To understand wine, you have to look closer than the glass. You have to look at the anatomy of the berry. Most enthusiasts think “grape flavor” is one single thing, but a grape is actually a layered vault of aromatic potential.
The Skin (Exocarp):
The Perfume Factory
The most intense aromatics aren’t in the juice; they are tucked away in the skin. If you’ve ever smelled a glass of Syrah and been hit by a wave of black pepper, you’re smelling Rotundone—a powerful compound that lives exclusively in the grape’s “outer skin” or exocarp.
In this outer layer, we also find:
– Terpenes: These give varieties like Muscat their explosive floral notes (think rose and geranium).
– Norisoprenoids: The compounds responsible for complex cooked fruit and floral scents.
– Thiols: This is the “insider secret” of Sauvignon Blanc. These precursors stay hidden until fermentation, eventually releasing those famous notes of passionfruit and boxwood.
The Pulp (Mesocarp):
The Support System
While the skin provides the “perfume,” the pulp provides the “structure”. This is where the sugars (glucose and fructose) and organic acids (tartrate and malate) live. Without the pulp’s acidity and sugar-to-alcohol potential, the aromas in the skin would have no stage to perform on.
Insider Tip: This is why “skin contact” or maceration is so critical. If a winemaker just presses the juice and throws away the skins immediately, they are throwing away the grape’s aromatic soul.
