Working with Chlorophyll

Chlorophylls are the pigments in green vegetables and herbs. Though extracted chlorophyll can be flavored, the reason for extracting it is to color food or a sauce green, particularly things you want to cook, such as a fish mousse, since chlorophyll stays green through cooking. At the French Laundry, we add it to herb sauces for heightened visual impact, and to cream—say, a parsley cream for fish or a watercress cream for veal.

To extract chlorophyll, push your greens through a grinder (I use two parts spinach and one part each parsley and watercress, though flavor is not an issue here); place a collar of foil around the die so you don’t get spattered with green. You can also pulse the greens in a food processor, but don’t purée them. Add at least four times as much water to your ground greens and let them soak in the refrigerator overnight. Strain the liquid through a China cap into a pan, squeezing as much moisture as possible from the greens. Bring the liquid to a simmer, stirring continuously. You will see the chlorophyll separating from the water as it heats. As soon as the water and chlorophyll have clearly separated, shock the mixture by adding ice, just enough ice to cool it down but not so much that you’re left with a lot of ice cubes in the pot. Strain the liquid through a strainer lined with a kitchen towel or a cloth napkin. Let the liquid drain overnight.