Interesting stuff Dave. The reason for exploding bottles is that the fermentation hadn’t finished when you bottled it….it might have looked like it had….but it hadn’t
One wrong bacteria and you get souring as the bacteria proliferate, which is why yours went off. You need a monoculture of a known yeast and nothing else.
Yeasts are slow growing when anaerobic so are easily outcompeted by anaerobic bacteria. Once the fermentation is well underway this becomes less of an issue because the alcohol produced during fermentation is a preservative, preventing bacterial growth.
Cleanliness and sterility are essential for successful monoculture production. Scrub clean and rinse all of the kit before sterilising so that the sterilisation procedure can easily access all surfaces.
Best way to sterilise things is heat, but it isn’t that easy to do this at home. It takes a minimum of fifteen minutes at 124DegC to kill all bacteria. However, transferring heat alone to all surfaces is difficult, and is why professional establishments use autoclaves producing steam at 1.4 Bar and evacuate all the air before timing starts.
Glass bottles and metal utensils can be successfully treated in an oven on low heat for a couple of hours.
Anything that cannot be heat treated can be soaked in something like Milton sterilising fluid or sodium metabisulphite. Do this somewhere well ventilated though because the fumes can be nasty.
Everything that is going to touch the fermentation needs to be sterilised.