Interview: Perspectives on Whole-Cluster Fermentation

Interview: Perspectives on Whole-Cluster Fermentation

I like to think of winemaking as a choose-your-own-adventure novel, wherein the protagonist determines the character of his or her wine via a complex series of decisions. Some of these choices are more important than others (site selection, ripeness at harvest, fermentation vessel, percentage of new oak, etc.), but all contribute in some way to the final product. In this article, we will focus on one particular fork in the road: the use of whole clusters.

The phrases “whole cluster” and “stem inclusion” are often tossed around in winemaking conversations, but their meanings aren’t always clear. For the purposes of this article, we are considering “whole-cluster fermentation” to be an umbrella term that covers a range of intentions, including whole berry (potential carbonic), crushed clusters, and even the manual addition of stems into destemmed must. The latter two are often referred to as “stem inclusion” and are employed for the effect of the stems on the wine.

Let's define a few more terms while we’re at it. Carbonic maceration is typically achieved by placing whole clusters under a blanket of CO2 in a sealed tank for a variable amount of time. “Partial” or “semi-” carbonic maceration generally occurs in an unsealed tank, with pumpovers, and a combination of whole and broken berries. As with many winemaking terms, the precise techniques vary and are often the subject of debate.

Those using carbonic maceration are not seeking stem character at all—they only want to cultivate the enzymatic activities inside the uncrushed berry. Other producers proudly trod their whole clusters, macerating the juice in the presence of the stems in order to impart their spicy or tannic signature on the wine. And in between these two extremes is a range of middle positions, each with its own prophets and acolytes.

Carbonic maceration is most readily associated with Beaujolais. The use of whole clusters, on the other hand, is as old as wine itself. Destemming by hand is prohibitively laborious, and so historically, clusters were crushed, and red or orange wines were left to macerate on both skins and stems. As winemaking technologies have improved, the use of destemmed fruit has become increasingly widespread. These days, it seems there is a resurgence of interest in stem inclusion, especially among young producers in the New World, many of whom view it as a vehicle for complexity.

No matter where they stand on the issue(s), all winemakers seem to be passionate in their beliefs. To highlight a variety of regions and styles, I posed a set of questions to Jeremy Seysses of Domaine Dujac in Burgundy, Taras Ochota of Ochota Barrels in South Australia, Pax Mahle of Pax Mahle Wines and Wind Gap in Sonoma, and Mathieu Lapierre of Marcel Lapierre in Beaujolais.

Left to right: Taras Ochota, Mathieu Lapierre with sister Camille, Pax Mahle, and Jeremy Seysses

Kelli White: When and how do you use whole clusters or stem inclusion?

Jeremy Seysses: We use whole cluster in high percentage (averaging 85%) almost every year. The destemmed fruit goes to the bottom of our open top fermenters. The whole clusters are put on top, by gravity. No crushing. Small dose of SO2 added. Natural fermentation.

Taras Ochota: I use whole bunches for pretty much everything red in varying degrees. From about 50% to 100%, with also a small portion of true carbonic maceration in some wines. I also like to destem some parcels and add the stalks back into the ferment. I find you can get this lovely umami chicken stock character with having the berries ruptured but with stalks included. It actually reminds me of adding herbs when cooking. I do it all to try to build layers.

Pax Mahle: In a perfect world, all of the red varieties that we work with would be 100% whole cluster. Every pick is evaluated on its own merits to decide how much will be whole cluster. We do not do any mechanical crushing or destemming; everything is crushed by foot.

Mathieu Lapierre: When vinifying by the carbonic maceration way, we never want to extract what is in the stems; we just need them as drains in the vat. So, we never use “stem inclusion.” We need whole cluster—the berry should not be separated from the stem, because if so, there is an entry point in the berry, which means the chemical degradation won’t happen fully. We focus only on the pulp of the berry. We never go up to 28° C so that the enzymes won’t chemically degrade the stems. The macerations last from two to eight weeks depending on the quickness of the enzyme reactions due to the particularity of the vintage.

