Producing good quality wine is a complex process, and it requires special crafts and techniques performed in the vineyard before the grape harvest. The type and style of the wine are determined by the vineyard manager who is in charge of all grape and wine operations. The key factor in producing a quality wine is to reach the necessary ripeness of the grapes, along with the desired yields.
Green pruning is a process performed during the winter months, after the previous vintage, and it is used to remove the extra vegetation for better sun exposure to the grapes. Early bud thinning allows maximum fruit size and quality in the following bloom season. In other words, these operations enhance the quality and ripening of the grapes, which further leads to a great vintage.
Green harvesting is another operation which determines the type and quality of the wine. Many vineyards in the Bordeaux region undergo green harvesting (removing unripe grape bunches) enabling the remaining grapes to enjoy more nutrients, which results in better concentration and flavours which are essential to producing great wine. Second green harvest can sometimes be applied to remove the bunches that lag behind the other berry fruits.
De-leafing is another process that can be performed in the vineyard and is directed by the winemaker. Leaf removal increases sun exposure while reducing the rotting potential at the same time. This method, however, depends on the vineyard, the growing season and the decisions of the wine producer.
GRAPE HARVEST
Different factors determine the harvest season, including the vintage, appellation or others, and it can start in the early to mid-September, or in October. The grape harvesting process is different in each estate, some prefer staying closer to nature and harvesting the grapes by hand, while others use special grape picking machines. Young vines are first harvested due to their faster maturation. Moreover, white wine grapes such as Sauvignon Blanc or Riesling are harvested prior to red wine grapes, while Merlot grapes are harvested before Cabernet Sauvignon and Cabernet Franc. Grape vinification is performed separately. For example, during the harvesting season, the largest Bordeaux wine houses hire more than 200 people to help with grape harvesting. The best fruits are selected at least twice in the vineyards, and later in the winery, a process typically made by hand.
Another important or maybe the most important part of the vineyard is the timing of the grape picking. This directly affects the final character and style of the product, along with the alcohol content, sugar and acidity.
Many winemakers begin the grape picking before the fruits are fully ripe. This results in lighter flavours, less alcohol, but more acidic notes.
Harvesting fully matured grapes can be very risky due to cold weather or rain conditions characteristic of the period. Fully ripe grapes have a sweeter taste, higher alcohol content and dark fruit flavours, with a velvety texture. Sometimes, winemakers wait too long to harvest the grapes, when they are over-matured, with higher sugar and alcohol content and give the taste of figs and raisins, which is not preferable.
One of the most prominent Bordeaux winemakers who owns a number of estates, including Chateau Pavie, helped in the development of an optical sorting machine to help speed up the harvesting process. This is an ideal solution for wine estates which tend to produce wine in higher volumes. The machine can remove unwanted foreign objects or residues, vegetation or unripe grapes. Although many growers oppose this mechanical method and follow the traditional manual harvesting, there are certain disadvantages of hand-picking apart from the time length, including the potential risk of rot in the vineyards while waiting for the full phenolic maturity of the grapes. Moreover, hand sorting and destemming could lead to side effects, including enzymes from to rot which could result in muddy fermentations and loss of colour. This problem has a mechanical solution which works in pair with optical sorters and it is known as the mechanical destemmer. This is a very beneficial innovation for wineries that produce both red and white wine.
DESTEMMING
However, the greatest Bordeaux estates tend to complete stem removal, which reduces the rustic and vegetal notes in the wine. Manual destemming is still widely preferred by growers and winemakers in the entire Bordeaux region. Some of the most experienced owners claim that manual destemming has many benefits, including reduced oxygenation, and keeping the freshness and the berries intact. The practice is also popular in Languedoc. Destemming is followed by fruit crushing which results in a juice-skin blend, known as must. The resulting product is further pumped or moved by natural gravity in wooden or stainless still tanks.
Moreover, there is a growing interest among Bordeaux vintners in whole-cluster fermentation. The amount of whole-cluster fermented fruits varies from 10% to 45%, and experienced winegrowers use it to lower the temperature fermentation process, which can result in reduced alcohol content. Moreover, stems are considered to add tannins and acidity, resulting in a fresh and lively character.
FERMENTATION
Fermentation depends on the vintner`s choice of firstly crushing the grapes, or with the skins slightly broken, or using whole grape fermentation. Nowadays, winemakers decide on whole grape fermentation to reduce the risk of oxidation. Many growers use cold soak or cold maceration of the grapes before fermentation. This process commonly occurs in stainless still tanks and vats, or wooden barrels. Open top fermentation is commonly used in Burgundy, and the process includes wild or cultivated yeasts which turn the sugar into alcohol. Some smaller estates use micro vinification which is a completely natural fermentation process, resulting in magnificent silky textures of the wine.
Fermentation is followed by maceration, a process in which the skins of grapes are left in contact with the juice for a certain time period. During maceration red wine gets its distinctive red colour because the raw grape juice has a greyish colour. The maceration process is generally avoided when producing white wine, or it is used in a short amount of skin-juice contact before the pressing.
SECOND FERMENTATION
The second fermentation, also known as Malolactic fermentation includes the conversion of tart malic acids into rich lactic acids, giving the wine a beautiful, creamy, and buttery tasting aroma like those in Chardonnay. It is commonly used in white wine production, but since it is labour-demanding, it is used only in smaller wineries.
BLENDING
Typically, the blending process occurs in January or February, after the fermentation is finished. However, it is a matter of the winemaker`s choice and tradition. Some prefer blending close before bottling, others decide to age the wine in barrels for several months before blending. This stage includes a selection of which grape varieties and percentages will be used, as well as which wine will be traded as Grand Vin, and which one will remain as a second wine.
CLEARING
One of the final processes prior bottling is clearing the wine since at this stage it is still cloudy. In this process, vintners use specific agents to dispose of the proteins contained in the wine which make them cloudy. Commonly used fining agents are egg whites or milk casein, gelatin,
and carbon.
Rarely, some wines are not being treated with fining agents, such as orange wines instead the winemakers wait for the wine to clear by itself.
BOTTLING AND LABELING
This is the final but very important step. During the bottling process, the wine should be exposed to oxygen as little as possible. Winemakers often add a small amount of sulfur dioxide to prevent oxidation and preserve the freshness of the wine. Typically, wines go into bottles two years after harvest. However, there are many wineries which age the wine in barrels for several years prior bottling. In this process, the bottles are filled and corked, but not labelled yet since the label content depends on different labelling practices in different countries.