Sloe

The astringency problem

Raw sloes are barely edible. The extremely high tannin content — significantly higher than almost any other common fruit — causes instant, involuntary puckering that makes the inside of the mouth feel dry and coated. This astringency decreases after the berries have been exposed to frost (or frozen), which breaks down some tannins. Even after frost, however, sloes are not pleasant to eat raw — they are strictly a processing fruit.

Sloe gin

The primary use of sloes, particularly in Britain: berries pricked all over (traditionally with a silver pin; modern practice uses a fork) are packed into a large jar with gin and sugar, and left to macerate for at least three months — ideally six to twelve. The berries bleed their deep purple-red pigment and astringent compounds into the gin, which sweetens, deepens in colour, and develops a complex plum-almond flavour from the kernel inside the sloe stone. Homemade sloe gin is a British autumn tradition.

Blackthorn hedges

Prunus spinosa (blackthorn) grows as a dense, thorny hedgerow plant across the British Isles and much of Europe. It was planted as stock-proof hedging for centuries — the dense thorns made it impenetrable to animals. Britain’s ancient hedgerows, many hundreds of years old, are the principal source of wild-picked sloes.

Autumn foraging

Sloe picking in September–November is a popular foraging activity in Britain. The competition is modest — few people eat them raw — and the hedgerows are prolific. The standard advice: pick after the first frost, or freeze the berries overnight before using, to break down the tannins.