frustrations with over-attenuation in IPAs

[Little_Lebowski]

Well, I've come to the point where I'm desperate for advice on issues with over attenuation. It doesn't seem to matter which thermometer I use for mash temps, the size of my starter ( 1L vs 2L), ferm temps, type of yeast... you name it. MY BEERS ARE FINISHING SO DRY!

I don't know if in the last 6 beers I've brewed I've been able to keep FG from finishing under a 1.010. Heck I'd be delighted with a 1.010! The last beer I made which was an Alpine Nelson clone, my OG was a 1.070 and the beer dropped to a 1.006! With things being so dry the bitterness really jumps at you and there's absolutely no malt sweetness at all to balance.

I typically use gigayeast VT IPA, but on this Nelson clone I used Wyeast dennys favorite. Regardless, both overattenuate for me. I typically use 2L starters for 5 gallon batches but tried to use a 1L instead to see if that amount of yeast was just too much but things were no different.

I switched over to batch sparging from fly sparging with a blichman autosparge about a year ago. I'm thinking back and cAnnot recall having these issues prior to batch sparging. Could this be a culprit? I may switch back for a brew to see if that helps. I also started hearing my first runnings while batch sparging to keep temps elevated post mash but to no really noticeable avail.

I'm just begging for some malt body here because I feel like I have to compensate so much with lowered hop additions, which pains me to do.

 

[mashinary]

What temp are you mashing at?

 

[mattdee1]

Sounds like you need a lower-attenuating yeast (e.g. WLP002), a less fermentable wort (add in some crystal malts, mash high), or some combination thereof.

 

[LLBeanJ]

Are you using BeerSmith or something similar to create your recipes so you have a realistic target FG based off of the grain bill, yeast choice, and mash temps? If so, and you're not hitting target FG (within a few points, anyway), then something is definitely wrong.

 

[Rush]

Are you sure your thermometer is calibrated correctly?

 

[Little_Lebowski]

Ideally i shoot for a 152F mash temp. At least in a perfect world this is the mash temp I shoot for given the medium body profile I'm looking for. I use a thermopop and 24" thermoworks thermometer to take temps in the kettle and mash tun. The thermometer on my Spike brewing kettle and the other two mentioned above have all been calibrated and I feel they're accurate.

My last few recipes I'm using ~ 4% honey malt with a 80/20 2row to wheat grist. I've added some Munich and Vienna to this base grist in varying amounts but they've added too much color for my liking.

I use beersmith and I'm no where near the FG that's being calculated. I've even seen recipes with an FG near 1.02 and still couldn't even keep it from running down below 1.01 in reality

 

[Little_Lebowski]

I want to try and tackle this issue one correction at a time. So, logically, I guess I'll try and shoot for a 154/155 mash temp in the belief that my thermometers are at the low end of their accuracy +/-

What would be suggestions for the next logical correction if mash temps don't seem to correct the issue? Back to fly sparging to assure my temps stay 152+ from mash to boil? I've tried to tackle this issue already by hearing my first runnings

 

[LLBeanJ]

Your grain bills seems to me that they would tend to finish somewhat low, so I'm not surprised to see it, however, I am very surprised to see FG not accurately predicted by BS. My FGs are usually spot-on, rarely off more than a point or two. All I can think of is you're mashing lower than you think (I.e., thermometer is not accurate at mash temps).

I would duplicate one of your recipes that finished lower than expected and increase the attenuation %'s of the yeast as much as needed to get BS to output an expected FG that matches your results. Then, start playing with mash temps and grain selection to see if you can get the predicted FG to come out more to your liking. Once you do, try brewing the recipe and see what happens.

Also, it might be a good idea to post your last recipe that finished low, so we can try working with it to see if anything jumps out.

 

[TennBrewer]

+1 on the lower attenuating yeast, that should be an easy mod. Experiment, split the batch and use two different yeasts and see if either solves your problem.

 

[Chanoc]

A few questions.
Do you mash out?
How long do you Fly-sparge?
If you don't mash-out and take longer to fly-sparge, you may be effectively mashing longer (and probably coplee) than desired.
This may lead to thinner bodied beers.

