Week 21/22 – Elusive yeast
I’ve been trying to get my head around sorting the yeast for the past few weeks, as it’s the only one of the four ingredients that I can’t actually see. This makes it somewhat tricky to collect, and without help my only choice is to put the beer out in the open air mid-brew, let all of the yeast and accompanying bacteria get into it before it ferments and hope it turns out okay. This is a perfectly acceptable technique, known as natural or spontaneous fermentation, and is used to make some outstanding beers (the most well known probably the lambic family of beers from Belgium). The downside to this approach though, is that it needs a long time to mature or develop and I only have weeks to ferment my beer, not months or years.
Ideally then, I need to isolate a domesticated strain of yeast from the wild, for example saccharomyces cerevisiae, but to do this I need help. Cue Guy and David (or Dr Leonard and Dr Milner to give them their proper titles), two rather clever people at the University of Exeter Living Systems Institute that have agreed to help me discover if there really is the yeast I need on the plot and if so, how I can get it to a usable form. I’ve gathered together 20 different cuttings and samples from the various plants and flowers on the plot and they are running them through a series of processes and machines that should help to confirm if we have the all important yeast or not.
It’s not a level of assistance I was expecting when I started Growing Beer and it’s certainly far beyond anything I could do on my own. Between the two of them the samples that I collect will go through a process that, amongst other stages, involves being spun at over 13,000 G, having their DNA deconstructed and identified against an international database and, if it turns out that sample is what we’re after, cryogenically frozen at -80C to keep it until I need to brew. It’s amazing stuff that has a definite air of science-fiction wonder to me, but it turns out this is fairly standard when you’re working in a world-leading research laboratory.
Early tests from the first batch of samples aren’t looking too hopeful, but the best time and place to collect is late summer and from slightly overripe fruit.We’ll be taking more samples over the coming weeks and I’ve got my fingers crossed something will turn up – there’s still no guarantees it will work, but if these guys don’t find a workable yeast, it’s basically not on the allotment.