Reverse spherification

Reverse spherification was developed as a solution to spherificate naturally calcium containing products, mainly dairy products.

In the direct spherification, alginate is added to the liquid to be spherificated and this viscous liquid is then dropped into the calcium bath. However, in the reverse spherification, the calcium is added to the liquid to be spherificated and this is deposited into the alginate bath with a semi-spherical spoon.
The alginate bath can be flavored either the same as the insides of the ball or with a different taste to get a contrast.

The different concept of reverse spherification determines some notable points:

- In the direct spherification, alginate produces a viscous and dense liquid which can be dropped into the calcium bath. In the reverse spherification, the viscous liquid is the alginate bath while the liquid to be spherificated is more fluid. In order to get a viscous, manageable liquid some thickener is needed (e.g. xanthane gum).

- Because of the viscosity of the alginate bath, the flavored liquid can not be dropped into the bath because it would remain on the surface. It has to be sunk into the alginate bath with a spoon and it needs to be rotated to maintain the spherical form. A trick to get homogeneous results is to freeze the flavored liquid + xantana + calcium in the desired form and warm the alginate bath up to 30 Celsius.

- Due to the previous point, in the reverse spherification it is easier to prepare olive- or cherry- sized balls rather than small caviar-like balls as in the direct spherification.

- In the direct spherification, the calcium salt can be removed from the final product just by rinsing the balls with fresh water because the calcium is on the surface. In the reverse spherification, the calcium salt is inside the ball and can not be removed. To solve this problem in the reverse spherification, we use calcium gluconolactate that has a mild taste, instead of calcium chloride that has an unpleasant bitter-salty taste.

- In the direct spherification, the alginate jellyfication is very rapid on the surface and it continues inside the balls if they stay in the calcium bath for a long time. In the reverse spherification the alginate gel grows in the bath from the ball surface outwards, making a ball bigger and bigger with thicker and thicker alginate “peel” but always maintaining a liquid core. If we keep some balls in the alginate bath at the same time for a long time they can join to each other.

For these reasons this technique is a bit more challenging to carry out than the direct spherification. It requires more practice to get the best results. But once you dominate it, the results are spectacular!