Real root beer, naturally carbonated: A strong taste without being harsh. As close as you can get to store-bought and still have all natural ingredients. The taste is much more honest than store-bought as well.
The keys are your choice of flavorings and using yeast to naturally carbonate. This recipe produces just under 2 liters. I found this after searching the Web for the easiest version possible that uses no special equipment, just household items, although you have to search for suitable real root beer extract.
To give proper credit, the basic recipe has been worked out by Dr. David B. Fankhauser, Ph.D. , Professor of Biology and Chemistry,
U.C. Clermont College, Batavia OH. The recipe is a perfect demonstration of Henry's Law. Look it up.
You must use fresh yeast, otherwise it won't be fizzy and it will taste like "skunky" beer that went bad.
You can try increasing the yeast a tiny fraction to get more carbonation, but again, too much and it's like drinking from a bicycle tire.
Use plain white granulated sugar. The sugar provides food for the yeast which makes the carbonation happen.
I searched my neighborhood for root beer extract, no grocery or health food store had it. I finally ordered directly from Zatarain's from their web site.
The bottle: Use a plastic 2-liter soda pop bottle with a resealable cap. CLEAN this thoroughly before using.
Do NOT, for safety's sake, use a glass bottle.
The funnel: A clean plastic funnel is best.