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Monday, 13 June 2011

Rhubarb Lambic Update

About two months ago I wrote this. An experiment with some surplus homebrew, some sour beer dregs and an overactive imagination.

Six weeks after giving birth to that beer I took a sample to see how things were progressing. It was warm and flat, of course, but it was also tart and lacking any signs of obvious oxidation. Even more positive was the BIG Brett flavour that now dominated. Things are going well I thought to myself, but what this beer could really do with is lots (and lots) more sourness.

Enter the lactic starter.

So a friend of mine sees an article in Zymurgy that he thinks might interest me. It describes a process by which you can make a lactic starter without the need for buying a lactic bacteria culture. He's right, it does interest me, and it seems like perfect timing.

Here's what you do. Lactic bacteria live naturally on the outside of malted grain. If you take a wort at 1.038 and you hold it at 38c, you produce the perfect environment for lactic bacteria. Add malted barley to this mixture, wait three days and this is what you get:

That bacteria on the outside of the grain will eat the sugar in the wort and will reproduce, making lactic acid along the way. That lactic acid is (part of) what you're tasting when you drink a sour beer like Lambic or Gueuze.

I used about 50g of dried malt extract in 500ml of water. I boiled this for about 5 minutes and then cooled to 38c. I poured this into a sanitised milk bottle, added 2 heaped dessert spoons of crushed pale malted barley, capped it with some tin foil and sat it in a temperature controlled water bath for the three days.

My lacto-friends now ready for battle, all it took was a sieve to strain out the junk and 300ml of new fresh wort at around 1.040. Both these things pitched into the main batch of Rhubarb Lambic and away we go. This is the pellicile that now sits atop my beer:

This might just be the most geeky post I've written on this blog, but I don't care - this is why I love homebrewing!


Neil, Eating isn't Cheating said...

really enjoyed reading this mate. But I am, to be fair, a beer geek.

Mark said...

Good to hear! Hopefully it turns out to taste good too. :)

Leigh said...

Geeky - nah; very interesting! would love to know how this badboy turns out.

Mark said...

We opened one of the pre-lacto bottles on Friday night. I was expecting it to be a bit crap to be honest, but it was actually pretty damn good. A little lacking in carbonation, but a massive peachy flavour that wasnt there before, some rhubarb in the background, lots of Brett character and a gentle tartness.

Hope I havent ruined it with all that lacto .... :P