I had too many bad experiences with "natural yeast" carbonation in root beers. I use forced CO2 now exclusivly. Plastic and putting them in the fridge is the way to go, but drink FAST. Yeast does not die in a fridge. It just gets slower. Especially when you are trying to stop it at about 1/2% alcohol only and a lot of yummy sugar left behind for it to nibble on.
Here's my recipe that is very well liked at beer festivals as an alternative for the designated drivers.
The kinds of sugar are less important than the quantity. Substitute cup for cup with whatvyou can find. The malto dextrine is for a creamy head. Get the extract at homebrew stores. I use the "homebrew" brand in the little brown boxes.
Root Beer
2 oz Root Beer Extract
1 oz Sarsaparilla Extract
1/2 cup honey
2 cups Dark Brown Sugar
2 cups Light Brown Sugar
2 cups Raw Cane Sugar Crystals
4 cups White Crystal Sugar
1 cup Malto Dextrin
1/2 teaspoon Black Strap Molasses
1 Cinnamon Stick
3 tablespoons Maple Syrup
2 tablespoons Vanilla Extract
1/2 teaspoon Coconut Extract
1/2 teaspoon Almond Extract
1/2 teaspoon Rum Extract
1 gallon hot water to dissolve the sugar
4 gallons cold water
*
Roll the keg on the floor to mix well.
Chill and carbonate at 30 PSI of CO2 for 3 days.
0% ABV* ;-)