I was watching an episode of Good Eats one day when the idea of using dry ice in the kitchen presented itself. Alton was looking for a way to fast freeze strawberries in the kitchen. The faster the freeze, the smaller your ice crystals inside of the fruit. Why would you want tiny ice crystals inside your fruit? Big crystals in a strawberry would produce a thawing effect the equivalent of tossing shards of glass into a plastic ziplock bag of water… a big wet mess.
I thought this was really cool, as I am always looking for more excuses to play with dry ice at work. Our lab often has spare dry ice left over from incoming shipments of frozen chemicals. My coworker Jeremy and I take it upon ourselves to make fun use of it and toss ice into our tubs of soapy water, creating a huge self-producing mass of bubbles that completely takes over our dish tub. Jeremy’s favorite trick is to put chips of dry ice into eppendorf tubes: plastic tubes with a snap-shut lid. This creates a string of SNAPS when the tubes sequentially explode open.
I headed out to the Farmers Market and bought strawberries and other fruits to bring back to the lab to freeze down just to munch on. I ended up tossing a couple strawberries and grapes in, because frozen grapes are an entity unto themselves!
Through out the day I couldn’t help but notce a zip on my tongue when eating the grapes. Not all of the grapes exhibited this phenomenon, but some of them had something going on with the tip of my tongue! Playing throughout the day we discovered that you can only “taste” the zip when the fruit is thawed. I’m thinking this zip is carbonation from carbon dioxide being taken up by the fruit when its being frozen.
It turns out I’m not the only one who thinks carbonated fruit is cool!
If you want to play with carbonating/freezing your own fruit, dry ice can often be obtained from ice cream stores. Dry ice cautions are detailed below in the following recipe.
Chocolate Carbonated Banana
First ready your container of dry ice. The dry ice should be stored in a small cooler to slow its evaporation. I used a small styrofoam box with a lid rested on top.
Handling dry ice is something to be approached with caution- it hurts! Use gloves to protect your skin if handling the ice itself. If you are deciding to get all crazy on your ice, go ahead and put on safety googles (ski goggles work too). Getting chips of dry ice in your eyes is yucky!
Be aware that dry ice creates carbon dioxide gas as it “ages”. This means that pieces of dry ice in a sealed shut container are effectively creating the conditions for a non-flammable bomb. If the build up of gas is great enough- your container will explode or burp. Burping vs exploding depends on your container volume to gas ratio:
- (tiny sealed container + big chunk of dry ice = explosion)
Freaked out yet? If you are, go get a rubber balloon, toss a couple of chips of dry ice in it and tie off the balloon. This will give you a nice visual of what gas building forces you are dealing with. The off gassing of the dry ice will inflate your balloon for you. Cool!
Never, say never, but there are chances of suffocation around dry ice. This would occur if you stuck your head down in your ice chest full of dry ice and decided to hang out and breath in the vapors for awhile. Remember the carbon dioxide that dry ice gives off? This pushes oxygen out of the way in your ice chest- thus creating an oxygen deficient pocket. So, only supervised contact around kids please.
Now, on to the fruit.
Remove the peel from half a banana, length-wise, leaving the remaining peel to act as a dish for the banana. Make slices across the banana fruit to help facilitate easier removal later. Place your half peeled banana on top of your dry ice and lid your container. Allow the banana to freeze completely (5-20 minutes), removing to a dish when solid. Thaw the banana before attempting to eat! You don’t want to damage your tongue with your super-frozen banana. Besides the carbonation effect comes forth with thawed, not frozen fruit.
Thawing your banana is a tricky step- if you let it thaw too much, you will get a dark brown peeled puddle of banana goo. I like to wait for it too just become unfrozen by watching the ends of the fruit, which will thaw first. Drizzle chocolate syrup across your fruit and enjoy!