Stems and whole bunches in red winemaking: a hot topic

Jamie Goode takes a closer look at the deliberate choice by many winemakers to leave the stems in their red wine fermentations

Let’s talk geeky for a bit. The subject? Whole bunch fermentation in red winemaking. It’s a hot topic.

What is it exactly? For most red wines, the first stage of winemaking is to separate the grape berries from the stems (here, the term ‘stem’ is used to refer to the main axis of the cluster of grapes, known as the rachis, plus the bits that attach the berries to this, known as pedicels). The stems make up about 2–5% of the weight of the cluster, and they vary in colour from green to brown.

This destemming can take place in the vineyard (where machine harvesting is practiced), or in the winery, with a crusher destemmer. Some very swanky properties even do ultra-precise hand destemming, but that’s very rare and expensive.

Not destemming, and using the whole bunches with the stems in the fermentation is widely considered to be old fashioned and rustic. But it is coming back into fashion for those who appreciate elegance and interest in their wines, especially for Pinot Noir and Syrah.

‘Clearly, in Burgundy at the moment there is a tendency to move towards stems,’ says Burgundy expert Jasper Morris. ‘I can see two main reasons for this,’ he says. ‘One is that Henri Jayer, who hated stems, is dead. And the other is that with global warming, the stems are more often riper than they used to be.’ Jayer, a trememdously high-profile grower, influenced many to move away from stems, and until recently this was the direction being taken across the region. And the popularity of destemming was  linked with a corresponding reduction in greenness and rusticity in many red Burgundies, so there was a good reason for doing it. In a sense, in the past people used stems by default, and the results weren’t always good. Now the choice to use stems is an active one, so the people doing it are doing a better job with it.

Jeremy Seysses

Jeremy Seysses at Domaine Dujac uses between 65% and 100% whole cluster fermentations depending on the cuvée. ‘We have the feeling that we get greater complexity and silkier tannins with whole cluster fermentation,’ he shares. ‘In high acid vintages, it helps round things out, and in high ripeness vintages, it brings a freshness to the wines.’ For Seysses, the decision about whether or not to destem depends on a number of factors. ‘Some terroirs don’t seem to do so well with whole cluster. The whole cluster character rapidly becomes dominant and can appear “gimmicky”, it doesn’t mesh well with the wine and can give the illusion of complexity, but it feels superficial,’ he explains. ‘Of our holdings, I like destemming a little more for the Gevrey vineyards than the others.’ He also tends to destem more frequently the grapes from younger vineyards with bigger clusters, and in vintages with rapid end of season ripening, where the ripening may be a little more uneven.

 ‘I normally find a strong correlation between the better sites and the amount of stem/whole bunch I am able to use,’ says Mark Haisma, an Australian working as a micronegociant in Burgundy and Cornas. ‘The stems from the best sites are generally cleaner and richer in character.’

Well known Aussie winemaker, Tom Carson of Yabby Lake, admits that he likes to play around a bit with whole bunches in his Pinot Noir ferments. ‘I am still experimenting, and I’m reluctant to go in too hard. When it’s good, whole bunch fermentation gives fragrance and perfume, and adds a bit of strength and firmness to the tannins. But when it’s not good it can dull the fruit, adding mulch and compost character,’ says Carson. ‘We want to highlight the fragrance of the Pinot. We don’t want complexing elements that are not vineyard-derived.’ Carson did 8% whole bunch in 2009 and 20% in 2010, but then backed off a lot in 2011 because it was a wet year and the stalks were quite green. ‘We are still learning what is the right amount.’

Nick Mills, of Rippon, in New Zealand’s Central Otago, uses some whole bunches in the Pinot Noir ferments, but decisions are made based on the fruit. ‘We do some whole bunches,’ says Nick, ‘but this is all done on the sorting table.’ He adds that, ‘the sorting table isn’t about taking stuff off, but it’s for me to taste pips and skins, and figure out what raw material we have. If we can chew the stems through then we’ll put them in. I’d put in 100% whole clusters if we could. It’s a better ferment.’ Overall, Rippon Pinot Noir has 25–40% whole clusters. ‘The vineyard is incredibly parcellated,’ says Nick, ‘with all these small microferments. If we get something really good, then we’ll put the whole lot in and do 100% stems, but if grapes come in that I don’t like the taste of we’ll use no stems.’

