Reverse Spherification

Reverse spherification is a method of molecular gastronomy that works similarly to ordinary spherification but is used for liquids containing alcohol or calcium, such as milk or yogurt, which the standard method cannot handle. Instead of adding sodium alginate to the liquid itself, a liquid containing calcium salts is dropped into a bath of sodium alginate, where cross linking between the calcium ions and the alginate forms a gel membrane around a sphere of liquid. Because calcium stops diffusing inward once the sphere leaves the bath, the center never fully gels, which lets reverse spherification make larger spheres than the standard method and store them for longer.