 

[LLBeanJ]

A few questions.
Do you mash out?
How long do you Fly-sparge?
If you don't mash-out and take longer to fly-sparge, you may be effectively mashing longer (and probably coplee) than desired.
This may lead to thinner bodied beers.

He's batch sparging, so a mash out shouldn't be needed. He didn't have the problem when he fly-sparged; it only showed up after he switched to batch sparging.

 

[Little_Lebowski]

I mash for 60 min. With five min to go, I stir and start to recirculate to clear things up. I then drain entirely into the kettle which is on low heat. I add in my sparge water at around 175-180F and stir. 5-10 minute later I'm recirculating and draining again into my kettle where the temp is already ~200F or so.

 

[Little_Lebowski]

Any other yeast suggestions? I do like a slightly fruity ester like Conan.

 

[logdrum]

1272 or WLP051 for slightly fruity esters & a bit less attenuation

 

[Yooper]

I mash for 60 min. With five min to go, I stir and start to recirculate to clear things up. I then drain entirely into the kettle which is on low heat. I add in my sparge water at around 175-180F and stir. 5-10 minute later I'm recirculating and draining again into my kettle where the temp is already ~200F or so.

First, I would try shortening the mash. If you get conversion by, say, 25 minutes in, letting it sit the full hour would continue the debranching of the amylopectins. Try mashing for 45 minutes the next time.

You can try adding near-boiling water for your sparge water, to bring the grainbed up to 168 or so, if you're going to let it sit for 5-10 minutes. I'm thinking that it's not necessarily the issue, but it will only help.

I batch sparge frequently, but I don't let it sit at all. I add the sparge water, stir like I mean it, and then I recirculate about 30 seconds to vorlauf, and then drain.

 

[Jtk78]

In for answers. I'm having the exact same issue. Different yeasts, different grain bills, all finishing below 1.010. I was mashing 151-152. Last batch I mashed at 154. My thermometers were calibrated in ice water and boiling water. I'm still waiting for results this batch.

1272 or WLP051 for slightly fruity esters & a bit less attenuation

I agree with the slight fruitiness, but I just had 2 beers go from 1.052 to 1.006, I held ferm temp at about 64f. Beersmith predicted FG at 1.017.

 

[kh54s10]

I see two possibilities. 1)The recipes are creating an easily fermentable mash. 2) The temperature of the mash. How well does your mash tun hold the temperature? If you start the mash at 152 and it drops quickly, you are in reality mashing at a temperature lower than 152.

But then again I mashed my last IPA at 148 for 75 minutes. I chose light body. It was not too dry. (for me) The yeast was S-33.

 

[TheMadKing]

A few other questions,

-Are you measuring gravity with a refractometer or hydrometer? (assuming hydrometer)
-Have you checked your hydrometer calibration on distilled water?
-Are you measuring your gravity samples at ~68F? Temperature greatly affects the readings
-Are you de-gassing your FG sample? CO2 in solution will make a difference
-Are you adding water or alcohol to your batches at any point after fermentation begins? (stupid question maybe, but I have to ask)
-Are you adding cane sugar, brown sugar, molassas, candy sugar, or any other form of simple sugar to your wort?

 

[griffi]

Are you reusing yeast beyond a couple generations?

 

[stz]

Ok, this might fly in the face of what is widely considered to be an absolute scientific truth, but I've found through quite a lot of experience that final attenuation is more easily influenced by yeast choice and grain bill than the mash temperature.

Yes enzymes become denatured at certain temperatures and yes I specify a mash temperature as part of recipe design, but the idea that we can influence this to a significant degree in the real world environment of the mash tun to a significant enough extent except at extremes not usually encountered in brewing is wishful thinking.

Like we can mash hotter and thinner to create a less fermentable wort, but the temperature range to some extent will vary across the mash. 0.5C is acceptable, but we've very little way to tell exactly by what level we've impacted the enzymatic process throughout the mash and then people mash for 60 minutes, even 90 minutes. 60 minutes is plenty of time to get the job done. The way people specify temperature with changes of a single degree Fahrenheit as if this is what will make all the difference without considering all the other aspects seems crazy to me.

