If you opened a tin of baked beans to discover a brown gloopy sauce containing brown haricot beans, rather than the orange-red sauce and beans you were expecting, what thoughts would run through your head? Is the tin punctured or past its sell-by-date or is it a different brand – inferior and cheaper, or, possibly, organic and more expensive.


Maybe the beans were processed in a country with different food regulations or practices? Why should brown beans look less appetising than red ones anyway? Such thoughts suggest inherent consumer awareness of why food manufacturers colour food: to make their products look fresher and more appetising, to create brand recognition, to maximise profits, to meet consumer expectations or to comply with national or international regulations.

In many ways, dyes are as important as flavourings in determining how we taste food, with experiments showing that food dyed with different colours, such as apple puree dyed red, changes flavour perceptions. As a result, loss of colour in food processing and the subsequent use of artificial colouring to make our food look fresher, more consistent or even novel is a major issue for food manufacturers.

Indeed, the colour of our food plays a central role in our cultural and psychological understanding of food and experience of consumption. When Burger King launched a black burger in a black bread bun in Japan in 2012, and even blacker versions in 2014, using bread coloured with bamboo charcoal and ketchup blackened with squid ink, American commentators cried ‘gross’ and ‘crazy’. Black was not a colour associated with food in the US, unless it was burnt!

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Yet black was an acknowledged food colour within Japanese culture and so was accepted more easily by consumers there. But within months, the alleged health benefits of activated charcoal led to black bread becoming the latest health fad globally, including in the US. Presenting new foods alongside medical or scientific claims has long been used to alter long-standing, culturally formed ideas about what food should be.

Today’s consumers are constantly bombarded with claims and counter claims surrounding the health benefits or otherwise of food ingredients and additives, much of it related to the colouring of food. Eat red, eat green, eat purple!

While manufacturers invoke science to market their food and improve production, consumer advocates and organic food movements scorn the industrialisation of food. A return to more ‘natural food’ free of ‘chemicals’ is demanded.

Yet all food is comprised of chemicals. So who determines which chemicals are ‘natural’ and which are ‘edible’?

Visit any food trade exhibition and you will experience the contradiction of dozens of food companies promoting natural food products and ingredients – ‘free from chemical additives’ – alongside dozens of manufacturers exhibiting new ‘functional’ food products containing a multitude of chemicals and other additives included to promote health.

Consumers’ confusion is demonstrated clearly in the oft-heard phrase ‘full of E Numbers’ a pejorative term used in Europe to describe supposedly ‘unhealthy’ manufactured food full of harmful chemical additives.

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However, E Numbers, which are ascribed to substances extracted from turmeric, saffron, salt, citric acid and yeast as well as those originally extracted from coal tar and now from petroleum, such as aniline and azo dyes, are only assigned to food additives deemed to be harmless to eat.

It is ironic that mid-20th Century attempts to increase the safety of, and trust in, food, through legislation ensuring that all food ingredients must be approved, scientifically named and included on food labels, have made consumers more concerned, not reassured, about the safety of their food.

Aniline and azo dyes synthesised from coal tar were the first of many new chemical substances, including drugs, fertilisers, perfumes, sweeteners and flavourings, which chemists began to synthesise and produce on an industrial-scale from coal-tar, a waste product of the gas industry.

While concern about their use in food was raised in the 19th Century and continued through the 20th Century, many of the coal tar dyes continue to be recognised as food ingredients despite ongoing legislation restricting their use.

Although manufactured for the textile industry from the 1860s, aniline and azo dyes were soon used to colour a wide range of food and drink products, passing through a complex international supply chain in which dyes were given new innocuous sounding names, such as ‘butter-yellow’, which concealed their industrial origins.

Synthetic dyes from around 1900 © Getty Images
Synthetic dyes from around 1900 © Getty Images

The new dyes often proved cheaper and more effective than alternative plant- and animal-based dyes such as saffron and cochineal. A tiny amount of the new substances could dye large quantities of food and their excellent stability compared with many plant dyes made them more reliable in food processing procedures such as heating, mixing and preserving.

Manufacturers quickly began to exploit the extensive new range of dyes to replace colour lost after processing and to make manufactured food look more natural.

However, the ability to reinforce colour artificially also made it easier for unscrupulous food manufacturers to reduce costs through dilution or bulking out with cheaper ingredients, such as water added to milk or flour added to mustard. The new dyes also helped to extend the shelf life of products, as many of the colours worked as a preservative, having anti-oxidant properties.

By the turn of the 20th Century, the presence of coal-tar dyes in food was a controversial and contested issue. Many people argued that the new synthetic dyes provided a scientific answer to colour and preserve food, increasing the variety and affordability of food available to the public.

Others claimed the safety of the new dyes was not established and that the synthetic dyes, like other artificial colourings before them, were used to disguise the quality and content of food products, thus deceiving the consumer.

To ban all coal tar dyes in food, after food producers and consumers had become accustomed to their use over several decades, would have been a politically and commercially difficult approach. Instead, governments took a variety of actions, including banning certain dyes that were known to be toxic or recommending a restricted list of harmless dyes for use in food.

Approaches varied according to different national cultures and philosophies from countries adopting precaution as a principle of public policy to those favouring a laissez-faire, buyer-beware approach. Regulators turned to chemists to choose which dyes to ban or recommend, and how to regularly update such lists regularly.

However, in a precursor to the risk and regulation dilemmas confronting scientists today, 19th-Century chemists struggled to arbitrate the use of the dyes that were being rapidly and widely introduced into everyday life, in varied and often unintended ways, and whose properties changed when combined with other chemicals.

Devising tests to detect and assess hundreds of new, and constantly appearing, substances was a formidable task, made more difficult both because most of the dyes were new to the testers.

Reaching any kind of consensus among chemists, from different countries and disciplinary backgrounds, over which tests were most appropriate or effective, or over how to standardise tests and their results, proved almost impossible. Chemists remained divided on the subject of toxicity, particularly as a result of the tiny quantities of individual dyes used in food.

Modern food colourings © Getty Images
Modern food colourings © Getty Images

An absence of agreement between chemists working in different sectors, from chemical and food manufacturing to public health, played a major part in ensuring that regulations were never fully secured, and still vary from country to country today.

Synthetic dyes, many of which were found during the 20th Century to be highly toxic, were never intended by their creators to be used as food additives. Their continued use for so long was the result of many factors, including a lack of consensus and status among scientists, political anxiety about food security, consumer expectations and economic competition in the marketplace.

Like many scientific risks we face today, this unintended and unmonitored application of science occurred without any one group being in a position to grasp the full situation. Regulation and control became increasingly complicated as the practice was normalised and vested interest heightened and widened.

We now live in a world saturated with synthetic chemicals. Our society couldn’t function without the hundreds of thousands of synthesised chemicals we use in everything from the food we eat to the packaging surrounding it, our cleaning products and pesticides, our clothes, cars and household furnishings.


However, concerns are increasing about the impact they are having on the environment and our health, with our bodies now playing host to hundreds of synthetic chemicals that did not exist before the 1850s. Aniline and azo dyes were the substances that led to the synthesised chemical industry that has reshaped our world and the food we eat.

A Rainbow Palate: How chemical dyes changed the West’s relationship with food is out now (£32, University of Chicago Press).
A Rainbow Palate: How chemical dyes changed the West’s relationship with food is out now (£32, University of Chicago Press)