From Crush Pad to Glass – How White Wine Is Made
Welcome back to the cellar! I am processing over 6 tons of white grapes this harvest and there are a lot of decisions I make during the winemaking process. It’s a series of seemingly small decisions, each one shaping the final wine. There is no recipe for each of my wines. Each vintage and variety is different, so I am constantly responding to the vintage conditions and creative ideas that come to me during the crush. I am also thinking about which wines have sold well and am constantly trying to improve my wines over the years.
Let's walk through the journey of a white grape from its arrival in the winery to the bottle, and the choices I make along the way.
1. Arrival: To Crush or Not to Crush?
When the white grapes arrive, the first major decision is how to process them. Do I crush and destem them, or whole cluster press? I generally add enzymes and a touch of sulfite at the press to preserve fresh fruit flavors and protect the must from oxidation and spoilage organisms.
Crushing/Destemming: Removing the stems and breaking the skins gives us higher yields and can coax out more robust fruit flavors. However, it risks extracting bitter phenolics from the skins and seeds. My approach varies with the grape varietal. Crushing Riesling before pressing releases more varietal aroma and flavor, while crushing Chardonnay before pressing can result in undesirable harsh flavors (in my opinion).
Whole Cluster Pressing: With this method, grape clusters are gently loaded directly into the press. The stems act as natural drainage channels, yielding an incredibly delicate, elegant, and pure juice. It's a lower yield, but often produces the highest quality wine.
2. Skin Contact: A Question of Texture
Red wines get their color from fermenting on the skins. For white wines, the skins are separated from the juice immediately—but not always.
Zero Skin Contact: Pressing immediately gives us the crispest, cleanest expression of the grape with the highest acidity.
24-Hour Maceration: Sometimes, especially with aromatic varieties, I let the juice chill on the skins for a day before pressing. This extracts beautiful aromatic compounds and adds a slight textural grip without extracting too many bitter phenolics.
Extended Contact: Leaving the juice on the skins for days or weeks creates an "orange" or skin contact style of white wine, which has a deeper color, more tannins, and complex flavors. These can be astringent and will always have lower acidity. Sometimes all of the fruit notes can be masked by the tannins of the skins, especially if the skins are left with the juice during fermentation.
3. Pressing: How Hard to Squeeze?
Pressing isn't a "set it and forget it" process. I change the press cycles depending on the variety and style of wine desired. As the pressure increases, more phenolics and potassium (which lowers acidity) are extracted. I taste the juice and test the pH constantly at the press pan, deciding exactly when to cut the pressure to avoid any harsh astringency.
4. Clarifying and Adjusting the Must
Freshly pressed juice (called "must") looks like cloudy apple cider. I usually cold-settle it for 24 to 48 hours so the heavy solids (gross lees) drop to the bottom, allowing us to rack the cleaner juice off the top.
At this stage, I also taste and test the juice again to decide if the must needs adjusting. If it was a hot vintage and the grapes lost their natural acidity on the vine, I might add a touch of tartaric acid to bring the juice back into balance before fermentation begins. I can also add a bit of sugar before fermentation starts to increase the final alcohol content. Finding a balance between fruit, structure, acid, and alcohol is key to creating a wonderful wine!
5. Fermentation: The Vessel and the Yeast
This is where grape juice becomes wine, and there are plenty of decisions here that affect the final wine style, specifically what yeast will complete the fermentation and what vessel I will ferment the wine in.
The Yeast: Should I rely on native/wild yeast floating in our vineyard and cellar for a complex, though sometimes unpredictable, fermentation? Or should I inoculate with a specific commercial yeast strain to guarantee a steady, clean fermentation with more reliable results? I usually opt to inoculate specific yeast strains. As a microbiologist and scientist I like this level of control. Different yeast strains can impact the final aromas, fruit flavors, and acid balance. Some yeast strains have metabolisms that can decrease sulfur off-flavors that are common in particular grape varieties, such as Gewurztraminer, as well. I have had good results with native yeast fermentations for Blaufrankisch and Riesling, but I feel that I can’t afford to risk an entire vintage to native fermentation.
The Vessel:
Stainless Steel: Tanks are perfect for temperature control and showcasing varietal character. They preserve bright, zippy, fresh fruit aromas and are neutral and clean.
Wood Barrels: Barrels allow micro-oxygenation, adding richness, texture, and—if the oak is new—notes of vanilla and baking spice. Barrels can be used with many different varieties, not just Chardonnay.
Clay Amphora/Concrete Eggs: An ancient vessel that is making a comeback. Clay breathes like wood, giving the wine a round texture and micro-oxygenation, but it imparts no oaky flavors, preserving an earthy purity. These vessels are expensive! I currently don’t have any to experiment with.
6. The Second Transformation: Malolactic Fermentation
After the yeast has consumed all the sugar and primary fermentation is complete, I face another crucial stylistic choice: do I encourage the wine to go through Malolactic Fermentation (MLF)?
This second fermentation is not carried out by yeast. Naturally occurring or inoculated lactic acid bacteria convert the sharp, tart malic acid in the wine into softer, rounder lactic acid.
Blocking Malo: If I am making a racy, energetic Riesling or a crisp Pinot Gris, I want to preserve the acidity. I will intentionally block MLF by chilling the tanks down and adding a small dose of sulfite.
Encouraging Malo: For a rich, textural Chardonnay or Vignoles, I inoculate lactic acid bacteria. Not only does this soften the acidity, making the wine feel rounder on the palate, but the bacteria also produce a byproduct called diacetyl, which gives the wine a hint of classic aromas of creaminess and butter.
7. Racking and Aging
Once fermentation is complete, the wine needs to rest. I must decide whether to rack it cleanly off the dead yeast cells (lees) for a sharp, linear profile, or leave it sur lie (on the lees). If I choose sur lie aging, I might perform bâtonnage (lees stirring) every few weeks. This breaks down the yeast cells, releasing mannoproteins that give the wine a fuller texture and added complexity. After the wines naturally clarify for a few months, I prefer to cold stabilize and lightly fine and filter my white wines to achieve crystal clear color and clean flavors.
In Summary
Every decision I make in the cellar, from the gentle pressing of whole-cluster grapes to the texture of lees contact, comes through in the glass. I believe that great wine isn't just manufactured; it's a creative expression of both the winemaker AND terrior.
The next time you open a bottle of white wine, take a moment to consider all the people and decisions involved in creating it. Better yet, come visit us at the tasting room—we’d love to pour you a glass and tell you exactly how it got there.
In Vino Veritas -
Dr. Sherry Seston