What Is Whole-Bunch Fermentation?

Quick answer

Whole-bunch fermentation is a red-winemaking technique in which intact grape bunches—including the berries, stems and central stalk—are placed in the fermenter. Instead of separating every grape from its stem, the winemaker might retain a small proportion of whole bunches, use a substantial portion, or ferment nearly all the fruit intact.

The stems can contribute tannin and alter the wine’s texture. They may also bring herbal, spicy, savoury or floral notes, although these effects are not guaranteed. If the stems are unsuitable or extracted too aggressively, the wine may instead seem green, bitter, coarse or overly drying.

The technique is particularly relevant to Australian Pinot Noir and Shiraz, but it is used selectively. The same approach can produce very different wines depending on the variety, vintage, stem maturity, fruit condition, fermenter and cap-management decisions.

If you see “whole bunch”, “whole cluster” or “stem inclusion” in a wine description, treat it as information about how the wine was made—not as a promise about how it will taste.

How whole-bunch fermentation works

1. Grapes arrive and are sorted

At the winery, the fruit may be sorted to remove damaged or unsuitable bunches. This matters because whole-bunch fermentation retains more of the physical bunch in the fermenter.

2. The winemaker chooses how much to destem

There are three broad approaches:

• Destemmed fermentation: the berries are separated from the stems.
• Partial whole-bunch fermentation: intact bunches are combined with destemmed grapes.
• Full or near-full whole-bunch fermentation: most or nearly all of the fruit is placed in the fermenter as intact bunches.

There is no universal percentage that defines the method. A wine labelled or described as “whole bunch” may therefore contain a very different amount of stem material from another wine with the same wording.

3. Whole bunches go into the fermenter

Bunches may be placed in stainless steel, concrete, wood or another suitable vessel. Some berries break during transport, filling or the weight of fruit above them. Other berries remain intact for longer.

As fermentation gets underway, the released juice surrounds the berries and stems. Winemakers then manage the cap—the layer of skins and other grape material that forms at the top of a red ferment—using techniques such as pump-overs, punch-downs or foot-treading.

4. The wine is pressed

After fermentation and maceration, the wine is separated from the remaining skins, seeds and stems. Pressing can extract additional colour, tannin and flavour, so the handling of press wine is another decision affecting the finished wine.

This is a broad overview rather than a recipe. Fermentation time, temperature, vessel and extraction methods vary between wineries.

What do the stems do to wine?

Tannin and structure

Stems contain tannin. When they are included in a ferment, they can add grip, firmness and structure. You might notice this as a more drying or savoury feel through the middle and finish of the wine.

That does not mean stem tannin always tastes harsh, or that it always makes a wine smoother. The result depends on how mature the stems were, how much was used and how intensely the wine was extracted and pressed.

Texture and freshness

Intact bunches change the physical structure of the ferment. Stems create spaces among the fruit and can influence how liquid moves through the fermenting mass. These changes may contribute to a wine that feels more lifted, firm or fresh.

However, “whole bunch” does not guarantee freshness. Acidity, alcohol, grape condition, climate and many other winemaking choices also shape that impression.

Aroma and flavour

Whole-bunch wines are often associated with spicy, savoury, herbal, floral or earthy characters. These are possible outcomes, not a fixed flavour profile.

Suitable, mature stems may add appealing detail. Unsuitable or immature stems can contribute green, grassy or vegetal notes, while excessive extraction may make the wine seem bitter or astringent. The same variety can respond differently in different seasons.

Why stem maturity matters

Stems are not identical from one vineyard or vintage to the next. Winemakers consider their maturity and condition alongside the ripeness and health of the grapes.

Immature or unsuitable stems can increase the risk of green flavours and overly drying tannins. Healthy fruit is also important: retaining whole bunches means retaining more vineyard material in the ferment, so damaged or diseased bunches can have a greater influence.

A winemaker may therefore adjust the proportion of whole bunches from one vintage to another. Whole-bunch fermentation is a flexible tool, not a button that produces the same result every year.

Whole bunch versus carbonic maceration

These techniques can overlap, but they are not interchangeable.

Whole-bunch fermentation describes the format of the fruit: some or all intact bunches, including stems, are retained in the fermenter.

Carbonic maceration describes a specific environment and process. Whole grapes are placed in a carbon-dioxide-rich tank, where intact berries can undergo intracellular fermentation before ordinary yeast fermentation becomes dominant.

A whole-bunch ferment does not have to be sealed or filled with carbon dioxide. Some intact berries may experience limited carbonic-like activity, but that alone does not make the wine a carbonic maceration wine.

For a broader comparison, see carbonic maceration.

Why would a winemaker use whole bunches?

A winemaker may use the technique to:

• add or reshape tannin and structure;
• change the wine’s texture;
• encourage savoury, spicy, herbal or floral dimensions;
• alter how the ferment behaves physically;
• express a particular variety or house style;
• respond to the condition of the fruit in a particular vintage.

These are possible aims rather than guaranteed benefits. Whole bunches may suit one variety, vineyard or season and be a poor choice in another.

Australian readers are especially likely to encounter the technique in discussions of Pinot Noir and Shiraz. Australian Wine Research Institute guidance identifies both as common applications, while noting that proportions vary considerably. The technique is not uniquely Australian, and it is not used uniformly across a region.

You can explore the broader variety context in what is Pinot Noir? and what is Shiraz?.

What does “whole bunch” tell you when buying wine?

It tells you that some stems or intact bunches were retained during fermentation. It does not tell you:

• the exact percentage used;
• whether the stems were fully mature;
• how long the wine was in contact with them;
• which fermenter was used;
• how vigorously the ferment was worked;
• whether the wine will taste spicy, herbal, floral, savoury or fresh;
• whether the wine is better, more natural or more premium;
• whether it also underwent carbonic maceration.

In practical terms, the phrase can help you form a question rather than make a prediction: What kind of texture or savoury character might this winemaking choice have added?

The best answer still comes from tasting the wine. Whole-bunch handling may be part of the explanation, but variety, vintage and the rest of the winemaking story matter too.

Frequently asked questions

Is whole-bunch fermentation only used for red wine?

It is primarily discussed as a red-winemaking technique because stems, skins and extraction play an important role in red-wine fermentation. The article’s focus is therefore red wine, particularly Pinot Noir and Shiraz.

Does whole-bunch fermentation make wine taste green?

Not necessarily. Mature, suitable stems may contribute attractive structure and savoury or spicy detail. Green or herbal flavours are a risk when stems are unsuitable or the extraction is poorly matched to the fruit.

Is whole-cluster the same as whole-bunch?

Generally, yes, in reader-facing wine language. “Whole cluster” is common in North American and international writing, while “whole bunch” is familiar in Australia and Britain. “Stem inclusion” can be broader and may include separately added stems.

Does whole bunch mean the wine is natural?

No. Whole-bunch fermentation describes how grapes and stems are handled. It does not define whether a wine is natural, organic, biodynamic or sustainable.

Is whole-bunch fermentation better than destemming?

Neither approach is automatically better. Destemming and whole-bunch fermentation are different tools. The appropriate choice depends on the fruit, variety, vintage and desired style.

Where can I learn more about winemaking?

Start with how wine is made or browse the WineDaddy winemaking hub.