“W” is for whole-bunch fermentation

Sounds weird right?  Truth be told, “W” proved more problematic than I thought it would when doing this A-Z, but then I though about a term I hear quite a lot when referring to a wine making process and one that you sometimes see mentioned on labels so I thought I would do a very quick (and hopefully not too geeky) explanation.

What is whole-bunch fermentation?  (aka whole-cluster) As the name alludes, it is a process which involves fermenting whole bunches of grapes (stems and all).  While white grapes may be whole-bunch pressed before fermentation, the process of whole-bunch fermentation is the original way of making red wines.  

A bit of background. Historically winemakers would ferment the whole bunches (grapes and stems) together – it was easier, less time intensive and produced what I would generously describe as ‘rustic’ red wines! 

The advent of more modern winery technology such as crusher/destemmer machines that enabled berries to be removed relatively undamaged from bunches saw a move towards more wines being made with destemmed fruit but these days many winemakers are experimenting with the inclusion of whole bunches. Some are using all whole-bunch fruit, some use a percentage of bunches depending on specific vintage conditions and the style of wine they are trying to produce.

Why?  There are lots of reasons actually.  Stems ensure the pomace cap remains loose, aiding drainage and helping the fermentation process by aerating it – meaning fermentation temperatures can be slightly cooler, ensuring lighter, fruitier wines.  The stems also provide additional tannins, add complexity and freshness and change the flavour and aroma profile of the wine.

Note – the stems must be ripe, if they are unripe, tannins can be harsh and the green flavours overpower the wine and accentuate astringency.

How does the process affect the taste and appearance? when you think about it, stalks and stems, even ripe ones, have a leafy/herbaceous/floral character. These ‘green’ notes can provide freshness and lift the aromatic profile of a wine.  Wines made with whole bunches often appear lighter in colour – this is because stems absorb colour.  Intracellular fermentation can also occur in the intact berries (but sensing that I may lose some of you here I won’t go into this in any more detail!).

It should be noted that some grapes have a more natural affinity to this process than others – Pinot Noir is the most suited, along with Gamay and increasingly winemakers are experimenting with Syrah

Grapes that have quite noticeable leafy characteristics (think Cabernet Franc and Cabernet Sauvignon) are less likely bed-fellows for this process …after all you can get too much of a ‘green’ thing! (Although some in Bordeaux are beginning to experiment).

Where is the process of whole-bunch fermentation most commonly used?  Burgundy.  No surprise I suppose given that the two major red grapes of the region are Pinot Noir (for red Burgundy) and Gamay (for Beaujolais).  Although increasingly producers of Pinot Noir across both the New and the Old world are experimenting with the style.

Right, I hope that wasn’t overly technical, if nothing else, in the future when you pick up a bottle and it says ‘whole-bunch fermented’ on the back label you will have an idea what it means!

Next up “X” is for Xinomavro.

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