Naturally fermented ginger beer

Question

I'm doing ginger beer sodas by using juices: ginger and lemon juices, cane sugar and natural flavours. I pasteurise the blend by cooking it to 150°F (66°C) for a good minute, then cooling it off and adding sparkling water. Later, bottling and capping.

I've never had any problems, even months later it's all good. But my last batch is for some reason fermenting. I'm not adding any yeast to it, so it's probably fermenting naturally. The glass bottles (beer bottles) are capped, so there is no air coming in, and then I'm not feeding it (adding sugar or ginger like when doing a ginger bug), so I wonder if the fermentation will stop, if so at what point it should, or will it keep fermenting and I can end up with my bottles exploding? I'm about 8.5% Brix in cane sugar.

Thanks,

Answer 1

If you rely on wild yeasts, did you expose the "beer" to air long enough? You could wait until you see bubbles on the surface as a sign of yeast activity, or you could take daily gravity readings. Once gravity starts going down, something is working on the sugars.

Fermentation will stop when either the yeast has consumed all fermentable sugars, or when the yeast dies from the alcohol it has produced. The former is much more likely; the later is only a concern for strong wines or beers. Many wine yeasts can tolerate 12 to 15 %ABV.

You get bottle bombs if you have too much fermentables in the bottle. Bottling 8.5% Brix (which is roughly a 1.033 specific gravity) sounds like a recipe for bottle bombs to me.

If you do fear you may have bottle bombs, you can try to fix this in 2 ways.

You can either open all bottles and dump the content in a bucket. Let it ferment completely, then put a reasonable amount of sugar in and bottle again.

The other option is to vent each bottle and let excess carbonation escape. This is fairly easy with swingtop bottles, but may be hard with caps.