Over attenuation - I think i may be on to something. Diagnosis and solution?

So I have been brewing all-grain for awhile (10+ batches). I think I just about have everything down. Efficiency is consistent, O.G.'s are getting hit, mash temps get hit spot on and held the duration of the mash, beer is tasting good.

The one "problem" that I have and can't seem to figure out and kick is over-attenuation. All my beers are finishing below 1.01. Most normal gravity beers (1.05-1.06) have been finishing at about 1.004. Some higher ones (1.07 to 1.08) might stay around 1.006-1.008 F.G. EVERYTHING finishes below 1.01.

So a little bit about my process .........

I have double batch sparged every batch - no mash out. Sparge water is about 175-180.

So I mash for 60 minutes holding temp at desired mash temp for the duration of the mash.

I then drain the first runnings into a bucket (for ease of measuring purposes). Add sparge round 1 to the mash tun, stir, let it sit for 5-10 minutes. Runoff into the bucket where first runnings are being held, Add final amount of sparge water needed to get to desired pre-boil volume, stir, let sit for 5-10 minutes, bucket contents (1st runnings & 1st sparge round) to boil kettle, and runoff final sparge round, turn on burner and start heating to a boil.

So back to over-attenuation, I think i might have an idea why this is happening.

I am running off into a bucket where the temperature will drop. If I mashed at 155 my first runnings are coming out at 155 and sitting in a bucket for 15 or so minutes where the temp will drop (to what, I don't know? I have never monitored this). Then I run off my first sparge round. Lets say this batch is coming out of the tun at 170ish ideally, combined with my first runnings that puts the combined 1st and 2nd runnings in the conversion temp range (possibly). I add third sparge round while first and second runnings sit in the bucket where the temp drops (i assume) for another 10-15 minutes.

So in short, If my collected runnings are sitting unheated at conversion temps (140s-160s) for 30-45 minutes (however long the double batch sparge process takes (longer if it gets stuck or slow). Would this contribute or be the cause of my over-attenuation problem?

The solution? get runnings on the heat as soon as they are run off?

It's the only thing I can think of and the only part of my process where temp isn't monitored. Sorry for the novel and thanks for your thoughts.

First thing: verify the accuracy of your thermometer(s) and your hydrometer.

Exa: I'm finishing my brew stand last night. Two dial thermometers, cheapo indoor/outdoor digital, temp reading from PID, and a mercury lab thermometer for my reference. The PID is 2 degrees low, the outdoor is 1 high, the indoor is 3 high, one dial is 3 low and the last dial is 10 DEGREES LOW! I was amazed! The lower temp mashed, the lower your FG.

Next would be ferment temps. Maybe fermenting too high?

High FGs is ultimately either 'sugars' that your yeast can't eat or weak yeast.
Low FGs is the opposite!

what duffer said...plus, as you suggested, i think it's a good idea to heat your first runnings as promptly as possible. if you let them sit for 30 minutes, enzymes are still at work and you've essentially extended your mash time, thereby increasing fermentability of your wort.

I batch sparge as well, and let my running sit until I'm ready to boil (30 min or so). I haven't had a problem with over-attenuation. A couple batched here and there, but certainly not consistantly. I would guess it's your equipment or possibly pitch rate. If you are concerned about letting your runnings sit, you could always mash for half the time. Or better yet, just raise your current mash temps and see if that helps.

So, you're heating the sparge water in your boil kettle? If not, run off into the kettle and get heat to the wort to stop conversion. You can calibrate your kettle to measure your runnings volume. If you do use your kettle to heat the sparge water, do a mash out by adding a certain amount of boiling water to the MLT if you have room.

I found this thread that seems to be along the same lines as my thought above.

https://www.homebrewtalk.com/f36/controlling-attenuation-through-mash-times-60576/

I'll double check thermometers while I am it but I think I am going to try and get my runnings on the heat and up above 170 as soon as possible to see if that solves my problem.

All other things seem to be in check. Temp in my
basement (where I ferment) is a constant 65. I have been using S-05 which I know is a pretty highly attenuating yeast but even with that being said I should be able to control it and keep my F.G.'s over 1.004 I would think.

dstar26t said:

So, you're heating the sparge water in your boil kettle? If not, run off into the kettle and get heat to the wort to stop conversion. You can calibrate your kettle to measure your runnings volume. If you do use your kettle to heat the sparge water, do a mash out by adding a certain amount of boiling water to the MLT if you have room.

