Carbonic maceration in wine || What is carbonic maceration, effects of carbonic maceration on wine || Wine making

 

What is Carbonic Maceration?

Carbonic maceration is the process of putting completely intact entire bunches of grapes in a closed fermentation chamber filled with carbon dioxide. A variety of intracellular responses occur within grape berries that have been handled in this way. Enzymes carry out these processes in the absence of oxygen, with no yeast or microbial activity. The enzymatic processes last about a week at temperatures up to 35°C, after which they stop due to the minimal amount of alcohol generated. The fruit is then destemmed, crushed, and fermented with yeast under standard winemaking conditions.

What reaction happens during carbonic maceration and what is the impact of carbonic maceration on the grape berry/ wine?

The grape berries absorb carbon dioxide, filling them up to around 50% of their capacity. Reactions within the berry, which is still alive while whole, transition from respiratory to anaerobic metabolism.

Malic dehydrogenase is an important enzyme in carbonic maceration because it converts malic acid to ethanol, succinic acid, and aminobutyric acid without creating lactic acid. As a result, titratable acidity decreases and pH increases.

Grape alcohol dehydrogenase converts sugar into ethanol and CO2. Only 0.5-2.2% of ethanol is created, which might be because at this concentration, ethanol begins to impair cell membrane integrity. The amount of carbon dioxide created during the first 24 hours is roughly equal to that absorbed.

Glycerol and shikimic acid are produced, with shikimic acid accumulating within the berry and then degrading to cinnamic acids, and then to the three main aroma compounds associated with carbonic maceration: benzaldehyde ('cherry', 'kirsch', 'almond'), vinylbenzene ('styrene', 'plastic'), and ethyl cinnamate ('cinnamon','strawberry', 'honey'). Other enzymes that can create volatile scents that may contribute to carbonic maceration flavor include ethyl and methyl vanillate ('vanilla'), ethyl 9-decenoate ('sweet', 'fruity', 'quince'), and 1-octanol ('almond'/'buttery').

Carbonic maceration wines generally have lesser primary fruit flavors, which might be due to reduced concentrations of some common wine esters. For example, hexyl acetate ('fruity', 'green', 'pear') can only develop in an oxygen-rich environment during crushing, therefore its formation would be reduced in the anaerobic environment of carbonic maceration.

What is the impact of carbonic maceration on the wine?

Carbonic maceration wines have a particular scent that frequently polarizes tasters. The scents can be characterized as 'fruity' or'musk-like', with'strawberry/raspberry' and 'cherry/kirsch' aromas (especially in Beaujolais wines), as well as 'vanilla','spice', 'almond', 'cinnamon','sandalwood', or 'oak-like' qualities. These characteristics frequently overpower any varietal fruit character, although they can also provide scent to wines with little varietal or fruit character.

In general, the wines are softer, less acidic, and have lesser phenolic component extraction. They are said to develop more quickly than normally fermented wines. As a result, the approach has traditionally been suggested for lighter-bodied/fruity wines meant for early consumption. According to sources, Australian winemakers are experimenting with carbonic maceration or partial whole bunch fermentations in Pinot Noir and Shiraz to produce more refined and aromatic wines, as well as to help in blending.

Effects of carbonic maceration on the phenolic compounds in wine/ grape berries.

Carbonic maceration differs from traditional winemaking in terms of phenolic extraction from grape skins, such as anthocyanins and tannins. While ethanol serves as a solvent for phenolic extraction in both procedures, conventional fermentations have a greater proportion of skin and seed contact time at higher alcohol concentrations than carbonic maceration, resulting in more anthocyanins and tannins being extracted. Carbonic maceration causes anthocyanins to spread from the epidermis into the pulp, resulting in a pink flesh. Any tannin extracted into the pulp at low alcohol percentages is more likely to be skin tannin rather than seed tannin, which may give the impression that the wine has softer tannins.

Risks during carbonic maceration.

Carbonic maceration increases the risk of spoiling by acetic acid bacteria and Brettanomyces yeast due to the higher pH, hotter temperatures, and lack of sulfur dioxide. Furthermore, if a carbon dioxide-rich atmosphere is not properly maintained, aerobic microbes can swiftly take control, resulting in wine deterioration.

How do you do it?

Michel Flanzy created the initial method in 1934. A modified version, patented by Stephen Hickinbotham in 1986, features complete grape bunches packed in a plastic bag supported by a pallet box, which already contains a tiny amount of dry ice in an insulated container. The plastic bag is then sealed and occasionally supplied with a one-way valve that allows carbon dioxide to exit while preventing air from entering.

Carbonic maceration flavor and structure are best achieved when grapes are held at temperatures between 30-32°C for 5-8 days. Lower temperatures provide more delicate and short-term scents, although the strength varies depending on the grape variety or wine style. Carbonic maceration occurs more easily in a gaseous atmosphere, hence the amount of juice produced by the berries is frequently inversely proportionate to the degree of carbonic maceration taste. With more juicing and more aerobic conditions, yeast and bacteria fermentation can occur, with the resultant flavors, as well as those from stem touch, limiting or outweighing those from carbonic maceration.

References

Etaio, I. Elortondo, F. J. P. Albisu, M. Gaston, E. Ojeda, M. Schlich, P. 2008. Effect of winemaking process and addition of white grapes on the sensory and physicochemical characteristics of young red wines. Aust. J. Grape Wine Res. 14:211-222.

Cowey, G. 2018. Ask the AWRI: Carbonic maceration Aust. N.Z. Grapegrower Winemaker (651): 70-71.

Ducruet, V. 1984. Comparison of the headspace volatiles of carbonic maceration and traditional wine. Lebensmittel- Wissenschaft & Technologie 17(4): 217-221.

Flanzy, C., Flanzy, M., Benard, P. 1987. La vinification par la maceration carbonique. Paris: INRA.

Sneyd, T. N. 1989. Carbonic maceration: an overview. Aust. N.Z. Wine Ind. J. 4(4): 281-282.

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