KW: How does your approach differ from the standard practices of your region?

JS: Whole-cluster fermentations were once rare, though used in a number of traditional flagship Domaines (e.g., DRC) in our area, but most other wineries destemmed 100%.

TO: Not really sure, as I just tick along in my little shed and try to not get influenced too much. Everyone has their own unique ways, but I guess I'm on the heavier end of use. (This applies to many things in my life, thinking about it!) Some are a bit more traditional, and some on the other end like to push that volatile envelope, which can be a problem with whole bunches, but I have been playing around with them for over 20 years now, and I like the results of [the] gorgeous purity [of whole cluster]. Plus, I love not having to clean that destemmer…!

PM: I couldn't say for sure what other people are doing. But I have heard of people air-drying stems and adding them to the ferments or destemming completely and then adding back some of the stems that have already been removed to the ferments. I wholeheartedly believe that both of these are ridiculous and fraught with issues that would affect wine quality and should be stopped immediately.

KW: Is whole or partial carbonic fermentation your goal, or are you specifically seeking to add stem-like characteristics?

JS: We are not looking to make the wine “taste of stems,” but we don’t want it to smell of carbonic fermentation either (hence punchdowns and pumpovers). We like the added complexity, texture, and freshness that whole-cluster fermentation can bring.

TO: It’s more to do with the structure. The best way to describe the tannin profile is to relate it to gravel. The bigger stones I find are from the skins, and the finer, tighter particles are from the stalks. So, the matrix together hopefully creates a mouthfeel that is long and wide and texturally magnificent. The other aspect I love is the aromatics. They seem to be more perfumed, spicy, forest floory, and eloquently lifted in a beautiful way.

PM: Depends on the grape variety, and the style of wine we are shooting for. For Pinot Noir, we like the partial or passive carbonic quality from the imperfection of foot crushing that adds a bit of spice. For Syrah, we will include more whole berry/whole cluster (not crushed at all) for more of that carbonic spice and punch. For Gamay, we will do it 100% whole berry/whole cluster for the majority of the fermentation and then maybe hop in and crush it by foot to finish up the fermentation.

ML: The theme of whole or partial carbonic does not mean anything, I am sorry. It was created by journalists, not winemakers or oenologists. To create CO2, you need juice fermenting at the bottom of your vat (under the grapes), so as you need part juice and part fruit, carbonic is always partial. Added stem characters are just green tannins or lignified tannins (this is bad), and we do not want them at all. We use conical vats to maximize the floating of grapes on the juice and to reduce the contact between juice and grapes.

KW: Are certain varieties better suited to it than others?

JS: We only do Pinot Noir, but I’ve tasted good examples in many other varieties (Merlot, Nebbiolo, Gamay, Trousseau, Poulsard, Syrah, Grenache, etc.).

TO: For me, the best are Gamay, Grenache, Pinot Noir, Syrah, and Mourvèdre.

PM: Yes, but it probably has more to do with the management of the fermentation than the grape variety. One size doesn't fit all.

KW: What are the good and bad characteristics it can add to a wine?

JS: Bad: what might be termed “bad vegginess.” Tomato leaves. Broccoli. Green bean smells. Harsh tannins. Monochromatic if dominant or poorly suited. Good: more expressive, jump-out-of-the-glass aromatics; more depth, complexity, and longevity.

TO: The good is the contribution to complex aromatics and an elegant structure generally, but there is that level of greenness, which really comes down to individual preference, like anything. No one is right or wrong. I like wines with energy, which are highly toned, so am fond of the earlier-picked, herbal-edged styles, where others may find them too much.

PM: Texture, aroma, length, all positive. The negatives only happen when winemakers doesn't adjust their protocol to fit the fermentation and the vintage and insist on following the script used for everything else.

ML: Carbonic allows you to extract by enzyme reactions what is in the berry. By this way, you do not have to physically extract the color and flavor elements (like Burgundian maceration). So, it preserves your wine from all the rustic tastes that stems, skins, or seeds can give to it.

KW: In what ways does it change a wine’s chemistry?

