Leather Aromas in Wine: How Tannins, Aging & Terroir Shape the Flavor

Wine comes in a wide variety of styles, each offering its own delightful and complex flavor profile. Although every wine tastes different, people typically evaluate a wine by looking at its color, acidity, sweetness, aroma, flavor, and tannins. Consistent storage conditions—often provided by a wine fridge—also influence how wine develops over time.

1. Acidity and Sugar

The acidity of wine mainly depends on the grapes themselves, originating primarily from the pulp and juice of the fruit. Acidity is an essential structural component in wine. If a wine lacks sufficient acidity, it will taste flat and dull. If the acidity is too high, it may come across as sharp or harsh. Fortunately, winemakers can often adjust acidity through various techniques. Maintaining a proper wine storage temperature can also help preserve acidity balance over time.

The two primary acids in wine are tartaric acid and malic acid. Both develop naturally during grape growth and ripening. In warm climates, some of these acids are broken down as the grapes respire, resulting in lower acidity compared to grapes from cooler regions. During malolactic fermentation—which occurs in most red wines and some white wines—sharp malic acid is gradually converted into softer lactic acid, thereby altering the overall acidity of the wine.

2. Aromas and Flavor Compounds

Every wine carries its own unique aromatic and flavor profile. But where exactly do these aromas and flavors come from? They are mainly derived from three sources: grape variety, terroir, and winemaking techniques.

There are thousands of grape varieties in the world, and each produces wines with distinct aromas and flavor characteristics. Different varieties contain different chemical compounds, resulting in unique scents and tastes—naturally giving each wine its signature personality.

In wine culture, terroir refers to the entire ecosystem connected to grape growing, including sunlight, air, humidity, fog, temperature, and soil. These elements influence the accumulation of chemical compounds in the grapes, ultimately shaping the character of the finished wine. For example, soil plays a crucial role in Chablis. The finest vineyards in Chablis grow on limestone and a type of calcareous clay known as Kimmeridgian. Wines from this region often exhibit a pronounced “Kimmeridgian” mineral quality.

Both fermentation and aging significantly impact a wine’s aroma and flavor. Winemakers can influence these characteristics in various ways—through maceration time, fermentation duration, the choice of fermentation vessel (oak barrels or stainless steel tanks), the type of oak (American or French), and the size of the barrels (small or large). All these decisions contribute to the unique sensory profile found in the final wine.

3. Tannins

Tannins are natural phenolic compounds widely present in red wines—they are often described as the soul of red wine. Some white wines aged in oak barrels may also contain detectable tannins. As a distinctive component of wine, tannins not only contribute astringency but also help build the wine’s “structure.” They interact with other substances in the wine, creating new compounds and adding complexity. Tannins typically give a dry, puckering sensation. When tasting tannins, the center of your tongue and the front of your mouth are the most sensitive areas, allowing you to clearly perceive their characteristic grip and astringency.

The tannins in wine mainly come from grape skins and oak barrels. Grape tannins originate from the skins, seeds, and stems of the grapes. During red winemaking, tannins and pigments dissolve into the wine through skin contact and maceration. Oak tannins enter the wine through contact during barrel aging, which is one of the most popular winemaking methods today. Wines aged in oak barrels often develop more complex aromas, such as hints of vanilla.

Wine can be categorized by color into red, rosé, and white wines.

- Red wines typically range from purple-red and ruby to garnet or brick-red.

- White wines usually appear in shades of greenish-yellow, straw yellow, lemon yellow, or golden yellow.

- Rosé wines fall between red and white, commonly showing hues of orange-pink or blush pink.

Where does the leathery flavour in wine come from?

The reason red and white wines differ so dramatically in color lies in the winemaking process: red wines are fermented with their skins, while white wines are fermented without the skins. In other words, the pigments in wine come primarily from the grape skins. For red wines, the depth of color also depends on the length of skin contact during winemaking—the longer the maceration, the deeper the color. Rosé wines, with their very short skin-contact time, naturally exhibit a lighter hue than red wines.

In addition, some people say they detect a leather aroma in certain wines—does that make you curious, or hesitant? In reality, some wines do express leather notes, but rest assured, this characteristic does not negatively affect the taste of a well-made wine.

Of course, winemakers do not throw actual pieces of leather into the fermenter. So where does this leather-like aroma come from?

In fact, the scent of leather is closely tied to tannins. In leather production, the tanning process uses plant-derived tannins to preserve hides. These tannins penetrate the leather and bind with its proteins, creating the distinctive aromatic compounds associated with leather. Red wines, which contain abundant tannins, undergo a similar interaction: during maturation, the wine often contains spent yeast cells from fermentation. When the proteins in these yeast cells bind with tannins, they can create leather-like aromas. This is especially common in red wines with high tannin content that have undergone long-term oak barrel aging before bottling.

Therefore, you shouldn’t be alarmed when you detect a leather aroma—it often appears in well-aged, high-quality red wines. As mentioned earlier, leather notes do not overwhelm or distort the wine’s aroma or flavor. They are subtle, secondary, or background notes rather than primary ones. However, if leather becomes the dominant smell—especially in a young wine—it may indicate spoilage, since leather notes usually develop only as the wine matures over time.

Leather aromas appear more frequently in wines from warmer climates. For example, wines from southern France often exhibit this characteristic. Madiran, made from Tannat grapes in the southwest; Bandol, made from Mourvèdre in the southeast; and even certain Médoc wines from Bordeaux commonly show leather notes. Some Greek wines are also known for this aroma. In fact, even some sweet wines may carry an attractive leather scent reminiscent of a Havana cigar.

Among Mediterranean regions, many red wines display particularly elegant leather notes, and well-aged Bordeaux—especially wines matured for over 30 years—can also show this distinctive character.