Destemming

Destemming is the process of removing grape stems from clusters prior to fermentation. It is a common step in wine production, though not universal. Stems can contribute grassy or vegetal flavors, green tannins, and increased bitterness, and they can affect juice yield and pressing behavior. For these reasons, many producers destem grapes to obtain a cleaner juice and more predictable fermentation. Some winemakers opt for partial destemming or even whole-cluster fermentation to influence structure and aromatic profile.

The operation is usually performed with a destemmer, a machine that separates berries from stems while conveying the fruit to the next stage. Many destemmers are combined with a crusher in a single unit, known as a crusher-destemmer. In such setups, the berries pass through while stems are expelled, though some fraction of the berries may be crushed lightly for extraction. Depending on style, winemakers may choose to crush after destemming or press the berries whole.

Practices vary by style and variety. For white wines, destemming is common to avoid extracting compounds from seeds and stems that can impart bitterness or green flavors. For red wines, destemming is often paired with controlled crushing to manage tannin extraction; some producers employ partial destemming or whole-cluster fermentation to add structure and complexity.

By-product stems are typically composted or otherwise recycled. The decision to destem, partially destem, or use whole clusters depends on grape variety, vintage conditions, and the winemaker’s stylistic goals.