October 18, 2014

Spontaneous Fermentation Project Part 13 -- Week 38 (and on...)

Over the past few weeks what I have dubbed zombie jellyfish have continued to get bubbly but nothing particularly interesting is going on with the beer. I decided to play around with the beer a little and try to figure out what's going on. I'm really trying to drink down my supply of homebrew so I haven't brewed since mid-July and that is making me sad. So working on this beer is a nice project to keep the brewing itch subdued. I decided to try pulling a yeast culture out of the fermentor and try to put together sort of a side beer I can play with and taste without ruining the big batch.

My process was simple. A basic starter of DME cut with table sugar for a 1.044 gravity will form a breeding ground for whatever I got out of the fermentor. I added approximately 0.15 oz. of Belma hops to help fight off some of the bacteria and see if I could produce a mixed culture suited for brewing versus the base beer which was gently hopped. I used a straightened out paper clip as an inoculation loop. My hypothesis was that I would gently break off a small piece of one of the zombie jellyfish and transfer it to the starter wort. Surprisingly, the jellyfish attacked the paper clip.

No, actually I was surprised because the damn things are solid. I tried to pull off a piece but the whole thing lifted up and then slid off the paper clip. I was expecting more of a gelatinous texture. I wish I could have taken some pictures but my hands were full. I tried to fish out a smaller clump but I couldn't reach any. So I am working on the assumption that I scrapped some cells off the clumps I touched. I then inserted the end of the paperclip in the starter wort and swirled it around.

After two days there was visible signs of fermentation, including CO2 output and the aroma of fermenting beer. No krausen but definitely something fermenting in there.The foam was white and reminiscent of soap bubbles. The spontaneous beer went through a similar stage without ever producing the typical creamy krausen of a cultured fermentation so perhaps this is just normal for wild yeast where there is a lot of CO2 but not quite the volume of top fermenting yeast necessary to produce it. In addition to the foam on top there was also a layer of trub building up. No layer of yeast but it was unmistakably trub as the liquid began to clear up as fermentation went on.

The aroma was bready, spicy and woody. The best I can describe it is like a blend of saaz hops and yeast fermentation. Really unusual but not unpleasant. I actually liked it.

By day four most of the activity had died down and the liquid had dropped fairly clear. Then these white chains began to form in the beer. You can kind of see them in this second picture if you look past the small bits clinging to the interior of the flask.  I marked one with a red arrow but you can kind of see that there were quite a few.

At first I thought it was the start of another yeast fermentation because saccharomyces can sometimes develop that wispy appearance on the surface before krausen starts to form but they didn't seem to expand beyond roughly half an inch in length. They were just multiplying and then floated on top. Not really sure what that is.

I cold crashed the starter in my fridge for a couple days to drop everything out and try to get an idea of the quantity of yeast in there. Not a visibly large layer of yeast. I tested the gravity and tasted it.
According to my refractometer, the gravity went up. That didn't make a lot of sense. However, it was very sweet, with a little peppery spice. So at a minimum the gravity is still very high.

I left this to sit while I left town for GABF and checked on it a couple weeks after that. Gravity still shows up some 0.2 gravity points above the starting gravity. (I feel like I misread the OG reading...) It is sweet but less sweet than before. The flavor is all banana like a weizen strain gone nuts. Checked gravity a few days later and no change. The starter has dropped clear so I'm not sure there is even any more activity. My thought is that the primary yeast that I captured in coolshipping this beer are just terrible malt sugar fermenters and I'll have to wait for brett or whatever to show up in force and dry this beer out. I'm going to dump this starter. I will just watch the main batch for activity.

While I was at it, I checked in on the full batch on 10/14/14 and the gravity is 1.010. It is still somewhat sweet but it is starting to get some funky flavors going on. So I still have hope that this is going somewhere interesting. I'm surprised there is zero perceptible acidity to the beer after ten months. I guess I picked a bad time to try to try to pick up bacteria out of the air but I am going to let this beer keep going and see what happens.


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