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From insects to bacteria: new ‘bugs’ make red colouring

By David, 14 April 2021 News

a close-up of a cactus with many white, dusty looking insects on it

These tiny insects are used to make red food colouring
Image: ©iStock.com/crossbrain66

Do you like eating red lollies or drinking strawberry milk? If so, there’s a good chance you’ve been eating insects! But soon there might be a new way to make these treats red.

What’s all this about eating insects? A popular red food colouring called carmine is made from carminic acid. This carminic acid is created by small cochineal insects which live on prickly pear cactuses. It can be hard to spot this colouring on an ingredients list as it has many other names, including carmine, cochineal, colour 120, E120 and natural red 4.

While carmine is a very stable red, some people are allergic to insect proteins that can contaminate the colouring. That’s why Korean scientists recently developed a new way of making carminic acid without insects – they’re using bacteria! But engineering those bacteria was a tricky task.

Creating carmine

Carminic acid is a complex chemical. It’s made from glucose, but it takes several steps to make the change. Each of the reactions is guided by enzymes, which are molecules made inside living cells.

The team knew some of the enzymes they needed to make carmine. But for the last two reactions, they weren’t sure. To start with, they ran chemical tests to find some enzymes that could do the job.

After finding likely candidates, they created 3D models of the enzymes and ran computer simulations to see how the reactions would perform. Using what they learned, they made tiny changes to the enzymes to make the reactions perform better in the simulation.

Finally, they engineered E.coli bacteria to make all the enzymes in the process. They gave the bacteria a nice place to grow and multiply, plus the necessary glucose, and they started making carminic acid, the key ingredient in making carmine!

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