yeasts present on the grape skins will interact with the
sugars in the grape juice to start conventional ethanol fermentation. Carbon
dioxide is released as a by product and, being denser than oxygen, will push
out the oxygen through any permeable surface (such as slight gaps between wood
planks) creating a mostly anaerobic environment for the uncrushed grape
clusters to go through carbonic maceration. Some of the earliest documented
studies on the process were conducted by the French scientist Louis Pasteur who
noted in 1872 that grapes contained in an oxygen rich environment prior to
crushing and fermentation produced wines of different flavors than grapes
produced in a carbon dioxide rich environment. This was because the
fermentation process had already started within the individual grape clusters
prior to the introduction of yeasts during conventional fermentation.
WHITE WINES
Two initial operations distinguished the white-winemaking process from the
red one: first, an immediate pressing to extract the juice and separate the skins,
and, second, the purging, or cleansing, of this juice. But for white wines of
expressive varietal character the grapes are now
often crushed and then macerated in a
vinimatic for 12 to 48 hours to extract the aromatics that are stored in the
skins. The juice that is run out of the vinimatic, and the juice that is
pressed out of the macerated pulp left inside it, then undergoes cleansing and
fermentation like any other white wine. With the exception of wines macerated
in a vinimatic, the grapes are either pressed immediately on arrival at the
winery or lightly crushed and then pressed. The juice from the last pressing is
murky, bitter, and low in acidity and sugar, so only the first pressing, which
is roughly equivalent to the free-run juice in red wine, together with the
richest elements of the second pressing, should be used for white-wine
production. Once pressed, the juice is pumped into a vat where it is purged, or
cleansed, which in its simplest form means simply leaving the juice to settle
so that particles of grapeskin and any other impurities fall to the bottom.
This purging may be helped by chilling,
adding sulfur dioxide and, possibly, a fining agent. Light filtration and
centrifugation may also be applied during this process.
After cleansing, the juice is pumped
into the fermenting vat or directly into barrels if the wine is to be
cask-fermented. The addition of selected yeast cultures occurs more often in
the production of white wine because of the wine’s limited contact with the
yeast-bearing skins and the additional cleansing that reduces the potential amount
of wine yeasts available. The optimum temperature for fermenting white wine is
18°C, although many winemakers opt for between 10ºC and 17°C, and it is actually
possible to ferment wine at temperatures as low as 4°C. At the lower
temperatures, more esters and other aromatics are created, less volatile
acidity is produced, and a lower dose of sulfur dioxide is required; on the
other hand, the resulting wines are lighter in body and contain less glycerol. With
acidity an essential factor in the balance of fruit and, where appropriate, sweetness
in white wines, many products are not permitted to undergo malolactic
conversion and are not bottled until some 12 months after the harvest.
Oak-matured wines which, incidentally, always undergo malolactic conversion, may
be bottled between 9 and 18 months, but wines that are made especially for
early drinking are nearly always racked, fined, filtered, and bottled as
quickly as the process will allow in order to retain as much freshness and
fruitiness as possible.
ROSÉ WINES
A rosé (from French: rosé also known as
rosado in Portugal and Spanish-speaking countries or rosato in Italy) is a type
of wine that incorporates some of the color from the grape skins, but not
enough to qualify it as a red wine. It may be the oldest known type of wine, as
it is the most straightforward to make with the skin contact method. The pink
color can range from a pale "onion"-skin orange to a vivid
near-purple, depending on the grape varieties used and winemaking techniques.
There are three major ways to produce rosé wine: skin contact, saignée and
blending. Rosé wines can be made still, semi-sparkling or sparkling and with a
wide range of sweetness levels from bone-dry Provençal rosé to sweet White
Zinfandels and blushes. Rosé are made from a wide variety of grapes and can be
found all across the globe.
When rosé wine is the primary product,
it is produced with the skin contact method. Black-skinned grapes are crushed
and the skins are allowed to remain in contact with the juice for a short
period, typically one to three days. The must is then pressed, and the skins
are discarded rather than left in contact throughout fermentation (as with red
wine making). The longer that the skins are left in contact with the juice, the
more intense the color of the final wine.
When a winemaker desires to impart more
tannin and color to a red wine, some of the pink juice from the must can be
removed at an early stage in what is known as the Saignée (from French
bleeding) method. The red wine remaining in the vats is intensified as a result
of the bleeding, because the volume of juice in the must is reduced, and the
must involved in the maceration becomes more concentrated. The pink juice that
is removed can be fermented separately to produce rosé.
In other parts of the world, blending,
the simple mixing of red wine to a white to impart color, is uncommon. This
method is discouraged in most wine growing regions, especially in France, where
it is forbidden by law, except for Champagne. Even in Champagne, several high-end
producers do not use this method but rather the saignée method.