Until recently, Eben Sadie of South Africa’s Swartland region didn’t use any stems in making his celebrated Columella wine, but he decided to change this with 35% of stems included in the 2009 vintage. ‘For the next 10 years we will work with 20–40% whole bunch,’ he says. For Sadie, stems are a way to achieve freshness in his wines, but he uses them on a vineyard-by-vineyard basis. Of his eight vineyards, five get destemmed and three are 100% whole bunch ferment.

Stems have a number of effects on fermentations, but this is where the story becomes complex and somewhat unclear. There are many different ways of using stems in the fermenter, and the stems themselves can be quite different in terms of how green or lignified they are. ‘There is an immense difference in flavour profile from all the people who do use stems,’ says Jasper Morris, referring specifically to Burgundy. ‘You also have to look at the techniques involved. Here it gets very complicated.’

‘In small vats, like those used in Burgundy, stems are useful because they drain the juice in a more homogeneous way and keep the temperature of fermentation one or two degrees lower,’ says French wine commentator Michel Bettane. Jeremy Seysses agrees: ‘The cap is far more aerated, meaning that it doesn’t get quite as crazy hot as it would without any rachis in there, letting some heat escape. It also drains much better when you punch down or pump over as you get no clumps.’ Nick Mills of Rippon in Central Otago adds that the presence of stems allows the yeasts to move around more easily, and the pressing is better. And Rhône winemaker Eric Texier claims that in whole bunch fermentation, the conversion factor of sugar to alcohol is slightly different, resulting in wines with lower alcohol.

In addition to these benefits, Bettane also adds that stems in the fermentation can also help diminish the negative influence of any fungal infection on the grapes. ‘In 1983 for instance, curiously the whole bunch-made burgundies were less flawed by rotten berries than destalked ones.’ But if large tanks are being used, he points out that it is impossible to keep the stems, because they make the cap too resistant to mechanic pressure. Seysses also says that whole bunch ferments are harder to punch down. ‘You have to do it by foot or by piston, you can’t do it by arm. All these things change your extraction profile.’

Inside a crusher/destemmer

Another physical effect of stems in the ferment is a loss of colour. ‘The stems also absorb colour, leaching the colour of the wine,’ explains Eben Sadie. ‘These days everyone wants to make more powerful, impressive wines, so whole bunch is an unfashionable move because your wine looks weaker. For many people, colour is an important property of the wine.’ But Sadie doesn’t see this as a big problem. ‘I’ll lose some colour to gain freshness and purity. The wine has more vibrancy and life in it. Where we work in South Africa, the biggest flaw is our wines are often too ripe. It’s good to get our wines fresher and more vibrant.’

There are many variables involved in how the actual stems are added to the vat. ‘One question is, if you don’t use all stems—and there is probably quite a lot to be said for using just some stems—when do you put them in?’ asks Jasper Morris. ‘Do you put them in first, as a sort of base to the cuve, and then you put your destemmed grapes on top? Or do you put them in last, so the stems slowly float down through the juice? Or do you do some sort of lasagne-like layering between stems and non-stems, which I have heard some people do?’

‘With many cuvees and the destemmed fraction being so small, I inevitably coferment,’ explains Jeremy Seysses of Domaine Dujac. ‘The practicalities of harvest don’t always allow it, but I usually like putting the destemmed fruit at the bottom and the whole cluster on top, so that it really stays whole. And as it can take a few days for the ferment to get going, I don’t want my healthy whole clusters to be covered with juice as they sit waiting for the yeasts to get going.’

Tim Kirk of Clonakilla, from Australia’s Canberra District, uses some whole bunch to make his Shiraz Viognier, but unlike Seysses’ preference, the bunches go in first. Whole bunches are put into 2 ton fermenters, only part full. Some Viognier is typically crushed and destemmed and put on this, and then some Shiraz is destemmed and put on top. Kirk reports that some of the grapes in the whole cluster portion stay attached to the rachis and don’t burst: he estimates around 20% of them. Instead, these berries begin fermentation from inside, as in carbonic maceration. If you take these whole berries out part way through fermentation, their pulp is coloured red, so they are extracting colour from the inside. They are also still a bit sweet, and on pressing, these berries release sugar, which acts to prolong fermentation.

