Attenuation Issues

[DisturbdChemist]

I just got a freezer with temperature controler attach to it. These last two batch i done in the freezer did not attenuate as i want it to. I have it in the range the yeast operate in but i dont know what's going on. Any ideas?

 

[BryceL]

There are a lot of variables such as your grain bill, mash temperature, pitching rates, oxygen, etc. If you can post some more details about you recipe and process, I'm sure we can narrow it down.

 

[DisturbdChemist]

The last one i made is an english mild. I'll try to remember whats in it

5 lbs maris otter
1 lbs Special B
8 oz Crystal 120
8oz Pale Chocolate
4 oz oats

I used WLP 002 (english ale) I dont have a stir plate but i so have a flask which i started the night before and swirled it often as i could.

i mashed around 157-158 range for an hour.

for the oxygen I've do the same with every batch. I poured the cool wort roughly into the fermenter to get oxygen and make it bubble a little.

I BIAB so for mash out i raise the temp to 170 while stirring and left it at temp for 10 mins before taking them out and start the boil.

I took it out of the freezer and see if it warms it might start fermenting again.


OG 1.038
Right now 1.018-1.020. Which needs to be about 1.013ish. Though i might be just taking it too early because it's only been in a week and i only saw it ferment for one day. which i figure because this is a low ABV it shouldnt take long

 

[ayoungrad]

What is the fermentation temperature? Are you using a temp controller?

 

[ayoungrad]

Also, 157-158 is pretty high. That will certainly result in some degree of lower attenuation...

 

[DisturbdChemist]

Yes i have a temperature control. I had it around 67-68 F which is the upper range for the optimum temperature for the yeast

I'm thinking because the bucket sits on the bottom it might be getting colder than what the controler said. I might add a a little stant in it so it wont be on the bottom of the freezer



From another English mild in here said he did mash at 158 so i went with that temp

 

[BryceL]

Like mentioned, 158 might be a bit high. Maybe something around 154 would help you out a bit. Even so, you should be getting better attenuation that what you are. How long has this one been fermenting? Also, once you transfer your wort I would rock the carboy back and forth pretty good for 5 minutes or so. This will help to get some more oxygen in there.

 

[DisturbdChemist]

I use a bucket. Guess i like the bucket better than the carboy. It's only been a week fermenting, i'm worried because i thought this will be a quickly fermenting beer because of the low ABV

 

[betarhoalphadelta]

Is the temperature probe loose in the freezer?

Before I had a thermowell, I'd duct tape the thermowell (with some wadded paper towels as insulation) to the side of my fermenter, so that the thermowell was accurately measuring beer temp.

There's a chance your beer is not at the temperature your thermometer is registering due to hysteresis of the freezer.

 

[DisturbdChemist]

Yes the probe is loose in the freezer. You think that the beer was just too cold?

 

[Yooper]

Yes the probe is loose in the freezer. You think that the beer was just too cold?

No, it should be fine. It depends on the yeast strain, but mashing at 158 means lots of long-chained sugars which are less fermentable so you'd have a full bodied beer with a higher FG than if it was mashed at something lower.

 

[DisturbdChemist]

With these Milds i want a full body because of the small grain bill that can be watery. I figure the FG will go down a little more. It's only at 2.6% abv at the moment but it is a sessionable and was aiming at 3.3% ish. I'm just used to my beers in the 6-7% range. So if it doesnt go down anymore i'll be fine with it and just have a very easy drinking Mild.

It also happen to my Black IPA, I wanted it to drop to 1.018 but stopped at 1.022. I think i mashed that at 156 and had some carapils in that one which i think caused that. I'm enjoying that brew because it was a hoppy stout, i'm impressed and going to enter it in a competition soon.

Those are the two beers i made when i first had the freezer it's just making me think it might be the freezer

 

[Yooper]

Those are the two beers i made when i first had the freezer it's just making me think it might be the freezer

No, I am pretty certain it's the high mash temps. I have a couple of beers I mash at 156-158, and they don't drop below 1.020 even if I use a highly attenuative yeast strain.

As long as your temp is above about 59 degrees, for most ale strains you'll be fine and if fermentation started it would take quite a drop for the yeast to stop fermentation. Fermentation temperature is strain dependent, but I can't think of any ale yeast strains that would struggle at 63-64 degrees and most would happily go lower than that.

 

[DisturbdChemist]

Should i just shoot at a mash temp at 154 for all my beers? Though I BIAB and heat the grain to 170 for 10 min will that release unfermentable sugars?

I just opened my black ipa and its over carbonated. Yet i use the same amount as my 60 min clone. Guess it wasn't done fermenting 100% but no bottle bombs. Now i don't know if i should submit it because its over carbonated.

 

[Yooper]

Should i just shoot at a mash temp at 154 for all my beers? Though I BIAB and heat the grain to 170 for 10 min will that release unfermentable sugars?

I just opened my black ipa and its over carbonated. Yet i use the same amount as my 60 min clone. Guess it wasn't done fermenting 100% but no bottle bombs. Now i don't know if i should submit it because its over carbonated.

Each beer is different, so it really depends on your goals. I mash my "Dead Guy" clone high (156) because it should be full bodied with a full mouthfeel and plenty of residual sweetness and it should finish at 1.018-1.020. I mash my oatmeal stout at 158 at times, for a full rich bodied stout. (In the summer, I mash it a bit lower just so it's a bit lighter).

For pale ales and the like, I mash at 152 and they finish at 1.010-1.012.

For cream ales and some of my IIPAs, I've mashed as low as 147 and had them finish at 1.005!

Part of it is knowing your system. Knowing that if you mash at 156 you'll end up at or over 1.020 is good to know, so you can use that knowledge in the future!

FG is also recipe dependent, and recipes with lots of crystal malt or less fermentable specialty grains might mean it finishes higher as well, and yeast strain choice makes a difference as well.

For example, in my oatmeal stout mashed at 158 with Windsor yeast, I can almost bank on it being 1.020-1.024 when at FG.

If you're still tweaking your system, I'd suggest mashing beers you want to finish really dry at 151 or less, medium beers at 152-154, and full bodied beers at 155+. That's just a rule of thumb that may work for you until you know your own system and it's more predictable for you.

 

[DisturbdChemist]

Thanks a lot Yooper. I'm still learning and i dont know even close to everything yet lol. That will be helpful in the future on my next recipe. I'll be happy with the mild. Just need to condition longer then bottle