How can a wine taster distinguish between so many different types of "pepper" in a wine?

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Dear Dr. Vinny,
I often read tasting notes that mention pepper, crushed pepper, black pepper, white pepper, green pepper, peppercorn, etc. How does a taster identify such specific notes of “pepper”?
—Lynn, Dana Point, Calif.
Dear Lynn,
Wine can offer an incredible array of aromas and flavors. The peppery notes found in wines might be coming from chemical compounds found in the grapes themselves, or from chemical compounds released by the fermentation process. For example, rotundone is a chemical compound found in black pepper and other spices as well as in grapes. Pyrazines, also found in some wines, are aromatic compounds that cause bell pepper or grassy aromas. Either or both of those chemical compounds can result in various types of pepper notes in a wine.
Other times, the collection of tastes and aromas in the grapes that are unlocked by fermentation and mingled with the influence of oak barrels might just remind someone of peppery notes.
As far as making that specific distinction between white pepper vs. cracked black pepper vs. peppercorn, that’s in the mouth and nose of the taster and their effort to craft a tasting note that is as evocative as possible of the wine as they experience it. And not all tasters are going to experience a wine the same way, so it’s great when you find a taster whose tastes align with your own.
And some wines have more precision to their flavors and aromas than others—a simple wine might just taste like generic red fruit while a more complex wine might reflect raspberry sorbet and fresh cherry compote. It’s the same with pepper, and how those notes come across can also be very dependent on the other characteristics of the wine—sometimes the pepper might be dominant, while more frequently there’s just a hint.
—Dr. Vinny