This delayed sugar release from intact berries is also noted by Blair Walter, of Felton Road in New Zealand’s Central Otago, who uses a little bit of whole bunch to add complexity to his wines. ‘We typically put in a quarter whole bunch and destem the rest of the bunches. And then when we punch down we don’t go to the bottom of the tank. After 28 days you can still pull out whole bunches. They have fermented inside [the intact berries] and there is still some sweetness that is pulled out.’ He thinks this remaining sweetness is important because it keeps fermentation ticking along for a while. ‘Burgundians typically chaptalise in six-to-eight small additions,’ claims Walter. ‘This results in a slightly stressed fermentation producing more glycerol. This changes the texture and adds some fruit sweetness. It surprises me that more people don’t use whole bunches.’

This partial carbonic maceration character is likely to contribute significantly to the enhanced texture and aromatics often seen in wines made by whole bunch fermentation. But Michel Bettane thinks that some of this benefit can also be derived from very careful destemming. ‘Don’t forget that new destemmers are so precise and delicate that they allow winemakers to put “caviar” destemmed berries in the vats with almost the same effect as whole bunch fermentation,’ says Bettane. ‘The beginning of the fermentation takes place inside the berry, helping to preserve the best quality of fruit, delicacy of texture and capacity to age, keeping the youth of fruit and avoiding barnyard undertones.’

Mark Haisma is a winemaker with broad experience across different hemispheres. In his previous employ he was at Yarra Yering, in Australia’s Yarra Valley, but he’s now a micronegociant in Burgundy, also making a wine in Cornas in the northern Rhône. At Yarra Yering he developed an innovative approach to stem use, which he calls a ‘macerating basket’. ‘The fruit would be completely destemmed, and I had some stainless steel mesh cylinders made,’ he explains. ‘These would be stuffed with the stems. I could take them out when I felt I had what I wanted.’ And the results of using stems this way? ‘I find it adds a great spicy complexity to the wine and also builds your tannin profile. And this way I have absolute control.’ Haisma is working on this in Burgundy, with some interesting results, but he doesn’t know anyone else doing it this way.

‘Whole bunch for me is about controlling the ferment, slowing it down, with a slow release of sugar.’ Says Haisma. ‘It is a great way to build loads of complexity and savoury characters, and still keep a lush creamy feel to the palate. I think of velvet. This is especially noticeable with my Cornas. As for burgundy, it’s all about the complexity and finesse. In the big appellations I feel it adds a structure to the fruit, without adding coarseness or bitterness, characters I hate in Pinot Noir.’

We have discussed the positive aspects of whole-bunch fermentation. What about the negatives? Blair Walter of Felton Road says that he used to do one fermenter with just whole bunches each year, but has now given up. ‘For us it is too much,’ he says. ‘It is interesting but the wine becomes too herbal—it is like a hessian sack character.’ But he still uses smaller proportions of stems in many of his fermentations. ‘With stems, people expect the wines to become angular. I find the opposite. Destemmed wines taste more angular. A lot of people don’t have the courage [to use stems]; they aren’t willing to tolerate earthiness and herbal characters in the wine.’ Tom Carson finds that using too many stems gives his wines a mulchy, herbal character.

Greenness is the problem most often associated with stems. While there has been increased interest in the use of stems in red wines worldwide, one region stands out as an exception: Bordeaux. This is likely because the main Bordeaux varieties of Cabernet Sauvignon, cabernet Franc and Merlot all share a degree of greenness in their varietal flavour signature, something that most winemakers will seek to minimize, and won’t want to risk exaggerating by including stems. However, Paul Pontallier at Château Margaux has looked at the impact of stems in the course of the extensive in-house research program that this famous estate has established. This stem trial was with 2009 Cabernet Sauvignon from a plot which, in good years, makes it into the first wine. ‘We wanted to see how important it is to destem,’ recalls Pontallier. ‘Our tradition has been to almost totally destem. From the early 20th Century at Margaux destemming was a standard procedure.’ He points out that some are now suggesting that using some stems could be a good thing. And on the other side, some estates have become more fastidious about removing even the tiniest bits of stem. The destemming regime in practice at Margaux leaves some tiny pieces of stems in the ferment, such that 0.03–0.05% of the ferment is stems. In this trial, the standard Margaux destemming was compared with 1% stem additions, and 1% stem additions but with the stems cut into tiny pieces. To Pontallier, the results from this trial are obvious. His view is that the current approach produces the best wines, and the 1% stems in pieces the worst. But he is still cautious about generalizing the result. ‘We shouldn’t draw too general conclusions. For this wine I think destemming works, but for other plots, such as a rich wine with soft tannins, it might be different.’

