Stems and Substance: The Revival of Whole Bunch Fermentation in Red Wine

The debate over whole bunch fermentation in red winemaking has been ongoing for years, with winemakers often finding themselves on opposing sides. However, even those who traditionally favored clean, stem-free fermentations have begun to recognize the potential benefits of including some stem material. A conversation I had with Tom Rinaldi, the former winemaker at Buckhorn and Provenance, illustrates this point perfectly.

Rinaldi, known for his meticulous approach to winemaking, once confided in me about an unconventional practice he had adopted. He expressed concern that wines were becoming too “clean” due to the widespread use of optical sorting technology. This high-tech approach, while effective at removing substandard grapes, was also eliminating elements that could contribute complexity and character to the final wine.

In response to this perceived over-cleanliness, Rinaldi admitted to occasionally sneaking handfuls of discarded stems and jacks (the small, woody parts that attach grapes to the stem) back into the fermentation tanks. His goal was to reintroduce that little “something wild” – a touch of rusticity and complexity that he felt was being lost in the pursuit of perfection.

This anecdote from a respected winemaker like Rinaldi highlights the growing recognition that absolute cleanliness and uniformity may not always produce the most interesting or characterful wines. It also serves as a fitting introduction to the broader discussion of whole bunch fermentation, a technique that is experiencing a renaissance in the world of red winemaking.

As we delve into the topic of whole bunch fermentation, it’s important to keep in mind that even winemakers who don’t fully embrace the technique may still see value in the subtle complexities that stem inclusion can bring to a wine. This nuanced approach, balancing modern technology with traditional techniques, is at the heart of the current debate surrounding whole bunch fermentation in red winemaking.

Whole Bunch Fermentation in Red Winemaking: A Resurgence of an Old Technique

The wine industry is experiencing a renewed interest in whole bunch fermentation, particularly for red wines. This technique, once considered outdated, is now gaining popularity among winemakers seeking to produce more elegant and complex wines. The process involves fermenting red grapes with their stems, contrary to the more common practice of destemming before fermentation.

Traditionally, red winemaking begins with separating grape berries from their stems, which make up 2-5% of the cluster’s weight. This separation can occur in the vineyard during machine harvesting or at the winery using a crusher destemmer.

The resurgence of whole bunch fermentation is particularly noticeable in regions producing Pinot Noir and Syrah. In Burgundy, for instance, there’s a growing trend towards including stems in fermentation. This shift can be attributed to two main factors: the passing of influential winemaker Henri Jayer, who opposed stem inclusion, and the increased ripeness of stems due to global warming.

Winemakers are now making conscious decisions about stem inclusion, rather than using them by default as in the past. This deliberate approach has led to improved results and a better understanding of the technique’s potential benefits.

The effects of stem inclusion on fermentation are complex and can vary based on several factors, including stem ripeness and fermentation methods. Some reported benefits include:

• Improved juice drainage and more homogeneous fermentation temperature in small vats.
• Better cap aeration, preventing excessive heat buildup during fermentation.
• Enhanced yeast mobility and improved pressing.
• Potential reduction in alcohol content due to slightly different sugar-to-alcohol conversion (needs further study)
• Possible mitigation of negative impacts from fungal infections on grapes.

However, stem inclusion can also lead to some challenges, such as:

• More difficult cap management during fermentation.
• Potential loss of color as stems absorb pigments from the wine.
• Risk of imparting green or herbaceous characters to the wine if stems are underripe.

The method of adding stems to the fermentation vessel can also impact the final wine. Some winemakers prefer placing whole clusters at the bottom of the vat, while others layer them throughout or add them on top. Each approach can result in different fermentation dynamics and flavor profiles.

Partial carbonic maceration, which occurs when some berries remain intact during fermentation, is another factor contributing to the complexity of whole bunch wines. This process can enhance texture and aromatics, as well as prolong fermentation due to the gradual release of sugar from intact berries.

While many winemakers are embracing whole bunch fermentation, it’s important to note that the technique is not universally applicable. For example, Bordeaux varieties like Cabernet Sauvignon, Cabernet Franc, and Merlot, which naturally possess some green characteristics, may not benefit from stem inclusion as it could exacerbate these flavors.

The impact of whole bunch fermentation on wine flavor and structure can be summarized as follows:

Texture: Often described as silky or smooth, particularly in Pinot Noir.
Tannin structure: May increase, sometimes mimicking the presence of new oak.
Aromatics: Can enhance floral and spicy notes, adding complexity to the fruit profile.
Freshness: Often contributes to a livelier, more vibrant wine.
Elegance: When done well, can result in more refined wines compared to fully destemmed counterparts.

However, whole bunch fermentation can also introduce distinctive flavors that may be polarizing, such as broccoli, soy sauce, compost, forest floor, or herbal notes. These characteristics often integrate and resolve with bottle aging.

The renewed interest in whole bunch fermentation aligns with a broader trend in winemaking away from the powerful, robust styles that dominated in the 1990s and early 2000s. Many winemakers are now seeking to produce more expressive, elegant wines that better reflect their terroir. Whole bunch fermentation offers a tool to achieve this goal, even in warmer climates where wines tend to be naturally more robust.

It’s worth noting that the effectiveness of whole bunch fermentation can vary greatly depending on factors such as grape variety, vineyard site, vintage conditions, and winemaking approach. As such, many winemakers take a nuanced approach, adjusting their use of stems based on these variables.

For example, some winemakers find that certain vineyard sites or grape varieties are more suitable for whole bunch fermentation than others. They may also adjust the proportion of whole clusters used based on the ripeness of the stems in a given vintage. This flexible approach allows winemakers to harness the benefits of stem inclusion while minimizing potential negative impacts.

Innovative techniques are also emerging in the realm of stem usage. For instance, Burgundian winemaker Mark Haisma developed a “macerating basket” method where destemmed grapes are fermented with stems contained in mesh cylinders. He claims this approach allows for greater control over stem influence and can be adjusted during fermentation.

The revival of whole bunch fermentation represents a broader shift in winemaking philosophy. Many producers are moving away from a one-size-fits-all approach and instead embracing techniques that allow for greater expression of terroir and vintage variation. This trend reflects a growing appreciation among consumers for wines that showcase complexity, elegance, and a sense of place.

However, it’s important to recognize that whole bunch fermentation is not a panacea for all red wines. Some varieties and regions may not benefit from this technique, and overuse can lead to undesirable green or herbaceous characters in the wine. Skilled winemakers must carefully consider when and how to employ whole bunch fermentation to achieve their desired results.

The resurgence of whole cluster fermentation demonstrates the cyclical nature of winemaking trends. Practices that were once considered outdated are being reevaluated and reimagined in light of new knowledge and changing consumer preferences. This willingness to revisit and refine old methods, combined with modern understanding of wine chemistry and fermentation dynamics, is driving innovation in the industry.

As the wine world continues to explore the potential of whole bunch fermentation, it’s likely that our understanding of its effects and best practices will continue to evolve. Ongoing research and experimentation by winemakers around the globe will undoubtedly yield new insights into how this technique can be used to craft distinctive, terroir-driven wines.

In conclusion, the renewed interest in whole bunch fermentation represents a significant trend in contemporary winemaking. While not suitable for all situations, this technique offers winemakers an additional tool to create complex, elegant wines that express the unique characteristics of their vineyards and vintages. As with many aspects of winemaking, the key lies in understanding the nuances of the technique and applying it judiciously to achieve the desired results. As consumers continue to seek out wines with character and sense of place, whole bunch fermentation is likely to become an important part of the winemaker’s repertoire.