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'''Wild yeast isolation''', sometimes known as "yeast wrangling" or more formally [https://en.wikipedia.org/wiki/Bioprospecting "bioprospecting"], refers to the process of catching wild yeast, and isolating it with agar plates as a pure culture. This article will also contain information on growing up a ''captured'' culture in wort rather than isolating yeast cultures on agar plates. Culturing wild yeast and bacteria should not be confused with [[Spontaneous Fermentation]] because many of the microbes that might make a flavor impact during spontaneous fermentation are killed off during the wild yeast culturing processes.
:''Special thanks goes out to Bryan from Sui Generis blog and Jeff Mello from Bootleg Biology for providing the information in this article.''
* Monitor for mold growth. If mold begins to grow on the growth media, scrape it out and continue on with the isolation process. This should be safe since isolating the yeast will separate it from any potential mycotoxins that developed during the initial catching. Do not consume any growth media that has had mold grow on it (see [[Mold]]). One suggested method is to remove any materials (fruit, leaves, etc.) that were used as an inoculant as soon as visible fermentation happens; this can help avoid mold growth by removing floating material <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1812527172108822/?comment_id=1812566615438211&comment_tracking=%7B%22tn%22%3A%22R%22%7D Caroline Whallen Taggart on removing fruit to prevent mold. Milk The Funk Facebook group. 09/05/2017.]</ref>.
* In general, summer and spring are more successful times to catch wild yeast, however any time of year can be successful. Simply choose fruits or flowers that bloom/grow during that particular season. For example, in spring, flowers and fruit blossoms are a good source. In summer, wild summer fruit can be a good source (raspberries, strawberries, cherries, etc.). In the fall, apples and grapes can be a good source. In winter, juniper berries <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1683379841690223/?comment_id=1683799054981635&comment_tracking=%7B%22tn%22%3A%22R%22%7D Milk The Funk thread on the best seasons for bioprospecting. 05/11/2017.]</ref>.
* A new study showed that wild yeast actually exists more so in leaf matter on the ground than it does on bark or fruit. See the [[Wild_Yeast_Isolation#Videos|"Where (Do) the Wild Yeast Roam" video by Bryan from Sui Generis blog]] belowand the below studies. Unless isolating microbes, this method could be dangerous unless the starter medium pH is lowered to be under 4.5 and enough ethanol (vodka) is added to reach 3-5% ABV. Purging the flask with CO2 might help prevent mold growth.** [http://onlinelibrary.wiley.com/doi/10.1111/1758-2229.12446/full A systematic forest survey showing an association of Saccharomyces paradoxus with oak leaf litter.]** [http://onlinelibrary.wiley.com/doi/10.1111/mec.13120/abstract The interaction of Saccharomyces paradoxus with its natural competitors on oak bark.]** [http://macau.uni-kiel.de/receive/dissertation_diss_00018537?lang=en The natural ecology of Saccharomyces yeasts.]** [https://www.facebook.com/groups/MilkTheFunk/permalink/1910439962317542/ Associated MTF thread.]
* [https://www.facebook.com/groups/MilkTheFunk/permalink/1034954619866085/ David Thornton's use of foam as stoppers.]
* Bryan of [https://suigenerisbrewing.blogspot.com/ Sui Generis Blog] instructions for using a jar of wort and cheesecloth to catch microbes in the airs/MilkTheFunk/permalink/1817522898275916/?comment_id=1817911281570411&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Bryan of Sui Generis blog. milk The Funk Facebook group post on catching wild yeast. 09/10/2017.]</ref>air:
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3) Hoped wort can be used as well, although my success at getting yeast + lacto with hopped wort is poor...I usually only get yeast, even with a meagre 3-5 IBU.
4) Raccoons, possums, rats, squirrels, deer, and pretty much every other fur-bearing animal (and some of the feather-bearing kinds as well) love unfermented wort, so try to place your jar somewhere they cannot get at it - while still maintaining airflow. We've got wild turkeys in the back, and those f***ers can fly (editor's note: language, Bryan!), so its a real challenge to keep them out." <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1817522898275916/?comment_id=1817911281570411&comment_tracking=%7B%22tn%22%3A%22R1%22%7D Bryan of Sui Generis blog. Milk The Funk Facebook grouppost on catching wild yeast. 09/10/2017.]</ref>
</blockquote>
Once the wort has fermented out (allowing 2 weeks total is a good rule of thumb), decant the beer and pitch the collected yeast into 500ml of starter wort, again lowering the pH of the starter wort to 4.5 with lactic acid. After the starter wort has been fermented, the yeast should have enough of a population to ferment out a 1 gallon batch of wort. Keep the recipe of the wort simple, and in the 1.050 gravity range. The yeast cell count should be high enough at this point to out-compete bacteria and lower the pH of the wort within a few days. The pH of the 1 gallon batch, therefore, does not need to be lowered, although the brewer may choose to do so anyway. For [[Wild_Yeast_Isolation#Safety|safety reasons]], test to make sure that the beer fully attenuated and has a pH of 4.5 or less. Allow for one month after fermenting the 1 gallon batch of beer before sampling. If it smells like feces or vomit, do not sample it and throw it away. If the beer smells ok, feel free to sample the beer to see if the wild yeast produced a good tasting beer. David Thornton from [[SouthYeast Labs]] estimates that only about 10% of yeast that can fully attenuate produces favorable results, so failures are to be expected (keep trying!) <ref name="Thornton"></ref>. Fermenting a few batches of beer at different temperatures is a useful method for identifying the ideal fermentation temperature range for the yeast.
Once a wild culture has been determined to be something that the brewer wants to keep for future batches, yeast harvesting methods can be used to maintain the culture. See [http://www.wyeastlab.com/yeast-harvesting-re-pitching Wyeast's article on yeast harvesting] and [http://brulosophy.com/methods/yeast-harvesting/ harvesting from an over-built yeast starter].
See also:
====Videos====
<youtubeheight="200" width="300">-tmbnPXZcFQ</youtube><youtubeheight="200" width="300">y43x7nLTEPo</youtube><youtubeheight="200" width="300">SwDjJKkuT74</youtube><youtubeheight="200" width="300">viXPMtkTfk8</youtube><youtubeheight="200" width="300">ChHcR9qaxj0</youtube>
==References==