Click to expand...

No, I have an HLT to hold sparge water. The BK is just sitting idle. I recently just got the HLT (2 batches ago). Prior to this I was heating sparge water in BK so heating first runnings was not an option.

Just now thought about this being a potential cause of my problem

I had the same exact problem about 4 years ago or so. I even posted threads about it- my mash temperatures were accurate, and I was always overattenuating. I was going crazy! I even adjusted my recipes' mash temps up, so that I wouldn't have a maibock at 1.005!

I thought maybe it was a wild yeast but my beer tasted great (but finished too low). I recalibrated and bought new thermometers. I never did find out the exact cause, but I changed a few things in my procedure. I bring my first runnings up to a boil right away, instead of waiting for my sparge. I sparge a bit hotter to ensure enzyme denaturing. I pitch the proper amount of yeast. Whatever the cause, it seemed to be resolved within 6-8 months or so. I really want to pin it on the first runnings sitting during the sparge, but I can't say that was it for sure.

I will say that I still reach higher attenuation than others might, so I still mash nearly everything at 153-154 or higher, but it's not out of line for the yeast strain's average attenuation. If a yeast strain gets 69-75% attenuation, I'll usually hit 78%ish. Not bad.

YooperBrew said:

I had the same exact problem about 4 years ago or so. I even posted threads about it- my mash temperatures were accurate, and I was always overattenuating. I was going crazy! I even adjusted my recipes' mash temps up, so that I wouldn't have a maibock at 1.005!

I thought maybe it was a wild yeast but my beer tasted great (but finished too low). I recalibrated and bought new thermometers. I never did find out the exact cause, but I changed a few things in my procedure. I bring my first runnings up to a boil right away, instead of waiting for my sparge. I sparge a bit hotter to ensure enzyme denaturing. I pitch the proper amount of yeast. Whatever the cause, it seemed to be resolved within 6-8 months or so. I really want to pin it on the first runnings sitting during the sparge, but I can't say that was it for sure.

I will say that I still reach higher attenuation than others might, so I still mash nearly everything at 153-154 or higher, but it's not out of line for the yeast strain's average attenuation. If a yeast strain gets 69-75% attenuation, I'll usually hit 78%ish. Not bad.

Click to expand...

Ain't troubleshooting great! I really enjoy this stuff. This is the "art" part of home brewing as much as the "science". Spending real bonding time with your system, learning it's idiosyncrasies, tweaking the processes, stabilizing your results and finally adjusting your input to reach your output targets!

I start heating the runnings immediately, unless I want high attenuation. If you let the wort sit, you're effectively extending the mash time.

I the advice here is spot on and I would agree that this problem is likely related to your mash stage (assuming you are using a variety of yeasts and not the same one over and over with a known high attenuation characteristic, like say Nottingham). You should try mashing not more than 60 minutes (or given your situation, even less if starch test shows conversion sooner) at the higher temp range and then incorporate a mash-out in some form or fashion as others here have mentioned (higher sparge temp, boil first runnings, etc.). If your thermometer is calibrated and accurate, this will give you dextrins and unfermentables in your wort that yeasts known for mid- to low attenuation are incapable of drying out. Dump in a yeast known for leaving residual sweetness and your dry beer issue is likely fixed.

A simple way to check your hypotheses.

Instead of running out your mash tun, add enough boiling water to get to a mash out temp. 168+-

Mash out for 10 min and then continue as before.

At least you'll know if holding your wort at conversion temps is your problem.

Hope this helps,

Bull

bullinachinashop said:

A simple way to check your hypotheses.

Instead of running out your mash tun, add enough boiling water to get to a mash out temp. 168+-

Mash out for 10 min and then continue as before.

At least you'll know if holding your wort at conversion temps is your problem.

Hope this helps,

Bull

Click to expand...

That is exactly how I was going to test this. I will do a mash out to get everything to 170 pretty much instantly after 60 minutes. I will then drain all runnings directly into my kettle on the burner which will be fired up as soon as the first drops hit the bottom.

