Sam Lin-Sommer chronicled Heinz Tomato Ketchup’s victory of catsup for tomato sauce supremacy in Atlas Obscura. It came down to marketing, and an attack on those using preservatives:
Thanks in part to high-quality ingredients, Heinz’s new tomato ketchup cost two to three times more than its competitors. But the price increase also paid for the largest advertising campaign the industry had ever seen. In one of several advertisements to grocers, “Heinz stated that grocers should ‘get rid of any chemically preserved foods’ before they were confiscated by the government,” Smith writes. Heinz took out a two-page spread in the Saturday Evening Post that shouted, in block letters: “WARNING! THE U.S. Gov’t Says benzoate of Soda in Foods Produces Injury to Digestion and Health.”
There’s also a good article about the history of Heinz Ketchup on The Lange Law Firm’s website:
Although the ketchup was free of more novel preservatives like sodium benzoate, it wasn’t preservative free in the strictest sense. Instead, the shelf life of the sauce could be attributed to a particular blend of tomato pulp and acidic vinegar developed by Heinz’s cousin Samuel Muller. Blum writes that “He wanted a bacteria-killing acid concentration in the formula and so sought the right balance of vinegar and pectic acid, the latter occurring naturally in tomatoes. To get the acid levels right, Mueller discovered, he needed both high-quality tomatoes and high pulp content. Ketchups had traditionally been thin sauces of mixed content. To create its preservative-free ketchup, the company switched to a thicker, tomato-rich version—the foundation for the condiments of today.”