Winemaking: Stomp by Stomp

Winemaking, from a distance, seems like a straightforward process - pick the grapes, stomp them in a huge vat, and set them aside to age, right? But like most things, when you focus in on the details, on the individual brushstrokes, there’s a whole lot more to it.

Decisions about when to harvest, how to manage the vinification, influence the fermentation, determine the specifics of the aging process, and even choose the bottling - every one of these choices play a part in the ultimate product - its bouquet, flavor, texture, and even its appearance.  Winemaking involves far more than just picking and stomping grapes, and it’s truly a fair statement to say that it’s much more an art than a science.

The fundamental steps of making wine are essentially the same, although red and white wines differ in some important ways. With a bow to the art of the process, each vintner will add tweaks and make different choices as they seek to make an appealing product.

White wine tends to be lighter, fruitier, and crisper, with more floral overtones. It’s made from green grapes and goes from vineyard to final bottled product in about five months. Red wine is made from black (purple) or red grapes and the grape skins are included in the fermentation process in order to dye the wine. Red wine is heavier, richer, and dryer, with more complex overtones and a somewhat bitter taste and it can take up to three years or more to finish drier varieties.

Harvest and Preparation

Arguably, the most important step in winemaking is the first one - harvesting the grapes. Since grapes do not continue ripening after they’ve been picked, it’s critical to harvest them at the perfect ripeness. Some grapes are harvested based on their taste and even their mouth feel, while others are harvested based entirely on their sugar content (known as BRIX). In most cases, though, grapes are harvested based on their overall chemical parameters, including pH, Titratable Acidity (TA), and BRIX.

The harvest process should begin in the early morning, when the grapes are cool. All clusters are picked from each plant, whether by hand or using specialized harvesting machinery. The winemaker must decide at this point whether to remove the stems or ferment the grapes as whole clusters. Leaving stems in will decrease sourness but will add astringency to the finished wine. Damaged or under ripe grapes are discarded, and the remaining grapes are closely checked for insects, then may be washed before being run through the crusher/destemmer.

Pressing and Maceration

Additional juice is extracted from crushed grapes (must) for white and blush wines using a wine press, pressing by hand, or even just by the weight of berries and clusters. Interestingly, some winemakers even still stomp their grapes, claiming the foot method gets fermentation going quicker and adds to the flavor intensity. It’s undoubtedly reassuring to hear that bare feet stomping is considered safe, thanks to the balance of acid, sugar, and alcohol that prohibits human pathogens from surviving in fermented wine. 

Many red wines, in contrast, are not pressed before fermentation - rather the crushed grapes are left in contact with the juice, a process called maceration. Maceration is used to extract phenolics (flavor and aromatic compounds) and intensify color, characteristics unique to red wines.

For white and blush wines, after pressing, the extracted juice is immediately cooled and sulfur dioxide is added to prevent spoilage. For red wines, crushed or macerated grapes are moved to fermentation tanks and stored in a cool environment. Here, too, sulfur dioxide is added to prevent spoilage.


Red Wines

For red wines, yeast is added to extract tannins from skins and seeds as fermentation begins. At about 60-70% through fermentation, the must is pressed, and the remaining juice is moved to a tank to complete fermentation.

White and Blush Wines

Racking is a process of moving wine (usually by siphoning rather than pumping) from one vessel to another during fermentation - in general, it acts as a filtration process, where sediment like dead yeast cells and grape particles are removed. Without racking, the yeast and sediments can import specific tastes which may not be desirable. Racking for clarity should be performed every 2-3 months, while racking for other goals, such as controlling certain flavors during the aging process of red wines, will vary.

After each transfer, winemakers will typically measure levels of free sulfur dioxide (SO2), pH, and TA, making adjustments if any of these parameters are out of whack. The wine is often tasted to ensure there’s no spoilage developing.

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