SPARKLING WINES
Sparkling wine is a wine with
significant levels of carbon dioxide in it making it fizzy. The carbon dioxide
may result from natural fermentation, either in a bottle, as with the méthode
champenoise, in a large tank designed to withstand the pressures involved (as
in the Charmat process), or as a result of carbon dioxide injection.
Sparkling wine is usually white or rosé
but there are many examples of red sparkling wines such as Italian Brachetto
and Australian sparkling Shiraz. The sweetness of sparkling wine can range from
very dry "brut" styles to sweeter "doux" varieties.
The classic example of a sparkling wine
is Champagne, but this wine is exclusively produced in the Champagne region of
France and many sparkling wines are produced in other countries and regions,
such as Espumante in Portugal, Cava in Spain, Franciacorta, Trento DOC, Oltrepò
Pavese Metodo Classico and Asti in Italy (the generic Italian term for sparkling
wine being spumante) and Cap Classique in South Africa. Most countries reserve
the word Champagne for a specific type from the Champagne region of France. The
French terms "Mousseux" or "Crémant" are used to refer to
sparkling wine not made in the Champagne region. German and Austrian sparkling
wines are called Sekt. The United States is a significant producer of sparkling
wine with producers in numerous states. Recently the United Kingdom, which
produced some of the earliest examples of sparkling wine, has started producing
sparkling wines again.
MÉTHODE CHAMPENOISE
The traditional method is the process
used in the Champagne region of France to produce the sparkling wine known as
Champagne. It is also the method used in Spain to produce Cava. It used to be
known as the méthode champenoise, but the Champagne producers have successfully
lobbied the European Union to restrict that term to wines from their region.
Thus, wines from elsewhere may not use méthode champenoise when sold in the EU,
and instead traditional method, méthode traditionnelle or the local language
equivalent can be seen; for instance, in Germany the term used is
"klassische flaschengärung". Consumers outside the EU may still see
méthode champenoise on labels, but it is becoming less common.
After primary fermentation, blending
(assemblage in Champagne) and bottling, a second alcoholic fermentation occurs
in the bottle.
Second fermentation
The blended wine is put in bottles along
with yeast and a small amount of sugar, called the liqueur de tirage, stopped with a crown cap or another temporary
plug, and stored in a wine cellar horizontally for a second fermentation. Under
the Appellation d'origine contrôlée, NV (non-vintage) Champagne is required to
age for 3 years to develop completely. In years where the harvest is
exceptional, a vintage (millesime) is declared and the wine must mature for at
least five years.
During the secondary fermentation, the
carbon dioxide is trapped in the wine in solution. The amount of added sugar
determines the pressure of the bottle. To reach the standard value of 6 bars
(600 kPa) inside the bottle, it is necessary to have 18 grams of sugar; the
amount of yeast (Saccharomyces cerevisiae) is regulated by the European
Commission (Regulation 1622/2000, 24 July 2000) to be 0.3 gram per bottle. The
liqueur de tirage is then a mixture of sugar, yeast and still Champagne wine.
Aging on lees
Non-vintage wine from Champagne cannot
legally be sold until it has aged on the lees in the bottle for at least 15
months. Champagne's AOC regulations further require that vintage Champagnes be
aged in cellars for five years or more before disgorgement, but most top
producers exceed the requirement, holding bottles on the lees for 6 to 8 years.
Riddling
After aging, the lees must be
consolidated for removal. The bottles undergo a process
known as riddling (remuage in French). In this stage, the
bottles are placed on special racks called pupitres that hold them at a 45°
angle, with the crown cap pointed down. Once a day (every two days for
Champagne), the bottles are given a slight shake and turn, alternatively on
right then left, and dropped back into the pupitres, with the angle gradually
increased. The drop back into the rack causes a slight tap, pushing sediments
toward the neck of the bottle. In 10 to 14 days (8 to 10 weeks for Champagne),
the position of the bottle is straight down, with the lees settled in the neck.
(This time can be shortened by moving the bottle more than once a day, and/or
by using modern, less sticky strains of yeast.) Manual riddling is still done
for Prestige Cuvées in Champagne, but has otherwise been largely abandoned
because of the high labour costs. Mechanised riddling equipment (a gyropalette) is used instead.
Many stores now sell riddling racks for
decorative storage of finished wine.
Disgorging
The lees removal process is called
disgorging (dégorgement in French), traditionally a skilled manual process
where the crown cap and lees are removed without losing much of the liquid, and
a varying amount of sugar added. Before the invention of this process by Madame
Clicquot in 1816, Champagne was cloudy; this style is seen occasionally today,
under the label méthode ancestrale. Modern automated disgorgement is done by
freezing a small amount of the liquid in the neck and removing this plug of ice
containing the lees.
