February 28, 2015

Spontaneous Fermentation Project Part 15 -- Thirteen Months

Did a more robust inspection of the beer this time in an effort to try to figure out what the heck is going on than my previous attempts. I guess I don't really know much more than I did before but I feel increasingly more confident that I should let the beer ride out and keep seeing what it turns into.

It's sitting at around 4.3-4.4 ph (I'm only using strips so I can't be more specific) and the gravity is hovering around 1.019. By those specs it could easily pass off as a generic extract kit wheat ale. However, the flavor is definitely not the generic kit beer. It doesn't even taste like beer anymore. The weird hefeweizen-like flavor is completely gone and now it just tastes like pear juice. Not like Duvel or a beer with pear. Just pear juice. It's about as sweet as pear juice with roughly the same mouthfeel. It's very unusual. The batch is definitely heading somewhere. I'm hopeful it's not heading towards five gallons of nail polish remover.

Visually the weird islands of yeast are still floating on the surface. The surface seems slightly oily but definitely not a pellicle. There are some clumps of tiny bubbles on the surface. They do not appear trapped under a pellicle-like cover, just too lazy to pop. The airlock has some bubbles built up as well. The combination of all these bubbles suggests there is some internal activity. It could be continued release of CO2 from the initial fermentation but the airlock on this beer is far more bubbly than any other sour beer I've seen. By holding an LED light up to the beer I could see that there is quite a bit of suspended material in the beer. Small random shapes about 1-2mm in diameter. They did not appear to be falling off the yeast islands or in any kind of movement, just suspended in the beer. Small bubbles passed by the lit area every few seconds. That might be normal behavior for the beer or the result of my jostling. Impossible to say without jostling the beer for a view.

2 comments:

  1. Brett can consume butyric acid (created by enteric bacteria, tastes like cheese or vomit) and turn it into ethyl butyrate which can be perceived as pear or pineapple. Perhaps this is what's happening here?

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  2. It's a smart hypothesis and I can't say that's not what's going on. There's absolutely none of the usual brett character and no pellicle so it sure doesn't look like brett activity. I've also never seen a fermentation that looks like this beyond the occasional picture of a crazy lambic bottle so who knows.

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