Spherification means exactly what it sounds like it means. It’s the process of taking liquid, which takes the shape of its container, and reshaping it into a sphere. The liquid is barely solidified on the outside, and left to be itself on the inside – a raviolo with itself as both delicate skin and liquid filling.
The technique relies on a simple gelling reaction between calcium chloride and sodium alginate: enrich a tasty liquid with either calcium or alginate and then drop it with a squeeze bottle, syringe, spoon, or whatever else will get the job done, into a bath of either calcium or alginate. After a certain amount of time (the longer the time, the thicker the jelly-shell that develops) gently remove, rinse, and serve.
At el bulli, where Ferran Adria first made the olive spheres and coined the term, they’re truly perfect spheres. Adria’s kitchen uses a machine to shake hundreds of droplets at a time from a group of tubes into a bath below, allowing the spheres to form as they fall through the bath. In his classic trompe l’oeuil dish, spherified melon juice is so small and perfect that it passes for caviar. In his more recent dishes, Adria has refined the technique to contain solids and encapsulated individual mussels in a soft skin of brine filled with warm mussel liqueur.
At the International Chefs Congress, Jose Andres presented his tribute to Ferran Adria and the technique, examining the natural jelly inside a tomato and recreating it with the process of spherification. He presented the two, natural and fabricated, side by side.
The technique relies on a simple gelling reaction between calcium chloride and sodium alginate but experimentation with percentages of the chemicals in the liquid might be necessary if you're not following a recipe:
Step 1: Enrich a liquid with either calcium or alginate
Step 2: Drop it with a squeeze bottle, syringe, spoon, or whatever else will get the job done, into a bath of either calcium or alginate
Step 3: After a certain amount of time (the longer the time, the thicker the jelly-shell that develops) gently remove
Step 4: Rinse and serve
Jose Andres teaches Spherification 101 at the International Chefs Congress
Meanwhile, blend the alginate into the water, then add the sodium citrate to the mixture and blend for an additional minute. Allow this water mixture to rest in the refrigerator overnight or use a vacuum machine to extract all the air bubbles.
With a deep, rounded tablespoon, scoop a spoonful of the olive juice and carefully drop the liquid into the alginate water. Slightly agitate the submerged olive to prevent it from sticking to the bottom of the container. Allow the olive to sit in the alginate water for two minutes before removing it and rinsing it in plain water. Once rinsed, the olive may be stored in extra virgin olive oil. The holding oil may be flavored to your preference.