Tertiary aromas: what develops with age

Primary aromas come from the grape, secondary from fermentation and winemaking, tertiary from time. The three-part scheme is a teaching device rather than a hard chemistry boundary, but it is a good one.

The important caveat is that these are things that may develop in some wines. A descriptor list is not a schedule.

Fruity esters hydrolyse and decline over the first years, so the fruit character recedes. Very little replaces it in a wine that had nothing else, which is why most wine does not benefit from age.

In wines that do, several slow processes run in parallel: tannin and anthocyanin polymerisation changes texture and colour; bound aroma precursors hydrolyse and release new volatiles; and a small, steady oxygen ingress through the closure drives further reactions.

Characters commonly reported include dried fruit and fig in reds, leather and tobacco, forest floor and mushroom in aged Pinot Noir and Nebbiolo, nuts and honey in aged whites, and petrol in Riesling.

Oxidatively aged wines follow a different and much faster route, driven by deliberate air contact, producing the nut and caramel characters of Tawny Port and Oloroso.

Storage conditions govern the rate. Warmth accelerates all of it, and not always in the desirable direction.

It explains what a drinking window is describing, and why "how long will this keep?" is a different question from "when will this be at its best?".