On sterilisation/sanitising...

[calumscott]

So here's a couple of thoughts, mostly from my school/uni days studying microbiology...

It must be known, purely by applying the logic that beers sometimes get infected and that must happen commercially as well as domestically at a rate that's high enough to make it "interesting", what alien microbes are poluting our brews.

If you know that - you also know their properties, you can study them, you can learn where they come from, what inhibits them, what kills them.

When you know what it is and how it works you can mitigate against it.

The obvious example is pasteurisation. It doesn't sterilise milk, because the heat treatment to get there denatures proteins in the milk and makes it taste odd (UHT anyone?), all it does is raise the termperature far enough for just long enough to kill anything likely to be pathogenic.

Surely the same logic could apply to brewing if it were known what the evil brew spoiling monsters were?

Anyone seen anything on the topic around the interweb that would make an interesting 10 minute read?

 

[graysalchemy]

Beer when brewed is relatively sterile because of its alcohol content and low pH. However it does spoil I have lost 2 brews to fruit fly aceto bacteria and one to something else.

The trick is obviously to keep everything sterile whilst it brews. Don't fiddle with it leave it to get on. Once it has stopped brewing keep it covered and a layer of co2 will give some protection. Most importantly bottle or keg it and let the yeast get to work producing co2 which will protect it for a fair while especially in a bottle.

Most commercial breweries pasteurise any beer going in a bottle or tin or keg (not cask obviously) so it can be forced carbonated resulting in consistent bland beer.

 

[Bertie Doe]

The obvious example is pasteurisation. It doesn't sterilise milk, because the heat treatment to get there denatures proteins in the milk and makes it taste odd (UHT anyone?), all it does is raise the termperature far enough for just long enough to kill anything likely to be pathogenic.

I make my own yogurt, which means you heat the milk to 90C, which bumps off all the nasties. You drop the temp down to 43C and then innoculate with friendly bacteria and you incubate overnight. These are the instruction which came with the heated flask - and it works, no rancid batches so far.
Mind you, boiling the wort for 90 mins does the trick. I use VWP for sterilizing before brewing.
I also like to leave a trace of VWP in the fv when I store them after use. I find this prevents that beer smell you get, when you start your next brew.

Beer when brewed is relatively sterile because of its alcohol content and low pH. However it does spoil I have lost 2 brews to fruit fly aceto bacteria and one to something else.

In the thread "irritating flies" you thought you might lose 60L of stout was this the case, or just a false alarm?

 

[graysalchemy]

No I have 60l of stout vinegar ready for next years pickled onions. :lol: :lol:

Still a sore point as i am low on decent beer and I won't get to brew till next week.

 

[Bertie Doe]

No I have 60l of stout vinegar ready for next years pickled onions. :lol: :lol:

I only do 20l at a time, so 60 is an awful lot of medicinals - ouch. I've just racked 20 into a spare fv and the more you handle the hooch, the more nervous I become. I need to start a new thread on casking, maturing and priming.

 

[graysalchemy]

I have put it all into open topped dj's and a plastic jerry can. Last years disaster is the dogs danglies but I only kept 2 gallon of that. I have also infected some cider for cider vinegar just a few pints.