The Science Behind Carbonation
1) WHY DO WE FEEL THE EFFECTS OF CARBONATION ON OUR TONGUES?
The reason cold carbonated beverages effervesce on your tongue is because of temperature change. When the liquid interacts with your body (tongue and stomach) it experiences nearly instant change in CO2 concentration. The warmer temperature will purge a liquid pressurized at 3 to 4 volumes all the way down to about 1 volume! That’s why we burp! When the gas changes equilibrium in the liquid it has to be expelled somewhere. Thankfully our bodies are pretty remarkable machines and they expel the gas through our mouths safely.
2) WHAT DO WE NEED TO KNOW ABOUT ADDING CARBONATION TO A LIQUID?
The two things that are most important when carbonating a liquid are the temperature of your liquid and the amount of headspace left in the container. CO2 has a higher rate of absorbtion and dispersement in colder liquids, so it is important to chill your water before using the system. You also want to make sure there is ample room in the container for CO2 to infiltrate the water. When there isn’t much headspace you can’t properly get enough interaction between water and CO2.
When you dispense gas into the bottle, you have to shake it. Seems counterintuitive right? We’re always told not to shake our soda. But, in fact, carbon dioxide does not readily dissolve into water. Agitation creates more surface area for the gas to come in contact with the liquid, and that larger surface area means more of the gas will filter into the water.
Water naturally has some gas dissolved in it already, though it’s a mongrel collection of elements. We carbonate twice in a home system in order to take care of that problem. The first carbonation and venting will force out most of the other gasses, then the second round permeates the liquid with pure carbon dioxide.
3) CAN YOU CONTROL HOW FIZZY YOUR LIQUIDS GET?
The great thing about home carbonation units is that you can experiment with how fizzy you like your water. Soda is standardly pressurized to 3.5-3.8 volumes, but when you do this at home you can get it pressurized all the way up to 4 volumes safely if you like. You can also play with lower pressures and have lightly fizzed drinks. This works exquisitely with wine and other liquids, though I suggest you keep to clear drinks (no pulpy orange juice in the system).
WHAT DO WE NEED TO MAKE OUR OWN CARBONATION SYSTEM?
- CO2 tank, purchased or rented from soda supply store
- Pressure regulator
- Braided hosing
- Ball-lock clamp and threaded coupling
Carbon dioxide tanks come in a few forms, and they are measured by the weight of the compressed gas. A 5-pound tank of gas weighs close to 15 pounds, because the net weight includes the actual steel tank and fittings. The smallest and least expensive form of CO2 tanks are sold at sporting supply stores for use in paintball guns. These tanks are all refillable, something that contributes to major savings at home. There are two types of CO2 available, food-grade and industrial. Food grade CO2 is measured at 99.9% or higher purity, while industrial grade CO2 is rated at 99.5-99.8% purity. When refilling your tank the best place to visit is a soda supply shop, home-brew shop, or restaurant supply store.
Pressure regulators can be $50-60 dollars, but it’s necessary for the operation. There are two gauges on my regulator, one tells me the internal pressure in the tank and the other tells me the output pressure of my gas into the bottle. Less expensive regulators don’t have gauges, but I wouldn’t recommend them.
After you purchase everything it’s just a matter of screwing the pieces together. I have a completed system here and a bottle of cold water. Let’s hook it up and charge the seltzer!
Homemade Lemon Soda:
1/2 ounce Simple Syrup
1 ounce Lemon Juice
10 ounces Soda Water
In the bottom of a glass, stir the lemon juice and syrup together. Pour cold soda water over the mixture and enjoy!
For more info on Dan Kohler, go to: www.RenegadeKitchen.com