Green food coloring is important in confectionery work, as with all the other colorings. There are many different ways to make a greed food coloring, using vegetables and other ingredients. These authentic food color recipes come from The Complete Confectioner, Pastry-Cook and Baker.
Spinach Green - This is prefectly harmless and will answer most purposes. Wash and drain a sufficient quantity of spinach, pound it well in a mortar, and squeeze the pounded leaves in a coarse cloth to extract all the juice; put it in a pan and set it on a good fire, and stir it occasionally until it curdles, which will be when it is at the boiling point; then take it off and strain off the water with a fine sieve; the residue left is the green; dry it and rub it through a lawn sieve. This is only fit for opaque bodies, such a ices, creams, or syrups.
Another green- is made with a mixture of saffron or gamboge, and prepared indigo; the lighter green the more yellow must be used.