Mushrooms in Britain. (Photo: Andrew/CC BY 2.0)

Halfway through the process of making traditional mushroom ketchup, the dark and leaking fungi looked like a rotting puddle of chunky bog. Chopped, salted generously, left to sit for 24 hours, the pile of portobellos had given up their juice. After the first hour, the mushroom chunks were sitting in a shallow pool of brown liquid. Now they were bathing in it.

It seemed unlikely that this marshy mixture would lead to anything tasty. It was even harder to believe that this was the forebear of today’s sweet, sharp and gloopy tomato ketchup.

The rest of the process was simple enough: Add spices, and boil down. None of this improved the look of the stuff. Boiling, it bubbled up into a dirty foam, like chemicals on the surface of a polluted river. It left a brown ring of mushroom detritus on the sides of the pot. But because of the spices, it had started to smell a bit like mulled wine.

The final product was a deep brown, almost black. I dipped my finger in for a taste. It did not taste bad, or at all like mushrooms. It was salty—very salty—but had a meaty, umami essence. More than anything else, it tasted like soy sauce.  

Which, in a way, was not surprising at all.

That brown stuff is mushroom ketchup—it’s a lot like soy sauce. (Photo: Tummy Rumble/CC BY-SA 2.0)

Ketchup came to England as an idea, rather than a recipe or a product. There’s little agreement on the exact origin of the word ketchup or on the first sauce to have that name. But, according to Andrew F. Smith’s Pure Ketchup, it is clear that British people learned about ketchup from colonial forces and traders that had returned from southeast Asia—they thought of it as a “high East-India sauce,” Smith writes.

It’s not exactly clear what sauce those British travelers were thinking of, though. It might have been a variation of a fish sauce or a soy sauce; one early English-language recipe for ketchup used nutmeg, cloves and peppers as spices but, with beans as the base, it would have been more of a paste than a thin sauce.

The British cooks who first recorded recipes for ketchup didn’t seem much concerned with authenticity, anyway. They were using the name, ketchup, and spices from the east to give a certain excitement and exoticism to an idea they knew well: a mushroom pickle.

Mushroom ketchup in progress is pretty unappetizing. (Photo: Rex Roof/CC BY 2.0)

Early mushroom ketchup recipes, Smith reports, were not that different from the recipes for mushroom pickles that came before them—mushroom ketchup was merely a new twist on the idea that the juice extracted from pickled mushroom could be a sauce in its own right. Some variations included anchovies, creating a fish sauce. One variation, Worcestershire sauce, has its origins in this same tradition of thin, fermented sauces borrowed from Asia.

These pungent, umami sauces were popular from early in the 18th century through Victorian times, and were used on fish, meat, and chicken. (I tried mine on a bite of steak, and it did give it a little extra oomph in flavor.) Today there’s only one commercial brand left, Geo Watkins Mushroom Ketchup, manufactured in Kent by a major British food corporation.

In the past decade or so, mushroom ketchup has had a shade of revitalization among revered British chefs as a throwback ingredient: Heston Blumenthal and Nigel Slater both have published popular recipes for it. Some versions, it must be noted, produce a more paste-like result, less like soy sauce and more like wet cat food.

To be fair sometimes the finished product is, too. (Photo: Rex Roof/CC BY 2.0)

How, though, did the idea of a thin soy or fish sauce evolve into pure-blooded American ketchup? In the 18th and 19th century, Americans were still making recipes that had been imported from Britain, including mushroom and walnut ketchups. Tomatoes, a new world ingredient, were becoming increasingly popular to eat, and it seems the word “ketchup” was a catch-all term that inventive cooks felt they could apply to their experiments with tomato sauces.

The sauces that were categorized as ketchup rather than plain old sauce did share some important qualities with the ketchups of yore, mushroom or otherwise. They were meant to keep a little longer, so they had higher concentrations of vinegar, salt and other preservative ingredients. And they had that key flavor, umami—the original Heinz ketchup recipe used tomato solids to increase the sauce’s umami burst.

Then came the real American innovation. Commercial tomato ketchup recipes added sugar. Lots of it. It probably also helped that tomato ketchup didn’t look like a pile of swamp mud halfway through the process of making it. But soon enough, mushroom ketchup was a faint memory, and tomatoes ruled the condiment aisle.

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