This post was written by Claire D’Mura, a research and reference specialist in the Library’s Science Section.
So smooth, so dependable. That cheerful red sauce that balances sweet and tangy, forever wedded to French fries. The diplomatic arbiter between toddlers and…well…all other food. Truffle aioli this is not; it’s ketchup. Every day it sits out on tables and counters in diners and cafeterias as plainly as the most basic salt and pepper, reliable and unassuming, perhaps even friendly.
When we dip our fries into a pot of ketchup we don’t often think twice about its quality or safety. While the taste of various brands may differ, we generally know what to expect when buying something labeled “ketchup.” The United States didn’t enact nationwide food manufacturing regulations until 1906. At this time, ketchup was one product that received exceptional scrutiny.
Canned food became a booming industry during the Civil War. After the war, canners began to make products for home use, and ketchup was one of the products that gained popularity. In these early days, the condiment was often made with waste products from tomato canning collected from the cannery floor. Preservatives were not added until cooking, after spoilage had already begun. Food colorings, often made from coal tar, were added to make the product look better. The product did not keep well and was very different from the ketchup we use today.

That we now have such consistent and shelf-stable ketchup available at every turn is thanks in part to the work of renowned culinary collector, Katherine Bitting. At the Library, Katherine is most known as the author of the Gastronomic Bibliography and a donor of more than 4,000 books on food, cooking and preservation — one of the most robust collections of culinary texts in the world. The Katherine Golden Bitting Collection is part of the Library’s Rare Books and Special Collections.
Katherine and her husband, Arvill, were analysts in the United States Department of Agriculture’s Bureau of Chemistry. Arvill was an inspector, a role created with the 1906 Pure Food and Drugs Act, and Katherine worked in the lab as a microbotanist. Their most well-known project at the USDA was to analyze commercially bottled ketchups for defects and adulteration. They were also asked to show a method for making the sauce shelf-stable without leaning on preservatives.
Arvill inspected factories and reported on conditions that would make anyone’s skin crawl. The poor practices began at tomato canning factories, before any product was being made into ketchup. Sanitization was practically nonexistent, with barrels, machinery and bottles having only been rinsed prior to use, if even that. At these factories, tomato pulp was made from leftover skins, cores, and peels; from tomatoes that were either green or rotten, and from drippings from the machinery. This muck was collected in barrels that sat out until they could be loaded onto train cars for delivery to the ketchup factories. At this stage, the tomato pulp began to spoil. Arvill noted in his 1909 report Experiments on the Spoilage of Tomato Ketchup, “As a result, it is not uncommon to see an inch or more of pulp in the bottom of a car at the end of shipment, caused by the blowing out of the barrel heads from fermentation (pg. 13).”

To be fair, there were some manufacturers at the time that used only ripe red tomatoes and more meticulous production practices. However, these were the exception rather than the rule, and the public had few resources to tell the difference.
Due to the inadequate sanitation practices, most manufacturers relied heavily on preservatives, particularly sodium benzoate, to extend the short life of their bottled ketchup. This preservative had been part of Harvey Wiley’s Poison Squad experiments, and he opposed its use fervently. Many manufacturers clung to the preservative just as fiercely, arguing to Wiley that it was not possible for them to make preservative-free ketchup, and calling into question the truth of any manufacturer’s claims that their product did not have any. An article in the June 24, 1907 issue of the Food Law Bulletin called out Wiley, arguing, “Dr. Wiley should prove his case or inform the manufacturers how to put up catsup before making a ruling against its use” (pg.120).
Wiley responded to that challenge and assigned the Bittings the task of demonstrating a way to make ketchup a sound product without preservatives.
The Bittings put together a laboratory in their home. Andrew F. Smith, the author of Pure Ketchup: A History of America’s National Condiment (2001), described the setup as “a small copper kettle jacketed at the bottom so that steam could be used as a heat source, a boiler with one hundred pounds of pressure, and a small retort for sterilizing bottles after they were washed” (p. 82). Homemade ketchup was known for being less prone to spoilage than commercial ketchup, so Katherine collected recipes for ketchup from magazines and cookbooks as part of her research. They examined store-bought ketchup as well as ketchup they made themselves.

Katherine analyzed commercial ketchup products to assess the presence of molds and fungi and observed the cellular appearance of the tomato pulp itself. Through these observations, she could tell if a ketchup was made using already-spoiling tomato pulp, or if it had been dyed artificially. One particularly egregious sample was described thusly:
“This ketchup was guaranteed to be made from fresh, ripe, tomatoes by a new process. The color is an unnatural red, has not faded, and the odor is good. The microscope showed the presence of much refuse, and large quantities of fungi, whole colonies of molds, the filaments distorted, many yeast cells, and bacteria. The red color was not confined to the red crystalline bodies, as is the case in ripe tomatoes, but the whole of the protoplasm of the cells, including the nucleus and nucleolus was red, as were also most of the mold filaments and yeast, indicating the presence of considerable artificial coloring matter. The structure indicated that the stock had been manufactured from “trimmings,” and further, that they were not fresh when used, but had fermented.” (Experiments on the Spoilage of Ketchup, United States Bureau of Chemistry Bulletin #119. 1909, p. 34)
In all, the Bittings examined over 1,600 bottles of ketchup, visited 40 canneries producing tomato pulp, and toured 20 ketchup factories. In their research, they found that homemade ketchups were thicker and contained more vinegar and sugar. The vinegar was added earlier in the cooking process, giving time for much of the pungent edge to boil off.
The findings from these experiments were first published in USDA Bulletin #119 in January of 1909 and were expanded in 1915 into Ketchup: Methods of Manufacture (Lafayette, IN, Murphey-Bivens Co. Press). This publication described the Bittings’ research in detail, from the harvesting of tomatoes to the finished product.
The Bittings recommended changes at every step of ketchup production. Per their guidance, ketchup should be produced in a sanitary factory using fully ripe (but not overly ripe) tomatoes. More vinegar should be added, it should be cooked till thicker and sterilized upon finishing. Tomato pulp should be stored in lacquer-coated cans, not wooden barrels or casks.
The Bittings weren’t the first to come up with a way to mass produce preservative-free ketchup. A few companies, such as Heinz, Shrewsbury, and Columbia Conserve Company, had already begun making preservative-free ketchup through their own proprietary recipes. The Bittings’ research brought these methods into the open. Manufacturers could no longer cling to the argument that preservative-free ketchup was impossible.

In the end, an advisory board of scientists from universities around the country declared that sodium benzoate was safe in small quantities, and as of January 2025, the preservative is still “generally recognized as safe” in small quantities by the Food and Drug Administration. By that time, however, the market had spoken. It was clear that sodium benzoate was not necessary, regardless of whether the ingredient was harmful, and most manufacturers moved on from the preservative. The preservative’s reputation had been damaged, and the public now saw the additive as dishonest and an attempt to hide unscrupulous manufacturing practices.
After their ketchup experiments, Katherine and Arvill also moved on, leaving the USDA for the National Canners Association, and later the Glass Container Association, where they continued to investigate foods and their preservation.
Today, standards for ketchup are defined in the United States Code of Federal Regulations (21 CFR 155.194) and the USDA Agricultural Marketing Service assigns quality “grades” to products meeting those standards.
Of course, the U.S. still experiences food-related scandals every year, but the differences between now and the early 1900s are stark. Instead of worrying about whether the ketchup in the bottle you just picked up is putrid, has been colored red unscrupulously, or even has tomatoes at all, you can focus on more mundane ketchup concerns: “Can I have more ketchup for these fries?” or “Is there a spare bottle in the cupboard?”
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