Low Attenuation

[bradthebold]

I have had consistent low attenuation issues and have just accepted it's a brew in a bag thing? I generally mash 1-2˚ lower than a recipe and still end up ~5 points high.

I just kegged a pumpkin that only had 59% attenuation with S-04, vs the 72-75% it should be. 1.055 to 1.022. And vs the recipe 1.053-1.015. I mashed 2 degrees lower than the recipe to try to combat it. At 30mins into mash I heat/stir for a minute to get the 1-2˚ I lost back. I fermented at 66˚ for 2 days, then raise to 68˚ for a couple days then to 70˚ as fermentation was almost done.

I just did an Irish Ale that was 1.058 to 1.019. 66% vs 71-75% for 1084. 63˚ starting fermentation, bumped to 68-70˚ as it finished.

I use Mr Malty for pitch rate calculating. It there anything I should check or sound like I'm doing anything wrong?

 

[RM-MN]

With those results the first thing I would check is the thermometer. You could be mashing a lot higher than you think.


I'd insulate the kettle and leave it cool naturally. Your heating could be denaturing the beta amylase and that will cause a high FG.

 

[bradthebold]

With those results the first thing I would check is the thermometer. You could be mashing a lot higher than you think.


I'd insulate the kettle and leave it cool naturally. Your heating could be denaturing the beta amylase and that will cause a high FG.

I use 2 different thermoworks thermometers, so temp should be accurate. Someone at my local club recommended just letting the temp fall during mash too, so I will try that next time at least.

 

[North_of_60]

I don't know what could be causing this. I'm just guessing but, maybe your wort pH.

I do BIAB and I use S-04, US-05 and Nottingham and always get good or better than advertised attenuation. I don't rehydrate, I just sprinkle the dry yeast on top of the cooled wort (Less than 70 degrees) seal the bucket. I keep it in the mid 60s till the krausen drops then let it go to room temperature and wait 10 or more days before I open it. When I open it the FG has always been within a point or two of BearSmith's prediction.

What temperature are you mashing at? After 30 minutes the conversion is pretty much complete so there is no need to heat it back up. I do the same as you and stir it at 30 minutes, I check the pH and then leave it another 60 minutes at what ever the temperature is.

Some one else will most like have a better answer for you.

 

[bradthebold]

I don't know what could be causing this. I'm just guessing but, maybe your wort pH.

I do BIAB and I use S-04, US-05 and Nottingham and always get good or better than advertised attenuation. I don't rehydrate, I just sprinkle the dry yeast on top of the cooled wort (Less than 70 degrees) seal the bucket. I keep it in the mid 60s till the krausen drops then let it go to room temperature and wait 10 or more days before I open it. When I open it the FG has always been within a point or two of BearSmith's prediction.

What temperature are you mashing at? After 30 minutes the conversion is pretty much complete so there is no need to heat it back up. I do the same as you and stir it at 30 minutes, I check the pH and then leave it another 60 minutes at what ever the temperature is.

Some one else will most like have a better answer for you.

I tested my water and adjust minerals and pH, so that should be ok.

I do rehydrate my dry yeast. For the liquid, I make a stir plate starter. I ferment 2-3 weeks normally. I have been mashing lower than recipes. 152˚ for the irish ale and 156˚ for the thunderstruck pumpkin ale.

I will try just stirring and letting the temp fall though if that's messing it up.

 

[North_of_60]

I will try just stirring and letting the temp fall though if that's messing it up.

It a mystery. If you are stirring all the while you are heating it that shouldn't affect it either. I used to do that too but stopped. Even when I did reheat I never had low attenuation.

 

[GreenDragon13]

I'd skip the re-heating at 30 min. I think the application of heat is causing a stoppage or partial stoppage of enzymatic action in your wort. Like when (in all grain brewing) you raise your temp to 170F to mash out (i.e. halt enzymatic activity)
A 1-2 degree drop is absolutely nothing to worry about!

 

[bracconiere]

ph? i just posted in a similar thread. that i just had a 'stuck' ferment at 1.006 using gluco, and found out it was sour, and the ph dropped to 3.4....

and only wine/cider yeast like ph's like that, not ale yeast.

 

[bradthebold]

ph? i just posted in a similar thread. that i just had a 'stuck' ferment at 1.006 using gluco, and found out it was sour, and the ph dropped to 3.4....

and only wine/cider yeast like ph's like that, not ale yeast.

I have never checked post fermentation pH. I can see. Though, I use US-05 for kettle sours lower than that without issue.

 

[bradthebold]

Update. I made a Two Hearted clone with US-05, 1.062 to 1.011, which is 81% attenuation, exactly what fermentis claims and within 1 point of the recipe. The only thing I changed was not reheating mid mash. It's only one batch, but hopefully that fixed my problem.

 

[bracconiere]

Congrats!

 

[Redpappy]

I have been having the same issues as of late. Due to the colder temps I have been reheating mid stream. I will have to see what happens Friday without the reheat.

Thanks for the update

 

[dmtaylor]

I've had inconsistent results with S-04. It used to get me like 75-77% efficiency on average. Then with my last batch, it wouldn't budge past 58% for no apparent reason. I don't know what could have caused this. I'm not worried, though. I just might not use it much in future.

 

[Ninoid]

I make near ten No Boil batches (wort is only heated up to 75'C and not boiled) and have 75% attenuation with US-05. After I start boil my wort (5 or 15 minutes) attenuation is below 67%. But, with BE-134 (Saison very attenuated yeast) attenuation is always over 85%.

Maybe mash temperature is too high, but with No Boil this is not problem.
On the other side, BE-134 is very aggressive yeast and eat and non-fermentable sugars.

