*It’s another guest post from Andy Kirk, a MSc (Horticulture) candidate at Lincoln University in New Zealand and alumnus of The Ohio State University! Having grown up in Akron and Canton, he worked under the employ of Arnie Esterer at Markko Vineyard in Conneaut for much of 2011 and 2012. He enjoys New Zealand, but often finds himself relating his viticulture and enology learnings back to the shores of Lake Erie. Many thanks to Andy, and for you, dear readers, enjoy!
If you put your ear to the ground in wine circles, you may notice an increasing buzz around the great grape of Beaujolais, Gamay Noir a Jus Blanc. For instance, you may have read in the OARDC grape newsletter that Gamay outperformed all other vinifera varieties in a recent cold hardiness trial. In these post-polar vortex times, the significance of this needs no elaboration. If not, maybe you’ve read that Gamay was essentially the James Dean of medieval grapes, getting itself banished by royal decree for its refusal to post low yields. Otherwise, perhaps you have marveled at the marketing brilliance that is the annual release of Beaujolais Nouveau. If somehow these stories don’t quite pique your interest, just wait until you hear how the wine is (usually) made. In the winemaking world, Gamay Noir is nearly synonymous with a technique that is as polarizing as it is intriguing. Let’s find out what it’s all about!
Please welcome carbonic maceration to the stage. To provide a quick overview, this technique has the winemaker leaving the grape clusters fully in-tact to undergo partial fermentation inside the berry. When carried out correctly, the conditions of this fermentation are highly anaerobic which catalyzes unique reactions and has a drastic effect on the usual reactions. It is most famously used in Beaujolais on Gamay Noir grapes to create a light, fruity red wine, ready for consumption only several months after harvest. As mentioned above, Beaujolais Nouveau is the textbook example of this type of winemaking. A discussion of this red wine is often accompanied by Renoir-esque scenes of a French café in the summertime. What exactly makes this particular style of wine so famously light and fruity, you ask?
Let’s start with that bright red color. Generally speaking, studies have found that carbonic maceration yields lower levels of anthocyanin, the building block of pigment in red wines (8, 9). Interestingly though, given two wines with the same level of anthocyanin, one made with carbonic maceration will still have less color than its counterpart, due in part to changes in pH. In this scenario, fewer anthocyanin pigments are ionized, and therefore less color is exhibited in the wine (11). This comes despite the fact that carbonic maceration can actually yield higher levels of total phenolics, which could, in theory, provide the substrate for the formation of deeply pigmented polymers (9, 11). Alas, in reality, studies have shown that carbonic maceration tends to yield predominantly monomeric anthocyanin, which is responsible for the bright red color typical of most young red wines (7, 9, 11). Whether this color evolves into a deeper shade of ruby depends on the degree and nature of polymerization, as well as the pH. That is sort of a moot point, though, as most Gamay wine is consumed during its bright red peak, only a few months after fermentation.
What about mouthfeel and tannins, those things that make red wine unique? This seems like an appropriate time to pause and say that all those elements that affect traditional red wine phenolic extraction still apply during carbonic maceration. Mainly, we’re talking about time, temperature, maturity, varietal differences, and ethanol concentration in the fermentation. This makes it very difficult to categorize the effect of carbonic maceration on the end amount of phenolic compounds. As noted above, a number of studies have highlighted the ability of carbonic maceration to yield similar or higher levels of phenols compared to traditional maceration when other factors are optimized (7, 9, 11). However, there has been at least one study that attributed a decrease in tannin content to carbonic maceration (2). A more recent study from Portugal found that carbonic maceration yielded smaller amounts of polymeric phenols (6), which are known to be more astringent with increasing size (1). This idea certainly fits with the perception of Beaujolais Noveau as a bright and fruity wine. That said, it should be re-emphasized that carbonic maceration does not act in a vacuum and interacts with all those winemaking factors listed above.
On the other hand, we know that carbonic maceration has a clear and noticeable effect on the acidity of a wine. In an ideal carbonic maceration fermentation, oxygen levels in the berry will plummet to less than 5 per cent and CO2 levels will rise to 50 per cent. As a result of these conditions, a series of enzymatic reactions are catalyzed, including the degradation of malic acid into (mostly) ethanol (3). This means a drop in the total acidity and an increase in pH for the resulting wine. For a variety such as Gamay, which was said to be too acidic for the golden slopes of Burgundy, this can be a very useful tool.
Furthermore, carbonic maceration has been shown to make a wine more susceptible to induced malolactic fermentation (2), possibly by enabling the survival of the corresponding bacteria inside the must. Malolactic fermentation, for those new to winemaking, is the conversion of malic acid to the weaker lactic acid via a specific family of bacteria, known as lactic acid bacteria. A reduction in total acidity follows, along with an increase in pH and overall sense of softness.
