This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
A recent post over at Ptak Science Books taking a look at the golden age of gelatin inspired me to dig up one of my favorite older posts from 2006. Behold, the glory of Jell-O!
One of my favorite scenes in the film My Best Friend's Wedding is the heart-to-heart conversation between bride-to-be Kimmi (Cameron Diaz) and Julia Roberts' would-be groom stealer, right after the groom has called off the wedding because of a misunderstanding (orchestrated, it must be noted, by a now-repentant Roberts). Attempting to explain why the groom would change his mind so suddenly, Roberts' character -- a food critic by trade -- draws a culinary analogy between creme brulee and that All-American staple, Jell-O.
A diner in a fine restaurant might be enamored with the sweet, elegant perfection of creme brulee, she maintains, but could then suddenly realize that what he really wants is... Jell-O. Why? "Because he's comfortable with Jell-O," she says. "I can be Jell-O," Kimmi tearfully offers, to which Roberts tartly replies, "No. You can't. Creme brulee can never be Jell-O."
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I'll spare you my exasperated rant over Kimmi's insistent follow-up -- "But I have to be Jell-O!" -- with all its implications for the character's sad lack of self-esteem. That's another post altogether. Roberts' food critic has a point: creme brulee can never be Jell-O, even though both depend on cross-linking proteins for their jiggly consistency. With creme brulee, proteins in the eggs and milk form stronger bonds in response to heat, changing its consistency from a liquid to a semi-solid. The opposite occurs with Jell-O: the proteins form stronger bonds as they cool.
I'm kind of with Roberts on the creme brulee vs Jell-O debate, to be honest, although Jen-Luc Piquant prefers the former. (We're both suckers for a tasty Grand Marnier souffle, served to perfection at Fleur de Lys, a restaurant in San Francisco.) I mean, can creme brulee do this?
Drop a creme brulee and it would just go splat -- although that, too, might look pretty good in super slo-mo. The components of Jell-O are gloriously simple: nothing but gelatin, water and sugar, plus any artificial flavors and colorings that are added to bolster the fun factor. But where does the gelatin come from? You might be sorry you asked.
Gelatin is a processed protein called collagen, derived from the bones, hooves and connective tissues of cows or pigs. Those parts are ground up and mixed with acid or other chemicals to break down the cellular structure, thereby releasing the collagen. Boiling the whole mess causes a layer of gelatin to form on the top, which can be skimmed off for further processing. Eventually it ends up in your local grocery store aisle in powder form.
Different proteins have different structures, and this gives them different properties, which in turn determines whether they solidify into gelatin or creme brulee (or a yummy flan, for that matter). Gelatin 's structure is similar to DNA, except where DNA has two chains twisted together into a spiral, the proteins that make up gelatin have three chains of amino acids tightly bonded together. The only thing that breaks those bonds is energy. A lot of energy.
That's where the boiling water comes in: it adds a great deal of energy, in the form of heat, sufficient to cause the three strands of amino acids in collagen to unwind. Adding cold water, and then putting the Jell-O into the refrigerator to cool, causes the chains to start bonding again.
Because it takes so long to cool, the amino acid chains become entangled (when stirred) and water gets into gaps between the chains. That's why Jell-O wriggles so appealingly. It's also why the "short-cut" method of adding ice so the gelatin will set more quickly, is never quite as firm as the Jell-O produced by the slow-set method. The various molecules cool so quickly that they can't self-organize in the most efficient and strongest bonds possible; instead, only a loose matrix forms. If the energy levels of the requisite molecules are lowered more gradually, as in the slow-setting method, they have more time to align properly, forming a much denser lattice structure, trapping the mixture of sugar, pigments and water in between the strands of amino acids.
Fans of Jell-O shots, take note: adding alcohol to the starting mixuture means it will take that much longer to gel, as one intrepid amateur scientist deduced in a fun experiment a few years ago. He set out to determine the highest possible concentration of alcohol (using 80% proof vodka) a given Jell-O shot could contain while still maintaining "structural integrity."
See, alcohol has a lower freezing point than water. That's why legend has it that the cook aboard the doomed Titanic managed to survive being plunged into icy ocean waters: he'd been drinking heavily, and all that extra blood in his alcohol kept him from freezing to death before he could be rescued. So it stands to reason that adding more and more alcohol to Jell-O shots would make it harder and harder for the substance to gel. (BTW, the same dude also experimented with what happens when you try to light a Jell-O shot on fire. I'll bet he's a blast at parties.)
Jell-O's unique consistency -- hovering somewhere between solid and liquid -- and its mold-ability make it an intriguing potential medium for, say, artists. Back in 2006, the San Francisco Exploratorium marked the 100th anniversary of the great 1906 earthquake that laid waste to that great city with a special one-day art installation by local artist Liz Hickok.
She crafted a scale model of the entire city out of multi-colored Jell-O: everything from City Hall to the Golden Gate Bridge. (She's also continued to work with Jell-O versions of San Francisco, and also recreated a model Scottsdale, Arizona, in Jell-O.)
Hickok relied on satellite images to design scaled-down molds, which she used to cast the buildings in various flavors of Jell-O. The entire jiggling array was mounted on a slab of plexiglass and then placed on a vibrating table to demonstrate to the gathered museum visitors exactly how those violent earthquake tremors can affect buildings. Specifically, it demonstrates "liquefaction," which is what happens when the earthquake pressurizes the water in soil underneath a building. Liquefaction is responsible for much of the structural devastation wrought by earthquakes.
So Jell-O is good, jiggly fun, even if it can't compete with creme brulee on the haute cuisine front. But it's also good science. Scientists have found that adding stem cells -- which can cure rats of spinal cord injuries, if not humans -- to spinal implants made of hydrogels can help patients with old injuries regain a certain degree of function. The gels are basically polymers whose properties are very similar to those of Jell-O, resembling the soft tissue that surrounds the human spinal cord as it develops in the womb. The hydrogel fills the spaces in the injured areas, creating a kind of scaffolding that new cells can grow around, building a bridge of sorts to repair the damage.
Let's see creme brulee do that.
Photo credit: “Alamo Square” by Liz Hickok (Source)