Experienced wine connoisseurs can readily distinguish a dry red like Cabernet Sauvignon from a fruitier one like Pinot Noir. Tannins have long been linked to that puckering 'dry' sensation, but the precise way these molecules create it over time remained elusive. Now, researchers have pinpointed how tannin structure, concentration, and interactions with saliva and other wine components shape dryness perception.
Astringency—the wrinkling, rough mouthfeel from wine—occurs as tannins bind saliva proteins, causing them to aggregate and precipitate, which dries out the mouth. To explore further, scientists examined how tannins from a dry Cabernet Sauvignon and a less dry Pinot Noir interact with saliva proteins and the wines' unique traits to influence this sensation.
Extracting tannins from both wines, the team found Cabernet Sauvignon has more, larger, and more pigmented tannins than Pinot Noir, forming greater protein aggregates with saliva. Trained sensory panelists rated Cabernet as drier with longer-lasting dryness than Pinot. Remarkably, adding opposite tannins to Cabernet or Pinot wines yielded no detectable dryness differences—for instance, Cabernet tannins in Pinot wine matched the original Pinot's dryness. Yet, Cabernet tannins in a model wine (ethanol and tartaric acid in water) heightened dryness intensity and duration beyond the base. This indicates the wines' distinctive aromas likely modulate dryness perception, masking tannin swaps.
