Fermentation has been used by mankind for thousands of years for raising bread, fermenting wine and brewing beer. The products of the fermentation of sugar by baker's yeast Saccharomyces cerevisiae (a fungus) are ethyl alcohol and carbon dioxide. Carbon dioxide causes bread to rise and gives effervescent drinks their bubbles. This action of yeast on sugar is used to 'carbonate' beverages, as in the addition of bubbles to champagne).
Set up a fermentation in a closed system and capture the generated carbon dioxide to carbonate our home made ginger ale. You may of course adjust the quantities of sugar and/or extract to taste. Note that the lemon called for in step eight is optional. And if you want a spicier drink, you can increase the amount of grated ginger. As with any yeast fermentation, there is a small amount of alcohol generated in the beverage (about 0.4%).
Equipment
clean 2 liter plastic soft drink bottle with cap (not glass: explosions are dangerous.)
funnel
Grater (preferably with fine "cutting" teeth
1 cup measuring cup
1/4 tsp and 1 Tbl measuring spoons
Ingredients
cane (table) sugar [sucrose] (1 cup)
Freshly grated ginger root (1 1/2-2 tablespoons)
Juice of one lemon
fresh granular baker's yeast (1/4 teaspoon)
cold fresh pure water