A new natural blue for food coloring

A naturally brilliant blue color was discovered by an international team of researchers, including chemists at the University of California, Davis. The new cyan blue, obtained from red cabbage, can be an alternative to synthetic blue food dyes, such as the commonly used FD&C Blue No. The work will be published on April 7 in Scientific progress.

“Blue colors are actually quite rare in nature – many of them are really red and purple,” said Pamela Denish, a graduate student working with Professor Justin Siegel at the UC Davis Division of Chemistry and Innovation Institute of Food and Health, said.

The right blue color is also important to mix other colors, such as green. If the blue is not right, it will produce muddy, brown colors when mixed, Siegel said.

Red cabbage extracts are widely used as a source of natural dyes, especially red and purple. These dyes are called anthocyanins. For about a decade, a team led by scientists from the Mars Advanced Research Institute and Mars Wrigley Science and Technology, in collaboration with the UC Davis Innovation Institute for Food and Health, The Ohio State University, Nagoya University, Japan, the University of Avignon. , France and SISSA University, Italy, are in the process of isolating a blue anthocyanin from red cabbage. But the natural blue color is present only in small amounts.

Enzymes to convert colors

Denish, graduate students Kathryn Guggenheim and Mary Riley and Siegel devised a way to convert other anthocyanins into cabbage in the blue color compound. They selected public libraries of millions of enzymes for candidates who could do the job and tested a small number in the laboratory. Based on these results, they used computational methods to search for a large number of potential protein sequences – 10 to the power of 20, more than the number of stars in the universe – to design an enzyme that would effect the conversion with high efficiency.

“We used these tools to search the universe for the enzyme we were interested in,” Siegel said.

With this enzyme, they were able to convert the anthocyanin blue of a small fraction of red cabbage extract into a primary product, which allowed the researchers of the institute and other collaborators to fully characterize the new blue color.

Siegel and Denish founded a start-up company, PeakB, to develop the technology for commercial applications. Enzymatic conversions are widely used in food production, for example in cheese making, Siegel said.