My first wild yeast fermentation

[winnph]

So I brewed an experimental beverage that involved, among many steps, allowing a puree of dates and water to spontaneously ferment, and I decided to try to isolate some of the more promising microbes that were in that mixture.

So, I streaked some agar plates, selected the colony that looked the most like brewers yeast, and put it into a starter on a stir plate. It fermented pretty vigorously, and was reminiscent of commercial yeast strains, at least visually. The smell was very fruity and... slightly acrid. Near the end of fermentation, there was a definite solventy smell, so I was discouraged a bit.

However, I tasted the starter a few days later, and it seemed pretty good to me -- definitely a little sour, definitely lots of esters and whatnot, but the solventy taste wasn't anywhere near as strong as I'd feared. It was still slightly sweet, though. So, encouraged again, I brewed up a 2.25 gallon batch, and it's fermenting away now, producing some pleasant odors at the airlock!

Has anyone else had any experience using yeast harvested from dates? I was a little concerned about its ability to digest maltose, since dates are mostly glucose, fructose, and sucrose. Presumably the yeast is biologically adept at targeting those sugars more than maltose.

I'll post back when I taste the final product in a few weeks.

 

[El_Exorcisto]

Sam Calagione did an episode of Brewmasters around a wild yeast collected in Egypt from dates. He brewed an adaptation of an ancient Egyptian beer with it.

 

[winnph]

Ahh yes, I was probably indirectly inspired by that, since I was inspired by a post someone made on another brewing forum that shall remain unnamed about making a Sumerian beer that had as one of its ingredients a date wine.

Here's what the beer with the wild yeast looks like a little over 40 hours after the yeast was pitched, a nice healthy looking krausen:

 

[elucify]

So what's going on with this brew now? (And hello from Silver Spring!)

 

[winnph]

Actually, I had asked another question about this brew in a separate thread, and posted the latest updates there instead of here. I probably should have just stuck to one thread, but here's the other one:

https://www.homebrewtalk.com/f127/identifying-wild-yeast-based-krausen-pellicle-237410/

I actually just finished bottling the beer about 15 minutes ago. It tasted phenomenal... very clean, ever so slightly tart (though that might grow more in the bottles), but not a whole lot in the way of unpleasant flavors.

Since it formed a pellicle after about a month, I'm assuming this is probably some wild Brett species or something, but if so, it's not very funky at all, at least when the beer is young. I saved 5 jars of washed yeast, and I'll probably do a longer-aged batch with it soon.

 

[winnph]

So I tasted one of these yesterday -- it has hints of funk, but is really a pretty clean-tasting beer. I'm definitely confused about what kind of yeast this is, as it produced a definite pellicle after about a month, but it doesn't seem too fruity or funky. Here's a picture:

I'm really curious about the yeast... does anyone know of any labs that will analyze a yeast sample for a reasonable fee and tell you the genus/species?

P.S. I'd be happy to do a yeast swap with anyone in the area if you're interested in trying this one out.

 

[ReverseApacheMaster]

White Labs does that analysis but I don't know how precise they could be.

If there was a pellicle it could have been lacto or something similar chewing up some leftover sugars. Could have been brett but brett usually takes a little longer to show up out of a wild culture (in my experience). I would suggest you watch those bottles for increasing carbonation and/or bottle pellicles. I had pedio start to dump diacetyl about two months after bottling (three months after pitching) and brett show up three months after bottling (four months after pitching).

 

[winnph]

I isolated the yeast using a series of agar plates where single colonies were isolated, so I am about as sure as one can ever be that this was only a single species of yeast, and nothing else.

EDIT: I mean as sure as one can ever be when you're not using a microscope and literally isolating a single cell. However, the odds of anything else making it through two cycles of isolated colonies on agar plates seems pretty low. Maybe someone can chime in and tell me I'm wrong?

 

[Steve973]

Very cool. I am interested in hearing whatever you find out.

 

[winnph]

Unfortunately, this was the response from White Labs:

Wild yeasts are pretty difficult to identify, and it would require very specific tests which are quite expensive. It would be a couple of hundred dollars to try and id a specific wild yeast.

 

[jtakacs]

hey, its only your money - go for it!

 

[winnph]

Haha, to give an idea of how clean this yeast is, SWMBO's complaint about this test batch was "the flavor is so flat... it's like Budweiser with a slight aftertaste."

Wonder how often people using wild yeast get that kind of complaint?

 

[statseeker]

Check out the mad fermentationist's blog and do at least a characteristic comparison between the yeast you are using and some of the flavors and behaviors he sees in the yeasts he uses. Use your yeast cake to do one of his recipes and do a comparison. This is at least where I would start in narrowing down a species.

 

[winnph]

Check out the mad fermentationist's blog and do at least a characteristic comparison between the yeast you are using and some of the flavors and behaviors he sees in the yeasts he uses. Use your yeast cake to do one of his recipes and do a comparison. This is at least where I would start in narrowing down a species.

I actually live right near him (like, walking distance), and have been meaning to offer him a taste of this beer and a sample of the yeast. Maybe I'll drop him a line and try to set a day to swing by there. Right now the main characteristics of the yeast are: healthy krausen, highly flocculent, ever-so-slightly funky, develops acetic qualities in the starter (but not the fermenter), and forms a slightly bubbly pellicle after about 5 weeks of fermenting in a carboy.

 

[mutedog]

What temperature were you fermenting at? I have a wild yeast that ferments super clean at cool temps but adds a little grassy/barnyard flavors when it ferments warmer.

 

[winnph]

What temperature were you fermenting at? I have a wild yeast that ferments super clean at cool temps but adds a little grassy/barnyard flavors when it ferments warmer.

I fermented it ambient, and according to the sticker thermometer that ranged from about 65 to 72 over the couple weeks of more vigorous fermentation, but mostly around 68-69.