Bubble, Bubble

• Without yeast, your soda won't possess the fizzy carbonation. The yeast is the catalyst for the fermentation process. As yeast feeds, it produces carbon dioxide, which cause of the carbonation bubbles. Feeding yeast in a closed container prevents the bubbles from escaping, which makes your soda fizzy when you open the top. This process also produces a small amount of alcohol, but in a homemade soda, the amount is only a negligible 0.4 percent, so the soda isn't considered an alcoholic beverage.

Feed the Yeast

• Yeast feeds on the glucose in sugar. Soda recipes typically contain enough sugar to both feed the yeast to create carbonation and give the beverage its sweet flavor. If you prefer a sugar-free soda, you must still add a bit of sugar to feed the yeast. Use 1 tablespoon sugar for every 8 cups of soda to feed the yeast; add the sugar substitute of your choice for the desired flavor. Although most homemade soda recipes call for white sugar, natural sugars such as honey also work because they contain the glucose necessary for the yeast. The yeast are only allowed to feed and produce bubbles for 48 hours or less, which isn't long enough for full fermentation and is why homemade soda doesn't contain high amounts of alcohol. Refrigerating the soda stops the fermentation process.

Blowing Bubbles

• Although yeast feeds and produces carbon dioxide bubbles in an open container, those bubbles escape into the air and don't result in a carbonated beverage. Brew soda in a closed container so the carbon dioxide can't escape. Although glass bottles are attractive, they can cause serious harm if they break when too much pressure builds up from the carbon dioxide. Plastic is a safer alternative, especially if you are new to the homemade soda process. It can still burst under the pressure of too much carbon dioxide, but it won't throw glass shards.

The Perfect Brew

• Experiment with different flavorings and sugar amounts to find what you prefer. Generally, 1 cup of sugar per 2 liters of water results in a bubbly, sweet soda. You can use commercial soda flavorings, or flavor the soda with grated ginger, lemon juice, crushed berries or other fruit juices. Use ¼ teaspoon of baker's yeast or 1/8 teaspoon of brewer's yeast for every 2 liters of water. Mix your ingredients in the bottle, cap it, and store it in a warm but not hot area for about 2 days, or until the bottle becomes too hard to press the sides inward easily. Refrigerating stops the carbonation process so the bottles won't explode. Setting the homemade soda in a closed plastic tub as it ferments contains any mess if the bottles burst.