Tuesday, June 14, 2022

Homeschool Chemistry of Cooking: Gelation and Spherification


Gelling and spherification are good hands-on activities when you're studying proteins, as it's the unfolding of proteins that allows the hydrophobic amino acids to cross-link and form a gel.

You can even look up the exact amino acids that make up the gelatin (probably glycine), and you can model those amino acids. You can also chemically test foods for proteins, if you want to make your study as hands-on and context-building as possible.

Syd and I have been working through this Harvard EdX class, Science and Cooking: From Haute Cuisine to Soft Matter Science, and that's where we learned how spherification works. When cooking, you gotta love your polymers!  

Although the process that Syd and I used does result in spherified liquids, this isn't exactly the type of spherification that occurs in fancy molecular gastronomy restaurants. There, they use alginate and calcium to build that gel layer only around the outside of what they want spherified, leaving the inside as liquid.

These gel spheres are a solution of liquid and gelatin, and we used physical processes to shape them. 

Syd and I found a really easy-to-follow recipe for making edible spheres in The Complete Cookbook for Young Scientists, written by America's Test Kitchen, but they've actually also put the complete recipe here. It involves lots of fun stuff, like nuking pomegranate juice and unflavored gelatin--

--whisking it (tiny whisk optional but encouraged!)--

--prepping some VERY cold vegetable oil--

--and using a squeeze bottle to drop the solution into the cold oil:

Rinse the oil off, and you've got tiny, edible spheres of pomegranate gelatin!

The process IS very interesting, but alas, Syd and I both thought that the edible spheres were super gross. We never did get every minute speck of oil rinsed away, so they definitely felt oily, and they'd lost a lot of sweetness, as well. 

If you ever could get all the oil rinsed off, I think that these edible spheres would be fun as ice cream toppers, or even as a boba substitute in tea. For us, though, we marveled at our cross-linked polymer chains enabled by the heat-activated unfolding of proteins to reveal the hydrophobic amino acid components...

... and then we fed them to the chickens.

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