A Quick Introduction to Winemaking
Making wine is a multi-step process which can span anywhere from 6 months to
several years. Although the process can vary greatly depending on the
variety of grape and the style of wine being produced, the major steps are
outlined below for making red wine.
- Harvest Beginning in September, the wine grapes are
harvested, usually by crews of people who begin work early in the morning in
order to harvest all of the grapes while the temperature is still
cool. The timing of the harvest is chosen by the grape grower, who
carefully monitors the sugar levels, also known as brix, of the
grapes. Once the brix reaches the optimum value, which can be
different for each variety of grapes, the grower determines that the grapes
should be picked, and harvest is scheduled as soon as possible. For
most varietals, this optimal level occurs just as the grapes begin to
shrivel. Sometimes, the grower will contract with the winemaker (when
they aren't the same individual!) to leave the grapes on the vine for an
extended period of time. The longer the grapes stay on the vine, the
higher the brix, and the higher the brix, the higher the alcohol levels in
the finished wine. This is why late harvest wines are high in alcohol,
and become after dinner wines or ports. However, as the brix rises,
the grapes shrivel, and decrease in weight and volume. Thus, it takes
more grapes to produce a late harvest wine, then a normal, dry wine.
- Crush As soon as picking as possible, the grapes should be
crushed. When most people think of crushing grapes, they imagine the
barefoot, stamping parties that are depicted in the movies. In
reality, a machine called a crusher-destemmer or destemmer-crusher (yes,
there is a difference, in both price and results) is used. The
crusher-destemmer will, as its name implies, crush the grapes and then
destem them, before depositing the resulting must, a mixture of grape skins
and juice, into a container below the machine. It is important to
remove the stems from must because they can introduce a tannic acid into the
wine which isn't typically desired. For "natural", non-sulfited
wines, it may be desired, but that is probably it's own topic...
- Fermentation The must is poured into a fermentation
container. The primary fermentation is the process of converting sugar to
alcohol. This conversion is achieved by adding a yeast to the must,
which essentially eats the sugar and produces alcohol as a by-product.
Before the yeast is added, however, the must is first cleansed by
adding a sulfur dioxide mixture, which kills any wild yeast that may have
been living on the grapes in the vineyard. Most wineries take this
step because they don't want the wild yeast to become active in the must and
begin producing alcohol, because it can also add flavor components which may
or may not be good; it is wild after all. In addition, most wineries like
to add their own commercial yeast, whose properties are know, and the wild
yeast can inhibit or interfere with the commercial yeast. Therefore,
it must go, and sulfur dioxide is the chemical used because it is natural,
and will dissipate over time. Usually a day or so after the sulfur
dioxide is added to the must, a yeast suitable to the grape variety is added
to the must in the fermentation container. At first, the activity is
limited; the must appears to be unaffected by the yeast. However,
within the next 24 to 36 hours, the yeast really gets to work. The must begins to boil
and bubble, and the temperature begins to rise. At the same time, the
brix begin to fall - which means the sugar is being converted to alcohol and
new wine is conceived! As the fermentation process continues, the
grapes skins are forced to the top of the fermentation container, which is
referred to as the cap, while the
actual wine sinks to the bottom. Because of this, the winemaker must
"punch down the cap" at least twice a day, which essentially means, mix
things up by pushing the skins to the bottom of the container, and allowing
the wine to come to the surface. This is necessary for two reasons: it
provides oxygen to the yeast, which may die otherwise, and it creates more
wine/skin contact, which will transfer more pigment and color to the
wine. A secondary fermentation, also known as malo-lactic
fermentation, may be started by the winemaker at this time. Malo-lactic
fermentation is the conversion of malic acid to lactic acid, and will change
the character of the wine from an acidic to more of a buttery texture.
Primary fermentation process can contain for anywhere from 5 days to
several weeks. At the end of fermentation, the brix will be zero (a
simple floating device, known as a hydrometer, is used to measure brix), meaning all of the sugar
has been consumed by the yeast, and the winemaker will know that they are
ready for the next step.
- Press At the end of the primary fermentation, the cap
will typically fall to the bottom of the fermentation tank. When this
happens, it is time to separate the new wine from the skin and seeds, also
called the lees. A device called a press is used to achieve this
separation. There are many different types of wine presses, but the
most common, and perhaps the oldest, is the basket press. A basket
press uses a large screw device to compress the skins inside a basket made
of wooden slats, and squeeze out the new wine from gaps between the
slats. The wine is collected in buckets and poured into a waiting
barrel.
- Aging and Racking There is a saying that new wine is alot
like a newborn baby: gaseous, messy and at times a bit stinky; but give it
some time, and it will mature into a wonderful adult. This saying is
very true (and the same analogy may apply to this website! :). New
wine must undergo a large number of chemical changes, which will happen over
the course of anywhere from 6 months to several years. In addition,
there are solids (bits of spent yeast, skins and so forth) suspended in the
wine which must be allowed to settle so that they can be removed.
These two steps are achieved in the barrel. Aging is the name given to
the process of maturing a wine through its complex chemical reactions.
Racking is the process of allowing the solids suspended in the wine to
settle to the bottom of the barrel over time, and then siphoning the clear
wine off of the solids into another barrel, after which the remaining solids
are rinsed from the barrel. Racking may happen many times while the
wine remains in the barrel.
- Bottling The final step in the process of making wine (not
counting the drinking!) involves removing the wine from the barrel, and
placing it in 750 ml bottles. Bottling wine can be achieved using
anything from a professional, high-tech bottling line all the way down to a
simple, suction powered valve which is connected to a tube inserted into the
barrel and placed in one bottle at a time.