Whilst you might love drinking wine, you might not know exactly how it is made. It’s a complex but natural process that starts with grapes, so read on to find out how it happens and get all of your questions answered.
Ancient Winemaking
Wine has been made for at least 6,000 years, and some things have changed drastically since then. For starters, all grapes in antiquity were crushed by feet. It wasn’t until the Romans invented the wooden vertical press that the process got somewhat faster.
Wine was typically stored in underground amphoras. Sometimes, herbs, spices and even saltwater were added to the wine to improve its flavour. Interestingly, you can still find some of these techniques are actively used today in traditional winemaking countries around the Mediterranean.
Step-by-step process of Winemaking | From Grapes to Glass
There are many steps involved to turn the grapes you see in the vineyard to the wine you hold in your glass! Here are some of the most important ones.
The Harvest
Harvest is done either by hand or by machine. The grapes must arrive at the winery as fast as possible in the best possible condition.
Crushing & Pressing
Once at the winery, the grapes are roughly crushed. If they’re meant for red wine, they are led to the tanks, otherwise, they are pressed to get the juice out.
Fermentation
During fermentation, yeast turns the sugar present in the juice into alcohol. For red wines, fermentation happens together with the grape skins in the tank, and that gives its colour and tannins. Whites and rosés are typically fermented without the skins.
Clarification & Filtering
Once fermentation is finished, filtering and fining are used for clarification. Most wines are filtered to avoid sediments in the bottle. Fining happens when supplementary substances
are added to the wine in order to remove elements causing the wine to haze or affect its aromas.
Ageing
Wines are usually left to mature. For some, the maturation period may last a couple of months, for others several years.
Bottling
The final step of winemaking is bottling. Winemakers try to ensure consistent quality on all bottles.
Keep reading to discover every detail of all the 6 winemaking phases.
The Harvest | Step 1 of Winemaking
Grapes are usually harvested in late summer and autumn, so from August to November in the northern hemisphere. There are two main ways to harvest: by hand and by machine. Harvesting by hand allows the harvesters to select the best grapes and discard those of lower quality. Hand harvest is mandatory for steep areas and terraces, where machines can’t reach, like Cinque Terre. However, mechanical harvesting can be quicker and cost-effective for large vineyards. Harvesting grapes with a machine does not necessarily produce lower quality wines.
Some winemakers are proud of their night harvesting. This is because temperatures during the day cause warmer grapes to arrive at the winery. Once the grapes are crushed, they’re very sensitive, so it is preferred to harvest at night, where temperatures are cooler. It is also possible to harvest during the day and chill the grapes in a fridge overnight.
Different wines are harvested at different times of the year. It depends on the variety and style. Sparkling wine grapes are harvested first, in order to keep sugar levels low, followed by white and rosé grapes, and lastly red wine grapes as they take longer to reach full maturity.
Crushing & Pressing | Step 2 of Winemaking
Crushing grapes involves bursting the skins to get the juice out of them. This was historically done by physically stomping on the grapes, using nothing more than just hands and feet. Modern wineries use a machine that pushes the grapes between two rollers. “Must” is the name for the result of this process, fresh grape juice which contains seeds, solids and grape skins.
Pressing grapes represents the process of removing the skins and other solids from the must. Nowadays a mechanical press or a basket press is the default option for most winemakers; some more established wineries may use continuous presses, which are fed a steady stream of grapes. Generally speaking, gentle pressing results in finer wines, with less bitterness.
Over the years, advancements in crushing and pressing machinery have significantly improved the quality of the wine, making the whole process more sanitary while reducing the need of preservatives.
Red and white wines go through a very different process, read on to understand the differences.
Red wines
After the crushing phase, the “must” (the grape juice) is allowed to come into contact with the skins, in order to acquire additional tannis, flavour and its iconic “red” colour. This is essential for red wines. When making red wines, the grapes may be left on the stem so that it can add extra tannin or the stems can be removed with a de-stemmer before crushing.
White wines
White wines don’t require skin contact. The wine must is quickly pressed in order to separate the juice from the skins, seeds, and solids. This is a necessary step to avoid unwanted colour and tannins.
