Why does Ribera del Duero taste like that?

Characteristically medium-plus tannin and medium-full body. Commonly associated with red cherry, dried strawberry, leather, tobacco.

Not claiming: That every wine from this variety shows these characteristics. This is the range across the category, and site and winemaking move wines within and beyond it.

A wide day–night temperature range is associated with better acid retention, because cool nights slow the respiration that consumes malic acid while warm days continue to ripen the fruit.

Not claiming: That altitude or continentality guarantees high acidity. Both widen diurnal range on average and neither determines the outcome.

Elevation lowers mean temperature and generally widens the diurnal range, both of which are associated with better acid retention. It also raises ultraviolet exposure, associated with thicker skins and higher phenolic content.

Varies: High-altitude sites at low latitude can be extremely hot by day despite a low mean temperature, so the effects do not all point the same way.

Not claiming: That high altitude always means high acidity.

Fermenting on the skins extracts phenolic compounds, including the tannins that produce astringency. Extraction rises with time, temperature and alcohol level.

Varies: Extraction is not linear. Anthocyanins come out early and quickly; tannins continue throughout and beyond fermentation, and post-fermentation maceration can reduce perceived astringency by polymerising them.

Not claiming: That longer maceration always means more perceived tannin. Extended maceration frequently softens a wine rather than hardening it.

Anthocyanins are extracted from black grape skins during skin contact, which is where red wine colour comes from. Most extraction happens in the first days.

Not claiming: That colour depth indicates quality or body. Nebbiolo is pale and highly tannic; deeply coloured wines can be light-bodied.

Vanillin and oak lactones are extracted from oak into the wine, in quantities that fall sharply with each use of a barrel.

Varies: Species, grain, seasoning, toast level, barrel size and the age of the barrel all change what is extracted and how much.

Not claiming: That oak produces buttery character. That comes from malolactic fermentation. Nor that a given oak origin yields a given flavour.

Slow oxygen ingress through the staves and bung promotes polymerisation of tannins and anthocyanins, which stabilises colour and is generally associated with a softer perception of tannin.

Not claiming: That an old barrel is equivalent to a steel tank. Aromatic extraction falls with use; oxygen permeability does not.

Rioja’s ageing classifications set minimum periods in oak and in bottle, so extended oak maturation is a legal requirement for the higher tiers rather than only a stylistic choice.

Not claiming: That Tempranillo requires oak, or that the convention applies outside the regions that codify it.

Eight to fifteen years for Reserva and Gran Reserva. The altitude and the diurnal swing give Tempranillo here more acidity and firmer tannin than Rioja, and it needs longer to open.

Not claiming: That a wine of this style will develop these characters. Ageing potential varies by producer, vintage and storage, and most wine is better young.