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17, April 2023

The Whole Bunch Influence

Whole bunch, sometimes known as whole cluster, refers to the winemaking practice of using the whole bunch of grapes, including the stems, in the fermentation process.

Prior to the invention of crushing and destemming machines in the 20th Century, whole bunch fermentation was a means of normal winemaking practice but today it is used as a stylistic tool in winemaking.

Most commonly used in making red wine, the winemaker may choose to keep anywhere between 10–100% of the grapes as whole bunches depending on the desired outcome.

Once the bunches, including the stems, have been placed into a fermenter the winemaker may choose to use either:

  1. An oxidative fermentation process, by crushing or partially crushing the bunches and allowing naturally occurring or introduced yeast to begin the fermentation process;
  2. An anaerobic (without oxygen) fermentation process known as carbonic maceration, in which the intact, uncrushed berries are placed into a fermenter, pumped with Carbon Dioxide (CO2) and sealed to allow for intracellular fermentation within each berry; or
  3. Semi-carbonic maceration in which a combination of the oxidative fermentation and carbonic maceration processes are used.­

So, why use whole bunches in winemaking?

We asked some of McLaren Vale’s winemakers why they choose to use whole bunches and what influence this has on their wines:

Alan Varney, Varney Wines

In which of your wines do you use whole bunch fermentation?

For my style, whole bunch works very well for our Grenache based wines, so our straight Grenache, GSM, and Grenache Mourvedre Touriga blend all see some whole bunch treatment. The last couple of years I have also been playing with some whole bunch percentages in my Chardonnay which has been really eye-opening.

What proportion of whole bunch is used in the wine(s)?

Anywhere from 10% to 100%. This really depends on the block of fruit and more specifically the ripeness of the stems themselves. Much like the grapes, the stems have their own ripeness level. I often make the decision about how much whole bunch to include on the day the grapes are picked, when I can see the condition of the fruit and believe it or not, chew on a few stems to check if they will respond well to being included in the ferment. As much fun as whole bunch can be, there is nothing enjoyable about a stemmy green wine so it is important not to over do it.

Why do you use whole bunch fermentation?

It’s all about balance in anything related to grape growing and winemaking. Whole bunch lends a special fruit driven roundness to wines and can bring on chewy tannins that are softer and more suited to younger, more approachable wines. Ferments can also benefit from the slow release of sugars and can be easier to control and extend. Extended time on skins is a big part of my fermentation regime and whole bunch helps with long slow ferments and therefore slower more gentle extraction.

Do you use Carbonic Maceration? If so, why?

Every year a couple of special parcels are earmarked for carbonic maceration and I love the aromatic lift this brings to these blending components. When it goes well there are amazing aromas of ripe melons, bubblegum, and a touch of sweat. I don’t know if it is a pheromone thing but it really appeals to me and I do splash these components around in my red blends. Our drink now style Mencia really benefits from this added lift. I’ve also been experimenting with small parcels of carbonic maceration in my Chardonnay and I’m loving the added layers it brings to the finished wine.

Rob Mack, Aphelion Wine Co.

In which of your wines do you use whole bunch fermentation?

We produce 6 different Grenache wines, and all of them except for one has some portion of whole bunch fermentation in them. The Welkin Grenache is an early drinking, fresh and fruit pure wine and we don’t use whole bunch for that one as we want to fruit to be as lifted and vibrant as possible.

What proportion of whole bunch is used in the wine(s)?

The Confluence Grenache varies between 30-50% whole bunch depending on the vintage conditions.

The Rapture Grenache is usually around 60% whole bunch.

The three single vineyard Grenaches that we produce are always 100% whole bunch.

Why do you use whole bunch fermentation?

Whole bunch fermentation has a range of benefits. It creates wines that are naturally slightly lower in alcohol due to some moisture leaching from the stems and also some alcohol being absorbed back into the stems. It also softens the acidity of the wine due to potassium released from the stems during ferment. There is a small amount of additional tannin provided by the stems, and I really like how the herbal flavours created balance the sweet Grenache fruit character.

Do you use Carbonic Maceration? If so why?

No, we use whole bunch in an oxidative fashion, not carbonic. I find the carbonic results with Grenache are too fruit sweet. I’d rather have the savoury, herbal character that the oxidative approach creates which then balances the sweet core of Grenache fruit.

Skye Salter, Paralian

In which of your wines do you use whole bunch fermentation?

We use whole bunch in our Marmont Vineyard Grenache and Springs Hill Shiraz (these make a single vineyard wine each and then also some gets blended into our Blewitt Springs Grenache Shiraz blend). We are usually using around 20% whole bunch each year on these two wines.

Why do you use whole bunch fermentation?

We are using the whole bunch differently in the Grenache vs the Shiraz. In the Grenache the whole bunches go in the bottom of the ferment and then we destem the remaining fruit on top - we are really aiming to get those vibrant 'whole bunch'/slightly carbonic aromatics by leaving the berries intact on the stems while extracting some structural tannins from the stems. With the Shiraz it is less about the bright whole berry character and more about stalk tannin and spice, so we actually foot tread the whole bunches prior to destemming the remainder of the fruit on top to break open the berries a little.

Do you use Carbonic Maceration? If so why?
We don't do any true carbonic maceration - just the little effect we get from the mini fermentations inside every unbroken berry.