“I like to be prepared and experiment at the same time, so I have been doing some testing of failsafe colours you can make yourself, with a red cabbage. I wanted to know what was possible, easily, with stuff you would probably have on hand immediately as a failsafer.
I have used all these colours to ice the back of a Yummy Biscuits (recipe Fedup website) – see photo – by adding each to icing sugar.
PINK: cabbage juice + citric acid
BLUE/GREEN: cabbage juice + bicarb soda (the colour becomes greener as you add more bicarb, but it affects the taste)
PURPLE: cabbage juice alone
YELLOW: icing sugar + egg yolk
“INTERESTING” grey/brown colour: cabbage juice + egg yolk (made in error actually)
To make cabbage juice: boil approx. 2 cups of chopped red cabbage in a medium saucepan of water for about 20 minutes. Remove from heat and strain the liquid, discarding the cabbage. Allow to cool. Add the above as required.
NOTE: add each ingredient gradually until the desired colour is reached. You can always add more, you can’t take some out.
Hope this proves helpful to some.”