Author Topic: Harvesting wild yeast (but NOT brett!)  (Read 4847 times)

Offline phillamb168

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Harvesting wild yeast (but NOT brett!)
« on: May 26, 2011, 04:27:06 AM »
I live close to the Gâtinais (been thinking about calling my brewery Bracino Wastinensis, the old Frank derivation of the Latin pagus appellation for the region) and have thought long and hard about what I'd like to do that could be "hyper local" in terms of beer. So what I'd love to do is harvest wild yeast - but not anything else. I don't want funky beers, I just want something done with a local yeast. So, how would I do it?
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Offline morticaixavier

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #1 on: May 26, 2011, 08:23:05 AM »
I'm guessing it's gonna involve a microscope
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Offline thomasbarnes

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #2 on: May 26, 2011, 04:15:23 PM »
So what I'd love to do is harvest wild yeast - but not anything else. I don't want funky beers, I just want something done with a local yeast. So, how would I do it?

Most wild yeasts will give you funky flavors - lots of phenols. They also tend to be poor fermentors, poorly flocculant and otherwise not good for brewing.

If you're wanting to literally trust to the winds, you can just leave your cooled wort uncovered outdoors overnight. That's (sort of) how lambics are innoculated. If you're wanting to isolate the local strains, then you need to learn about yeast cultivation, which will require special equipment.

Looking at where you live, you're not that far from some of the classic commercial producers of Biere de Garde and Saison. They're the sources for your classic local brewing yeasts. See if you can beg some yeast slurry from a local brewery or brewpub. Alternately, find an interesting local bottle-conditioned beer and cultivate your yeast from that.

Offline tubercle

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #3 on: May 26, 2011, 07:01:43 PM »
So what I'd love to do is harvest wild yeast - but not anything else. I don't want funky beers, I just want something done with a local yeast. So, how would I do it?

Most wild yeasts will give you funky flavors - lots of phenols. They also tend to be poor fermentors, poorly flocculant and otherwise not good for brewing.


 Unless its wine.

 Get some local fruit and make a "natural" wine (add sugar if needed) to get to about 14%. Grow your culture from that. The high alcohol content of the wine will kill all the baddies and you will have a local culture left over for your beer.

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Offline tschmidlin

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #4 on: May 26, 2011, 09:54:10 PM »
Out of curiosity tubercle, how can you be sure what you have isolated is not brett?  I've been trying to figure out how to do this and make sure he doesn't get any brett, but haven't come up with an easy way to distinguish it from sacch.  I know 14% is on the high end for most lab brett strains, but it doesn't seem like it would be out of the realm of possibility for a truly wild strain.

Either way, this seems like a better method than the stuff I've been thinking about. ;)

So do you toss the first batch, or does the nasty stuff die off fast enough that it is still drinkable?  I've been thinking about doing the same thing with some of the fruit I grow in my yard.
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Offline phillamb168

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #5 on: May 27, 2011, 01:43:20 AM »
Out of curiosity tubercle, how can you be sure what you have isolated is not brett?  I've been trying to figure out how to do this and make sure he doesn't get any brett, but haven't come up with an easy way to distinguish it from sacch.  I know 14% is on the high end for most lab brett strains, but it doesn't seem like it would be out of the realm of possibility for a truly wild strain.

Either way, this seems like a better method than the stuff I've been thinking about. ;)

So do you toss the first batch, or does the nasty stuff die off fast enough that it is still drinkable?  I've been thinking about doing the same thing with some of the fruit I grow in my yard.

I'm certainly willing to give this a shot on a small batch (I have 1-gal fermenters I use for test batches). With the fruit fermentation, how do I make the 'wine?' We have some prunes that are gonna be ready in a few weeks, I could use those. Just mash them up and leave them in a fermenter with a bunch of sugar and an airlock?
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Offline thomasbarnes

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #6 on: May 27, 2011, 02:46:28 AM »
Most wild yeasts will give you funky flavors - lots of phenols. They also tend to be poor fermentors, poorly flocculant and otherwise not good for brewing.
Get some local fruit and make a "natural" wine (add sugar if needed) to get to about 14%. Grow your culture from that. The high alcohol content of the wine will kill all the baddies and you will have a local culture left over for your beer.

I was thinking of airborne wild yeasts. Like you said, wild yeasts on fruit skins tend to be better fermentors, although they might still be "powdery" and reluctant to flocc. It's not just grapes, either; I've made and tasted plenty of batches of decent cider fermented using only the wild yeasts.

The problem is that fermenting beer with yeasts adapted to fermenting fruit juice produces beer with an odd wine-like taste. It works, but not that well. Conversely, producing cider using ale yeast works fairly well. I guess if you were to do a sour beer, starting with wild fruit yeast, then add a blend of lactic, pedio, brett, etc. bugs the vinous taste might blend in, though.

But you're absolutely right. If you want to work with a wild yeast and produce a truly local, artisanal product, you can't get more basic than wine or cider.

