The bright red bottle of ketchup on the modern condiment shelf has wandered a long way from its original. The English word descends, by general scholarly agreement, from kê-tsiap — a southern Chinese (Hokkien) word for a salty, fermented sauce made from fish. The original ketchup contained no tomato at all.
A Sauce Carried by Sailors
In the 17th century, Hokkien-speaking traders from Fujian province carried kê-tsiap across Southeast Asia. Malay sailors picked it up as kechap — a name that survives today in Indonesian kecap, the salty soy sauce. English merchants encountered the sauce in the Malay-speaking ports they used as way-stations on the route to China. By the late 17th century, "katchup" or "catsup" had appeared in English cookbooks.
English Mushroom Ketchup
Early English ketchup recipes were various and inventive. Once the basic idea — a long-keeping, savoury, fermented sauce — had crossed the Channel, English cooks made it from whatever local ingredients gave the right umami punch. Mushroom ketchup, made by salting and fermenting mushrooms, was for two centuries one of the standard pantry condiments of British cooking. Walnut ketchup, oyster ketchup, and anchovy ketchup also had their followings. Each was a fermented sauce, dark and salty, used to flavour stews and meats.
The American Tomato Takeover
The use of tomatoes in ketchup is a 19th-century American innovation. Tomato ketchup was being sold commercially in the United States by the 1830s, and Henry J. Heinz launched his now-famous bottled version in 1876. The Heinz formulation — thicker, sweeter, and made for ease of pouring — spread back across the Atlantic in the 20th century. By the 1970s, "ketchup" almost universally meant the tomato kind, and the older mushroom and walnut versions had become culinary curiosities.