Dosage
Immediately after disgorging but before
final corking, the liquid level is topped up with liqueur d'expédition,
commonly a little sugar, a practice known as dosage. The liqueur d'expédition
is a mixture of the base wine and sucrose, plus 0.02 to 0.03 grams of sulfur
dioxide as a preservative. Some maisons de Champagne (Champagne brands) claim
to have secret recipes for this, adding ingredients such as old Champagne wine
and candi sugar. In the Traité théorique et pratique du travail des vins
(1873), Maumené lists the additional ingredients "usually present in the
liqueur d'expédition": port wine, cognac, elderberry wine, kirsch,
framboise wine, alum solutions, tartaric acid, and tannins.
The amount of sugar in the liqueur
d'expédition determines the sweetness of the Champagne, the sugar previously in
the wine having been consumed in the second fermentation. Generally, sugar is
added to balance the high acidity of the Champagne, rather than to produce a
sweet taste. Brut Champagne will only have a little sugar added, and Champagne
called nature or zéro dosage will have no sugar added at all. A cork is then
inserted, with a capsule and wire cage securing it in place.
Champagne's sugar content varies. The
sweetest level is 'doux' (meaning sweet) and then, in increasing dryness,
'demi-sec' (half-dry), 'sec' (dry), 'extra sec' (extra dry), 'brut' (very
dry-dry), 'extra brut' (very dry), 'brut nature/brut zero/ultra brut' (no
additional sugar, bone dry).
BOTTLE-FERMENTED
This refers to a wine produced through a
second fermentation in a bottle, but (and this is the catch) not necessarily in
the bottle in which it is sold. It may have been fermented in one bottle, transferred
to a vat and, under pressure at 3°C, filtered into another bottle. This is also
known as the “transfer method.”
MÉTHODE RURALE
This refers to the precursor of méthode
champenoise, which is still used today, albeit only for a few obscure wines. It
involves no second fermentation, the wine being bottled before the first alcoholic
fermentation is finished.
CUVE CLOSE, CHARMAT, OR TANK METHOD
This is used for the bulk production of
inexpensive sparkling wines that have undergone a second fermentation in large
tanks before being filtered and bottled under pressure at -3°C. Contrary to
popular belief, there is no evidence to suggest that this is an intrinsically
inferior method of making sparkling wine. It is only because it is a bulk
production method that it tends to attract mediocre base wines and encourage a
quick throughput. I genuinely suspect that a cuve close produced from the
finest base wines of Champagne and given the autolytic benefit of at least
three years on its lees before bottling might well be
indistinguishable from the “real thing.”
CARBONATION
This is the cheapest method of putting
bubbles into wine and simply involves injecting it with carbon dioxide. Because
this is the method used to make lemonade, it is incorrectly assumed that the
bubbles achieved through carbonation are large and short-lived. They can be, and
fully sparkling wines made by this method will indeed be cheapskates, but
modern carbonation plants have the ability to induce the tiniest of bubbles,
even to the point of imitating the “prickle” of wine bottled sur lie.
FORTIFIED WINES
Any wine, dry or sweet, red or white, to
which alcohol has been added is classified as a fortified wine, whatever the
inherent differences of vinification may be. Still wines usually have astrength
of 8.5 to 15 percent alcohol; fortified wines a strength of 17 to 24 percent.
The spirit added is usually, but not always, brandy made from local wines. It is
totally neutral, with no hint of a brandy flavor. The amount of alcohol added,
and exactly when and how it is added, is as critical to the particular
character of a fortified wine as is its grape variety or area of production. Mutage,
early fortification, and late fortification are all methods
that may be used to fortify wines.
MUTAGE
This is the addition of alcohol to fresh
grape juice. This prevents fermentation and produces fortified wines, known as
vins de liqueurs in France, such as Pineau des Charentes in the Cognac region,
Floc de Gascogne in Armagnac, and Ratafia in Champagne.
EARLY FORTIFICATION
This is the addition of alcohol after
fermentation has begun. This is often done in several small, carefully
measured, timed doses spread over several hours or even days. The style of
fortified wine being made will dictate exactly when the alcohol is added, and the
style itself will be affected by the variable strength of the grapes from year
to year. On average, however, alcohol is added to port after the alcohol level has
reached 6 to 8 percent, and added to the vins doux naturels of France, such as
Muscat de Beaumes de Venise, at any stage between 5 and 10 percent.
LATE FORTIFICATION
This is the addition of alcohol after
fermentation has ceased. The classic drink produced by this method is sherry,
which is always vinified dry, with any sweetness added afterward.