I will keep all other variables the same. I'll post the results in case anyone was interested.

It will be awhile ..... out of town for two weeks, plus the time it takes to get around to brewing a batch when I get back, plus the time it takes to ferment out a batch.

In any case I'll revive this thread with results.

I also have this problem. I just brewed my fourth all-grain batch. I was under the impression that you should never mash out until everything is finished to avoid unconverted starches in the wort. I thought the mash time was supposed to be long enough for all the enzymes to totally finish--extra time has no effect. Some recipes say "60 min. or until converted." Some say "mash at 150--a longer mash time may be needed for conversion at this low temp," etc.

I guess I just still don't have a very clear picture (despite Palmer's yard work illustration) of what is actually supposed to be going on in the mash.

Anyone care to weigh in on the definition/relationship between conversion, extract efficiency, and fermentability?

You might find this helpful:

http://braukaiser.com/wiki/index.php/Understanding_Attenuation

yeast_infection said:

That is exactly how I was going to test this. I will do a mash out to get everything to 170 pretty much instantly after 60 minutes. I will then drain all runnings directly into my kettle on the burner which will be fired up as soon as the first drops hit the bottom.

I will keep all other variables the same. I'll post the results in case anyone was interested.

It will be awhile ..... out of town for two weeks, plus the time it takes to get around to brewing a batch when I get back, plus the time it takes to ferment out a batch.

In any case I'll revive this thread with results.

Click to expand...

You don't have to worry about starting your boil asap. The mash out temp will stop the conversion.

Then you can still collect all your wort and get a preboil gravity without messing around with near boiling wort. ( I once melted a hydrometer tube this way)

Keep brewing,

Bull

This is mainly echoing what was already said, but I would do two main things. First, check or thermometer. You might be surprised.
Next - really calibrate, or even replace, your Hydrometer. One thing that may be happening is that you are regestering a higher level of attenuation than reality because the alchohol is acting like a thinning agent of the beer, especially if you are brewing beers with some decent ABV percentages.

I got this from Noonen's book, I think. It actually helped me understand a similar problem I had.

Just a thought to look into.

Uhm... How are runnings still converting? Runnings are the start of your wort, and are drained off of the grains.

Are you all saying that conversion keeps going within the runnings? and does not rely on the grain?? -
This is where I'm at in my process, and I really don't have a clear picture in my mind of concept. I'm just asking
I just imagined that conversion had to come from the Mash that is still in contact with the grain...

interesting point I think ??

What about those Aussies that "no chill" and store their wort? is all that delayed fermentation hitting 1.090's?? They are not chatting us all up drunk off their butts and yelling about it!!

steakandale said:

Uhm... How are runnings still converting? Runnings are the start of your wort, and are drained off of the grains.

Are you all saying that conversion keeps going within the runnings? and does not rely on the grain?? -
This is where I'm at in my process, and I really don't have a clear picture in my mind of concept. I'm just asking
I just imagined that conversion had to come from the Mash that is still in contact with the grain...

interesting point I think ??

What about those Aussies that "no chill" and store their wort? is all that delayed fermentation hitting 1.090's?? They are not chatting us all up drunk off their butts and yelling about it!!

Click to expand...

The runnings contain sugars extracted from the grains. The chains may contnue to break down into more fermentable bits if held at optimal temps. Therefore the hot break.
Got it?
Good luck,
Bull

Just to re-iterate the points above - I have been having the same issue - my beers finish lower than expected, and my process was almost identical to the one initially described. Checked my hydrometers (I have 2) - both read the same and read 0 in water. Next I stuck 2 of my 3 thermometers under my tongue - low and behold, they were off. One measured 105... the other 108. I had been mashing 7-10 degrees lower than I thought.

Unfortunately, I did 2 things at the same time for my last 2 batches:

1. Added a mash out (about 2 gallons of 200 degree water for a 11 lb grain/ 5 gal batch)

2. Re-calibrated my thermometers (and bought a new one).

First beer with the new thermometer / process is ready to come out next week. I'll post results.

steakandale said:

Uhm... How are runnings still converting? Runnings are the start of your wort, and are drained off of the grains.

