Making red wine is similar in process to producing white wine in that it involves transforming the must into alcohol.
One of the fundamental differences when making red wine is maceration.
This is the infusion stage where the colour, tannins, and aromatics of the grape skins and pulp are dissolved in the juice, which gives the wine its colour and character.
Maceration techniques will vary depending on the grape variety, local traditions, and climate.
Red grapes are gently crushed and then de-stemmed. The resulting must is transferred into temperature controlled stainless steel or wooden vats. Whilst in these vats the skins and pulp will gradually rise to the top forming what’s called a cap. Over time the colour, tannins, and aromatics within the cap will transfer to the juice, a process known as extraction.
Temperature is critical during this stage and has a big impact on the final wine. At a temperature of around 24C fruit flavour and finesse are extracted. At temperatures between 30-36C, maximum colour and intensity of flavour are extracted.
To facilitate extraction the winemaker can employ various techniques such as punching down, remontage, or by using a rotary vat.
Punching down involves pushing the cap into the juice with a paddle, hydraulic press, or even feet.
Remontage is the process of pumping juice from the bottom of the vat over the cap.
A rotary vat contains blades that turn to mix the cap with the juice automatically.
For many red wines only a short maceration period is required because the emphasis is on the primary flavours.
For a wine like Barolo the maceration period will be longer (20 to 30 days) to extract maximum character. These wines are subsequently rich in tannins and will require long ageing before drinking.
Carbonic maceration involves uncrushed grapes. Whole grapes are transferred into sealed vats that are then filled with carbon dioxide. This leads to a process called intracellular fermentation, which is where a small amount of fermentation occurs inside each grape. After a short period the carbon dioxide is released and fermentation continues as normal.
This process is used for wines like Beaujolais and produces a very floral and soft wine.
Once maceration is complete, whether or not fermentation is complete, the winemaker will drain the liquid from the vats, separating it from the solids.
The juice, known as free-run, is of the finest and highest quality. The remaining solids are pressed to extract any remaining juice, which is known as press wine. These may be blended at a later stage depending on the wine being produced.
The free-run and press wine are placed into separate tanks where the winemaker will check the alcohol and acidity levels. Alcoholic fermentation will be completed now if it was not complete during the time of running off.
After alcoholic fermentation, malolactic fermentation will occur (we’ll cover fermentation in detail at a later date). The wine will then be clarified during the maturation phase, which we’ll cover in detail at a later date.