[7][8][9] In the United States, mushroom ketchup dates back to at least 1770, and was prepared by British colonists in the Thirteen Colonies.

In 1824, a ketchup recipe using tomatoes appeared in The Virginia Housewife (an influential 19th-century cookbook written by Mary Randolph, Thomas Jefferson's cousin).

People were less hesitant to eat tomatoes as part of a highly processed product that had been cooked and infused with vinegar and spices.

[20] Modern ketchup emerged in the early years of the 20th century, out of a debate over the use of sodium benzoate as a preservative in condiments.

In response, entrepreneurs including Henry J. Heinz, pursued an alternative recipe that eliminated the need for that preservative.

[citation needed] Katherine Bitting, a bacteriologist working for the U.S. Department of Agriculture, carried out research in 1909 that proved increasing the sugar and vinegar content of the product would prevent spoilage without use of artificial preservatives.

[22] They had less vinegar than modern ketchups; by pickling ripe tomatoes, the need for benzoate was eliminated without spoilage or degradation in flavor.

But the changes driven by the desire to eliminate benzoate also produced changes[clarification needed] that some experts (such as Andrew F. Smith[23]) believe were key to the establishment of tomato ketchup as the dominant American condiment.

[24] Some fast food outlets previously dispensed ketchup from hand-operated pumps into paper cups.

This method has made a comeback in the first decades of the 21st century, as cost and environmental concerns over the increasing use of individual plastic ketchup tubs were taken into account.

In October 2000, Heinz introduced colored ketchup products called EZ Squirt, which eventually included green (2000), purple (2001), mystery (pink, orange, or teal, 2002), and blue (2003).

There are citations of koe-chiap in the Chinese-English Dictionary of the Vernacular or Spoken Language of Amoy (1873) by Carstairs Douglas, defined as "brine of pickled fish or shell-fish.

"[33] Ketchup may have entered the English language from the Malay word kicap (pronounced [kitʃap], sometimes spelled kecap or ketjap).

American anthropologist E. N. Anderson relies on Elizabeth David to claim that ketchup is a cognate of the French escaveche, meaning "food in sauce".

[29] The word entered the English language in Britain during the late 17th century, appearing in print as catchup (1690) and later as ketchup (1711).

[38] The following table compares the nutritional value of ketchup with raw ripe tomatoes and salsa, based on information from the USDA Food Nutrient Database.

[39] Commercial tomato ketchup has an additive, usually xanthan gum, which gives the condiment a non-Newtonian, pseudoplastic or "shear thinning" property—more commonly known as thixotropy.

[citation needed] This increases the viscosity of the ketchup considerably with a relatively small amount added—usually 0.5%—which can make it difficult to pour from a container.

However, the shear thinning property of the gum ensures that when a force is applied to the ketchup, it will lower the viscosity, enabling the sauce to flow.

[40] These techniques work because of how pseudoplastic fluids behave: their viscosity (resistance to flow) decreases with increasing shear rate.

[43] In 2017, researchers at the Massachusetts Institute of Technology reported the development of a bottle coating that allowed all the product to slip out without leaving a residue.

[44] In 2022, researchers at the University of Oxford found that splatter from a near-empty bottle can be prevented by squeezing more slowly and doubling the diameter of the nozzle.