Rosé wines
Rosé wines follow a unique process. They start as red wines, which means that the wine must is not immediately separated from the skins. After a certain period of time, usually a few hours (maximum two days), the must is transferred to the press where the grape skins are removed, which causes the wine to acquire a pink colour.
Fermentation | Step 3 of Winemaking
Yeast is necessary for the alcoholic fermentation of the wine, since such substances consume the sugar of the grapes and produce alcohol. Crushing the grapes allows the natural sugar found inside the grapes to get in contact with the yeast, which is naturally found on the skin of the grapes.
While it is possible to ferment wine only by using the yeast found in the grapes, it is a risky process for the winemaker, as there is no control over the strain of yeast that performs the fermentation. To avoid any unpleasant surprises, many larger or commercially focused wineries add laboratory grown yeast.
Fermentation might take place in stainless steel tanks, plastic or concrete vats or even barrels. During this phase, the yeast activity produces heat, which increases the temperature of the wine. The temperature is closely controlled during the whole fermentation process to ensure that it does not get too high and kill the yeast.
For white and rosé wines, the ideal temperature is around 17°C during the fermentation. Red wine requires a higher temperature to encourage the pigments out of the skin and into the wine. Such temperature can vary from 24 to 32°C, depending on the winemaker.
For sparkling wine, a secondary fermentation takes place in the bottle, which produces the iconic fizz. Carbon dioxide is a natural by-product of the alcoholic fermentation. Sugar and yeast are added to the base wine and create carbon dioxide which builds up in the sealed bottle.
What is Malolactic fermentation?
Aside from alcoholic fermentation, there is another important fermentation in wine: malolactic fermentation. This is not technically a fermentation as it does not use yeast but a bacteria called Oenoccocus Oeni; it is a process where tart-tasting malic acid (the same one found in apples), which is a natural part of the wine must, is converted into lactic acid, softer and cremier acid (the same one found in milk).
This has a stylistic effect on the wine since it smoothens its tannins and produces creamy flavours like butter, adding a nicer texture to the wine. This process occurs in nearly all red wines, but many winemakers choose not to allow white wines to go through malolactic fermentation in order to preserve crisp freshness, with the notable exception of Chardonnay.
Clarification & Filtering | Step 4 of Winemaking
Once fermented, the wine is clarified in order to remove any sediment which causes the wine to appear cloudy. After the fermentation is completed, sediments form at the bottom of the fermentation vessel: mainly tannins, proteins and dead yeast. These are removed through a fining process which involves using a series of additives that stick to the unwanted particles, increasing their size so that they can be filtered out easily.
Most fining agents traditionally came from animal products, such as milk, egg whites, gelatine, casein and fish guts. The demand for vegan alternatives has significantly increased in the last few years, with winemakers turning their attention to non-animal derived additives, such as bentonite (clay).
Some wines, especially more artisanal wines (such as biodynamic, organic, and natural) do not go through the above fining process. The end result may appear more cloudy and may have more texture or different flavours.
Ageing | Step 5 of Winemaking
Ageing wine is a key step, which heavily depends on a series of choices winemakers go through and the type of wine they want to produce. It boils down to three points: ageing time, ageing medium and ageing temperature.
Some wines can skip the ageing phase completely (such as Beaujolais Nouveau) while some require a very long time, such as Barolo which requires at least 3 years of ageing by law. In Italy, regional regulations often make it mandatory for a producer to age certain wines for a specific amount of time.
However, almost all wines are aged, at least for a few months before they reach the market. Most Italian wines are aged for much more than that. Wines that benefit from long ageing are those naturally rich in tannins, so mainly red wines. White wines can also age but generally for less time.
Time: how long is the wine aged for?
Only a few wines will benefit from significant ageing, whilst others will be better when they are still young. This depends on the grape variety, style and regulations.
Medium: where is the wine being aged?
Barrel ageing may be used to add flavour to the wine. Oak barrels can impart vanilla flavours and a silky texture to both red and white wines. Some wineries may choose to use other wood barrels such as chestnut or acacia, but oak is the most popular.
