Wine 101: What Makes Red Wine Red?

You probably have a basic understanding of how wine is made (if not, here’s a primer). There’s one huge difference between making white wine and red wine: for red wine the juice needs to sit with the grape skins, seeds and stems for some time to extract colour, flavour and tannins. This is also called maceration. In this article, we’ll look at some of the techniques winemakers apply to macerate wine. Or, plainly put: to make red wine red. 

Where Does the Colour in Wine Come From? 

Think about it, if you squeeze a red grape, the juice that comes out is clear. And yes, it is possible to make white wine from red grapes. (There are a few red–fleshed grape varieties, called teinturiers, but they’re really rare.)

six wine glasses with different shades of red wine

What Makes Red Wine Red and White Wine White?

When you make white wine, the skins usually don’t sit with the juice, or just for a short amount of time before pressing. For red wine, the anthocyanins (what gives the wine its colour), flavour compounds and tannins need to leach from the grape skins, seeds and stems via maceration. This is sometimes done before, but mostly during and after the fermentation process. 

For a winemaker, it’s important to know what technique to use, depending on the type of red grape and the style of wine they’re going for. They don’t want to over-extract, which can lead to harsh, even bitter flavours in the wine. Over-extracted wines have a lot of colour, but also a lot of tannin, making them taste astringent and unbalanced. 

Extraction during Fermentation

Most often, extraction happens during alcoholic fermentation, where the alcohol and heat produced act as a solvent. However, when grape skins, seeds and stems are in contact with the grape “must” (grape juice), the carbon dioxide that is produced during fermentation pushes these solids to the top of the vat, forming a floating “cap”. This cap needs to be carefully managed, not only for extraction, but also to prevent it from drying out (and spoiling!). Breaking up the cap also helps in dissipating some heat that is created during fermentation.

The two most common cap management techniques are:

  • Punching Down

The cap is broken up and submerged with a special tool. This “pigéage”, or punching down, is typically done by hand and happens a few times a day. 

punching down the cap in making red wine
  • Pumping Over 

The French call this technique “remontage”. Red wine is pumped off from the bottom of the tank and then splashed back over the cap. 

pumping over red wine
  • Racking and Returning

“Délestage”, as the French call it, is a two-step process. It involves draining off the wine must from the solids (racking). The liquid is then returned back to the fermentation vessel, re-soaking the solids. This oxygenates the wine, making it less astringent. Racking and returning is a method to extract loads of colour and flavour at once.

The choice (and frequency) of the technique generally depends on the style of wine. While punch-downs are used for lighter wine styles, pump-overs are used to create bolder, more extracted wines. 

What is Cold Soak Maceration?

Some winemakers decide to extract colour, aromas and flavour before fermentation. This is called “cold soaking” or “pre-ferment cold maceration”. 

It requires keeping the must at a low temperature after crushing the grapes, so that fermentation doesn’t kick in. Winemakers use cooled fermenters or dry ice, and it’s common to add sulfur dioxide at this point to prevent microbial activity. 

The idea behind the technique is that, before any alcohol is formed, there is a better aqueous extraction of anthocyanins (colour), as well as aroma and flavour compounds, without extracting tannins, which mostly happens during alcoholic extraction. Cold soaking temperatures range from 5 to 10 ºC. The time can range from a few hours to a couple of days – depending on the style the winemaker is going for and the grape variety. Pinot Noir sees a lot of cold-soaking, as this grape variety tends to give off little colour during maceration. 

The origins of the practice of cold-soaking actually lie in making white wine, where it’s used to get some aromas and flavours from the skins – without extracting phenolics and bitterness. 

As it seems that there are as many different opinions as there are winemakers, some say this technique isn’t very efficient or effective. They say that vigorous pump-overs or punch-downs are much more effective to extract colour. 

crushing grapes barefeet

But Grape Stomping Is Extraction Too, Right?

There is another technique that you might associate with “making red wine red”: good old grape stomping. Crushing grapes barefoot, also known as grape treading, is a very traditional practice. In the Douro region in northern Portugal, this technique is still used to make some of the best port. Port wine requires an intense, but careful extraction, which is hard to achieve with machines. Foot-treading is a labour-intensive (not to mention messy and exhausting) process, so these days you’ll be most likely to find it as a fun activity at wine festivals and fairs.

So, there you have it: next time you pour yourself an almost inky Malbec, you know it probably had quite a few pump-overs. Or when you read “cold soak” on a California Pinot Noir label, you can confidently explain what it means to everybody who wants to know (and doesn’t).

Watch this space for more interesting insights into winemaking, or learn more about viticulture, grape varieties and wine regions. And why not sign up as a WineCollective member? Because nothing beats tasting what you just learned!

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