My interest in brewing has been life-long; I remember helping my grandfather to make schnapps and applejack when I was a little kid. As soon as I was legally able to (that’s all I’ll admit to here) I began homebrewing beer. At the same time I began my undergraduate degree in Cellular, Molecular and Microbial Biology, leading to a early fusion of my education and hobbies. By the age of 20 I had engaged in a series of experiments to evolve brewing strains (discussed extensively in this thread, over at homebrewtalk). At the same time I began brewing sour & wild beers.
I then made the choice (no comment on whether it was a good one or not) to do a PhD, and thus entered a 7 year period where I was constantly moving and never sure where I’d be 6 months into the future (followed by another 4 years of the same whilst post-doc’ing). Over successive moves I lost my library of “custom yeasts”, but not the passion and interest in developing my own strains & wild brewing.
This interest was rekindled last year, after I joined the London Homebrewers Build, my local brew club. Within the first two meetings I had run into a couple of people interested in brewing with wild yeast. These (beer fueled) discussions led to what I think is a unique project – we aim to capture, purify and characterize a range of local wild yeasts, with the hopes of developing a strain (or two, or three) suitable for brewing.
This is the introductory post in what will be a series cataloguing this process. Below the fold is an outline of the strategy and some resources we are using.
So where do we begin?
The answer is, “with those who have done similar things before us”. I say ‘similar’, because at this point the closest I’ve seen to what we’re aiming to do is people isolating yeasts from commercial wild beers, or working with Brettanomyces. Below is a list of links to blogs and other resources covering the purification and identification of these yeasts. This list will likely grow as this project progresses:
- Brettanomyces Project – An on-line MSc dissertation & blog series on the culture of brettanomyces.
- BKYeast – A blogger who has done some wild yeast harvesting from commercial beers and has some interesting media options for those without access to lab-grade chemicals.
- Brew Science Hombrew Blog – A blogger who has, among other things, applied more lab-based methods for purifying yeasts from commercial sour beers.
- Eureka Brewing – another blog covering several attempts at purifying wild yeasts from commercial beers.
Where do you find wild yeast?
- On fruit. This is the mother-load; yeasts thrive on the skins of fruits – especially on grapes, berries and tomatoes (i.e. things high in sugar and acid).
- On trees (fruit or otherwise). Yeasts love sugar, and tree sap is full of it.
- In your house. While the amounts are not as high as in the above examples, there should be enough.
- Sourdough starters (or flour). Wheat flour (and other flours) come pre-packed with yeasts and bacteria capable of consuming the starches and sugars made by these grains. These organisms are often harnessed to make sourdough bread, but given these are the ones living on grains, they also likely represent yeasts similar to those which brewed the first beers ~10,000 years ago.
- In the ‘wild’. Yeasts can be harvested nearly anywhere there is plant growth – be it a forest, a vineyard, a farm, or a city park.
How do you capture wild yeast?
- Yeasts from fruits, grains and flours: Simply place a bit of the fruit/grain/flour in a solution that will support the growth of yeast (i.e. low-gravity beer wort). In a few days the wort should be bubbling away with active fermentation – of both the yeast and bacterial sort.
- From the environment: A container of wort, or an agar plate with suitable media, is placed open in the environment, usually at night, and yeast spores allowed to collect in the media. Care must be taken to protect the wort/plates from insects and animals, but this method allows the capture of yeast from nearly any site.