A look into red wine and the wine making technique of carbonic maceration

Carbonic Maceration:

Known as “Cab Mac” in Australia due to Stephen Hickinbotham invented a new way to produce wines made via the carbonic maceration method.

Carbonic Maceration is an important winemaking technique that can help produce lighter, fresher, more confectionary reds, easier for earlier drinking. Don’t be fooled though, many Beaujolais wines using this method can be just as big in flavour, and sometimes bigger in flavour than Burgundian Pinot Noir.

Beaujolais is the region most closely associated with this Carbonic Maceration, and semi-Carbonic Maceration. Modern winemakers use a percentage of “whole bunch” ferments, no matter what region they are in, or what grape variety used to add a variety of characteristics to their wines.

Many producers don’t traditionally practice full carbonic maceration, but a semi-carbonic technique where whole clusters of grapes are put into different vessels, be they wooden, cement or stainless steel vessels without the addition of CO2. The berries at the bottom are crushed under the weight of those at the top. They undergo a yeast fermentation, which creates carbon dioxide in addition to alcohol. Meanwhile, berries toward the middle and top remain intact and undergo intracellular fermentation.

Elsewhere, producers may combine whole-bunch and whole-berry fermentations, where a portion of the bunches may be mashed up to kickstart a yeast fermentation. They’re then layered with a combination of whole bunches and destemmed grapes on top.

These various approaches contribute to the final style and flavours of the wine, but none quite as dramatically as a 100% carbonic maceration.

Carbonic maceration generally reduces the depth and brightness of the wine’s colour and can completely change a wine’s style and flavour profile. Think of a red wine that had a pronounced confectionary/bubble-gum aroma, or earthy, cinnamon, vanilla and/or stalky/stemmy aromas and flavours. This is probably a carbonic maceration wine.

What is carbonic maceration?

Carbonic maceration is a winemaking technique that’s applied to red wines to make them fruitier and to soften their tannins. Very few wines are 100% Carbonic Macerated. Many red-wine winemakers will use varying percentages of “Whole Bunch fermentation”.

How most red wines are made: Grape juice is transformed from grape juice into alcohol via a yeast fermentation. Grapes are picked in bunches, then destemmed, and crushed. The yeast, whether naturally present on the grape skins or added by winemakers, “eat” the natural sugars in the grape juice and converts them into alcohol (and Carbon Dioxide).

In carbonic maceration, however, the initial fermentation is not caused by yeast but due to the lack of oxygen occurs intracellularly (from the inside of each berry) until a certain level of alcohol is produced which initiates the breaking down of the grape skin, allowing the colour and tannin of the skins to leach into the fermenting juice.

Carbonic Maceration involves filling a sealed vessel, holding whole-bunches of grapes (intact) with carbon dioxide to produce an oxygen-free environment, the berries, starved of oxygen, begin to ferment from the inside. They use the available CO2 to break down sugars and malic acid (one of the main acids in grapes) and produces alcohol along with a range of compounds that affect the wine’s final flavour and colour. At the same time, polyphenols (tannins) and anthocyanins (colour), make their way from the grapes’ skin to the pulp, which turn the white flesh to a pink, then red colour of various hues. Once the alcohol reaches 2%, the berries burst, releasing their juice naturally. A normal yeast fermentation will then finish the job (once the original seal that kept oxygen away from the berries is taken off the fermenter to allow Oxygen to enter the fermenter).

The result is a wine that’s light/er in colour with low levels of acidity and tannins, and highly fruity/confectionary aromatics, intended generally to drink young.

Partial Carbonic Maceration occurs naturally in any vessel where oxygen is limited, and with an abundance of carbon dioxide, and a percentage of intact, non-split berries (it is inside these whole/intact berries that carbonic maceration will occur). The science is as ancient as winemaking itself and like most developments in winemaking it was due to accident and/or error.

But modern, controlled maceration carbonique was invented in the Beaujolais region of France, just south of Burgundy, where the light- to medium-bodied Gamay grape rules.

In the mid-to-late 20th century, Beaujolais’s reputation was elevated thanks to carbonic macerated wines, particularly Beaujolais Nouveau, an early-drinking wine released just weeks after fermentation is complete. Beaujolais Nouveau eventually was the reason for the demise of Beaujolais because to many unripe, thin wines were produced in the race to be the first Beaujolais on the market.

The man credited with the discovery of carbonic maceration is French scientist Michel Flanzy who used carbon dioxide as a grape preservation technique in 1934.Around the same time, Jules Chauvet, a négociant and chemist from Beaujolais widely considered the godfather of natural wine, also made great strides with his studies in semi-carbonic maceration of Gamay grown on Beaujolais’s granite soils. The technique is used widely by natural winemakers today.

In 1986, Australian winemaker Stephen Hickinbotham patented a method that involved using a sealed plastic bag to contain the juice and dry ice to create carbon dioxide.

Flexibility in winemaking

Like many winemaking techniques, carbonic maceration offers seemingly endless variations, depending on what works best for a specific grape variety, the grape’s terroir, and the style sought by the winemaker. Semi-carbonic techniques are often referred to simply as “carbonic” or “whole bunch”, and this can cause confusion.

Beaujolais is the region most closely associated with this Carbonic Maceration, and semi-Carbonic Maceration. Many producers don’t traditionally practice full carbonic maceration, but a semi-carbonic technique where whole clusters of grapes are put into wooden, cement or steel vessels without the addition of CO2. The berries at the bottom are crushed under the weight of those at the top. They undergo a yeast fermentation, which creates carbon dioxide in addition to alcohol. Meanwhile, berries toward the middle and top remain intact and undergo intracellular fermentation.

Elsewhere, producers may combine whole-bunch and whole-berry fermentations, where a portion of the bunches may be mashed up to kickstart a yeast fermentation. They’re then layered with a combination of whole bunches and destemmed grapes on top.

These various approaches contribute to the final style and flavours of the wine, but none quite as dramatically as a 100% carbonic maceration.

Beaujolais good or bad, natural or not?

While semi-carbonic may be known as Beaujolais’s maceration traditionelle, some local winemakers argue that the technique is a post-industrial invention which expresses little of a wine’s unique terroirs. Therefore, a growing number of producers have returned to pre-World War I production techniques. In other words, they’re making Gamay like its Pinot Noir neighbour in the north, solely through a yeast fermentation.

While carbonic may have lost some fans in Beaujolais, a growing number in the wine world still seem enthusiastic with the technique. It’s been embraced by natural-leaning winemakers looking to make easy-drinking “confectionary” wines with some meant to be consumed young.

So, forget the “scientific” terminology with its connotation of interference in a natural process. Carbonic maceration is a natural “chemistry” process that makes wines more fun and accessible, so go out and buy a carbonic maceration wine this week.