Video Demo: Alginate Polymer

A polymer, sodium alginate, reacts with calcium chloride to produce calcium alginate. Calcium alginate is a gel that is not soluble in water.  A new branch of cooking, called molecular gastronomy, uses this technique to trap flavor sauces in gels to put over food.  Not familiar with molecular gastronomy?  Lifehacker has a good set of simple videos on the subject.  You can order the kit that I used from Educational Innovations.

Comments

[Earl Lee]

Hey,

Maybe you explained it this way for simplicity, but I believe sodium alginate itself is a polymer. However, I believe that the calcium alginate precipitate is a polymer. Also, the calcium does not necessarily "replace" the sodium in sodium alginate, since, in solution, the sodium alginate will have dissolved into individual sodium ions and alginate ions. Nonetheless, this is a great informational video. I wrote an article about calcium alginate precipitation reactions—also known as "spherification" in the molecular gastronomy world— before, and it includes a recipe for watermelon caviar! You might want to check it out here.

[Darren Fix]

In a lot of my demos I try to simplify the explanation as to what is going on (keep it at the middle school level). I was looking for a recipe that I could do with my students that would be easy to do. I will definitely check out the watermelon caviar. Thanks so much!