Mutage

What it is

Mutage (English: fortification) is the addition of neutral grape distillate to the base wine of sherry after first fermentation, to raise the alcohol content to the level that defines the desired style. It is the critical decision step that ultimately determines whether a sherry becomes a Fino, Manzanilla, Amontillado or Oloroso.

The distillate

Not just any alcohol. Consejo Regulador rules require:

• Grape distillate: alcohol must come from grapes, not grain, not sugar beet
• High percentage: usually around 95 percent alcohol by volume, near pure ethanol
• Neutral: no aromatics, no flavour of its own
• EU origin: distillate must be produced inside the EU

The neutrality is essential. The character of the sherry comes only from the grape, vinification and ageing. The distillate does nothing but raise the alcohol content.

Second key decision

After first fermentation the base wine (from Palomino grapes) sits at around 11 to 12 percent alcohol. At that moment the capataz decides how to proceed:

Mutage to 15-15.5 percent → wine goes under flor, biological ageing → Fino or Manzanilla. Above this threshold flor cannot survive, so the level is hit precisely.

Mutage to 17+ percent → flor dies off, only oxidative ageing is possible → Oloroso. The higher alcohol also acts as preservation during long oxidation.

Amontillado and Palo Cortado

Special cases:

• Amontillado: starts as a Fino (mutage to 15 percent), ages biologically under flor. Later in the process (after 5-10 years) the wine is fortified again to 17 percent. Flor dies, oxidative ageing begins.
• Palo Cortado: emerges spontaneously when a Fino loses its flor during biological ageing (without additional fortification). Rare.

In practice

Mutage takes place in a combinador tank: a large tank in which the distillate is gradually mixed with base wine under strict temperature control. Too fast and you get thermal shock; too slow and there’s a risk of uneven distribution. The wine rests for several weeks before the classification is final.

Important rules

• Not all sherry is fortified. Vino de Pasto experiments and some new still wines from Jerez are bottled as ordinary white wine (~12 percent) without mutage.
• Mutage must take place before the start of oxidative ageing.
• The alcohol percentage on the label reflects the post-mutage figure plus any evaporation during years of ageing (can rise to 18-20 percent in old Olorosos).

For the drinker

A sherry’s alcohol percentage tells you something direct about its production route: 15-15.5% = biologically aged (Fino, Manzanilla). 17-18% = oxidative (Oloroso, old Amontillado). 17-22% = long-aged and partly evaporated.