Brewery Master
Posts: 1696
Joined: March 11 2006
Location: Alberta, Canada
Thanks given: 0
Thanks received: 0
Dry Ice-Cream
I found this while I was searching the web for a science project, it is pretty interesting so i chose to do my project on this.
Quote:
"Skip the fancy ice-cream maker—all you need is a pillowcase and a fire extinguisher.As liquid Evaporates, it gets cold. This effect, familiar to anyone who has been wet, happens because it takes energy to turn a liquid into a gas, and that energy comes from heat drawn out of the liquid. How that interaction works is one of the most complicated subjects in science, but what’s important is that it can be used to make ice cream.
Now, you can’t just let cream evaporate and expect to get ice cream. Water in the open air won’t freeze from evaporation alone. But evaporating pressurized liquid carbon dioxide (CO2) draws so much energy out of it that about a third ends up frozen solid: That’s dry ice.
Where do you get a tank of liquid CO2? From a fire-equipment dealer, of course (try smokesign.com). Discharge a 10-pound CO2 fire extinguisher full blast into a pillowcase for about 10 seconds, and you’ll have several pounds of finely powdered dry ice. (Don’t play with it though. Dry ice can give you frostbite in a few seconds.)
Then it’s a simple matter of pouring it into a bowl of ice-cream ingredients—two cups each of half-and-half and heavy cream, two eggs, three quarters of a cup of sugar, two teaspoons of vanilla and a dash of salt—and stirring until frozen. Add the dry ice slowly to avoid hard-as-rock syndrome. I had to microwave my batch to get it back to merely frozen.
So is it edible? Because they’re intended to be used in restaurant kitchens, CO2 fire extinguishers are usually filled with food-grade CO2. (Do not try this with a dry-chemical fire extinguisher.)
The result is … interesting. Carbon dioxide is what makes soda fizz, so the ice cream actually comes out carbonated. Not bad, but don’t expect to see CO2 Crunch in the ice-cream case."
-Popular Science
http://www.popsci.com/popsci/how20/289ac50bc45cc010vgnvcm1000004eecbccdrcrd.html
This topic will definatly be a cool science project, i am thinking of demonstrating it during my presentation