Protein-Precipitable Tannins (pTAN)

Figure 1. WINEXRAY's representative phenolic profile of a 21-day macerated Bordeaux varietal fermentation (The Future of Winemaking: Honoring the Vision of Professor Roger Boulton, 2022). Protein-Precipitable Tannins (pTAN) are grape and stem derived tannins that react with saliva and are responsible for structure, aka the breadth of tannins on the palate. They are very stable and malleable using different controls throughout the grape growing and winemaking. To quantify pTAN, we use the Adams-Harbertson Assay which was designed to mimic human senses using Bovine Serum Albumin to precipitate grape-derived condensed tannins. For this reason, it has the highest correlation to astringency out of any analysis in the world. In our experience, pTAN is a better metric for structure, or the breadth of astringency on the palate, as astringency depends on the concentration and activity of the tannins as well as other matrix variables related to the wine (sweetness, ABV, etc.). The assay also do