Co-Fermentation Versus Blending

At Dos Abogados, like most wine producers, we strive for wines that provide a high quality sensory experience in terms of aromatics and flavor profile: balance and refinement, complexity, purity of fruit and persistent finish. We grow and bottle two distinct red varietals: Malbec and Cabernet Franc.  Most of our wine is tank fermented and aged in first or second use French oak; limited lots are barrel fermented and aged in new oak only.  We also make a “blend” composed of roughly 50/50%  Malbec and Cabernet Franc, which we call Gran Corte, but we do something quite different in creating this wine, as discussed below.

With the benefit of several vintages of our wine before our first commercial releases at the start of 2023, we discovered from our own tastings, and blending sessions with our winemaker (conducted about 18 months after harvest), that the overall aromatic and flavor complexity of our two distinct varietals was enhanced by blending in each a discrete amount of the other varietal.  Thus, theoretically, following a blending session for a particular vintage, we might conclude our Malbec would benefit from an addition of 8% Cabernet Franc; or that our Cabernet Franc would be enhanced by 5% Malbec.  In each such instance, our Dos Abogados wine remains labeled solely as Malbec or Cabernet Franc, respectively, because the content of the predominant varietal is far above Argentinean statutory mandate that a bottle include at least 85% of the variety on the front label.  You will, however, always find the precise percentages of each grape variety on our back label.

The blending of two or more varieties after fermentation is complete and each component has aged separately to achieve a wine superior to the individual grape components, is, of course, a long established practice. For example, the vast majority of high quality red Bordeaux are the product of blended grapes, principally, Cabernet Sauvignon, Cabernet Franc, Merlot, Petit Verdot and/or Malbec.  Blending can also involve both red and wine grapes, such as in Châteauneuf du Pape, where some producers include discrete portions of one or more varieties of white grapes in their red wine, or in Cote Rotie, where small amounts of the white grape Viognier are added to the red Syrah to achieve greater aromatic complexity.

Blending in theory can also refer to the combining of lots of the same varietal that have received different aging treatment.  We have, on occasion, opted to blend a lot of a barrel fermented varietal with lots of that grape which have received our more traditional aging regimen to increase the overall quality of the combined lots.  (These wines, the first of which will soon be released, we label as “Special Edition”.)

What we do with our Gran Corte is quite different because it is the product of a co-fermentation and subsequent aging of the combined Malbec and Cabernet Franc, rather than the product of the two varieties having been fermented and aged separately, then blended 18 months after the harvest.  Co-fermentation simply means the grape must of each of the two varietals is combined shortly after the harvest and before fermentation commences, then fermented together and so aged in whatever oak regimen we have chosen.  Thus, if you research the technique, you will find co-fermentation often defined as “the simultaneous fermentation of two or more varieties in the same vessel.”  FN1  Interestingly, it appears that co-fermentation was routinely practiced in both the Old and New World in years long past, in part because vineyards were more likely to be populated-intentionally or not-with multiple grape varieties.  As a result, for practical reasons, all the harvested varieties were thrown together in the fermentation, constituting what is often called a “field blend”.  As the focus in modern times led to more clearly defined vineyards of a specific grape variety, the practice waned.

In recent years, this historic technique is making a comeback.  Why? A discussion of what may be chemically happening during co-fermentation is beyond the scope of these comments, but some winemakers conclude that co-fermentation allows for an integration of complementary varieties that yields unique flavor profiles and aromas, purity of textures and “mouth feel” and/or enhanced clarity or intensity of color which surpass the characteristics that result from a later blending of the varieties post-fermentation. Winemakers in this camp reason that the chemical makeup of the must is different than, and offers a superior overall sensory experience to, blending the varieties after fermentation.  One analogy that resonates with us likens the difference between a dish with separately sauteed onions added to the other ingredients later and that same dish in which the onions and other ingredients are sauteed together from the start.

The question is whether co-fermented wines would have exhibited the same outstanding characteristics if simply blended post-fermentation?  The answer to this question is the subject of different opinions. While, as noted, some winemakers and researchers find it results in noticeable positive differences from later blending, others are not convinced of such improvements.  Also, there can be limitations associated with the co-fermentation technique.  The varieties involved must be complimentary in flavor profile (Malbec and Riesling might well not work), and ripen about the same time.  And the ability to later adjust the final wine may be restricted because the basic makeup is set before fermentation commences.  Our Malbec-Cabernet Franc combination is quite complimentary. And our tastings have confirmed our 50/50 approach best yields a unique wine.

What we can offer to the debate is our personal experience.  Before we opted for co-fermentation, we tasted samples of co-fermented Malbec-Cabernet Franc, and in our mind they were superior to the wines in which the same components had been blended later.  At the time we approached the experiment, we had no preconceived notions.  Yet we clearly concluded the co-fermented wines had a more complex nose, and a purity of fruit that surpassed that offered by the blended wines, and perceptibly so.  We have also done a test, admittedly not blind, by creating a blend of same vintage, same percentage varieties from our separate Malbec and Cabernet Franc bottlings and comparing that to a bottle of same vintage, co-fermented Gran Corte.  We reached a similar conclusion-the Gran Corte was superior to that blend.

1  Robinson, J.  The Oxford Companion to Wine, 3rd Edition; Oxford University Press: Oxford, 2006