I had a hand in inventing a new kind of beverage. I was making home made cola. I would get flavor concentrate and mix that with the other ingredients, including a bit of champagne yeast to carbonate it with and put it in half liter resealable bottles:
Cola is not known for having a lot of nutritional value, so the yeast would only get as far as turning some of the sugar into enough CO2 to carbonate it before going dormant from a lack of complete nutrition. I used to drink apple juice for the malic acid to keep my gall stones from forming, but I began to gain weight from all the apple juice I did have to drink. I figured out a better way. At Tri-State, the hardware store here in Moscow Idaho where I would get the resealable bottles, champagne yeast and cola concentrate, I also get malic acid, an acid used to acidify home brewed wine. I would dissolve the malic acid in juice, usually grape, as I like tart juice and drink that instead of large amounts of apple juice. As I do not want this to degenerate into a medical post, do not try this at home without the advice of a real doctor.
I realized I could carbonate my “liver medicine” if I added the champagne yeast and refrigerated it after it got carbonated but before it could become wine or hard cider. It took about twelve hours for it to get seriously bubbly. I told my friend Nels, who owns Panhandle Artisan Bakery http://panhandlebread.com/ less than a block from my home about this. He wanted to try some and wondered if I could use the on going bread start, what many people simply call sourdough start to make it. I tried differing amounts of bread start and found it either gave the juice an odd flavor or took too long to get the juice carbonated. When the start got a bottle carbonated, though, I simply used the bottle to inoculate juice to make more sparkling juice. Now I simply set aside one bottle from a previous batch to start the next one. The wild cultures in the juice add an interesting subtle flavor pleasantly reminiscent of the sour in sourdough bread. My friend Nels likes my “home made soda” so well, I routinely trade him a liter of it for a loaf of his artisan bread.
I have been told by numerous people it is good enough to sell, but I do not, as it would be a nightmare dealing with the regulations and liability issues. I imagine that minors could simply let it turn to wine or hard cider by leaving it unrefrigerated long enough, for example. I found most any flavor of fruit juice other than citrus or pineapple works well. Citrus and pineapple just came out really nasty tasting. I have no idea what tomato or vegetable juice would be like. I usually use just grape juice, but I brew up a variety for special events and family holiday get-togethers.