Then people perform a mash out high temperature infusion to prevent further conversion during the sparge? Or they don't? I'd rather people just say "attempt to create a less/more fermentable wort with your system" because experience will usually tell you what you can do to influence this factor.

Or far simpler, just add some crystal or dextrine malt. Dextrine malt is 9% maltodextrine by weight and is very light without an impact on colour.

What we do at work is we aim to mash at a certain temperature and from experience pick a strike temperature to start with. We record that strike temperature as well as the ambient temperature and then the mash temperature over 4 different positions at the start of the mash. We record final attenuation at the end of fermentation and we will update the recipe for next time bringing the mash temperature up or down a little depending on the final attenuation, our feelings about the beer and the recorded ambient temperature.

I've generally found that after almost 100 brews with 80% of them being core beers and thus repeated recipes it has made almost no difference in the final attenuation. Variation across batches of malt, human or mechanical error, less than optimal yeast practice and so on make a much bigger difference.

Also for pale/IPA we expect less than 10. Brown/bitter expect less than 12. Dark/stout expect less than 14. The difference is some dark beers we do can be 30-40% speciality grains.

 

[Jtk78]

I see two possibilities. 1)The recipes are creating an easily fermentable mash. 2) The temperature of the mash. How well does your mash tun hold the temperature? If you start the mash at 152 and it drops quickly, you are in reality mashing at a temperature lower than 152....

My mash tun hold very well, I lose no more than 1 degree, if that (Coleman Xtreme)


QUOTE=TheMadKing - A few other questions,

-Are you measuring gravity with a refractometer or hydrometer? (assuming hydrometer) Hydrometer
-Have you checked your hydrometer calibration on distilled water? yes,
Reads just under 1.001
-Are you measuring your gravity samples at ~68F? Temperature greatly affects the readings My hydrometer is calibrated at 60F. The warmest I've taken a reading was 65F
-Are you de-gassing your FG sample? CO2 in solution will make a difference do you mean spinning the hydrometer?
-Are you adding water or alcohol to your batches at any point after fermentation begins? (stupid question maybe, but I have to ask) No addition other than a dry hop. Same issues on no dry hopped
Beers
-Are you adding cane sugar, brown sugar, molassas, candy sugar, or any other form of simple sugar to your wort?None at all

Are you reusing yeast beyond a couple generations?

Nope. It's happened with fresh yeast and a starter (1.036 starter wort), and I haven't been past 3 generations. I will note that my beers are on the dryer side, but not excessively dry. I'm getting about 83% mash efficiency.

 

[stz]

So there are opinions regarding the mash tun losing temperature and as such a mash starting at 69C and falling over the hour to 67C or so being the factor in creating more fermentable wort.

Doesn't this ignore the aspect of enzymes being denatured at higher temperature? I mean, they don't come back to life once the temperature falls, they are denatured. Of course holding the heat for a longer time at a higher temperature will denature more enzymes within a mash with variable temperature throughout than the same heat over a shorter time, but this just highlights how variable a 60 minute or more mash actually is under real world conditions in the mash tun.

Again, I'd say from experience (and I started out prepared to defend the idea that mash temperature is the major factor in FG) that FG is best influenced by yeast selection and grain bill.

 

[10_degrees_play-doh]

It's possible that your 20% wheat content is driving your fermentability up as well, as wheat has a ton of diastatic power. More amylase in the mash means longer for it to denature. I'm not sure what exactly your aim with the wheat is, but if it's something to do with the protein content, you may want to consider oats as an alternative. As everyone has been saying, your wort fermentability and yeast strain choice are probably the biggest contributors. Less likely but possibly, you could have an infection in your brewhouse that metabolizes some of your higher sugars.

 

[Little_Lebowski]

How much "off gassing" would need to be done from a sample taken 7-10 days into a solid fermentation. I'm aware of co2 being dissolved into the beer at this point but wondering how much. If it is significant, i could be throwing off my refractometer... in that same vein: can I trust using a refrCtometer post fermentation with the calculators available online? Or is there some serious accuracy issues I need to be aware of?

 

[IslandLizard]

Are you recirculating your mash continuously or just let it sit in the cooler? Then vorlauf and lauter.

