Coolship inoculation

What is actually happening

The vessel’s very high surface-area-to-volume ratio cools the wort by morning and simultaneously exposes a great deal of it to the air. Both effects are the point.

The resident microbiota of the brewery building itself — in the timbers, the barrels and the fabric — matters at least as much as the outside air, which is why producers are reluctant to alter their premises.

Typical conditions

Ranges, not targets. These describe what is usual across the styles and breweries that use this step, and a value outside the range is a decision rather than an error.

Styles where this step is decisive

• Lambic5–6.5% ABV

  Spontaneously fermented Belgian wheat beer, matured in oak for years — funky, acidic, dry and unlike any other beer.

Related steps and concepts

• Spontaneous fermentation — What it initiates.
• Coolship — The vessel.