Contemporary debates about food harken back to unresolved questions from the 19th century when industrial processing was in its infancy. The transformation of food into a commodity, produced far away by people one did not know presented several dilemmas, among them: where was the line between purity and adulteration? What was the balance between consumer choice and safety? And, who was responsible for an increasingly complex food system? Carolyn Cobbold’s A Rainbow Palate: How Chemical Dyes Changed the West’s Relationship with Food addresses these fundamental questions by examining the widespread incorporation of synthetic dyes into food and drink starting in the mid-19th century. Cobbold’s carefully researched and well-argued book encourages readers to rethink common assumptions about the food system.

Cobbold’s story begins with an explanation of how the ubiquity of synthetic food dyes in the late 19th century was unforeseen, even accidental. The classes of aniline and azo dyes created from coal tar (a byproduct of coke and coal gas production) were first used and intended to color textiles. The assumption that textile dyes should be used in food was perhaps not as illogical as it might appear. First, new mass processing techniques sometimes changed the appearance of foods, making them less appetizing. Second, the mineral and metallic dyes used in the mid-19th century were increasingly shown to be toxic, as frequently discussed in the Victorian press. And, finally, the coal tar dyes were cheaper, more effective, and more stable than plant-based dyes. With this starting point, Cobbold proceeds to explain how these dyes were “legitimized as food ingredients” over subsequent decades (p. 18).

There are many reasons that Cobbold’s story is compelling. Her research is detailed and extensive, using many archival sources along with other primary and secondary ones. She also makes good use of the scientific and mainstream press, juxtaposing the opinions of chemists, government policymakers, and consumers. Lengthy excerpts from press articles, in particular, convey the flavor of shifting public discourse. A Rainbow Palate is also compelling due to Cobbold’s clear writing, accessible to those with little background in chemical history; the book is punctuated by helpful signposts summarizing and linking sections together. One other strength of the book is Cobbold’s decision to compare and contrast the differing reactions to synthetic food dyes in four countries: Great Britain, France, Germany, and the United States.

In each of the four countries that Cobbold discusses, the reactions to synthetic dyes hinged on how food “purity” was defined, as well as the roles of particular actors: chemists, government regulators, food manufacturers, and individual citizens. The juxtaposition of purity and adulteration appeared to be straightforward in particular instances, such as the use of toxic mineral dyes or the addition of any dye that was intended to disguise spoiled food (turning grey meat red) or deceptively misrepresent its nature (using yellow dye to make people think margarine was butter). Yet, Cobbold demonstrates that defining adulteration was “a slippery and contested concept” depending on the intent of using a particular ingredient and “disputes between rival groups of knowledge experts and merchants.” (p. 27)

Such disputes among experts were fueled by the institutional roles of various groups. For instance, the “high profile” of chemists in the “political, educational, and industrial circles in both France and Germany” – as opposed to Great Britain – led these chemists to view food dyes as an opportunity to burnish their reputations as experts; the reputation of German chemists was also solidified by the growth in that country’s industry which dominated world production by the 1880s (p. 157). Meanwhile, government chemists in Britain were less secure in their status and were keen to assert their identity as “researchers” not “regulators.” (p. 132) No matter what the country, chemists who worked in universities, for food manufacturers, and as government employees all served different masters, and thus held different opinions about the meaning of “adulteration.” For example, food manufacturers and their chemists might argue that if an ingredient (such as a dye) was not harmful – and even made a food more appealing by improving its appearance – than it was not an adulteration, whereas chemists hired to analyze food to determine its “purity,” argued that any additions unknown to consumers were deceptive and therefore adulterations.

One impediment to determining what was pure and what was adulterated was the difficulty of detecting synthetic dyes in the late 19th century. Cobbold explains that chemists in various countries used trial and error to uncover the presence of dyes. Not only were the dyes used in minute quantities, but so many were being synthesized quickly that chemical analysts could not keep up. Moreover, the explosion of new dyes – made without standard formulations by different companies – made it more difficult to figure out if any were harmful. Such confusions contributed to the different regulatory solutions chosen in Britain, France, Germany, and the United States. For example, France and Germany banned particular dyes for use in food, implying those not banned were safe (although they had not been proven so); and, by 1907, the United States allowed only seven designated dyes to be included in food, though the safety of this list was also unreliable (as demonstrated by later analysis). Britain lagged behind the other three, not adopting any meaningful regulation of dyes until well into the 20th century.

Haphazard regulations point us back to the balance between choice and safety, and who was responsible for the safety of food. If consumers wanted food items whose appearance was enhanced by dye was that less important than if such a food was adulterated? Moreover, if food were to be deemed safe, was such a standard absolute or relative? Whatever the definition of pure or safe food, who would enforce those protections? To one degree or another, each of the countries Cobbold discusses logically gives at least some of that responsibility to the government (though it took longest to do so in Britain). But Cobbold explains the ineffectiveness of government regulations with the conclusion that by the early 20th century, “there were already too many dyes on the market to police effectively.” (p. 180) There is no doubt that challenging an entrenched market and all its constituencies is extremely difficult, though I would caution not impossible had governments implemented more stringent regulations instead of deferring to a powerful food industry, the self-interested expertise of chemists, and unthinking consumer desires.

Carolyn Cobbold’s A Rainbow Palate lays out the confusions and competing interests that follow the widespread use of synthetic food dyes in the late 19th century. She explains how the debates over food dyes were not just about this one ingredient. They illustrated the broader issue of creating “a system of trust surrounding industrialized food.” (p. 192) Cobbold’s insights about the 19th century help us to understand why this system of trust has become frayed in the 21st century.