Despite all the intricacies surrounding the winemaking process, it is essentially just fermented grape juice. And the basic winemaking process is a pretty simple one.
First, the grapes are harvested from the vineyard. The time of harvest varies depending on the region, the varietal of grapes being grown, and the style of wine being produced. However, harvest usually occurs between August and October in the Northern Hemisphere and between February and April in the Southern hemisphere. Harvest season is often referred to as “the crush”.
The winemaker determines the optimal time to harvest the vineyard based on the ripeness of the grape, ensuring the desired levels of sugars, acids and tannin levels. Unseasonable weather can also impact the time of harvest. Threat such as excessive heat or frost may force a harvest earlier than would otherwise be desired, leaving the grapes less time to mature on the vine. Learn more about grapes and their role in the characteristics of a wine.
Traditionally, grapes were harvested by hand and some wineries continue to observe this practice today. The main advantage to hand picking is that it allows for selection of only the best grapes. Grapes that are unhealthy can be discarded and grapes that are not yet ripe can be left on the vine to mature longer.
However, mechanical harvesters were introduced in the 1960s and are utilized by most modern vineyards. These machines are considerably more efficient, harvesting up to 200 tons of grapes per day versus the one ton that a human picker could harvest.
After the grapes are harvested from the vineyard, the first step is crushing them. The grapes are put into a mechanical crusher, which gently squeezes the grapes to break the skins and release the juice. The resulting mixture is called the must. Some very small wineries may still crush grapes by trampling them barefoot or using a small hand wielded crusher. But nearly all large scale wineries have moved to mechanical methods, and the old fashioned “grape stomp” is now mostly reserved for entertainment value at wine festivals.
Next comes the fermentation. Fermentation occurs when yeasts come into contact with the grape juices, and slowly convert the grape’s sugar into alcohol. Yeast exists naturally on the grapes, so simply leaving the must to sit undisturbed would likely result in some degree of natural fermentation. However, most modern winemakers utilize cultured yeasts as well in order to give them more direct control over the fermentation process.
This process can take anywhere from a few days to a few months. When this fermentation process is complete, you have wine! The wines are typically allowed to rest for a time period before drinking – which is known as maturing or finishing the wines.
Of course, this is an extremely simplified explanation of the process and winemakers employ many different techniques to achieve the wine they desire.
For example, some wines are ‘barrel-fermented’, which simply means they are allowed to ferment inside oak barrels, while others are fermented in stainless steel tanks. Oak barrels will add an oaky flavor to the wine, as well as impact the texture and color. Stainless steel on the other hand, is considered ‘neutral’, and will not add anything beyond what the grapes already bring to the table.
You may also hear of wines that are ‘barrel-aged”. These wines are typically fermented in stainless steel tanks and then allowed to mature in oak barrels.
The flavor and character of the final wine can be influenced by so many things – including the specific type and age of the oak barrels used, the temperature of the wine during fermentation, and how long the wine is allowed to mature.
Depending on the winemaker’s preference, the total winemaking process can take anywhere from a few months to a few years.