 

[jeeppilot]

Someone please step in and correct me here if I’m off, but I have had similar issues. However I recently did a Vienna lager that called for a protein rest at 125, beta at 147 and alpha at 164. So, if I were to mash at 152, and then direct fire the kettle, I could denature both beta and alpha enzymes since they are both active at these temps. But, in this step scenario, I am only denaturing a specific enzyme AFTER it has done its work. i.e. at 147, the beta has already completed, then I denature it when I fire the kettle, but the alpha is still okay since I haven’t reached its active temp. Is this correct?

 

[dmtaylor]

Someone please step in and correct me here if I’m off, but I have had similar issues. However I recently did a Vienna lager that called for a protein rest at 125, beta at 147 and alpha at 164. So, if I were to mash at 152, and then direct fire the kettle, I could denature both beta and alpha enzymes since they are both active at these temps. But, in this step scenario, I am only denaturing a specific enzyme AFTER it has done its work. i.e. at 147, the beta has already completed, then I denature it when I fire the kettle, but the alpha is still okay since I haven’t reached its active temp. Is this correct?

Pretty close to right. Alpha won't be denatured at 152 F, but beta will, slowly and gradually. In reality the denaturing occurs gradually and the ranges all overlap. At 152 F, both the alpha and beta are working in pretty high gear. Meanwhile the beta is starting to fall apart while the alpha is doing just fine. That temperature is in the Goldilocks range where there's really little if any benefit to mashing lower and then higher, and instead you can just hang out with Goldilocks for a while and everybody is happy for the most part, or at least, the beta hangs around plenty long enough to get almost all of the benefit out of it. I see very little if any value in complicating matters if we can get excellent results just holding at one temperature. And don't even get me started on the protein rest... which I think is harmful with 21st century malts. If you were using a lot of feed-grain, then I can see some value, but otherwise, no.

 

[jeeppilot]

Pretty close to right. Alpha won't be denatured at 152 F, but beta will, slowly and gradually. In reality the denaturing occurs gradually and the ranges all overlap. At 152 F, both the alpha and beta are working in pretty high gear. Meanwhile the beta is starting to fall apart while the alpha is doing just fine. That temperature is in the Goldilocks range where there's really little if any benefit to mashing lower and then higher, and instead you can just hang out with Goldilocks for a while and everybody is happy for the most part, or at least, the beta hangs around plenty long enough to get almost all of the benefit out of it. I see very little if any value in complicating matters if we can get excellent results just holding at one temperature. And don't even get me started on the protein rest... which I think is harmful with 21st century malts. If you were using a lot of feed-grain, then I can see some value, but otherwise, no.

Yeah seems like a lot to do with all the well modified malts we have. But in any case, just trying understand why I might be having beers regularly finish high when I’m also firing the kettle about 30 minutes through the mash to bring it back up to temp. But I’m only heating for two, maybe three minutes? Doesn’t seem like enough heat to denature anything.

 

[dmtaylor]

Yeah seems like a lot to do with all the well modified malts we have. But in any case, just trying understand why I might be having beers regularly finish high when I’m also firing the kettle about 30 minutes through the mash to bring it back up to temp. But I’m only heating for two, maybe three minutes? Doesn’t seem like enough heat to denature anything.

Are you stirring constantly while heating? You could kill a lot of enzymes at the bottom of the mash if you don't.

I'm a little late to this thread, didn't contribute much until now, but anyway.... for you and a lot of these folks, I wonder how hard the grains are milled. If anybody is getting their grains milled by a LHBS, that can be a big issue. LHBS's are notorious for doing a very sh***y job milling the grains. With larger starch granules, it's a lot harder for the enzymes to get in there to take action. Get your own mill, and watch as both your efficiency and attenuation improve significantly.

Also likely to be a thermometer problem. You must calibrate in both ice water and boiling water. Mine reads low at boiling but high in ice, so in between at mash temperatures it's actually quite accurate within a degree. But your mileage may vary... very significantly in some cases. Worth a look for everyone.

 

[LittleRiver]

... firing the kettle about 30 minutes through the mash to bring it back up to temp...

If you're not already insulating your kettle during the mash, it's an easy way to hold consistent temps.

 

[jeeppilot]

If you're not already insulating your kettle during the mash, it's an easy way to hold consistent temps.

Being as this is my first brew since reading this post, I haven’t yet tried leaving the mash alone and not heating it at the 30 minute mark. I wasn’t stirring it during the 2-3 minute heat cycle. I do want to try that. Of course, I ended up on a step mash program for this brew that does just the opposite. Will try it next brew.

On other notes, I am insulating the mash, but not very well. It’s a reflectix type material but temp on a cold day will still drop 5 degrees or more over the course of a 60 minute mash. I also mill my own grain and use a Thermopen in addition to the kettle mounted thermometer.

 

[RM-MN]

On other notes, I am insulating the mash, but not very well. It’s a reflectix type material but temp on a cold day will still drop 5 degrees or more over the course of a 60 minute mash. I also mill my own grain and use a Thermopen in addition to the kettle mounted thermometer.

How much does it drop while conversion is going on? That's the only time the temperature is critical. The rest of that hour is only doing what a steep would if you were doing extract batches.

With my mill set as tight as it will go, conversion is over in less than 5 minutes.

 

[jeeppilot]

How much does it drop while conversion is going on? That's the only time the temperature is critical. The rest of that hour is only doing what a steep would if you were doing extract batches.

With my mill set as tight as it will go, conversion is over in less than 5 minutes.

Can’t say for sure... I never do an iodine test or anything to know when conversion is complete. But at the 30 minute mark it has usually lost a few degrees. I use a corona mill so I don’t have a numeric setting per se, but I do crush pretty tight so I’m probably taking unnecessary and even possibly detrimental steps by heating it. I’m simply going to not heat at all next (non-step) batch and see if I get the same results as @bradthebold did.