Sugar (any kind) + yeast + water give you Carbon Dioxide (fiz) + ethyl alcohol + acid (acetic, lactic, etc.). This process is called fermentation. After a day or two of fermentation, the alcohol content is still low (about the same as in a ripe banana), but the acid content is strong enough (pH ~ 4.5) to produce a sour taste and inhibit growth of pathogenic bacteria.
Below is a recipe for making 2 Liters of Soda Pop.
1. Take an empty and clean 2 Liter plastic pop bottle.
2. Add ¼ to ½ cup sugar (depending on your taste).
3. Add ½ cup lemon juice (real lemon?), or ½ cup prune or fruit juice.
4. Add 1/8 tsp frozen bread yeast.
5. Fill the bottle with water up to 2 inches from the cap.
6. Tighten the cap and shake the water and contents to mix.
7. Loosen the cap and let bottle sit at room temperature for 2 days.
8. Squeeze the bottle until the liquid level is at the top of the bottle, and tighten the cap.
9. Let the bottle sit at room temperature until the bottle fills out and gets hard.
10. Refrigerate until cold enough to drink.
11. Slowly remove the cap (don’t shake it) over a sink in case it wants to foam over.
12. Pour contents into a glass and enjoy.
13. Leave residue in bottom of the bottle to use as a starter for your next bottle.