Aroma is often the most striking feature of wine made from carbonic maceration. This is particularly true for the Gamay Noir grape. Staying within the Beaujolais Noveau framework makes it easier to conceptualize. For instance, banana is often one of the first associations to be recalled when tasting a Noveau wine. This is consistent with work done by French researchers, who found that esters such as isoamyl acetate (used artificially for banana) and ethyl cinnamate dominate the bouquet of a young carbonic maceration wine. These aromas will dissipate somewhat after several months, to be replaced by those more typical of an aged wine (5). So given that Beaujolais Noveau is typically enjoyed within the first few months of aging, it should be no surprise that banana aromas dominate our memory. In a typically aromatic variety such as Muscat, though, it is thought that carbonic maceration actually enhances varietal character by liberating terpenoids that are normally bound and odorless (4). In the case of Gamay Noir, carbonic maceration is so pervasive that I wonder whether the varietal aromas have ever been fully separated from the winemaking bouquet.
One of the reasons carbonic maceration is polarizing is that some winemakers insist that it creates wines of inferior aging potential. At least one study, however, has shown that carbonic maceration can actually decrease the rate of degradation for phenolic compounds, creating a more stable wine in the long term (10). The variety in that trial was the Portuguese red grape, Tinta Miuda, which, as a guess, may have naturally high levels of anthocyanins and polyphenols. That begs the question of how Gamay Noir stacks up in terms of initial levels of phenolic compounds. It is nearly impossible to find a credible source on that issue, which leaves me free to speculate. Having recently tasted a 2010 wine from the Beaujolais region of Julienas, I, for one, believe there is aging potential with the Gamay grape.
Looking back on this review, it is clear that there is still room for understanding, in terms of this technique and the grape that made it famous. There are a few points, however, that stand out:
- The anaerobic conditions of carbonic maceration catalyze the degradation of malic acid, which reduces total acidity and raises the pH.
- Color will be lighter compared to traditional fermentation, either because of changes in ionization at a higher pH, or through less and different types of anthocyanin.
- Carbonic maceration promotes the production of esters such as isoamyl acetate that typify the fruity style of young Beaujolais wine.
- The effect of the technique varies in terms of tannin and other flavonoids, and is heavily dependent on the manner in which it is applied.
- Arnold, R.A., A.C. Noble, and V.L. Singleton. 1980. Bitterness and astringency of phenolic fractions in wine. Journal of Agricultural and Food Chemistry 28:675-678 doi: 10.1021/jf60229a026.
- Beelman, R., and F. McArdle. 1974. Influence of carbonic maceration on acid reduction and quality of a Pennsylvania dry red table wine. American Journal of Enology and Viticulture 25:219-221.
- Beelman, R., and J. Gallander. 1979. Wine deacidification. Advances in Food Research 25:1-53.
- Bitteur, S., C. Tesniere, J. Sarris, R. Baumes, C. Bayonove, and C. Flanzy. 1992. carbonic Anaerobiosis of Muscat Grapes. I. Changes in the Profiles of Free and Bound Volatiles. American Journal of Enology and Viticulture 43:41-48.
- Etiévant, P., S. Issanchou, S. Marie, V. Ducruet, and C. Flanzy. 1989. Sensory impact of volatile phenols on red wine aroma: influence of carbonic maceration and time of storage. Sciences des Aliments (France).
- Isabel Spranger, M., M. Cristina Clı́maco, B. Sun, N. Eiriz, C. Fortunato, A. Nunes, M. Conceição Leandro, M. Luı́sa Avelar, and A. Pedro Belchior. 2004. Differentiation of red winemaking technologies by phenolic and volatile composition. Analytica Chimica Acta 513:151-161 doi: http://dx.doi.org/10.1016/j.aca.2004.01.023.
- Pellegrini, N., P. Simonetti, C. Gardana, O. Brenna, F. Brighenti, and P. Pietta. 2000. Polyphenol Content and Total Antioxidant Activity of Vini Novelli (Young Red Wines). Journal of Agricultural and Food Chemistry 48:732-735 doi: 10.1021/jf990251v.
- Sacchi, K.L., L.F. Bisson, and D.O. Adams. 2005. A Review of the Effect of Winemaking Techniques on Phenolic Extraction in Red Wines. American Journal of Enology and Viticulture 56:197-206.
- Sun, B., I. Spranger, F. Roque-do-Vale, C. Leandro, and P. Belchior. 2001. Effect of Different Winemaking Technologies on Phenolic Composition in Tinta Miúda Red Wines. Journal of Agricultural and Food Chemistry 49:5809-5816 doi: 10.1021/jf010661v.
- Sun, B., and M.I. Spranger. 2005. Changes in phenolic composition of Tinta Miúda red wines after 2 years of ageing in bottle: effect of winemaking technologies. European Food Research and Technology 221:305-312.
- Timberlake, C., and P. Bridle. 1976. The effect of processing and other factors on the colour characteristics of some red wines. Vitis 15:37-49.