Extended maceration

The technique is traditional in Barolo and Barbaresco, where macerations of a month or more were once standard, and it has been adopted selectively elsewhere.

It is the clearest counterexample to the assumption that longer skin contact simply means more tannin.

Once fermentation finishes, extraction continues but the population of extractable compounds is changing. Smaller, harsher tannin fractions polymerise into larger ones, and some of those become insoluble and fall out.

Tannins also bind with proteins, polysaccharides and anthocyanins present in the wine, which changes how they are perceived.

The result reported by producers who use it is a wine that is analytically high in tannin and perceptually smoother — the "sweet tannin" language used in Piedmont.

The risks are real. The wine is unprotected by active fermentation, so the vessel must be sealed against oxygen and the microbiology watched, and volatile acidity can climb.

This is the practice that sits at the centre of the traditional-versus-modern argument in Barolo, alongside oak vessel size.

It is why "longer maceration means more tannin" is an oversimplification, and it is a large part of the difference between traditionally and modernly made Nebbiolo.