Are you all saying that conversion keeps going within the runnings? and does not rely on the grain?? -
This is where I'm at in my process, and I really don't have a clear picture in my mind of concept. I'm just asking
I just imagined that conversion had to come from the Mash that is still in contact with the grain...

interesting point I think ??

What about those Aussies that "no chill" and store their wort? is all that delayed fermentation hitting 1.090's?? They are not chatting us all up drunk off their butts and yelling about it!!

Click to expand...

The runnings contain the enzymes that are continuing to break down the long chain sugars in the wort into more fermentable ones. Raising the temps denatures the enzymes, halting the process.

I'm really not sure what you're asking about no chill? You might want to restate the question, but if you're suggesting that the process is continuing to occur, it is not. The wort has been boiled and enzymes denatured. Even if they weren't, the gravity would not increase, the wort would just become more fermentable.

steakandale - When the wort is heated to 170 degrees F it stops conversion. Buzzcraft explained it well, "The wort has been boiled and enzymes denatured. Even if they weren't, the gravity would not increase, the wort would just become more fermentable."

Thanks to those participating in this thread, very interesting!

I am going to start heating my first runnings in future batches, I have had an issue with almost all my beers finishing around 1.008, I made an irish red twice now, first batch finished at 1.011 with a 60min mash, the second batch was mashed for 90min due to unforseen pet issues, that one finished at 1.007, all other variables were the same, same thermos, same equipment, same digital scale, same final volumes and OG, this leads me to think that not heating the first runnings to insure enzyme denaturing as quick as possible has similar effect as a longer mash time. I hope heating the runnings will help, I also started adding boiling water as the mashout and have been hitting 168°-169° temps, I think adding a little more mashout water and heating right away will bring my numbers to where they should be.

All this finally came together as my possible issue after reading this thread and finally putting it all together, thanks guys!!

Never really paid much attention to this issue, but always wondered why many people were attenuating beers much lower then I was. Now I know. I start my BK burner as soon as the first inch of wort hits it. Recently I switch to a RIMS mash out so it's even less of an issue.

The more you brew the more complex it gets, yet it really does not get harder to do.

samc said:

Never really paid much attention to this issue, but always wondered why many people were attenuating beers much lower then I was. Now I know. I start my BK burner as soon as the first inch of wort hits it. Recently I switch to a RIMS mash out so it's even less of an issue.

The more you brew the more complex it gets, yet it really does not get harder to do.

Click to expand...

Yeah, i never really thought about it until my batches kept finishing really low. Then I kept walking through my process in my head trying to figure out where the problem was and a light bulb kind of clicked in my head one day. Basically I have been doing a 90 minute mash this whole time (assuming sparge process takes roughly 30 mintues) somtimes maybe even closer to 2 hours if I had a slow or stuck sparge. The first hour of this mash being in the 150's and the final 30 minutes (or whatever) at some unknown temp below my starting mash temp (I am guessing maybe 140's probably?)

I had always subscribed to the school of thought that a mash-out is not needed for batch sparging because it takes less time than fly sparging etc........

While this may be true under certain circumstances. ie. if you heat runnings rather than let them sit or sparge really fast so the time your wort sits at conversion temps is negligible.

The idea behind this school of thought just doesn't make sense given my particular process (which I described in the original post).

1.) I was using 175-180 degree water AFTER I had already runoff the first runnings which then sat in a bucket for awhile.
2.) while my batch sparge process may be slightly faster than fly sparging it still takes me 30 mintues on a good day.

Doing a mash-out or heating runnings as soon as you run-off (or both) seem like they would correct the problem (a brew is needed to determine if this corrects my problem).

So I guess, if your beers are ending lower than expected. Possibly consider the amount of time after run-off that your wort is sitting at conversion temps. If its significant than you may effectively be mashing longer than you think.


Brewing is so easy, but the longer I do it the more picky and critical of my process I get. Even though my beer might taste great at 1.004 it bugs the hell out of me knowing it was supposed to finish at 1.012 and didn't lol.

I wanted to post an update on this thread for those interested.

I finally got around to brewing a batch since I posted this. I took the final gravity today on this new batch and it is right at 1.014! Normally I would have expected a lighter beer like this to ferment down to 1.006 or 1.004 as I described in previous posts.

