Food: A chemical history

Chemical food additives have a long history. In ancient China, paraffin wax was burnt to ripen fruit—this worked because it caused traces of ethylene and propylene to combine with the food. The Egyptians coloured food with saffron, while the Romans added alum (potassium aluminum sulfate) to bread to make it whiter. 

The first deliberate use of a food additive was likely salt to preserve foods such as fish and meat, which works by dehydrating the food to limit bacterial growth. However, it wasn't until the 19th century that the microbial cause of food spoilage was understood.

In the 17th century, efforts were made to find a new method of food preservation without the need for additives. Robert Boyle—considered one of the pioneers of modern chemistry—led these investigations, experimenting with storing food in air-free containers. 

In the very early 19th century, a new preservation technology was developed in response to the military need for preserving food during the Napoleonic wars.

This revolutionary technology was the tin can, which combined sealing food in an air-tight container with heat sterilisation.  

Canned food is not without its risks to human health, however. The food inside could become contaminated with lead (early cans were sealed with lead alloys) and tin, which acidic foods like fruits can corrode. 

To avoid this problem, some modern cans have plastic linings made from bisphenol-A (BPA)—a now-notorious chemical compound that studies have found interferes with our hormones. Manufacturers have removed BPA from their can linings in recent years in response to these findings.

Food additives in the age of industry

The use of food additives increased dramatically during the Industrial Revolution, with toxic compounds used liberally in factory food production. These ranged from the colouring of Gloucester cheese with red lead to sweets being coloured green with copper arsenite—also used in the wallpaper that may have have been a factor in Napoleon's death. 

As the food processing industry grew and chemists synthesised new artificial thickeners, emulsifiers, colours and flavours, regulatory bodies were formed to control the adulteration of food for human consumption. 

Concern about the toxicity and carcinogenicity of additives intensified in the middle of the 20th century, as analytic chemistry made detecting and measuring additives easier.

This soon led to international regulation like the European Union’s E-number system for approved additives, introduced in 1962.

Science Museum Group Collection Image source for Glass vial with handwritten label

The invention of artificial substitute foods is a relatively recent enterprise.

Margarine was the first, developed in 1869 as a solution to Napoleon III's desire to find a cheaper alternative to butter—which was in scarce supply—for the working classes.

Its inventor, the French chemist Hippolyte Mège-Mouriès, derived his product from beef tallow, after experimenting with the fatty acid margarique. This had been discovered by his compatriot and fat chemistry pioneer Michel Eugene Chevreul. 

Mège-Mouriès sold his patent to the company that would become Unilever, the world’s largest producer of margarine.

Although it's chemically white, the margarine we know today is yellow, to imitate the colour of butter. But it hasn’t always been so. In the early 20th century laws were passed in several US states that made any colour but pink illegal, so that consumers wouldn’t be misled into thinking it was butter. 

At around this time, chemists refined the hydrogenation process (introducing hydrogen to turn oils into semi-solid fats) in the production of margarine, leading to the replacement of animal with vegetable fats.

In doing so, margarine became even cheaper. There was also a belief that such unsaturated fats were healthier than the saturated fats of animal products like butter. 

As the 20th century wore on, however, mounting evidence linked the trans-unsaturated fat of margarine with heart disease. 

Governments and industry responded. Butter substitutes now contain greater amounts of saturated fat, such as palm oil—though there are environmental consequences to this change, caused by the mass deforestation of oil palm trees. 

Science Museum Group Collection

As well as substitute foods like margarine, chemists have also developed substitute ingredients, such as artificial sweeteners. 

Saccharin was the first of these, named after the sugar cane genus.

Discovered in 1879 after a chemist noticed a sweet-tasting substance on his hand from experimenting with coal tar derivatives, saccharin is between 300 and 500 times sweeter than sugar. 

Its commercial success was driven by the need of people with diabetes (and later dieters) to find a sugar substitute.    

But like many chemical additives, there are concerns around the adverse effects of saccharin on health—for decades its use was banned in the USA.