Ketchup started out as a fermented fish sauce

The bottle of red tomato sauce on the table is a young impostor. The word ketchup descends from the Hokkien Chinese ke-tsiap, the name of a sauce “derived from fermented fish” - a salty, savoury brine related to the fish sauces still made across Southeast Asia.

British and Dutch traders met the condiment in Asia in the 17th and 18th centuries and tried to recreate it at home. Lacking the original fish, they improvised: early English “ketchups” were dark purees of mushrooms, walnuts, oysters or anchovies, used as a cooking seasoning rather than a table dip.

Tomatoes entered the story only in 1812, when American horticulturist James Mease published the first known tomato-ketchup recipe.

Even that early version had no vinegar or sugar. The sweet, tangy tomato sauce we know today was refined across the 19th century - most famously by Heinz, which began bottling it in 1876.