The only thing I changed was that I added a mash out step. I also added each runnings to the kettle and began heating immediately after the round of runoff was complete (don't have things arranged where I can runoff into the kettle yet).

I kept everything else the same. O.G. was approximately the same (1.056) as my previous over attenuated beers.

I used US-05 as I did with my previous 5 or so batches.

Fermented in my basement at 68 degrees.

So I'm not sure if it was the mashout step or the heating of the runnings. I don't really think that both would be necessary. One or the other would probably do just fine. At least I know not to leave my runnings sitting in the bucket for a half hour to an hour unheated.

I know it's only 1 beer but I have not been able to keep a 1.05ish beer over 1.008 since I started brewing all grain so I am pumped about this.

great info in this thread, I'm new to AG (2 batches) and I have not done a mash out or started heating my first runnings.

Hey thanks for thread yeast! I've always had low attenuation (w/ calibrated equip). I always did no mash out and recently even did a cool sparge (150 or so). Probably a bad idea, doh!

Did you do mashout and single sparge?

I did mash out (boiling water infusion method style lol) and let it sit for about ten to fifteen minutes. Drained and then did two sparge rounds (like normal but they were just a bit smaller since I had the mashout addition).

I still double batched sparged. The rounds were only like 2 gallons each but it seemed to work. I got my normal efficiency of around 75-80%. Can't remember exactly what it was without going back to my notes.

I have a megapot and boil off just over 2 gallons in an hour. So I was collecting just over 8 gallons preboil which probably helped me to be ablt to still squeeze in 2 rounds. I don't know how much efficiency suffers if you just do 1 sparge round. I have just always done 2.

I think if you can runoff into your boil kettle you could definately skip the mash out step.

I have to do the bucket collection method with my current brewing configuration though so I did the mash out. Plus I was paranoid and wanted to test my theory lol.

My sparge process was pretty long and drawn out and I had a couple that got stuck (in my previous batches) so I think that attributed to the dramatic effects I was seeing. If you can sparge relatively quickly and get everything going on the heat you might see a less dramatic effect.

But heck, if you over attenuating like crazy and everything else seems to be in check then give it a shot. Seems to have worked for me on my first batch that I tried it on.

I also had this same problem. FWIW I'm blaming it on not heating the first runnings. I've heated my first runnings right away and my FG's have gone from 1.006-1.009 up to 1.013-1.016 for average gravity beers. None of these beers are ready to drink yet, but they tasted pretty darned good when I kegged. I must say that I haven't really been able to tell much from tasting room-temp, flat, young beer. I've also raised my sparge temps some (I batch), but I figure the greatest quantity of sugars come out in the first runnings anyway, so that's where the money is.

steakandale said:

Uhm... How are runnings still converting? Runnings are the start of your wort, and are drained off of the grains.

Are you all saying that conversion keeps going within the runnings? and does not rely on the grain?? -
This is where I'm at in my process, and I really don't have a clear picture in my mind of concept. I'm just asking
I just imagined that conversion had to come from the Mash that is still in contact with the grain...

interesting point I think ??

What about those Aussies that "no chill" and store their wort? is all that delayed fermentation hitting 1.090's?? They are not chatting us all up drunk off their butts and yelling about it!!

Click to expand...

What's happening in the mash is that enzymes are breaking down the starch in the grain into complex sugars, and then breaking the comlex sugars down into more and more simple sugars. These enzymes and sugars are all contained in the liquid of the mash, and the process keeps happening until either the temperature denatures the enzymes (above 168F), or the enzymes have broken the sugars down as far as they can. How far the enzymes can break the sugar chains down depends on the type of active enzymes, which depends on the mash temp. Higher mash temp = more unfermentable sugars and higher FG.

The aussie "no chill" method refers to not chilling after the boil, which has no effect on the mash profile since the enzymes are denatured (killed) during the boil.

yeast infection...thanks for updating. glad to hear you're getting it worked out.

I often choose when to light the burner on my boil pot depending on how close my mash temps were. If they were a little low or right on, I start heating the first runnings immediately to lock in the mash profile. If they were a little high, I let the mash go a few extra minutes, and wait until all the runnings are in the pot before lighting to give the enzymes a chance to work a little more.

