And salami and so on. With cheese it is pretty extreme - you don't even bottle it so even the outside of it is made form bacteria too...

Bread's even more extreme: I caught my own wild sourdough a few times. (You can catch your own wild yeasts for beer too, but that's more hit and miss, I believe?)

I make cider using wild yeast. It's always worked fine so far. I think this is fairly common with small-scale cider making in the UK. I do add some sulphite to the juice (amount depends on pH) to discourage the undesirable micro-organisms. If you want consistency then it's probably not a good technique, but that's not what I am after.

Yes, I think it is common for cider still. Its entirely doable with wine, but only high end places tend to, cheap wine, like cheap cheese, is more industrial...

This sounds like a lot of fun, can you explain the process you went through to catch your own? How did you ensure you were catching something useable and not something you didn't want in your bread?

There are lots of good resources on the web for the details. The gist is: the micro-organisms you want are already on the flour in traces, so you start with equal parts unpasteurized (eg organic) wholemeal rye or wheat flour and water, mix them, and let them stand in a container for a few days (or even two weeks, if you don't heat your home in winter, like I did when I started in Cambridge, Cambridgeshire).

That's mostly all there is to it. Reading up, will teach you what to expect the starter to look like, how to troubleshoot, and how to turn the starter into bread.

I like the simplicity of flour, water, salt. (And air, time and kneading.) The simplicity leaves no room for covering up mistakes like cakes allow you to do.

> How did you ensure you were catching something useable and not something you didn't want in your bread?

Humanity is very lucky that the most probably natural occurring fermentation in grain dough is not only perfectly safe, it also improves taste, nutrition, digestibility and shelf-life of your bread.

Your nose will tell you if something is off. I think mold is the most common invader. But even mold will have a hard time in a healthy sourdough, because the low pH (=high acidity) and some enzymes keep the symbiosis of yeast and lactobacillus exceptionally stable.

You can make beer from wild yeast too, like gueuze. Unpasteurized cheese is from the bacteria already in the milk.