Vinification Explained

Vinification Explained

The conversion of the juice of the grapes to wine through the process of fermentation.

This is the process that provides the majority of each wine’s uniqueness. Each vineyard cultivates their vines differently but the next step of vinification has even more elements that can be changed and altered to fit the wine profile the winemaker wishes to create.

There are up to 15 steps that winemakers go through to create the delicious ready to pour wines you indulge in. 

Destemming and Crushing 

The process of vinification begins here with the stems being removed from the grapes and then crushed to release the juices. This is not the same as pressing the grapes, as this is simply the process of breaking the skin to allow the free-run juice to release. Crushing grapes too hard could result in the seeds being broken, this can increase tannins and astringency in the final wine. Some winemakers opt to keep the stems in for the whole process yet the skin and seeds provide more than enough tannins for majority of palates.

Must Settling/Racking

As the initial juice is cloudy, it is rested for a time to allow the heaviest parts to settle to the bottom of the tank, this is the must deposit and is discarded before continuing. This process can be accelerated with cooling.

Maceration

For each wine the juice starts clear and requires contact with the skins and pips of the grapes to bring colour and tannins to the wine. This step also can cause the natural process of alcoholic fermentation to begin. Upon the point of removing the skins, seeds, and stems from the juice the maceration process ceases.

Extended Maceration - a choice to leave red wine in contact with the grape skins, stalks and seeds even after the Alcoholic fermentation has finished. This helps optimise the flavour, colour and tannin structure of the wine.

Carbonic Maceration -  a form of whole bunch fermentation, with the grapes uncrushed and still full, with or without stems. It is mostly common among Gamay and Beaujolais wines.

Alcoholic Fermentation

Yeast enzymes convert the natural grape sugars into alcohol. Completed when there is no more sugar to convert or the alcohol kills the enzymes. Some winemakers choose to perform cap punching/pigeage. In which the cap of skin and pips is broken up and pushed down into the juice, this is done to release the heat trapped by the layer of skin and stalks at the top of the fermentation container. If not done, the wine takes on more ‘cooked’ characteristics, so is the winemaker’s choice as to their goal flavour profile.

Further, it helps to develop the colour and tannins as it places the skins and stalks back in contact with the juice.

Alternatively the technique of ‘pumping over’ wine is used, where wine on the bottom of the tank is used to cool the cap and homogenise the temperature within the tank. This results in less extraction than punching down and can be the best option for the wines of a more delicate variety.

Types of containers:

  • Clay Amphorae
  • Wood
  • Eggs and Concrete Tanks
  • Stainless Steel Tanks

Bleeding the Vats - this process helps to increase the concentration of the remaining wine, and keep the removed wine lighter. It is the process of removing, “bleeding off” a portion of the wine not long after the grapes are crushed as minimal colour has leached into the wine. Used for Roses to give it the pink tinge. The remaining wine has a higher proportion of seeds and skin resulting in ultra-dark, and ultra-concentrated red wine.

Running off/Devatting

At the end of fermentation the free running juices are transferred to tanks or barrels by gravity. The solid remainder, Pomace, is collected for pressing.

Pressing

The Pomace is then pressed within an inflated bladder to encourage any remaining juices to be released. This is Pressed wine (as opposed to Free-run juice).

Blending/Must Settling

The collation of the Free-run juice and Press wine is done before maturing. then left to settle as the resultant wine is still cloudy. Once the heaviest particles drop to the bottom of the tank, the ‘clear’ wine is transferred to barrels and the must deposit is removed.

Malolactic Fermentation

Once in the barrels the biochemical process of malolactic fermentation takes place. In which the hard malic acid on ripe grapes is converted to lactic acid. The existing bacteria in the wine activates this process. To ensure the process is occurring you can listen for carbon dioxide bubbles being released within the vessel. The bubbling sound ensures the wine is alive and well. The process has finished once the bubbles have stopped and there is no remaining malic acid. This can be noticed also through the wine gaining a creamy, oily mid-palate texture.This step is primarily used for red wines to smooth out the natural acidity and stabilise it. White wines may only undergo a short malolactic fermentation to ensure it has texture and body without losing the beautiful aromas.

Malic acid - the tart acid in grapes also found in green apples

Lactic acid- the more creamy acid found in milk, cheese, and yogurt

Racking

This removes leftover sediment (lees) following the fermentation. By draining the wine into another container (vat, tank, barrel), each rack it passes through, more solids are removed. As the wine remains fragile at this point, winemakers can choose to add sulphur to protect it.

Maturing/Aging

For wine to develop its characteristics that were formed during the initial fermentation it is left in oak barrels or stainless steel tanks to be aged over a period of time. During this time, the wine stabilises its colour, develops to the full aromatic potential and blends into a harmonious and balanced wine. Aging is done in tanks for the wines that are to be drunk young, as it is less impacted by added flavours. Whereas oak barrels provide its own unique flavours to be added to already complex wines. Choices regarding percentages of new and old oak, and length of time are made by the makers. During the ageing process, the red wines also undergo a second malolactic fermentation, during which the remaining malic acid turns to lactic acid, making the wines even smoother.

Stirring the lees - mostly used on white Bordeauxs, it is the stirring of the wine to keep it in constant contact with the lees. This increases complexity and roundness to the overall wine while preserving aromas.

Racking/Blending

Can occur both before and after Fining, as the wine is once again transferred between containers. the sulphur levels are then adjusted if necessary. Wine produced from the same plot or several plots in the same appellation is blended.

Fining

Fining is the process of clarifying the wine, to make it less cloudy. Various fining agents (enzymes) are used to interact with the proteins that are unwanted in the wine and form sizable particles that sink to the bottom of the vats and are filtered out. Most natural winemakers are skipping this step to not deprive the natural flavour and texture of the wine.

 Fining Agents - egg whites, tannin, gelatin, bentonite, isinglass, casein. 

Cold stabilization

This removes any fine deposits in wine, tartrates. By exposing the wine to temperatures as low as 0C for a minimum of two weeks it ensures tartrates can’t be formed.. Many newer winemakers choose not to do this step.

Filtration

This is the final clarification step to remove large particles prior to bottling. It can be quite expensive and time consuming so many winemakers are now choosing to not filter. The sediment left behind also provides an increase in the complexity of the wines.

Bottling

Finally the bottling process occurs, placing the wine into the bottles and sealing them for sale. Most vineyards now have this process automated.

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Types of Fermentation Vessels

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