I’ve been making ginger beer for a little over a year, so have some experience with short (soda) fermentation, but not much with anything over 1%abv.
On the burping, I think the primary purpose is to release just enough co2 to prevent explosions in a sealed brewing environment. Too much burping will make your brew go flat, so I try to only do it when something is really ready to pop. Brewing equipment has ways around this, but one good way to do it without the expense is to brew in 2 liter plastic bottles, leaving a couple inches at the top, and squeezing out any remaining air before sealing. As co2 builds up, the bottle expands, showing you how far along you are. Plus, soda bottles are built to take the pressure. My current brew is in very sturdy glass flip-top bottles, so I’m burping them just to see how they’re coming along.
If your making something more alcoholic, feed your yeasts for a week or so at a fairly high temperature in something that can breathe a bit, like a quart jar with muslin tied over the top, to give it a ‘head’ start (harhar) and then transfer to bottles later for carbonation, as above, at a lower temperature. If you’re wild fermenting, ignore the muslin
One thing about reusing store-bought juices, is they have preservatives that your culture might not be happy about (they don’t want to be preserved against!)
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I just went to a site a couple days ago, and ordered Ginger Beer Plant, a yeast and bacteria culture that loooves ginger. They also have Water kefir (tibicos), milk kefir, sourdough and yogurt cultures. Not too expensive. http://fermentedtreasures.com/
I’m in the GingerBeerPlant yahoo group, and they talk about kefir and tibicos all the time… its a pretty good source for peoples experience with brewing all kinds of things in many ways.
Ginger beer plant is the same way as milk kefir in that you can’t really make it from scratch. The different cultures are rather delicate, and I don’t think human intervention was responsible at first. The little guys may not like to go together on their own without ideal situations. They probably found a place to get together at some time in the past, and established a solid symbiosis over the years that you can’t duplicate easily in the kitchen or lab.