For centuries, it was standard practice for winemakers to vinify the stem portion of grape clusters, says Matthieu Mangenot, assistant technical director at Albert Bichot in Burgundy.
“If you look back, fermenting with the whole cluster was the ancestral method of winemaking, because there was no destemming at the time,” says Mangenot.
Now, winemakers choose whether to use stems and how as a style preference. Some remove them before they ferment their fruit because unripe stems can create overly acidic, green, bitter or harshly tannic notes in the finished wine. These are the negative characteristics that can lead a taster to wrinkle their nose and proclaim a glass “stemmy.”
“If the fermentation happens with the stems being too green, it will bring more of an aggressive tannic, or an unwanted astringent taste to the wines,” says Nick Briggs, winemaker for Dutcher Crossing Winery in Geyserville, California.
When Briggs makes Pinot Noir, Syrah and Zinfandel, he sometimes uses grapes with their stems in a technique called whole-cluster fermentation. If stems are lignified, or dry, hard and brown, they can lend peppery, spicy and woody notes to the finished wine.
The goal of whole-cluster fermentation is not to create a distinctly stem-like flavor in the glass, Mangenot adds, but rather to provide complexity and tannic structure.
Brent Stone, chief operating officer and winemaker at King Estate Winery in the southern portion of Oregon’s Willamette Valley, points out that the term “stemmy” can evoke negative or positive reactions in wine consumers.
“It often depends on the varietal, intensity of the aroma or flavor and consumer preference,” he says.
When stem inclusion is done suitably, the taster probably wouldn’t actually use the word “stemmy,” Stone says. Instead, they might praise the wine’s balance, structure, and pleasant spicy and floral notes in the wine’s aromatic profile.