Winemaking is one of the oldest and most traditional human
activity. Over thousand of years, winemakers have kept the same techniques and traditions. However, in the past 50 years,
oenology has progressed tremendously improving the understanding of the different processes involved in winemaking.
The transformation of sweet grape juice in an alcoholic beverage forms the basic process involved in
winemaking. The medium active in this transformation is the wine yeast called saccharomyce cerevisiae.
Numerous yeasts colonies can be found in the vineyard or the winery, but the cerevisae genus are the best to
to ferment the sugar into alcohol, gaz, and heat until dryness. This is why numerous winemakers (notably in the new world),
prefer to inoculate with commercial yeasts to avoid any stuck fermentation or off-flavors.
The timing of harvest depends
on different factors such as the berry's sugar content, its acidity, and its flavors. In addition, some varieties are early maturing
(such as Pinot noir, Chardonnay or Riesling) and other late ripening (Cabernet Sauvignon, Syrah, or Mourvedre), giving a predetermined timetable for the
harvest dates. Thewinemaking process is different depending on the color of the skins.
· White winemaking: The grapes are brought to the crushing pad where they will be either destemmed and crushed
or pressed as whole bunches. The juice coming from the draining and first pressed is called free run juice, and
constitutes the best quality juice. The pressed juice coming from the successive pressings (which have more undesirable elements
coming from the skins) is kept separately or blended with the free run juice. The bigger sediments can be eliminated
by gravitation with a short settling (24 hours) in a cool tanks, usually with the addition of sulfur dioxide to avoid any oxidation.
The tank's content is then racked to another one, where the fermentation can start.
White wine fermentation is a closely controlled phenomenon, particularly
temperature wise. The use of controlled temperature stainless steel tanks in most modern wineries of the world have had a profound impact on the white winemaking style.
The wine fermenting at lower temperature for a longer period will help with the accumulation of fruity aromas and the conservation of the
Once the fermentation is finished, the wine aging starts (in tanks or barrels). The use of new or newer small oak barrels will have an important effect
on the wine, importing oaky flavors and a slow oxydation to the wine and stabilizing its color. An important step in the making of the finished wine is the malolactic
fermentation, which mainly consists in the transformation of one type of strong acid (malic acids) into another weaker acid (lactic acid), and the addition of different flavors
to the wine's aromas (notably the famous buttery aroma present in numerous Californian chardonnay). The winemaker can decide to stop
the malolactic fermentation to keep the wine's acidity at a higher level.
Usually after a last filtering
(however, numerous high quality wines (white or reds) are bottled unfiltered), the wine is
bottled and stored in a cool place.
The grapes are processed at the crushing pad.
During the fermentation, the juice is pumped-over the skins to increase the extraction.
The barrel aging process is essential for high quality winemaking.
· Red winemaking: The red grapes are processed through the destemmer-crusher, the crushing is primordial
to liberate the juice and the maceration of the skins and the juice during fermentation. The winemaker can decide to cool the grape before the fermentation to stop any yeast activity
and soaked the must for few hours to few days to increase the extraction of color and flavors (It is called a cold soak).
The red wine fermetation
usually takes place at a higher temperature than white wine and is finished faster (from few days to a couple weeks). Once the fermentation is finished, the free run juice is
racked into another tank or barrel and the rest of the must is pressed to form the pressed juice. Both juice can be aged separately
or blended, depending on the style of wine the winemaker wants to produce (The pressed juice being more tannic and rustic than the free run juice).
Red wine aging can take place in tanks or barrels, the latter being favored for higher quality wine since it is transforming the wine's aromas and
mouthfeel, bringing more complexity to the finished wine. Red wines usually will go through the malolactic fermentation, reducing its acidity strength and making it more palatable.
The wine aging in barrel can lasts for years (up to three years in some case), and will help smooth the tannins and enrich the wine's flavors.
Once the wine is bottled, it can still be aged in bottles for few years before reaching the market.