One of the cool things about being a science educator is getting to play around in the lab. Sometimes this lab is the kitchen, which is also cool, especially if you get to eat the results. I had some requests for a recipe/instructions after posting the results of one of my experiments on Facebook last week. As I thought about it, I realized that this experiment also represented a new experience, the synthesis of molecular gastronomy spheres or “caviar.” I’ve put the succinct version of the recipe at the end of this post if you just want to scroll there instead of reading the blow-by-blow description.
There are two solutions to be prepared in this process, one that will become the spheres, and one that is the bath in which the spheres form. The sphere solution contains the flavor to be encapsulated, and a gelling agent, in this case sodium alginate, which is derived from brown seaweed. Sodium alginate is the most costly ingredient in this recipe, and can be obtained from a number of online vendors. I found the best value (without buying a huge quantity) at my favorite online spice purveyor, The Spice House, but they seem not to sell it anymore (try Amazon). A one percent solution of sodium alginate works well. This means about 1 gram of sodium alginate per 100 mL of solution. In kitchen terms, this translates to about a rounded 1/4 teaspoon for every 100 mL of solution you plan to prepare. I planned to prepare 250 mL of each flavored solution, so I measured out two heaping 1/4 teaspoons for each solution.
Next, I began preparation of the flavored liquids. Gatorade required no further preparation. I used some lovely blue Kool-Aid powder for another solution, measuring 1/8 teaspoon from the packet and 1/8 cup of sugar into a Tupperware Quick Shake container and added distilled water to the 100-125 mL line. If you don’t have multiple Quick Shakes in your cabinet (i.e. you are not one of my family members) any container with a tightly-fitting lid will work. My third solution was tea. I used our morning tea of choice, PG Tips, and added about 100 mL of boiling water and a tablespoon of sugar. After removing the tea bag, I added the previously measured sodium alginate to each shaker, capped tightly, and shook.
Sodium alginate dissolves slowly, so while the shakers were sitting, I prepared the other solution, the calcium ion bath. I used calcium lactate as a source of calcium ions. Calcium chloride works quite well, but tastes bad, so it is out for products that will be consumed. Another option is calcium lactate gluconate. I haven’t tried it, partly because it is more expensive. Both are available from Amazon from manufacturers including WillPowder. I used 4 teaspoons of calcium lactate in 250 mL distilled water. This later turned out to be too much, so I added more distilled water. In either case, stirring and time are required.
While the calcium lactate dissolves, return to the flavored solutions. Add distilled water to the Kool-Aid and tea containers and Gatorade to its container up to the 250-mL mark, then cap and shake vigorously again. The solutions should be quite viscous, but not gelled.
To make the caviar, pour calcium lactate solution into a bowl to about a 1/2 inch depth. Next, pour some of one of the flavored sodium alginate solutions into a cup. For ease of clean-up, a disposable cup is best. Using a disposable plastic pipet (you can get these on Amazon too), draw some liquid up and then dispense drops into the bowl containing the calcium lactate solution.
The drops will form spheres that hold their shapes. After a few seconds, collect the “caviar” from the bowl with a spoon or sieve. The spoon in the photo below was specially designed for or by (depending upon who you ask) Ferran Adria, molecular gastronomy pioneer, specifically for this process. It is convenient, but not necessary. Next, rinse the spheres in another bowl containing distilled water. Finally, place the products on paper towels to remove excess water.
Some things I learned:
➡️Use more flavoring than you think you need.
➡️Add extra sugar/sweetener.
➡️Consider adding food color for more vibrant spheres.
➡️Change the calcium solution out regularly (after making a couple batches of caviar). The solution will become depleted of calcium ions even though its appearance does not change.
Finally, the clean up. I would not recommend putting the sodium alginate solutions down the drain. Dispose of any excess in the trash to avoid plumbing clogs. Calcium solutions, on the other hand, can readily go down the drain (in most areas) with plenty of water.
Simple Flavored Spheres Recipe
✳️1/4 teaspoon sodium alginate
✳️100 mL flavored beverage
✳️1 teaspoon calcium lactate
✳️100 mL distilled water
Place sodium alginate and 50 mL flavored beverage in a bottle with a tightly-fitting cap. Shake vigorously. Add another 50 mL flavored beverage and shake again until dissolved and viscous.
Place calcium lactate and 100 mL distilled water in a (measuring) cup. Stir or whisk until dissolved.
Pour calcium lactate solution into a bowl to a depth of about 1/2″.
Add sodium alginate/flavored beverage solution to the calcium lactate solution in the bowl dropwise, forming spheres. Remove spheres with a spoon or sieve, then rinse in distilled water and dry on paper towels.