I noticed continuously recirculated mashes tend to be more fermentable, as long as the heating system doesn't denature the enzymes prematurely.

You can add some Carapils (dextrin malt) and/or low Lovibond caramel malt like C10 or C15 to boost the unfermentables and add some sweetness.

Definitely check that thermometer for accuracy calibration, preferably against another one.

And use a hydrometer to get your FGs.

 

[Yooper]

How much "off gassing" would need to be done from a sample taken 7-10 days into a solid fermentation. I'm aware of co2 being dissolved into the beer at this point but wondering how much. If it is significant, i could be throwing off my refractometer... in that same vein: can I trust using a refrCtometer post fermentation with the calculators available online? Or is there some serious accuracy issues I need to be aware of?

Sort answer- no, you can't trust the refractometer reading with calculators post-fermentation, but sometimes you can get fairly close.

I've never had an accurate reading, but others swear by this calculator: http://seanterrill.com/2012/01/06/refractometer-calculator/

If you know your wort correction factor exactly, it may be close for you. I have never found it to be accurate although I used my wort correction factor to the hundredth place.

 

[TheMadKing]

My mash tun hold very well, I lose no more than 1 degree, if that (Coleman Xtreme)





QUOTE=TheMadKing - A few other questions,



-Are you measuring gravity with a refractometer or hydrometer? (assuming hydrometer) Hydrometer

-Have you checked your hydrometer calibration on distilled water? yes,

Reads just under 1.001

-Are you measuring your gravity samples at ~68F? Temperature greatly affects the readings My hydrometer is calibrated at 60F. The warmest I've taken a reading was 65F

-Are you de-gassing your FG sample? CO2 in solution will make a difference do you mean spinning the hydrometer?

-Are you adding water or alcohol to your batches at any point after fermentation begins? (stupid question maybe, but I have to ask) No addition other than a dry hop. Same issues on no dry hopped

Beers

-Are you adding cane sugar, brown sugar, molassas, candy sugar, or any other form of simple sugar to your wort?None at all









Nope. It's happened with fresh yeast and a starter (1.036 starter wort), and I haven't been past 3 generations. I will note that my beers are on the dryer side, but not excessively dry. I'm getting about 83% mash efficiency.

The reason I'm asking these types of questions is because it has to be something all of your batches have in common. If you are varying yeast, grain, and mash temp, but your FG is always low anyway then it can't be any of these variables. So I'm looking for something that all batches have in common.

Do you have any off flavors that might indicate a mild infection? It might be hard to taste in a very hoppy beer.

One idea is to try a SMASH with Munich malt. If that overattennuates then you know there's either a measurement error somewhere, or an infection. Munich has the lowest diastatic power of any of the common base malts but is capable of making a fermentable wort. It just shouldn't attenuate much below 1.015 even if your mash is at 148F for 90 minutes.

A second idea is to run a fast-ferment experiment on a sample of your wort in parallel to your main fermentation. That will tell you what the absolute minimum final gravity should be given your yeast choice. If your main beer falls below that number achieved in the fast ferment, then its not your yeast causing the extra attenuation and must be an infection or measurement error.

 

[LLBeanJ]

How much "off gassing" would need to be done from a sample taken 7-10 days into a solid fermentation. I'm aware of co2 being dissolved into the beer at this point but wondering how much. If it is significant, i could be throwing off my refractometer... in that same vein: can I trust using a refrCtometer post fermentation with the calculators available online? Or is there some serious accuracy issues I need to be aware of?

Your refractometer could very well be the root of your issue. I have one and use it for OG on brew day, but any measurements after that are taken with a hydrometer. Do you have any of your finished beers that you believe came out low on FG that you can try measuring now with a hydrometer to compare readings?

 

[TheMadKing]

How much "off gassing" would need to be done from a sample taken 7-10 days into a solid fermentation. I'm aware of co2 being dissolved into the beer at this point but wondering how much. If it is significant, i could be throwing off my refractometer... in that same vein: can I trust using a refrCtometer post fermentation with the calculators available online? Or is there some serious accuracy issues I need to be aware of?

As Yooper said, refractometers are notoriously inaccurate when there's alcohol in the mix. You're much better off using a hydrometer.

