Pop Rocks are just sugar with super high pressure, carbon dioxide trapped inside.
When they hit the saliva in your mouth, the sugar dissolves and the CO2 bursts out with that
characteristic pop. That carbon dioxide can be trapped inside at pressures around 600 PSI. That's
seven times the pressure of bottle of champagne bursting out of the candy currently in my mouth.
And today I'm gonna try and recreate these at home. It might be a disaster.
Is this just gross? Pop Rocks were originally invented to be a kind of instant soda.
Think Alka Selzer, but tasty. Is Alka Seltzer gonna sue us? To make them,
the factory mixes sugar, lactose, and corn syrup together and heats it up.
The higher the temperature, the harder the candy will be when it cools back down.
But to make a Pop Rock, you don't just let it crystallize into sugar. Instead you make sugar
glass. This is a transparent and brittle form of sugar that looks just like glass. To make it,
you heat the mixture to what's called the hard crack stage between 146 and 155 degrees Celsius.
Then you add carbon dioxide to the mixture under high pressure and let it cool back down
to below the glass transition temperature, the temperature at which a substance changes from
an amorphous rubbery state to a hard and glassy one. Once it’s cool, you can open the chamber,
smash it up and you're left with tiny sugar rocks with pressurized bubbles of carbon dioxide inside.
They weren't really a hit as an instant soda, but people love them as a distinctive carbonated
candy. And we humans generally like carbonated things. Think of all the sparkling water and
fermented foods and sodas that we eat and drink every day. The best kimchi is fizzy kimchi.
Part of this is the sensation, but part of it is because we can actually
taste the carbonation itself. Enzymes on your tongue convert carbon dioxide and some of the
surrounding water into a mix of bicarbonate and protons. In this way, it behaves like an acid
because it's releasing protons and these protons are detected by your acid or sour sensing cells,
giving carbonated food and beverages part of their distinctive bite.
I wanna make these tantalizingly dangerous candies at home,
but working with a high pressure CO2 tank is just way too much for my security deposit to handle.
So instead I'm gonna try three slightly less dangerous methods with hopefully similar results.
First up is baking soda. Now, if you Google how to make homemade pop rocks, the first result is
going to be the internet's Dessert Queen, Claire Saffitz. You guys, it's popping. I can't beat
Claire, but maybe I can replicate her. So instead of using compressed CO2 to make her fizz, Claire
uses baking soda or sodium by carbonate. When you mix it with an acid, something like citric acid,
which you can also get out of lemons, it will give off CO2 gas. So this is our true chemistry method
of making carbon dioxide. We're gonna react two things together and we're gonna get gas.
And hopefully if we do that while the sugar is crystallizing, we'll be able to lock in some of
those bubbles and get that characteristic fizz. So let's try it first. I'm gonna heat up some sugar,
corn syrup and water in a pot. Once it hits 145 degrees Celsius, just at that hard crack
temperature, I'm gonna quickly mix in baking soda, citric acid, food coloring, and some
freeze dried, powdered strawberries for flavor. I'm gonna pour that onto a cold baking sheet,
pop it into the freezer and move on to the next method.
Side note, if you've ever had something called sponge candy in the great lakes area,
it's made using a very similar technique, but then covered in chocolate. Sounds amazing.
Next up is dry ice and dry ice is just solid carbon dioxide. So I think I might be able
to use this to carbonate my sugar mixture, but dropping hot sugar onto dry ice sounds really
dangerous. So I'm not gonna do that inside. What I'm gonna do is I'm gonna take it all outside and
I'm gonna slowly drip small amounts of the hot sugar mixture onto the dry ice. Very carefully.
With goggles. There are fizzy fruit recipes out there that work by just laying fruit over dry ice,
and then wrapping it in plastic wrap and that like, carbonates the fruit. So I think
we might actually have a shot at carbonating the sugar mixture by using the dry ice.
My hope is that when the hot sugar turns into sugar glass, when it hits the cold dry ice,
it'll encapsulate some of that CO2 at the same time.
And finally, we have yeast. This is my biological method of trying to create carbon dioxide.
So yeast is used to carbonate lots of things like beer and wine and kombucha. This is because
the yeast eats sugar. And then as they turn it into energy, they also release carbon dioxide.
And you can see that in the bubbles, in this yeast and sugar and water mixture. I made yeast. So if
yeast can make carbon dioxide bubbles in beer and bread, maybe it can do it in sugar too. But how do
I actually get these bubbles into my pop rocks? Because yeast starts to die at around 55 degrees
Celsius so if I just add 145 degree Celsius, hot sugar to it, it's just gonna die immediately.
But if I add the yeast once it has already cooled, it's gonna be hard. I'm not gonna be able to mix
it in. So my idea is that I'm only gonna warm the sugar up to a temperature where it's gonna
create like a soft caramel, rather than a hard crack. So about one 10 to one 20 degree Celsius,
then I'm gonna wait for it to come back down to about 50 degrees Celsius
and then try and mix the yeast in then. So instead of a Pop Rock, I'm gonna create like a pop carmel
taffy with yeast. I don't wanna think yet about how gross that's gonna taste.
Carmel Yeast Rocks is a product of ACS Reactions. It may not be reproduced,
distributed or sold without the express written and consent of American chemical society. Also,
they're pretty gross. So you may not want to anyway. Patent pending. Probably. I
don't know. I'm not a lawyer. I just talk really fast. Do what you want. See if I care.
First up is my baking soda, citric acid creation. There are a lot of bubbles that
were trapped in here. It got super foamy in the pot. Oh, oh, there's a lot of,
a lot of things happening. Lots of citric acid in whatever that little bite was.
Uh, let's take a little crumb. Can you hear this? No.
Here's the thing about this one is that it does get like foamy in my mouth.
I don't know that I'd call it pleasant and it's not the same pop as a Pop Rock. So it did create
bubbles and it trapped a little bit of sort of the baking soda and the citric acid,
which I think are reacting in my mouth to give it a little bit of the fizz,
but it's not like the pop of a Pop Rock. And that citric acid is like strongly sour. It’s not great.
Okay. So next up is my dry ice creation. You know, there are some little bubbles trapped in here.
Oh it’s too much. I mean… Let's take a smaller piece. It's just hard sugar.
I think it just hardened too fast when it hit the dry ice. You know,
there's a possibility that maybe I could have mixed like little particles of dry ice in, but
then you're trapping the dry ice in like that. Actually, I wonder if that might have
caused little explosions, like it might not have been safe. It just real sweet.
Okay. The final one is this, like, it didn't turn into taffy. It's like at best, a loose jam
that smells like yeast. Oh, it's got this weird
sticky texture I think from the pectin in the strawberries. It's not a Pop Rock. It,
it just tastes like sweet yeast.
Oh God. You can't beat the original.
Before you go, we wanted to invite you to participate in PBS Digital Studios annual
audience survey. Your feedback really helps us understand what our audience is interested
in so we can give you more of it. You even get to vote on potential new shows. There's
a link in the description below. If you have a few minutes, we would love your input. Thanks.
I brought so many pop rocks that the one at the store asked me if I wanted
a receipt. And I was like, yes, ma'am this is a business expense.