@ Tom: Wild yeast native to fruit skins generally isn't Brett. It tends to be strains of Saccharomyces Bayanus among other things. You'd need to do a lot of work to isolate just one strain of wild yeast from fruit skin. The good news is that most wild yeasts croak out at low ABV, so S. Bayanus and/or Cerevesiae have an advantage since they can stand higher ABV levels.
« Last Edit: May 27, 2011, 02:56:17 AM by thomasbarnes »

Offline phillamb168

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #7 on: May 27, 2011, 03:17:11 AM »
Most wild yeasts will give you funky flavors - lots of phenols. They also tend to be poor fermentors, poorly flocculant and otherwise not good for brewing.
Get some local fruit and make a "natural" wine (add sugar if needed) to get to about 14%. Grow your culture from that. The high alcohol content of the wine will kill all the baddies and you will have a local culture left over for your beer.

I was thinking of airborne wild yeasts. Like you said, wild yeasts on fruit skins tend to be better fermentors, although they might still be "powdery" and reluctant to flocc. It's not just grapes, either; I've made and tasted plenty of batches of decent cider fermented using only the wild yeasts.

The problem is that fermenting beer with yeasts adapted to fermenting fruit juice produces beer with an odd wine-like taste. It works, but not that well. Conversely, producing cider using ale yeast works fairly well. I guess if you were to do a sour beer, starting with wild fruit yeast, then add a blend of lactic, pedio, brett, etc. bugs the vinous taste might blend in, though.

But you're absolutely right. If you want to work with a wild yeast and produce a truly local, artisanal product, you can't get more basic than wine or cider.

@ Tom: Wild yeast native to fruit skins generally isn't Brett. It tends to be strains of Saccharomyces Bayanus among other things. You'd need to do a lot of work to isolate just one strain of wild yeast from fruit skin. The good news is that most wild yeasts croak out at low ABV, so S. Bayanus and/or Cerevesiae have an advantage since they can stand higher ABV levels.

What about taking a wild yeast strain a la the fruit-wine method and then having it ferment out for a few generations? I'm not in a hurry... I know that 'house yeasts' at least from a brewery standpoint can eventually evolve to better handle their environments. I don't know what yeast mutation rates are, but given the population size and the average lifespan, I don't see why we couldn't see mutation towards a more beer-friendly yeast in less than 4 or 5 fermentations. It'd make for an interesting experiment anyway.

I also wonder if it wouldn't work to sort of 'interbreed' a wild yeast with a small culture of lab yeast that has the characteristics I'm looking for. But given that they produce by budding as opposed to Missionary-style, this may not work. I Am Not A Microbiologist (although I play one on TV!)
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Offline nateo

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #8 on: May 27, 2011, 05:41:43 AM »
Here's what I've done: Carefully and as sanitary as possible, skin a peach and quarter the skin. I guess this could work with individual grapes, too, if you don't have peaches. I made a starter solution of about 1.020 gravity. Put each piece of skin into 3/4 of a quart of starter (that's about 700ml).

After a few days, some of the starters will turn green/gray and smell awful. Some of them will stay wort colored and smell like beer. Step up the beer-scented starters to 1l and 1.040. If it's still good after that starter is done fermenting, you can pitch into your beer.

The yeast flocc'ed in big pea-sized chunks. It was a strong fermenter, faster than average for the commercial strains I've used. It flocc'ed out better than average too. I made a wit with it, but was disappointed in the flavor. I was expecting the phenols/esters to be over the top, but it was actually pretty neutral. Mildly fruity but not nearly as phenolic as most Belgian strains. A bit of higher alcohols, but I fermented pretty warm, around 75*. Overall a good flavor, but nothing special.

I did have a few bottles I kept for a long time, and after about 6-7 months in the bottle, I noticed a very low-level acetobacter infection in some of the bottles. It could just have been my sanitation, but it may also have been on the peach skins in the first place.

Trust your nose and gut at every step. It won't behave exactly like commercial yeast, but if at any step it looks or smells "bad" toss it out and start over.
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Offline thirsty

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #9 on: May 27, 2011, 08:36:21 AM »
Sorry to get off topic, but...

So where did a brewery get it's yeast back in 1850 or so? Did they just use wild yeast over and over again for a few hundred years until it mutated into something that made good beer?

I am curious.

 ???

Offline tschmidlin

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #10 on: May 27, 2011, 10:58:10 AM »
@ Tom: Wild yeast native to fruit skins generally isn't Brett. It tends to be strains of Saccharomyces Bayanus among other things. You'd need to do a lot of work to isolate just one strain of wild yeast from fruit skin.
Brett is native to many fruit skins - maybe not all fruit, and maybe not as populous as other strains, but still present.  It would be fairly easy to isolate a single strain, you can just plate it and streak for singles.  The trick to me is how to tell brett from sacch using things your average homebrewer has access to.


The good news is that most wild yeasts croak out at low ABV, so S. Bayanus and/or Cerevesiae have an advantage since they can stand higher ABV levels.
How are you differentiating between S. bayanus/cerevisiae found on the fruit skins and "wild" yeast?


