Recently, food colorings that add color to food are being converted from synthetic pigments to natural pigments.However, it is difficult for only blue to develop a stable color with natural pigments, and blue No. 1, which is a synthetic tar-based pigment, has been used continuously.

　On the other hand, the anthocyanin pigment of red cabbage is acidic and red, neutral and purple, and alkaline and blue, but since blue is unstable, it has been almost impossible to use anthocyanin as a blue colorant.Although it is known that when anthocyanins and metal ions are combined to form a complex, they show a blue color even in neutral, the red cabbage pigment is a mixture of 10 or more kinds of anthocyanins, and it is difficult to develop a clear blue color. was.

　Therefore, the group isolated individual dyes of red cabbage, added metal ions individually, and investigated the color development.They found that only the anthocyanins numbered P2 showed a very beautiful and stable blue color comparable to Blue No. 1 when aluminum ions were added.It was also found that this dye has a structure containing P2 and aluminum ions at a ratio of 3: 1 and is a special complex that cannot be obtained with other dyes.

　When the confectionery was coated with this pigment, it was confirmed that a color comparable to that of Blue No. 1 was obtained and that it was excellent in storage stability. Since P2 is contained only in a small amount in red cabbage, in this study, we also developed a method to prepare a large amount of pure P2 by a selective hydrolysis reaction by an enzyme.

　This extremely promising new blue natural colorant is expected to further accelerate the switch to natural colorants in the food industry.

Paper information:[Science Advances] Discovery of a natural cyan blue: A uniquefood-sourced anthocyanin could replace synthetic brilliant blue