Spherification is the art of encapsulating flavoursome liquids in a small jelly sphere by the reaction of sodium alginate with a calcium salt. Create caviar pearls by adding sodium alginate to your liquid and dropping in a calcium bath, or larger liquid-centred spheres by adding calcium salts to your liquid and dropping in an alginate bath (known as reverse spherification).
Sodium alginate is a natural extract of seaweed and comes in a variety of grades. MSK sells only the finest grade, offering superior performance and reduced preparation time. Calcium salts differ mainly by taste and strength. Calcium chloride offers the strongest performance but is not suitable for reverse spherification (where the calcium salt remains in the sphere). Calcium Gluconate is the better option for this as it has a lower concentration and a more neutral taste.