Awesome, HBTers, just awesome. Very glad that I did this search.

Getting sick of summer session beers ending up at 1.002 and going up by 1-1.5 % ABV.

Cheers everyone!

While I generally agree with most everything everyone has posted on this, IMO low mash temperature is most likely the cause. Determining what your average mash temperature actually is can be tricky. Sure, it's a must to have an accurate and well calibrated thermometer, but how you measure the temp and if the measurement is an accurate representation of the actual average mash temperature is another thing entirely. Frequently the grain bed will not be of a uniform temperature throughout. This is the main reason that I built a RIMS. My attenuation is usually right where I want it to be or very close now. It wasn't always that way, but usually the beers finished out on the high side, not too low. That problem has largely gone away, thank FSM.

jldc said:

I also had this same problem. FWIW I'm blaming it on not heating the first runnings. I've heated my first runnings right away and my FG's have gone from 1.006-1.009 up to 1.013-1.016 for average gravity beers. None of these beers are ready to drink yet, but they tasted pretty darned good when I kegged. I must say that I haven't really been able to tell much from tasting room-temp, flat, young beer. I've also raised my sparge temps some (I batch), but I figure the greatest quantity of sugars come out in the first runnings anyway, so that's where the money is.

Click to expand...

Yeah, mine is not ready to drink yet either. I'm excited to do a side by side of my pale ale that fermented down to 1.004 vs. my pale ale that stopped at 1.014.

I don't expect it to be one of those "wow" moments in home brewing but it should be satisfying none the less to have solved a problem in my beer that probably only I (or a judge or fellow beer nerd) would have noticed.

thanks for the info, definitely helpful. I think I'll start using a mash out.

yeast_infection said:

I wanted to post an update on this thread for those interested.

I finally got around to brewing a batch since I posted this. I took the final gravity today on this new batch and it is right at 1.014! Normally I would have expected a lighter beer like this to ferment down to 1.006 or 1.004 as I described in previous posts.

The only thing I changed was that I added a mash out step. I also added each runnings to the kettle and began heating immediately after the round of runoff was complete (don't have things arranged where I can runoff into the kettle yet).

I kept everything else the same. O.G. was approximately the same (1.056) as my previous over attenuated beers.

I used US-05 as I did with my previous 5 or so batches.

Fermented in my basement at 68 degrees.

So I'm not sure if it was the mashout step or the heating of the runnings. I don't really think that both would be necessary. One or the other would probably do just fine. At least I know not to leave my runnings sitting in the bucket for a half hour to an hour unheated.

I know it's only 1 beer but I have not been able to keep a 1.05ish beer over 1.008 since I started brewing all grain so I am pumped about this.

Click to expand...

Here is a way to look at this issue from another perspective, and involves NOT heating the runnings into the boil kettle.

One of my favorite styles to brew is a very traditional Kolsch. I think half the reason I like this style is that it can be very unforgiving in regards to hitting the style profile (dry with high attenuation, crisp, extremely pale, slight grain taste and low to no hop aroma and flavor components.)

When working to perfect my recipe and process, I once had to leave in the middle of my brew session to attend daddy-daughter function at my daughters school. I did this immidiately after batch sparging. I covered the BK and left it sit for over 2 hours.

I did a single batch sparge at 182 degrees, which brought my mash temp to 170. Thing is, when it is added to the BK, you know it drops when it hits the 1st runnings, my guess is that it stabalized at 157 or so.

I usually start my BK when I begin my lautering, but in this case, as I stated, I had to wait for over 2 hours. However, the final result was fantastic! My attenuation jumped to almost 88% (which is desired for this style), where before I was getting high 70's. There were two main differences in my process.

First, I did a rest at 141 for 45 minutes, then a rest at 158 for 45 minutes. Second, the brew kettle delay. I really think the majority of the difference came from the BK delay. Granted, I used a starter, aerated the heck out of everythin and so on, but that is one monster jump.

I am a believer in the fact that delaying the heating of the wort will result in a higher attenuation of the beer.

Hope this view helped out in someway. Great topic! I learned a lot by following this post.

Cheers!

Great thread, everyone!

For those who heat their first runnings right away: any concerns/experiences with caramelization due to heating such a small volume?