High FG Question

ircbrewing · Oct 2, 2017

Hi all -

I brewed a coffee stout a few weeks ago and was excited because I just got a fermentation fridge so that I can finally ferment at a CONSTANT cooler temp rather than room temp.

But, I think my fridge might be too cool for the US-04 English Ale. I think it sat at around 58 degrees which is above the minimum on the package, but my beer after 3 weeks is stuck at 1.038. It started at 1.070, so I have about 4% ABV. The beer doesn't taste overly sweet and I actually like the way it tastes. It's got that bitter bite from the coffee and a great chocolatley-coffeeish taste in such a way that I don't think the coffee took away from the beer.

I think I now know that I need a digital temperature controller and should probably ferment at about 65. I suspect 58 was just a bit too cold for the yeast and I got a stuck fermentation. I thought it was going to just fine because there was activity in the airlock for about 5 days which is normal for US-04 in my experience. The krausen looked normal when I dropped in my coffee a few days ago so I assumed all was well. When I went to keg it last night and took my final reading I was extremely surprised to see it sitting so high. I went ahead and kegged it anyways and it's going to be a desert beer but wanted some opinions on that ferment temp.

Also, I pitched 2 packages of the US-04 to ensure there were enough cells to convert a higher OG so I don't think underpitching was the issue.

ircbrewing · Oct 2, 2017

Also, I maybe should have tried to reactivate the yeast by agitating the yeast cake and taking the bucket out of the fridge but my wife told me the beer tasted really good and just keg it since there is definitely alcohol in it. So I just did it...I had already sanitized my keg and equipment so I didn't want to not keg. And I am out of beer, so I needed it.

kh54s10 · Oct 2, 2017

How are you measuring for FG? Hydrometer or refractometer? If you are using a refractometer you need to correct for the presence of alcohol.

It doesn't seem that your temperature was so low as to cause a stall, especially since it appears you had a good steady fermentation. But I think a temperature controller is optimum.

ircbrewing · Oct 2, 2017

I used a hydrometer for the FG. I know you can only use refrac for measuring accurately before the presence of alcohol.

I thought at first it was because my sample of beer was taken at 57 degrees or so, but my hydro is calibrated for 70 I believe, but the calculator I used on brewers friend said that temperature difference is only a .001 difference, so 1.037.

A little frustrating because I thought the only thing missing in my beer making was the lack of ability to do a cooler controlled fermentation. but instead I believe I have a severly underattenuated beer.

mashinary · Oct 2, 2017

What does your water look like? It's possible you pushed the mash pH super low.

ircbrewing · Oct 2, 2017

My water shouldn't be an issue. I have a purified system and have never had water issues affecting mash or flavor. I will say, and I should have mentioned this, that I mashed at 156 which is at the upper limit of where you want to mash. My fear is that I pulled out too much beta amalayse and the yeast had too hard of a time converting. My beersmith app and the recipe I used had the mash temp there, but I personally have not mashed at that high of temperature before. I usually only go up to 153 because of this. If you go low then you just have a drier beer but you have good attenuation. I think it could possibly be that I just mashed too high and the US-04 had issue with the beta.

IKR · Oct 2, 2017

I think you adding a temperature controller will take care of the issue for your next batch. I cellar my big beers (e.g. RIS) in a second refrigerator and at the hottest setting (lowest number) I see 51-53F average temp (monitored w/ a thermocouple). Was 58F your average temp?

ircbrewing · Oct 2, 2017

Yeah, I'd say that's where it was. I mean the beer itself was about 57 degrees in the bucket when I took the temp before kegging. I had the temp of the refridgeration unit at its highest setting. I think to be sure I am not on the low end of an ale yeasts range I should be shooting for 63-65 temp range at which point I would need the controller to help regulate the turning off and on of the unit to maintain that temp.