Carbonated during fermentation

[XiRho]

Evening,

Trying to figure out what has happened or where I messed up -

Latest brew using an ingredient box I received some time ago as a promotion - basically unknown grain bill, single hop (Amarillo). OG of 1.049, no dry hop, 2 week ferment using US-05 @ 21C. Gravity hit 1.018 and has been stuck there ever since. Good chance I mashed a bit hotter than intended. What is confusing me is what I have left sitting in the fermenter. I have a very very murky (was pretty clear after boil) beer which seems to have carbonated quite a lot during fermentation. I had a blow off rigged up during fermentation and got a lot of activity after about 12 hours which stopped after about day 3/4. I checked the blow off and it isn't/wasn't blocked so I don't know how it has carbonated when it can vent easily.

I started cold crashing yesterday and chucked some gelatin in today to try to help clear it, will give it another couple of days crashing and then keg - but I have not seen this happen before.

Any thoughts?

 

[Zephyr259]

Beer will often pick up about 0.8 vol of CO2 during fermentation so it will have a definite sparkle if you handle it carefully when sampling, but it shouldn't really be "fizzy" more like a cask ale level.

On clarity, you'll always end up murky for a while in fermentation due to the yeast, but that should settle out again and leave the beer clear in most cases.

 

[Cwrw666]

This is why most people allow 2 weeks in the FV even if fermentation finishes after a few days. It gives the brew time to really finish all fermentation, to allow the yeast to `clean up' after itself, and for the beer to at least start to clear.

 

[peebee]

Beer will often pick up about 0.8 vol of CO2 during fermentation …

If you ferment under an airlock it will pick up CO2. The beer in a CO2 atmosphere is compelled to dissolve as much CO2 as it can until it reaches "saturation" levels at atmospheric pressure. The exact amount depends on temperature (and changes in atmospheric pressure), colder beer allows more CO2 to dissolve. So if you ferment a "lager" at 12C and let it warm up to say 17C (diacyl rest?) the beer will appear to start fermenting again (its actually dissolved CO2 coming out of solution), and likewise if you cool a fermented beer (cold crash?) more of the CO2 in the airspace starts to dissolve (if you've still got an airlock attached it starts bubbling backwards).

If you ferment in an open bucket very little CO2 dissolves as the beer attempts to keep in equilibrium with surrounding air (only containing 0.04% CO2). Of course, long before the beer can reach such an equilibrium, it goes off.

Beer doesn't dissolve or outgas CO2 instantly, it takes time (hours) to reach equilibrium with its new surroundings.