Fermentation and Carbonic Maceration

ISN’T FERMENTATION AMAZING?

Edouard Bourgeois
January 19, 2024

And I mean fermentation in general, not only alcoholic fermentation. Because yes of course, we may immediately think of wine and other alcoholic beverages when fermentation is mentioned but think about kimchi, coffee, cigars, soy sauce or your morning yogurt. All of these products wouldn’t exist without the magic process of fermentation. Anselme Selosse never fails to remind his audience about these other fermented products and how fermentation allows us to reveal the origin of the product, the terroir. There is something almost mysterious about the process and one can go deep into the scientifically complex aspect of it. In this article, I wanted to focus on a certain kind of fermentation we hear about often. And that is the carbonic maceration, famously used in my beloved Beaujolais region but in many other places as well. Also, this where it gets tricky. Is carbonic maceration a certain type of fermentation? To answer this question and dive deep into the matter, nothing’s better than the post from Mathieu Lapierre (of Domaine Lapierre in Beaujolais) that he recently posted on Facebook. This step by step process is perfectly illustrated and thoroughly explains what is going on. I wanted to share this with my English translation. Enjoy!

1.       HARVEST

The grape harvest and sorting of the grapes are handled by hand very meticulously in small crates so grapes stay intact and not crushed

Below, a cluster of Gamay Noir a jus blanc

Zoomed in: a peeled berry of Gamay Noir a jus blanc

2.       VATTING

The harvest is put into tanks quickly and at a cool temperature. A naturally occurring juice forms at the bottom of the vat. The quantity of juice depends on the firmness of the fruit and the method of vatting (by hand of mechanically) this juice is called “la tire”

La Tire: in the vat, only the “tire” starts fermenting thanks to indigenous yeasts (naturally present in the environment) this fermentation is immediate and spontaneous and create carbon dioxide (CO2). The quantity of “tire” will define carbonic (small quantity of juice) or semi- carbonic (high quantity of juice)

Whole Clusters: Grape clusters are whole. They do not ferment, they go under an enzymatic degradation

3.       ENZYMATIC DEGRADATION

The environment in the vat, saturated in CO2 stimulates the enzymes naturally present in the berries which extracts the color from the skin towards the core of the berry. The inside of the berry will go from light yellow, to pink, to red before turning a deep purple. The taste of the fruit will also evolve. There is no fermentation inside the berry

4.       END OF THE MACERATION

After 2 to 4 weeks on the vat, the harvest is de-vatted delicately and by hand in order to keep the grapes whole before pressing

Pictured: whole cluster of Gamay Noir a jus blanc. The berries are still intact on the stem, untouched and not fermented (na tannin extraction)

Pictured: close up of a peeled berry of Gamay Noir a jus blanc after maceration

The color, taste and chemical balance of the grapes has changed (decrease of the malic acid, color and aromatic extraction)

5.       THE PRESS 

Pressing is performed slowly and at low pressure to avoid the release of vegetal (green) tannins found in the stem

Pictured: one of the modernized presses at the domaine

Pictured: a “Gerle”, basket traditionally used to collect the press

The juice (must) that drips from the press is called “paradis”. It is already red and very aromatic even though it is not fermented

Le paradis - unfermented juice with high concentration of natural sugar

6.       GRAPES AFTER PRESSING

Grapes are still whole and the seeds remain intact with no tannic extraction thanks to the delicate handling.

Pictured: close up on a whole cluster after pressing

Pictured: berry after pressing

The malic acid has almost entirely disappeared after maceration so no malolactic fermentation may occur This also creates the risk of “piqure lactique”, inherent in carbonic maceration: without lactic acid, lactic bacteria may turn sugar into vinegar

7.       ENTONNAGE: FILLING THE BARRELS

La tire and the paradis are blended and put into barrels. At this stage, the tire contains an important concentration of fermentable yeasts (saccharomyces cerevisiae) and acts as its own fermentation starter

Pictured: our wines are unfiltered, only clarified during the elevage (aging)

Pictured: saccharomyces cerevisiae

Fermentation (alcoholic) starts as soon as Entonnage starts. During this step, a large quantity of oxygen blends into the must, stimulating the yeasts while making it difficult for the malic bacteria that perform best in anaerobic environment (in the absence of oxygen)

The shape, volume and composition of the wood barrel offers the ideal recipient for a slow fermentation and natural fining.

The elevage comes to an end the following spring

From the harvest to the bottling, no oenological additive is used (SO2, foreign yeasts, enzymes, tannins, acids) and no filtration.

A picture I took at Domaine Lapierre in 2017