Highbury Library University 001 - Carbonic Maceration

Welcome, welcome, young student! This will be the first, of hopefully many, many blog posts which will attempt to teach you something. 

Wine can be pretty intimidating. A world full of knowledgeable people that use descriptions such as "toasted sesame seeds" and "confected strawberries" to describe a taste. Not that surprising, hearing people talk like that, swirling the wine in their glasses like there's no tomorrow, smelling, tasting, smelling again. This blog series will aim at teaching you simple ideas, which will help you realise that after all, wine isn't all that intimidating, and with just a few concepts under your belt, you too can intimidate your non wino friends. After all, snobism is the true reason most of us get into wine in the first place, isn't it? Heh.

In today's lesson, we'll cover a topic that we often start to explain because someone might ask, before they realise they really didn't want to find out about it: carbonic maceration.

Okay, so a couple of slightly scary words. Two concepts here: carbonic, and maceration. Let's start with maceration.

What is maceration? Well, it's a fancy word for the concept of leaving grape juice in contact with grape skins. It turns out that the grape juice contained in grapes is actually almost always clear (it's not white for white grapes and red for red grapes). What gives wine its colour is maceration - crushing the grapes and leaving the juice in contact with the skins after the grapes have been crushed. That's how this gorgeous Pinot Noir Champagne appears white in the glass even though it's made from red grapes (press the grapes, but without a maceration), Vé rosé, our favourite natural Provence rosé is pink (press red grapes but with only a very light maceration), or this age worthy 2013 Andalusian Cabernet Sauvignon/Merlot blend is a bolder red (crush red grapes and have a longer maceration). Side note here, "orange wine", like this fragrant orange Gewurztraminer from Alsace is just white grape juice macerated with white grape skins. Beyond colour, maceration also gives wine tannins, structure (also referred to as body), and additional flavours.

Hopefully that makes sense. We know what maceration means now. But what's the word "carbonic" got to do with this. This is where things get interesting. The idea first became popular in the Beaujolais where it is the standard way to make red wine from the Gamay grape. When we spoke of maceration before, we saw that grapes are crushed, and then macerated. If we don't crush the grapes, and leave the bunches of grapes (hand picked from the vines), which we also sometimes call clusters, whole, and put them delicately in a tall stainless steel tank, and then add CO2 (this is where the word carbonic comes form) gas on top of these grapes, something interesting happens inside the intact grape berries - it's called "intracellular fermentation". As the grapes are now starved of oxygen, the juice starts fermenting inside the berries, and the flavours extracted in that way are different to the ones you extract when macerating the juice after the grapes have been crushed. They're often more subtle, more "candied". They're perhaps more likely to give a "glou glou", easy drinking, fruity style of wine.

So, to sum up:
intact grape clusters go in stainless steel tank -> CO2 is added in gas format on top -> grape juice starts fermenting inside the intact berries -> flavours are more subtle, more "candied". For example this affordable carbonic maceration Syrah from Ardèche is very fragrant, and has much more subtle flavours than a deep bold Syrah, or this 2023 Morgon by iconic wine house Lapierre (who very much defined the natural movement in Beaujolais) is a very classic expression of a fruit forward medium bodied Beaujolais, as opposed to this Loire valley Gamay (same grape variety) which was "destemmed", meaning no carbonic maceration, resulting in deeper less candied and more complex flavours.

After a while, leaving the berries intact in this tank, we press the grapes to separate the juice from the skins, and the fermentation process can be completed. You then get the finished wine.

There, a hopefully approachable explanation which explains some of the science behind a scary concept. 

Until next time, for some more wine university. Ciao!