What is "spherification"

n. The process of forming something into a sphere or spheres.

Spherification is the culinary process of shaping a liquid into spheres usually using sodium alginate and either calcium chloride or calcium glucate lactate, which visually and texturally resemble roe. The technique was originally discovered by Unilever in the 1950s (Potter 2010, p. 305) and brought to the modernist cuisine by the creative team at elBulli under the direction of executive chef Ferran Adrià.

There are two main methods for creating such spheres, which differ based on the calcium content of the liquid product to be spherified.

For flavored liquids (such as fruit juices) containing no calcium, the liquid is thoroughly mixed with a small quantity of powdered sodium alginate, then dripped into a bowl filled with a cold solution of calcium chloride, or other soluble calcium salt.

Just as a teaspoonful of water dropped into a bowl of vegetable oil forms a little bubble of water in the oil, each drop of the alginated liquid tends to form into a small sphere in the calcium solution. Then, during a reaction time of a few seconds to a few minutes, the calcium solution causes the outer layer of each alginated liquid sphere to form a thin, flexible skin. The resulting " popping boba" or artificial "caviar" balls are removed from the calcium-containing liquid bath, rinsed in a bowl of ordinary water, removed from the water and saved for later use in food or beverages.

Reverse spherification, for use with substances which contain calcium or have high acid/alcohol content, requires dripping the substance (containing calcium lactate or calcium lactate gluconate) into an alginate bath. A more recent technique is frozen reverse spherification, which involves pre-freezing spheres containing calcium lactate gluconate and then submerging them in a sodium alginate bath. All three methods give the same result: a sphere of liquid held by a thin gel membrane, texturally similar to roe.