I finally did it! I've been experimenting with homemade ginger ale for awhile, and although the results have always been passable, this week I finally brewed the perfect batch.
The big difference this time was that I was out of commercial yeast, so instead I used a tablespoon of my sourdough starter. I think the gentler action of the starter was just what was needed. The result is a sweet, tart, fizzy drink with the perfect gingery kick--and no hint of alcohol flavor, as some of the other batches had. The fermentation went just long enough. I think commercial yeast is probably far too active, so that the window of time between the perfect carbonation for ginger ale and having it turn to ginger beer is a much narrower one. Letting it ferment with natural yeasts gave me a wider window.
Here's my recipe:
(Makes one 3-liter bottle)
A chunk of ginger, peeled and grated--I like a lot, a piece up to the size of my palm, maybe a little less
Juice from 1 1/2 lemons
1 tablespoon sourdough starter or 3/8 teaspoon commercial instant yeast
1 1/2 cups sugar
Filtered or otherwise chlorine-free water.
Peel and grate the ginger. Mix the grated ginger (and its juices) with the sugar, lemon juice, and some of the water. Stir to dissolve the sugar. Pour into the bottle, top off with remaining water plus one tablespoon sourdough starter. Screw on the lid and shake well. Leave at room temperature for a day or longer. I use a large (3-liter) soda bottle. Do not use a glass container unless you have a fermentation lock as there is a danger of explosion as the carbonation builds. Even with the plastic bottle you will want to check it frequently. Give the bottle a squeeze every few hours. When it reaches a point where it doesn't yield under the pressure of your squeezing, it's time to put it in the refrigerator. This will stop (or nearly stop) the fermentation process. At this point it should be ready to drink. If you try it and it's not fizzy enough, set it back out at room temperature for awhile and taste it again in a few hours. When it achieves the desired carbonation, refrigerate it again. I use a fine-mesh tea strainer to strain each individual glass as I pour it, but you may want to strain it all at once and re-bottle it.