JS: It tends to make the pH rise.

PM: The inclusion of stems adds potassium to the must, which can change the buffering capacity of the juice, which can result in an increase in the pH of the finished wine.

ML: It completely changes the kind of molecules extracted—the subject is deep.

KW: Does stem inclusion change a wine’s ageability?

JS: I think it does and helps the wines to age better.

TO: I think it can help a bit, as stalk inclusion increases the phenolics, which act as a natural preservative. But, then again, a lower pH is better for ageability, hence a holistic approach is important. There are so many other factors that have more relevance to ageability.

PM: Yes. Theoretically, a higher pH could reduce the ageability, but the addition of stem tannins could increase the ageability and stability of a wine.

KW: How important is foot-treading?

JS: Not all that important. More important is gravity-loading of the tanks.

TO: Very. I tend to tread once early to create juice to percolate down through the bunches to encourage the wild yeast to start their wild orgy as soon as possible. Their creation of carbon dioxide protects the ferments from making lots of high-end vinegar. Then, I'm quite gentle on cap management.

PM: All important.

ML: We never do it.

KW: How important is stem-lignification?

JS: It’s important to have some. Up to the knuckle is what I usually shoot for.

TO: This depends on what you like in a wine. More spice comes from more lignification, but the negative, depending on the variety and the season, can mean higher sugar levels, therefore alcohol.

PM: Lignification is important, but not how most people think. The stems are bright green, even when they are lignified appropriately. The lignification is the hardening and firming up of the cells, not turning brown. This happens with time, so lignification could be affected by a shortened ripening in a warmer climate.

ML: The stems will be lignified when the berry is sexually ripe. We need ripe berries to make good wine.

KW: Have you ever used too much stem inclusion in a wine?

JS: Yes, one of my consulting clients did a trial. It really did not suit the grapes of the area. Anything over 10% whole cluster was hard, tannic, and green to the point of undrinkable.

TO: Yes. One Pinot block I have doesn't seem to like it, so I destem her to avoid this unattractive pine-needle character it develops. Maybe this block I should pick a bit later, but it is always the first to ripen, and I get a bit antsy early vintage.

PM: Nope.

KW: Have you seen trends in whole cluster use change over time?

JS: It has become currently very fashionable in Burgundy and beyond. I look forward to the trend slowing down. There are too many caricatures of whole-cluster wine in the market right now. If overdone, the winemaking can come to dominate the vineyard character. Not the point.

TO: There seems to be a lot more experimentation with the younger-at-heart cats where the 101 recipes have been added to or changed. Deliciousness seems to be the goal. This seems to be a good idea. Would you go to a restaurant where the food wasn't?

  • I've heard exactly the same thing.

  • I have heard that stems can absorb some of the color, but also that the contribution of stem tannins in low tannin grapes like Pinot Noir can help fix the color via a tannin/anthocyanin polymerization. 

  • Geoff why is that so? I would think that having the stems included and thus a more tannic, complex wine, the color could possibly end up being more pronounced not less? Or does it distract from the color rather??

  • Really great article which demonstrates that the use of whole clusters in red wine fermentation is certainly not a formulaic set winemaking protocols and might not necessarily something that can be definitively ascertained in a blind taste scenario. The variations in usage are surely diverse and  it was great to hear the perspectives from such top quality winemakers working in different climatic zones with different varieties Another similar report on the subject from Andrew Jefford here . As far as the measurable reduction in alcohol is concerned with whole cluster fermentation, what I was taught (which I happy to be corrected on this btw!), is not that stems preferentially absorb alcohol or sugars but in fact they contain and then release water during fermentation and subsequent pressing, thus actually diluting the final alcohol content compared to an identical batch that was 100% destemmed at equivalent ripeness. So the final abv is lower through a slight dilution in whole cluster ferments. Again yeast usage would need to be equivalent to act a s a control.

  • I grabbed this image from Jeb Dunnuck's instagram account. There's obviously a different amount of liquid in each glass but you can still see the difference in both the density of the pigmentation and its hue.