Interesting question from Mark:
Occasionally, we find ourselves with an old bottle of flat beer that
has lost all it’s effervescence. Rather than just throwing away before
we recycle, I’m wondering if this old beer would be good to inoculate
some bedding material or partially dry food scraps prior to top
feeding our worms? One would think that the sugars and carbs would be
a good addition!?
What you’ve described goes against my own “leave no beer behind” moral philosophy (some might even call this a “beer crime”), but I won’t judge you for it!
Joking aside, that’s a really good question! As is often the case with me, my response would be “it depends”. Would I recommend adding a fair amount of beer to a smaller system – absolutely NOT! But I wouldn’t hesitate to empty out a small amount from the bottom of a single bottle into a larger outdoor system.
Obviously we need to remember that beer contains alcohol, which is not a worm-friendly substance. This helps to explain why things can go terribly wrong in a bin containing a lot of sugary/starchy materials that goes anaerobic (fermentation is an anaerobic pathway). But if the worms have a sizable safe zone in their habitat, a little alcohol is not going to cause any issues – and will likely evaporate or get converted into something else pretty quickly.
You are right about the carb components of the beer – those should help to boost microbe activity once the alcohol is gone.
One side-note before signing off…
If you happen to be a home-brewer, the left over spent grains (“mash”) can be a really good “food” material for vermicomposting. But you need to be REALLY careful about how much you add. It is best if you feed them in moderation, and make sure to mix up with a variety of other materials (including bedding) as well.
Hope this helps!