Spontaneous Wild Yeast Capture

[Sillybilly]

I left out a hydrometer sample over night and thought “why not try to capture some yeast”, so I put the sample in a pint mason jar without a lid for a couple of days and noticed some slight activity going on so I put the lid on but loose enough it could release CO2. I noticed it had a smell that kind of like an overly ripe… pineapple, fruity with a little funkiness (excuse my limited descriptors) and to my surprise didn’t see any mold growth or smell any decaying/poopy flavors. Fast forward, to 2 days ago (8-9 days since leaving out) and it has a small krausen forming and much more activity. There is also a small (yeast?) cake that fully covers the bottom of the jar.

My plan is to use this jar to inoculate one gallon to grow it up and see what happens. Should I just pitch it in the next couple of days or wait a little longer? I may try to taste it but there is such a small amount (maybe 4oz?) I don’t want to disturb it for such a small taste so I figured one-gallon of wort out of something I was already going to brew isn’t going to hurt the bank or take up much space anyways. Any other useful advice would be appreciated, Thanks!

 

[HausBrauerei_Harvey]

sounds like fun, although I cannot offer any advice. FYI A zymurgy last summer had a long article about capturing wild yeasts. you may find some tips there.

 

[Dcpcooks]

I'd step it up in smaller batches. Maybe a 500 ml starter then up to a 2l step then pitch that into your batch.

There is a difference between growing yeast size and making beer. Start small with 1.030- 1.040 wort.

 

[bleme]

I disagree about needing a 2 liter starter for a 1 gallon beer. 500ml is more than enough. Personally, I'd probably go for a 4% beer oxygenate it well, and pitch what you have though.

 

[IslandLizard]

That's a nice find!

Many wild yeast don't attenuate very well, but some do. So try to keep her happy as long as you can. You may need to finish it out in a secondary with another yeast. But you'll have a nice primary cake you can inoculate a 3-5 gallon batch from.

 

[Sillybilly]

I was planning a low gravity beer, depending what I am brewing, I would collect 1.5 gallons of final runnings, aiming for about 1.035-1040 OG, of a subsequent 5 gallon batch and boil it separately. But it sounds like stepping it up at least once before pitching is advisable? Better to pitch in starter now or let it work awhile longer in the "capture" vessel?

Will the starter alone give me a reliable idea on what I can expect from it? Either way, I'd probably still pitch into 1-gallon, but I am just curious. This is my first go, so I am playing it all by ear...

 

[Sillybilly]

That's a nice find!

Many wild yeast don't attenuate very well, but some do. So try to keep her happy as long as you can. You may need to finish it out in a secondary with another yeast. But you'll have a nice primary cake you can inoculate a 3-5 gallon batch from.

I am hoping that the 1-gallon batch turns out nice so I can pitch the cake into larger batch! Is the subsequent batch likely to attenuate better?

 

[IslandLizard]

I would grow your 4 oz starter once more with 500 ml for a few days. Cold crash, then decant and pitch the slurry in your gallon-some batch. You may want to keep a little bit of the slurry behind, just in case.

 

[Sillybilly]

What it is looking like today, pencil for scale. Was surprised at the amount accumulated since a few days ago

 

[Owly055]

There are some methods to consider when "yeast wrangling", such as keeping the PH below 4.6 and using hops to suppress bacterial growth. You can take things to the next level, slanting yeast cultures to separate out the different yeasts, and then testing them individually for their various properties. It could turn into quite a hobby by itself.
Do a bit of Googling on capturing wild yeasts or yeast wrangling. There is a fair body of material out there on the topic.

H.W.

 

[Sillybilly]

Yeah, I have been looking here and there for different methods, I just wanted to pick some brains. The wort is from an ipa so its got some hops but you do make a good point about making sure pH is below 4.6 unfortunately I do not have a pH meter so I hoping that becuase the yeasties seem happy, they dropped it below that. I am guessing I would have noticed by now if some nastys were taking over?

Slanting and isolating would be neat, but I think that's a bit more than I want to take on at this point, but something I'd like to look into.