I also wonder if it wouldn't work to sort of 'interbreed' a wild yeast with a small culture of lab yeast that has the characteristics I'm looking for. But given that they produce by budding as opposed to Missionary-style, this may not work. I Am Not A Microbiologist (although I play one on TV!)
This could work, but would be pretty hard to do.  The wild sacch strains should sporulate without a problem, but the spores will tend to mate with other spores of the opposite mating type.  The way you would do it in the lab is to knock out the mating type switching locus so that each haploid mother would produce daughters of only one mating type.  Then you can sporulate and dissect the tetrad and get separate colonies of both mating types.  After that you can cross them with spores from other strains.

However, getting viable isolates from a beer strain is even more difficult.  Most of the strains I've tested don't form spores at all.  Of those that do, none had viable tetrads.  Some of the spores would grow, but never more than 2 of the 4.  So you'd have the same problem as above and need to knock out HO, but you've also got to get lucky on the spores.  In some cases it just might not be possible.  Most beer strains exhibit aneuploidy, meaning that they have different numbers of each chromosome - so they might have 2 copies of chromosome 2, 4, and 12, but 3 copies of 5, 6, and 14, and just 1 copy of 7, 8, and 9, etc.  Beyond that - even if you got viable spores, there is no guarantee that the genes would segregate such that beer made with those spores will be any good.

In general it would be much easier to stress the yeast or use a mutagen to alter the genes at random, then select isolates and do test ferments and find one that you like.  It would be tedious, but I think it would have a much higher chance of success.


So where did a brewery get it's yeast back in 1850 or so? Did they just use wild yeast over and over again for a few hundred years until it mutated into something that made good beer?
You have to go back a lot farther than the 1850s, but yes, it was more of a trial and error thing.  Beer was often fermented in wooden vessels which would harbor yeast.  If a vessel was known for making bad beer you'd get rid of it and make a new one.  Going back, brewers may have used a stick to stir the wort, and the stick would harbor yeast too, effectively inoculating the wort.
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Offline tubercle

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #11 on: May 27, 2011, 03:05:31 PM »
Out of curiosity tubercle, how can you be sure what you have isolated is not brett?  I've been trying to figure out how to do this and make sure he doesn't get any brett, but haven't come up with an easy way to distinguish it from sacch.  I know 14% is on the high end for most lab brett strains, but it doesn't seem like it would be out of the realm of possibility for a truly wild strain.

Either way, this seems like a better method than the stuff I've been thinking about. ;)

So do you toss the first batch, or does the nasty stuff die off fast enough that it is still drinkable?  I've been thinking about doing the same thing with some of the fruit I grow in my yard.

 I just make a small 2 gallon batch, usually out of muscadines. Just measure the juice and add sugar to get it up to ~14% and let the natural yeast do its thing. I will add some nutrient. I then take the cake and use it like one from a batch of beer and make a malt starter.

 I know its best to grow yeast in the enviroment it will ferment in but I have never used malt to "extract" the wild yeast for fear of the alchohol content not being high enough to kill other stuff off. I have been thinking of trying it with a high gravity malt & friut though, using DME to get the % up instead of cane sugar.

 Like someone else said, this is not going to taste like the beer yeast you are used to, its not US-05.
I didn't say it tasted good, just that it would work ;D
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Offline morticaixavier

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #12 on: May 27, 2011, 03:48:48 PM »
This could work, but would be pretty hard to do.  The wild sacch strains should sporulate without a problem, but the spores will tend to mate with other spores of the opposite mating type.  The way you would do it in the lab is to knock out the mating type switching locus so that each haploid mother would produce daughters of only one mating type.  Then you can sporulate and dissect the tetrad and get separate colonies of both mating types.  After that you can cross them with spores from other strains.


Tom are you just making these words up? ;D
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Offline tschmidlin

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #13 on: May 27, 2011, 09:58:32 PM »
Tom are you just making these words up? ;D
Daughter is a completely made up word ;)

Here is a pic you might enjoy.  Or not. ;D

On the left side is a wall of haploid yeast of mating type alpha* (MATalpha).  The rod-like things you see are individual yeast cells of mating type a*.  They are responding to a mating pheromone called alpha-factor secreted by the MATalpha cells.  The cell begins to shmoo (I'm not making this up) toward the opposite mating type.  Normally this wouldn't happen at that distance, but the abundance of MATalpha cells creates a large amount and causes the MATa cells to respond.  The small amount of pheromone secreted by the MATa cells is not enough to get the MATalpha cells to respond from that far away.

Fun stuff, eh? ;D






*Don't get me started on the "logic" of having mating types call "a" and "alpha".


<edit> very late edit, just fixing the pic link
« Last Edit: January 10, 2012, 03:39:21 PM by tschmidlin »
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Offline morticaixavier

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Re: Harvesting wild yeast (but NOT brett!)
« Reply #14 on: May 31, 2011, 02:42:10 PM »
SHMOO? :o
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