Men have been producing wine for thousands of years. While drinking a bottle may not last very long, its elaboration process is complicated and needs time!

Wine production can generally be split in several steps:

Wine production process

Harvest

Everything starts with harvesting, taking place between August and October - for the Northern hemisphere. To make the decision of harvesting a specific parcel, winemakers taste the grapes to evaluate its balance (sugar vs acidity) and measure grapes’ pH. If harvested too early, grapes will not be mature enough and will not achieve their full aroma potential. On the contrary, a late harvest will create the risk of over maturity (rotten grapes). This step is extremely important and the winemaker’s experience makes everything.

This is however not enough - it is also key to take weather forecasts into account! A winemaker may need to adjust the harvest dates slightly if bad weather is expected. For example, he might want to rush things if there is a potential for strong rain or hail.

Once harvested, grapes are sorted to take out rotten or damaged bits - and only keep healthy ones that will become wine.

Wine Harvest

Pressing

Once grapes are sorted and destemmed, they are ready to be crushed and turned into juice. Long time ago, this was done by stomping on grapes! This old technique has (nearly) disappeared for health reasons. Specific machines now exist to reproduce this process, using inflatable balers to gently crush grapes to obtain grape must - a mixture of  juice, skin and pips. For white wines, skin and pips are separated from the juice to avoid colour and tannins.

Wine Pressing

Fermentation

The must is then put into large vats (stainless steel, concrete... etc) or wooden barrels to start the fermentation process. This is the transformation of sugar into alcohol, carried out by natural yeasts. For an enhanced control, winemakers often use cultured yeasts to help them better predict the process. - This step needs to be watched closely, as the liquid’s temperature may not go over 26°C - this explains why these vats or barrels are “thermoregulated”.

Upon this step, the liquid has no colour yet - don’t panic, it is coming! The colour of a wine is the consequence of skin and pips staying with the juice during “maceration”. This process is different for each type of wine -and it is simply skipped for a white. To make rosé, juice remains in contact with skin and pips for only a few hours (8 to 48). For reds, maceration is a key step and can last up to 3 weeks to achieve a nice colour and enough structure.

Wine Fermentation

Pump over / Punch down

During fermentation, the lighter solid bits go up up to the surface and make what is called a “marc”. In order to obtain a homogeneous and colourful juice, a winemaker needs to mix these bits back into the juice, using either or both following techniques: pumping over to transfer the juice continuously back above the marc, punching down to break and mix the marc back down into the juice.

Wine Pomp over

Wine Punch down

Clarification

Once wine has reached the desired alcohol level, colour and tannins - this is really the winemaker’s touch! - time has come to clarify it to remove all solid parts such as dead yeasts, proteins and tannins. This can be done with filtration (simply filter it to only keep the juice) or fining (adding substances such as clay to gather all remaining solids at the bottom of the barrel).

The juice obtained after clarification is called “young wine” and will be the base of the future wine. The remaining marc is pressed again to obtain the “vin de goutte” - a highly concentrated juice - which can be blended with the young wine or not. Again this is the winemaker’s decision that will impact how the wine will look and taste.

Wine Clarification

Blending

This is a really important step of the process. Juices from different grape varieties or different vine plots are usually fermented separately to respect their identity and characteristics. They are then tasted and blended by the winemaker and / or oenologist to create the final product. This is where winemaker’s talent has the greatest impact, as this defines what wine will be. For example in Bordeaux, the winemaker will decide at this step how much of Merlot, Cabernet Sauvignon or Petit Verdot he wants in his wine.

Ageing

This step is not carried out for all wines, but it develops aromas further. After fermentation or blending, wine can be put in wooden barrels for several months (usually 3 to 24). Generally made of French oak, this technique provides the wine with additional tannins and flavours to enhance taste, structure and aromas.

During this process, a small part of the wine evaporates, or is absorbed by the wood creating an additional space in the barrels. Winemaker has to refill the barrels several times to prevent wine from oxidising - which is the worst threat for a wine, as you can see from our previous article.

Barrel ageing

Bottling

Last step of the process - bottling. Winemaker can do it by himself or have it done by a service provider, which most estates chose to do given the high cost of bottling machines.

Wine Bottling

You now have a tremendous knowledge of the winemaking process! You’ll be able to impress friends during diner parties… don’t hesitate to let them know where this knowledge is coming from!

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