Quirks & Quarks

'Where's the blue food?' Scientists find source for natural blue food dye in red cabbage

A natural alternative to blue food dye has been very challenging to find because nature doesn't provide a lot of options

Nature doesn't provide a lot of options for blue pigments without a purplish undertone

Blue ice cream made with the new pigment that came from red cabbage. (Rebecca Robbins, Mars Wrigley Global Innovation Center)

Food scientists who've long been searching for a natural alternative for blue artificial food dye have found a pigment they could work with in red cabbage.

Concerns about a possible link between behavioural problems such as hyperactivity or inattention in some children and artificial food dyes led many food manufacturers to go on the hunt for natural alternatives. 

Some colours were easy to replace, like turmeric for yellow or beets for red, but finding a non-purplish natural source for the colour blue has always stymied food scientists. 

Turmeric is a great alternative natural for yellow food dye. (Tropper2000 / Shutterstock)

Now a team of scientists partially funded by Mars Wrigley, the company that makes M&Ms, says it's found a way, thanks to a pigment called an "anthocyanin" in red cabbage. Their study was published in the journal Science Advances

Pam Denish, a biophysics PhD candidate at the University of California, Davis and lead author on the study said in an interview with Quirks & Quarks host, Bob McDonald, the reason a natural blue has been such a challenge to find is because it's so rare in nature. 

That possibility that candy and cereals containing artificial colours could have these side effects, led many food manufacturers to go on a hunt for natural colour alternatives. (Mat Hayward / stock.adobe.com)

The anthocyanin they found in red cabbage was close to the cyan blue they were looking for, but not quite perfect.  So the researchers decided to try a strategy found in some blue flowers when anthocyanins are combined with a metal ion, like aluminum.

Once they tried that, they got the blue they wanted, but since that pigment is only found in very small concentrations in red cabbage, the researchers needed a way to scale it up.

One pigment in red cabbage proved to be the one that when combined with aluminum produced a vibrant cyan shade of blue. (Shannon VanRaes / Reuters)

They found their answer with an enzyme that was able to convert other anthocyanins in red cabbage into the one they needed, so now it's more feasible to produce a natural blue dye at a mass scale in a cost effective manner. 

Produced and written by Sonya Buyting

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