The Science of Spherification

The transformation of a liquid into a solid has always been one of the most spectacular and fascinating modern culinary processes. Until a relatively short time ago, however, this could only be achieved through what we call “jellification”, the result of jellyfing: in other words, the magic consisted in thickening the liquid with a special ingredient such as agar agar.

What is spherification?

It is only recently that spherification has started to become widespread, even though this procedure, which consists in wrapping a drop of liquid in a solid membrane, was invented back in 1942 by William Peschardt. Does this remind you of anything? Exactly, just like caviar. The result is amazing: the consistency of small spheres is extremely agreeable because when you bite into them, they release their content for the joy of the palate, without forgetting that the flavour of the liquid is not altered in any way by a thickening agent.

Instead of the latter, in fact, calcium alginate is used which, like agar agar, is extracted from seaweed. However, it behaves in a way that is quite different and forms precious little spheres instead of gelatine. How is this possible? In brief, sodium alginate is mixed with the liquid you intend to spherify, such as fruit juice. Then it is collected in a needleless syringe, which is used to release the liquid droplets into a bowl containing a calcium chloride solution.

As soon as each droplet of alginate and fruit juice solution comes into contact with the chloride, a sphere is formed containing the precious liquid inside. At this point, the spheres only need to be rinsed in water (calcium chloride is edible but it does have a bitter taste) and let the imagination run wild. Both alginate and chloride can be purchased in a chemist’s shop or in well stocked grocery stores and, of course, online.

From the chemical viewpoint, the reactions that come into play are very simple and fascinating. Sodium alginate is made up of long chains with sodium atoms positioned along the sides. When it comes into contact with chloride, the sodium is replaced by the calcium. Now, owing to the fact that calcium has two positive charges unlike sodium, which has one, it may bind two of those long chains together. The latter, when intertwined, form a skin which enwraps the liquid droplets.

An Easy Spherification Recipe

Now that we have examined the theory, let’s consider a practical application with an easy spherification recipe; remember that spherification only succeeds with liquids that can be frozen, in other words, those that are water-based or have a low alcohol content by volume. Besides, it is preferable for the liquids not to be warm.

Pour one gram of sodium alginate into 200 ml of liquid (in a cup), and then mix thoroughly using a blender or a mixer (the alginate will not dissolve but will be well distributed). Then, prepare a solution by pouring four grams of calcium chloride into 130 ml of water, taking care to mix thoroughly. Using a pipette or a syringe, release the liquid droplets into the chloride solution.

The precious spheres will form immediately: they should not be left to rest for any more than thirty seconds otherwise they risk solidifying inside as well. At this point, remove the spheres using a draining spoon or a strainer, and place them in a bowl of water to rinse. In view of the fact that hundreds of different liquids may be used, there is no limit to the number of “sphere-based” recipes you can prepare. However, I would like to recommend one that is very simple and of great appeal.

Following the method described above, spherify some Aperol or, if you prefer, some tangerine or peach juice. Then pour a handful of the spheres you have obtained into a fine nice glass of prosecco. In no time at all, you have created an aperitif that is attractive and delicious, and you may like to accompany it with some nibbles. Any ideas? Well, what about some buttered toast with sepia black ink caviar? What did I tell you, there is no limit to the imaginative things you can do thanks to the spherification technique!