Recipe 15: Halloween Root Beer with Dry Ice

As the harvest season approaches, there are invariably countless Halloween parties at which homemade rootbeer is a staple. I don’t know if it’s the dry ice in the bubbling “witch’s brew” that makes us think of Halloween, or if enjoying a root brew has always been traditional this time of year. One thing is for sure, whenever I think of homemade soda with dry ice, I think of the large orange beverage cooler bubbling at a church Halloween party, with little kids hoping to get just a little sliver of that dry ice in their cup so they can watch it bubble and “smoke” until it quickly disappears.


If you’re planning a party with just such a brew, here are some tips on carbonating with dry ice to get the best carbonation in your beverage.

- A general rule of thumb is 1 lb of dry ice/gallon. This is going to bubble like crazy, so make sure you have a lid for your orange beverage cooler to contain the splashes.

- Also easy to remember is 1 lb of sugar/ gallon. This may seem like a lot, but it is the same amount of sugar as Kool-Aid, so it’s nothing you haven’t imbibed before.

- How much carbonation a drink will hold is mostly a function of temperature and pressure. As the drink gets colder and the more pressure the drink is under, the more carbonation it will hold. Increasing pressure can be difficult and dangerous (especially with 5 lbs of dry ice), placing the lid on the cooler will certainly help, but you’ll get more results with keeping it cold. Dry ice will chill it, but you’ll be much farther ahead if you start out as cold as you can go. Leave it in the refrigerator overnight if you have that much space, or add some of your water as ice. With that much sugar you should be able to get it just below 32 degrees before it freezes.

- You’ll get more mileage out of your dry ice if you don’t add it all at once. Add about 1 lb and stir until it’s gone. The agitation will ensure that you get even cooling, pH adjustment, and carbonation from the first pound, then add the rest and let it sit.

So why does dry ice carbonate water? Dry ice is solid carbon dioxide or CO2, it’s held at a temperature of about -110F. Instead of melting, it sublimates, meaning it goes straight from solid to gas. As the gas bubbles through the water, some of it dissolves into solution, creating carbonic acid, or H2CO3. Carbonic acid readily breaks down at room temperature and pressure to 1 molecule of CO2 and 1 molecule of H2O, carbon dioxide and water. Many people think that the tingle of soda in their mouth is the bubbles, but part of it is the bite of the acid.

5x5 Halloween Root Beer Recipe:

5 gallons water

5 lbs sugar

5 lbs dry ice

5 ounces extract(2 oz rootbeer, 3 oz vanilla)

Combine water, sugar, and extracts in a 6 gallon or larger beverage cooler (you’ll need extra space so it doesn’t bubble over). Make sure this is as cold as it can possibly get, or chill it overnight if you have space. 1-2 hours before serving, add 1 lb dry ice and stir until dissolved. Add the rest of the dry ice and let it sit for the remainder of the serving time.

I wish I had a lovely picture of this, it's always fun to see all that bubbling brew.  Maybe closer to Halloween one will pop up, no pun intended.