On the fading of coloring matters used for foods

Abstract

It has often been observed that imitated port-wine turns red, while it is kept in the show-window.
According to our observation, the coloring matters faded by sun-light are as follows:-indgo carmin, brilliant green, acid violct 6 B, light green SF, light green S and Guinea green.
The coloring matters faded by acid are as follows:-indigo carmin, light green SF and light green S.
The coloring matters faded by either acid or alcohol are as follows:-erythrosin A and cosine.
The most suitable coloring matter for wine was proved to be the mixture of amaranth, new-coccine, tartrazine and brilliant blue.