Colours on trial

You've heard of the Maguire Seven, the Birmingham Six and the Guildford Four. Now meet the Southampton Six: Sunset Yellow (E110), Quinoline Yellow (E104), Carmoisine (E122), Allura Red (E129), Ponceau 4R (E124) and Tartrazine (E102).

And their crime? A UK Food Standards Agency (FSA) study carried out by the University of Southampton found that children given drinks containing combinations of these colours and the preservative sodium benzoate (E211) became more hyperactive than those in control groups.

When the findings were published in The Lancet​ last September, they fuelled a media frenzy, prompting the UK's major retailers and manufacturers to accelerate programmes to get rid of them.

Despite the European Food Safety Authority's conclusion that changing acceptable daily intakes of these colours was unnecessary, the FSA still pressed for regulatory action at an EU level, which has baffled many observers.

The anti-synthetic sentiment seems to be spreading. In April, 42 organisations across Europe called for the EU Commission to suspend the use of the six colourings, and on June 3, the US Center for Science in the Public Interest filed a petition with the US Food and Drug Administration to ban eight artificial colours. And in Europe at least, it's worked. The European Parliament has since agreed that all food products using these six colours must now contain the phrase: 'May have an adverse effect on activity and attention in children.'

"As a global food colour company we see a strong trend towards 'naturalness' in food products in Europe and even globally," agrees Kristin Johannsen of Sensient Food Colors Germany. "The consumer preference for natural foods is growing Europe wide."

Leatherhead Food International's Food Additives Report valued the global market for food colours at $1.15bn in 2007, with sales growing by 2.5% year-on-year, with growth driven by the natural colours sector, which is increasing at nearly 5% vs growth in synthetics of just 1%. According to LFI, natural colours now represent almost a third (31%) of the market: Report author Catherine Hill predicts: "It's highly possible natural colours will push synthetics into second position in the medium term."

Although natural colours hold obvious attractions for consumers, from a product developer's perspective, the technical limitations that nature has imposed on them can cause headaches.

"It's a no-brainer for food technologists to work with synthetic food colours because they are so easy to use," says Stephen Lauro, general manager of colorMaker, a supplier of natural colour blends that works in partnership with US caramel colour specialist DD Williamson. "Synthetic colours are available as water soluble dyes and insoluble lakes. They are very heat stable, so you can use them in, say, retortable cans of soup or extruded breakfast cereal. They are pH stable, so are just as easy to use in an acidic salad dressing as a neutral mayonnaise."

Natural colours, on the other hand, may be sensitive to heat, light, oxygen and pH, which can limit their use and means that substitution is product specific.

"If you're using Sunset Yellow in a pasteurised beverage with a low pH, your replacement would be turmeric; in a canned drink, you'd use saffron because turmeric is light sensitive," explains Lauro.

No natural alternative​

For some applications, there is no natural alternative. Anthocyanins are the polyphenolic pigments responsible for the red to blue colour in a range of fruit. However, they are pH sensitive, and will change from being blue at pH7 to red at pH3, making it impossible to create a naturally coloured blue, purple or green beverage with an acid pH.

"There is no natural blue colour that is stable at an acidic pH," says Lauro. "Blue is a primary colour and, without it, natural colour blends are limited in the number of hues that can be achieved."

Carotenoids are oil soluble natural colourants such as beta-carotene, annatto and paprika. But they are not water soluble, which has made them difficult to disperse and use. However, colour suppliers have now addressed this issue. "To address oil soluble pigments like carotenoids in water-based food there is a need for emulsification," says Sensient's Johannsen. "We offer carotene emulsions which fulfil the highest stability requirements."

UK-based Overseal Natural Ingredients has developed water miscible forms of these oil soluble pigments, which are sold under the Em-Seal brand name. The company says Em-Seal emulsions offer excellent dispersability in a range of applications.

Where clarity is required, Overseal offers its Clear-Col micro-emulsions of naturally oil soluble pigments. The key factor which governs the clarity of the final product is the emulsion droplet size. Standard stable emulsions have a droplet size of 1µm, but to achieve the clarity of Clear-Col emulsions, droplets are just 0.1µm.

For some colours, like lutein and curcumin, light degradation as a result of oxidation is an issue. Overseal says that synergistic antioxidant systems minimise colour fading to the extent that it is not a limitation to use of these colours. Curcumin, for example, has successfully been used in confectionery applications.

Chr Hansen meanwhile, has developed a patented encapsulation technology which it claims ensures that all the standardised natural colours in its CapColors range stand up to the demands of modern food processing. Advantages of the CapColors range include improved stability to light, pH and oxidation, reduced colour migration, extension of natural colour shades, increased colour intensity and brightness and the availability of water dispersible forms of oil soluble pigments.

The challenges of using natural colours and natural foodstuffs are not just confined to technical limitations. Because natural colours are derived from plants, fruits and vegetables, there can also be issues with availability and variability.

"The weather and the quality of the harvest, the cost of raw materials and transport are challenging factors," says Charlotte Gylling Olsen, Chr Hansen product manager.

"We have limited our vulnerability by sourcing certain raw materials from several locations. One example is the black carrot, which we source from Denmark, Germany and France."

One raw material that is particularly vulnerable to natural forces is paprika. "India is the main grower of paprika, supplying 70% of global demand and the season is only two or three months long," says Brijesh Tibrewala of ROHA Caleb UK. "So this year, when the rain came in a little early and damaged the crop, it led to severe shortages and pushed up prices."

Natural options out of reach​

With margins already squeezed by escalating fuel costs, such price increases are pushing natural colours out of the realms of affordability for many, says ROHA.

Variability can also be an issue with natural colours, as Lauro explains: "These are agricultural products, so their colour depends on when they are grown, where they are grown, how they are harvested and how they are extracted.

"We often run into problems where we'll buy red cabbage from two different suppliers, and although they are the same cabbage, they are completely different colours. In the food industry, consistency is king, so we are constantly adjusting our standard to make sure we supply the exact colour each time."

One of the most exciting things about natural colours is that there are still many more out there waiting to be discovered.

"Some of the up and coming ones are the Amazonian berry açai, kokum from India and hibiscus from Central and South America," says Lauro, "and I believe Turkey has boundless varieties of carrots which have yet to be investigated. As demand grows we'll see more farmers and extraction firms looking at these fruit and vegetables."

Time will tell whether as yet undiscovered colour sources hold the key to seemingly insurmountable technical issues. But if they do, maybe food technologists could learn to love natural colours as much as consumers seem to.