AROMATIZED WINES
With the exception of Retsina, the resinated
Greek wine, aromatized wines are all fortified. They also all have aromatic
ingredients added to them. The most important aromatized wine is vermouth, which
is made from neutral white wines of 2 to 3 years of age, blended with an
extract of wormwood (vermouth is a corruption of the German wermut meaning
“wormwood”), vanilla, and various
other herbs and spices. Italian vermouths
are produced in Apulia and Sicily, and French vermouths in Languedoc and
Roussillon. Chambéry is a delicate generic vermouth from the Savoie and Chambéryzette
is a red-pink version flavored with alpine strawberries, but such precise
geographical aromatized wines are rare. Most, in fact, are made and sold under
internationally recognized brands such as Cinzano and Martini. Other wellknown aromatized
wines include Amer Picon, Byrrh, Dubonnet (both red and white), Punt e Mes,
St.-Raphael, and Suze.
ICE WINE
Ice wine (or icewine; German Eiswein) is
a type of dessert wine produced from grapes that have been frozen while still
on the vine. The sugars and other dissolved solids do not freeze, but the water
does, allowing a more concentrated grape must to be pressed from the frozen
grapes, resulting in a smaller amount of more concentrated, very sweet wine.
With ice wines, the freezing happens before the fermentation, not afterwards.
Unlike the grapes from which other dessert wines are made, such as Sauternes,
Tokaji, or Trockenbeerenauslese, ice wine grapes should not be affected by
Botrytis cinerea or noble rot, at least not to any great degree. Only healthy
grapes keep in good shape until the opportunity arises for an ice wine harvest,
which in extreme cases can occur after the New Year, on a northern hemisphere
calendar. This gives ice wine its characteristic refreshing sweetness balanced
by high acidity. When the grapes are free of Botrytis, they are said to come in
"clean".
Ice wine production is risky (the frost
may not come at all before the grapes rot or are otherwise lost) and requires
the availability of a large enough labour force to pick the whole crop within a
few hours, on a moment's notice, on the first morning that is cold enough. This
results in relatively small amounts of ice wine being made world-wide, making
ice wines generally quite expensive.
Ice wine production is obviously limited
to that minority of the world's wine-growing regions where the necessary cold
temperatures can be expected to be reached with some regularity. Canada and
Germany are the world's largest producers of ice wines.
NOBLE ROT
Noble rot -French: pourriture noble; -German:
Edelfäule; -Italian: Muffa nobile is the benevolent form of a grey fungus,
Botrytis cinerea, affecting wine grapes. Infestation by Botrytis requires moist
conditions. If the weather stays wet, the malevolent form, "grey
rot," can destroy crops of grapes. Grapes typically become infected with
Botrytis when they are ripe. If they are then exposed to drier conditions and
become partially raisined this form of infection brought about by the partial
drying process is known as noble rot. Grapes when picked at a certain point
during infestation can produce particularly fine and concentrated sweet wine.
Some of the finest Botrytized wines are literally picked berry by berry in
successive tries - French for "selections".
Internationally renowned botrytised
wines include the aszú of Tokaj-Hegyalja in Hungary and Slovakia -commonly called
Tokaji, Tokajské or Tokay, Sauternes from France - where the process is known
as pourriture or pourriture noble, and Beerenauslese or Trockenbeerenauslese
wines from Germany and Austria. Other wines of this type include the Romanian
Grasă de Cotnari, French Coteaux du Layon, French Monbazillac, Austrian
Ausbruch and South African Noble Late Harvest (NLH). Depending on conditions
the grapes may be only minimally botrytized. Botrytis has also been imported
for use by winemakers in California and Australia. In some cases inoculation
occurs when spores are sprayed over the grapes, while some vineyards depend on
natural inoculation from spores present in the environment.
Botrytis cinerea
Botrytis cinerea -"botrytis"
from Ancient Greek botrys (βότρυς) meaning "grapes" plus the Neolatin
suffix -itis for disease, is a necrotrophic fungus that affects many plant
species, although its most notable hosts may be wine grapes. In viticulture, it
is commonly known as botrytis bunch rot; in horticulture, it is usually called
grey mould or gray mold.
The fungus gives rise to two different kinds of
infections on grapes. The first, grey rot, is the result of consistently wet or
humid conditions, and typically results in the loss of the affected bunches.
The second, noble rot, occurs when drier conditions follow wetter, and can
result in distinctive sweet dessert wines, such as Sauternes or the Aszú of
Tokaji. The species name Botrytis cinerea is derived from the Latin for
"grapes like ashes"; although poetic, the "grapes" refers
to the bunching of the fungal spores on their conidiophores, and
"ashes" just refers to the greyish colour of the spores en masse. The
fungus is usually referred to by its anamorph (asexual form) name, because the
sexual phase is rarely observed. The teleomorph (sexual form) is an ascomycete,
Botryotinia fuckeliana, also known as Botryotinia cinerea.
