​The sauce that is today called ket

​The sauce that is today called ketchup (or catsup) in Western cultures is a tomato-based sauce that is quite distinct from Eastern ancestors of this product. A sauce called ke-tiap was in use in China at least as early as 17th century, but the Chinese version of the sauce was made of picked fish, shellfish and spices. The popularity of this Chinese sauce spread to Singapore and Malaysia, where it was called ketchap. The Indonesian ketjab derives its name from the same source as the Malaysian sauce but is made from very different ingredients. The Indonesian ketjab is made by cooking black soy beans, fermenting them, placing them in a salt brine for at least a week, cooking the resulting solution further and sweetening it heavily; this process results in a dark, thick and sweet variation of soy sauce.
​Early in the 18th century, sailors from the British Navy came across this exotic sauce on voyages to Malaysia and Singapore and brought samples of it back to England on return voyages. English chefs tried to recreate the sauce but were unable to do exactly because key ingredients were unknown or unavailable in England. They ended up substituting ingredients such as mushrooms and walnuts in an attempt to recreate the special taste of the original Asian sauce. Variations of this sauce became quite the rage in the 18th century in England, appearing in a number of recipe books and features as an exotic addition to menus from that period.
​The English version did not contain tomatoes and it was not until the end of the 18th century that tomatoes became a main ingredient of the newly created ketchup in the USA. It is quite notable that tomatoes were added to the sauce and that tomatoes had previously been considered quite dangerous to health. The tomato had been cultivated by the Aztecs, who had called it tomatl ; however, early botanists had recognized that the tomato was a member of the Solanacaea family, which does include a number of poisonous plants. The leaves of the tomato plant are poisonous, though of course, the fruit is not.
​Thomas Jefferson, who cultivated the tomato in his garden and served dishes containing tomatoes at lavish feasts, often receives credit for changing the reputation of the tomato. Soon after Jefferson introduced the tomato with the equal and exotic sauce known as ketchap began to appear. By the middle of the 19th century, both the tomato and tomato ketchup were staples of the American kitchen.
​Tomato ketchup, popular though it was, was quite time-consuming to prepare. In 1876, the first mass-produced tomato ketchup, a product of German-American Henry Heizn, went on sale and achieved immediate success. From tomato ketchup, Heizn branched out into a number of other products, including various sauces, pickles and relishes.