4-Methylimidazole (4-MeI), a trace element created naturally in the heat processing of everything from roasted coffee and baked goods to Class III and IV caramel colors - first hit the headlines a few years ago when Californian regulators proposed adding it to the Proposition 65 list of compounds that may require a warning label alerting shoppers that they contain 'known carcinogens'.
The eventual ruling - which came into force in 2012 - required warnings on all products sold in California containing levels above a 'safe harbor' amount of 29 micrograms a day.
Meanwhile, in early 2011, the Center for Science in the Public Interest (CSPI) upped the ante by petitioning the FDA to ban caramel colorings containing 4-MeI, which executive director Michael Jacobson claimed "may be causing hundreds or thousands of cancers in the American population".
According to the FDA, you'd have to consume at least 1,000 cans of cola a day to consume the amounts of 4-MeI used in the controversial rodent studies that prompted the media storm in the first place.
However, caramel color suppliers have worked hard to formulate products with substantially reduced levels of 4-MeI to meet Prop 65 standards, despite the fact that there is no evidence that the regular variety poses any health risk.
Low, not zero...
But how low can you go, and are media reports of 'zero MeI' colas accurate?
Not really, says caramel color specialist Sethness, which has seen strong demand for its DSL4 lowMeI product, which is ideal for colas.
"You can go down as low as 2ppm (parts per million), but there are trade offs with shelf-life when you get down that low. We describe our DSL4 low-MeI product [which is consistent with Prop 65 requirements] as 'less than 30ppm', although it's actually closer to 20ppm - or sometimes less.
"But it's not a 'zero' MeI product, and customers do not have to compromise on shelf-life."
PepsiCo vs Coke
So how has the industry responded to the Prop 65 challenge?
Some firms - notably PepsiCo - initially just reformulated products sold in California with low-MeI caramel colors - given that all major regulatory agencies including the FDA and EFSA have concluded that regular 4-MeI levels do not pose a health risk. However, tests conducted by the Center for Environmental Health suggest that rival Coca-Cola now uses low-MeI colors across the US and PepsiCo has since announced plans to switch to low-4-MeI nationwide by next February.
Requests for low-MeI caramel colors are also coming in from the baked goods sector, said Sethness, which produces the low MEI variants from plants in France and Iowa and has just started testing a product made in India.
But there are different challenges depending on the source material for caramel color, which varies by country, with the US plant using corn syrup whereas the French plant uses wheat, for example.
So what about GMOs?
It's a complex issue, says the firm, in that its US caramel colors made from GM corn are actually GMO-free in that PCR tests show they contain no detectable GM proteins or DNA. However, you can't label them as 'non-GMO' as they are still derived from GM crops.
While some US customers are starting to ask whether the firm has non-GMO varieties (it does), not many are actively switching at this point, says Sethness, although this may change in future if GMO labeling initiatives gain more momentum.
Petfood and upmarket beers
So what's next for caramel colors?
Carbonated soft drinks are a huge market, but cola volumes are flat or declining in many mature markets, says Sethness.
However, there are new growth opportunities for caramel colors, particularly in petfood and craft beers.
Pictured left to right: Brian Sethness and Tom Schfreider