It’s not necessary to age wine in wooden vessels. Some wines are aged in stainless steel tanks while others are aged in amphoras or concrete eggs. It all depends on the producer.
Temperature: what temperature is the wine being aged at?
The higher the ageing temperature, the faster the wine ages. A beneficial temperature for wine ageing is around 15°C, as it allows chemical reactions within the wine but at a slow pace. However, some wines around the world are aged in very high temperatures, like those produced in the island of Madeira producing distinctive flavours.
Bottling | Step 6 of Winemaking
Bottling is the last step of winemaking and it is a very critical one. If something goes wrong in this phase, a whole batch may be discarded. Bottling involves mechanically filling sterile glass bottles via a tube and then sealing such bottles, either with traditional corks or screw caps.
The process varies for still and sparkling wines: read on to learn the differences.
Still wines
Wine is poured into bottles, usually by a machine, which are then sealed. The corker will vacuum the air out of the bottle to remove oxygen which might otherwise undermine the quality of the wine. Removing the oxygen is usually less critical for red wines.
Sparkling wines
Bottling sparkling wine is a very different process. For starters, special stronger glass bottles are selected as they need to hold high pressure.
When producing sparkling wine with the traditional method, like Franciacorta, the bottling process initially resembles the one of still wines. However, since a sugar and yeast mixture gets added to the wine, a second fermentation happens in the bottle. After the second fermentation is complete, the wine is unsealed to remove the sediments, and then topped up with more wine and usually some sugar. Finally, the mushroom-shaped cork is used to seal the bottle.
When making sparkling wines with the tank method, a special bottling machine which can work under high pressure is necessary. This process is called isobaric bottling and it doesn’t allow many bubbles to disappear into the atmosphere. Prosecco is made using this method.
FAQs
How is alcohol produced in wine?
This happens during the alcoholic fermentation process. Yeast consumes the sugar in the grapes and turns it into alcohol. The level of alcohol will depend on the level of sugar in the grapes.
How long can you keep an unopened bottle of wine?
It depends on the type of wine. In general, an unopened bottle of white wine will last for one to two years. An unopened bottle of red wine should last three to four years. Fine wines may last decades when stored properly.
What is the world’s oldest drinkable wine?
It is possible to find extremely old wines that are still drinkable, but it is impossible to know until a bottle is opened. In 2009, a bottle of 1825 Perrier-Jouet Champagne was opened and found extremely drinkable despite being 184 years old.
What is unfermented wine?
Unfermented wine is produced by preventing the fermentation and production of alcohol, so it is basically a fancy name for grape juice. Unfermented wine has no alcohol.
What time of the year do you pick grapes?
Grapes ripen, and therefore are picked, in late summer and autumn. The picking time depends on the grape variety, region and wine style desired. In general, colder areas harvest later than warmer ones.
What’s the difference between a cork and a screw cap?
A cork is a natural material traditionally used as wine closure. It is permeable to oxygen allowing the wine to age in the bottle. Screw caps are an ideal closure when the wine is not meant to age.
Can you make wine at home?
Making wine at home is not as hard as it may seem. You just need grapes and a container for the juice. Once fermentation starts, the wine should be ready after 30 – 40 days.
What is grape stomping and when is a good time to travel to experience it?
Grape stomping is the most ancient winemaking technique. It involves stepping on grapes to crush them and release the juice. It is best to travel to winemaking regions between late August to October in order to find a suitable experience for your needs.
What is Malolactic Fermentation?
The malolactic fermentation happens in most wines, where the strong malic acid of the wine is turned into a softer lactic acid. This process enriches the wine texture, creating creamier and buttery flavours that add complexity to the wine.
What is blending wines?
Blending wines may involve blending different varieties, different plots, different vintages or different winemaking techniques. A winemaker will blend to achieve the best wine he can. Sometimes blending is needed to reach a certain volume.
How is the winemaking process different for organic wines?
The winemaking process is for the most part the same for organic and non-organic wines. However, organic wines have stricter regulations regarding the amount and type of additives that can be used during winemaking.
