A Whole Bunch of Choice

An increasing number of winemakers are now experimenting with whole-cluster fermentation
Contributed by Margaret Rand 

© Concha y Toro | Although not fully understood, leaving
the stems during fermentation can lead to a wide range
of effects on the resulting wines.
Can you imagine a technique that some producers would use to increase the weight of their wines, while others would use it to make them fresher, even lighter? It's whole-cluster fermentation, and it involves, as you might expect, putting the whole grape bunch into the vat just as it is. In the past, if you go back far enough, most people wouldn't have given it a name, because it was just what you did. Until crusher-destemmers became almost ubiquitous in the 1980s (although they were invented in the late 19th century), if you wanted to keep the stems out of your fermentation you had to do it by hand, rubbing the bunches over a wickerwork grid before they went into the vat. And at a large estate how feasible would that have been, even in an era of cheap labor?

The early crusher-destemmers were fairly crude, but they gave you a choice, and if your stems were green in an unripe year you would have been glad to have been able to press a button to keep green tannins out of your wine. You could de-stem everything and add some stems back, if you wanted, choosing the proportion according to the year. You might add some (ripe) stems back to give a bit more tannic oomph to your wine, or to help break up the cap, but adding stems back after they've been removed does not seem to have the same effect as putting in whole bunches. And it's the latter that has this miraculous double effect. It's not miraculous at all, of course. The effect of whole-cluster fermentation on your wine depends on your terroir as well as your grape variety and, most importantly, on how you use it.
The grapes
© Wikipedia | Stems can range from green to brown
and from the main stalk to the more delicate stems.

Let's look at the grapes part of the equation first. With whole-cluster you're getting intra-cellular fermentation in the unbroken grapes – an enzyme process rather than a yeast fermentation. It's the same as the carbonic maceration that is the classic technique of Beaujolais. As the grapes break open, more sugar is released into the juice, and this gradual release prolongs the fermentation, increasing the glycerol level of the wine. Some practitioners of whole-cluster find there are still a few unbroken grapes in the vat even at pressing. This intra-cellular fermentation produces specific flavours: Jasper Morris MW, whose updated new edition of Inside Burgundy comes out on September 15th, identifies esters like ethyl cinnamate and eugenol, which give, respectively, ripe strawberry and spice notes – though he cautions that they might come from the stems rather than from the intra-cellular fermentation. As you might infer, what is actually going on in whole-cluster fermentation is still a matter of study.

The stems

So, the stems; the magic stems. Stems consist of the main stalk of the cluster, the bit you pick up when you buy grapes at the market, which is called the rachis, plus the pedicels, which are the tiny stems that attach each grape to the main stem. They all consist mostly of water, but they have tannins as well, and it is these tannins that made producers rush to buy crusher-destemmers when summers were cooler than they are now and the stems less likely to be ripe. Ripe stems are brown; unripe stems are green. It's not for nothing that we describe unripe tannins as tasting "green". Removing the stems in unripe vintages lessened the impact of green tannins. But the stems do more than just contribute tannins and thus structure. Wines made with whole-cluster have darker, spicier flavors. That dark, serious, weighty aspect was what was noticeable in a lot of red Burgundies in the years when many producers were seeking more imposing wines, in line with fashion. Now fashion demands elegance and freshness, and the wonder of whole-cluster is that it can deliver this, too. Whole-cluster ferments tend to be slightly lower in alcohol and have a little less color; they also may have slightly less acidity, but more perceived freshness; just a touch of greenness from the stems can be helpful here. As ever, wine is contradictory. For every producer using a whole-cluster for more weight and structure, there'll be another using it for elegance and freshness.

The Vineyards

For example: Alvaro Palacios makes Priorat of an elegance and finesse that is whole galaxies away from the stand-a-spoon-up Priorat that you might have found from other producers in earlier years. He works mostly with Garnacha, a naturally pale, low-acid, low-tannin grape. What he needs is, he says, "more structure, more vinosity, more dry extract, more physical dimension – but you have to be careful not to overdo it. You don't want to lose freshness. In Rioja, you can feel whole-cluster [in the wine]. In Priorat, there is such a force of the soil in the wine that you don't feel the flavors but you do feel the texture of the stalks. You get color and concentration and structure."
Photo by Dylan de Jonge on Unsplash

Soil matters. Donovan Rall in South Africa says that "the most important thing is to identify vineyard-specific sites which will not be overpowered by whole-cluster. The obvious mistake is to over-extract, and it can easily be done." One old Cinsault vineyard, for example, gives really ripe stems at harvest, and here he uses 100 percent whole-cluster. "In another Cinsault vineyard, I would only go up to 50 percent because the effect is twice as much as in the first vineyard." Grape variety matters, too. Says Rall, "Syrah is a very easy grape, one of the easiest on earth. Even if you pick early, it has pretty ripe stems… Some Syrah vineyards, especially on granite, tend to have less structure than on schist. Then I add stems for structure. On schist, I do whole-cluster but I don't touch it: just one page a day, to be very wary of over-extracting. Cinsault, even if you pick at 12.5-13 percent, produces less acid and higher pH than Syrah picked at 14 percent. In Cinsault specifically, I like a bit of green from the stems." It gives a perceived freshness that is different from acidity. "It enhances it. But you have to be very careful; it's a very delicate balance. But I don't think my Cinsault would be as fresh and lively if not for the stems."

This is a whole cluster used to frame delicacy, if you like, rather than whacking in a lot of extraneous weight. It's the way that Dani Landi uses it in Gredos for his Garnacha, where the skins and stalks are treated so gently in fermentation that it's hardly more than a marinade. If you look at old-style Domaine Dujac, says Morris, which was all whole-cluster, it's light and ethereal. Château Rayas, famously, is made with whole cluster, but doesn't feel like it.

Does limestone in the soil tend to increase the effect of whole-cluster on the palate? Palacios suggests it does in Rioja. In Burgundy that could be the case, too, although equally, some producers will say that because they get lower acidity on more clayey soils they don't want to lose any more acidity so will avoid whole-cluster.

"The great point with whole-cluster is not to use sulfur at vinification," says Morris. "The results are fresher and more floral. Sulfur is more likely to leach anything bad or herbaceous from the stems." And indeed, the most successful whole-cluster wines – the ones where you don't notice it – are almost certainly made with indigenous yeasts, spontaneous fermentation, call it what you will. "The sort of person who would use whole-cluster is not likely to be using commercial yeasts," says Morris. "The safety-first brigade wouldn't use it."

Changing tastes
Photo by Dailos Medina on Unsplash

Are there any grapes for which it is a complete no-no? The obvious answer might be the Bordeaux varieties, because of their greater tendency to green flavors. But Rall points to old South African reds from the 1960s, 1970s, and early 1980s, "which were mainly Cabernet Sauvignon, Cinsault and Syrah because that was the blend, and people pull them out of their granddads' cellars and they're drinking like Burgundy, delicate, with no green flavors. And it must have been the stems that gave them longevity because there was no de-stemming then."

And indeed some châteaux in Bordeaux have been using some whole-cluster for the last few years. Carmes Haut-Brion and Smith-Haut-Lafitte have both tried it, for freshness rather than for structure, and always treat the ferments very gently. You can layer some whole bunches with crushed grapes in the vat; you can put some at the top of the vat, or at the bottom. You might de-stem with one of the new breeds of destemmers which can leave the grapes intact, just minus the stems, and then add a few stems back to the vat. The permutations are enough to keep winemakers happy for years. And probably to accommodate the next change in fashion, too.


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