There are many different ways of doing whole-bunch fermentations. Combine these different techniques with the variability in the state of ripeness of the stems, and it creates a complex matrix of factors liable to result in different flavours in the final wine. So it is with some trepidation that I’m going to attempt to sum up the way that whole cluster ferments affect the flavour of red wines.

The state of ripeness of the stems seems to be very important, and this is likely to be determined primarily by the vineyard site, with vintage variation playing a role. In some warmer regions with a shorter ripening time, the stems may still be very green at harvest and thus unsuitable for inclusion at all.

An element of carbonic maceration is an important part of whole bunch ferments. The intracellular fermentation that occurs in any intact berries will produce interesting aromatic elements, and the slow, gradual release of sugar into the ferment will change its dynamics. Together with this, the reduced temperature of whole bunch ferments is likely to have some effect on the resulting wine, usually in a positive direction. There may also be some direct flavour input from the stem material to the wine, which can be both good and bad, depending on the state of the stems. And the slight rise in pH that occurs with whole bunch may increase the susceptibility of the wine to Brettanomyces, but at the same time may improve the mouthfeel.

The benefits of whole bunch? One is textural: it seems to deliver a textural smoothness or silkiness that is really attractive, especially in Pinot Noir. Along with this, the tannic structure may be increased. I find that young whole bunch reds often have a grippy, spicy tannic edge that can sometimes be confused with the structural presence of new oak. Frequently cited as a benefit of whole bunch is the enhanced aromatic expression of the wine, and it’s common to find an elevated, sappy green, floral edge to the pronounced fruity aromas which is really attractive. Freshness is another positive attribute associated with whole bunch. Done well, whole cluster can help make wines that are more elegant than their totally destemmed counterparts. I would add that whole bunch wines sometimes start out with distinctive flavours and aromas that can be a little surprising (tasting terms associated with whole bunch include broccoli, soy sauce, compost, mulch, forest floor, herbal, green, black tea, cedar, menthol, cinnamon), but these often resolve nicely with time in bottle.

‘The wines of the 1990s were the Parkerized wines,’ says Tony Jordan, referring to the move at this time in Australia to make monster wines. ‘Everyone seemed to think bigger was better and the wines seemed to be getting bigger in every way. Now there is a big step back from that. And yet if you are in a warm climate, the wines are going to be robust. That’s the terroir speaking. But you can still aim for freshness, a bit of brightness of fruit, more elegance on the palate.’ This is one of the reasons why there is so much interest in whole bunch fermentation at the moment, because it does represent a tool for making more expressive, elegant red wines, even from sites not known for this attribute.

And even commentators such as UK merchant and Burgundy expert Roy Richards, who used to be opposed to whole bunch fermentation, are softening their attitudes. ‘I no longer have an ideological view on this question, and understand that it is rather more complicated than I used to believe,’ says Richards. ‘As a disciple of the late Henri Jayer, I followed his mantra that stalks led to green tannins and that new oak to creamy, soft ones. And it is true that in his time his wines stood out for their vibrancy and sensuality whereas those wines from more illustrious domaines seemed a little delicate and pasty alongside.’ Richards adds that, ‘he is doubtless turning in his grave, seeing his proteges, Jean-Nicolas Meo and Emmanuel Rouget experimenting with whole bunch fermentation in his beloved Cros Parantoux.’ Richards thinks that this could in part be down to changing weather patterns. ‘Burgundy is no longer such a marginal climate,’ he says. ‘I can understand from the results I have seen that stalks lend finesse and some floral perfume to wines that might otherwise be a little butch, say Corton, Clos Vougeot, Pommard and certain Morey 1er crus.’

It seems that the circle has turned. What was once seen as an outmoded practice—including the stems in red wine ferments—is now becoming a fashionable winemaking tool for those seeking elegance over power.