As for CO2 in solution, yes it can make a difference of 1-5 gravity points depends on how much there is. Just put it in a glass and toss it back and forth in a second glass a few times until there's no foam whatsoever. That's what a lot of pro-brewers do.

 

[stz]

Just put it in a glass and toss it back and forth in a second glass a few times until there's no foam whatsoever. That's what a lot of pro-brewers do.

We squirt just a little into a jug from the racking port and that clears any yeast from the port as well with a squirl rinses the jug. We toss that bit, then half fill the jug (a litre in a 2.2L jug?) and using a spoon vigorously beat the heck out of it side to side to knock any co2 out of the beer. Of course this causes it to foam up ridiculously so we add a few ml of n-butanol which immediately kills the head. We then beat the beer a little more, but not so much that you create more foam. We use a dash of the beer to rinse the trial jar and toss it, then fill the trial jar rapidly enough that any leftover foam will be pushed off the top of the beer so a clear and accurate reading is as easy as possible. Taking a gravity takes no longer than 2 minutes and this is important when you've got to do 6 of them twice a day including weekends and public holidays!

 

[TheMadKing]

We squirt just a little into a jug from the racking port and that clears any yeast from the port as well with a squirl rinses the jug. We toss that bit, then half fill the jug (a litre in a 2.2L jug?) and using a spoon vigorously beat the heck out of it side to side to knock any co2 out of the beer. Of course this causes it to foam up ridiculously so we add a few ml of n-butanol which immediately kills the head. We then beat the beer a little more, but not so much that you create more foam. We use a dash of the beer to rinse the trial jar and toss it, then fill the trial jar rapidly enough that any leftover foam will be pushed off the top of the beer so a clear and accurate reading is as easy as possible. Taking a gravity takes no longer than 2 minutes and this is important when you've got to do 6 of them twice a day including weekends and public holidays!

That works too! My local brewmaster just pours off a quart to clear his port, dumps, rinses the yeast sediment with beer, refills the quart, pours it back and forth between 2 glasses like a cocktail, lets it sit at room temp for a couple minutes for the head to dissipate, then fills his trial jar for the reading.

 

[Little_Lebowski]

They're all kegged at this point but I'm going to pull some samples off the taps and take some new measurements with a hydrometer and compare to the calculated FG I figured before with the refractometer. I appreciate all the guidance so far.

 

[RTL]

Beta amylase doesn't denature until 70C you are still sitting pretty well below that and if you aren't hitting it hard in the BK then you may not be bringing it up above that until much later than your 60' mash. Do you have the capability to heat your mash?

 

[Little_Lebowski]

No. I'm still mashing in a 10 gallon cooler. By "hitting it hard" I'm assuming you mean a vigorous rolling boil?

 

[RTL]

I mean heating as much as possible, personally I try to have the wort I'm collecting at or near boiling by the time I'm done sparging so I'm not wasting any time waiting for boil, and I know beta is denatured so my attenuation is fixed.

Kai has some really good information on his website about experiments he has done with different mash parameters. From his data and my experience as well my opinion is that mash temp, mash thickness, and duration of your rests have much more to do with attenuation than yeast strain. I am of the opinion that attenuation is up to the maltster and the mash until you hit the point where the yeast simply can't tolerate the alcohol level.

Having said that there are sugars that lager yeasts and certain ale yeasts can ferment that the majority of ale yeasts can't ferment. However in my experiments this has only accounted for a 2-4 point difference in FG which in my book is insignificant.

Try reading the following and doing your own tests:
http://braukaiser.com/wiki/index.php/Limit_of_attenuation_experiment
http://braukaiser.com/wiki/index.php/Mash_Time_Dependency_of_Wort_Fermentability

Good luck.

 

[Jtk78]

The reason I'm asking these types of questions is because it has to be something all of your batches have in common. If you are varying yeast, grain, and mash temp, but your FG is always low anyway then it can't be any of these variables. So I'm looking for something that all batches have in common.

Do you have any off flavors that might indicate a mild infection? It might be hard to taste in a very hoppy beer.

One idea is to try a SMASH with Munich malt. If that overattennuates then you know there's either a measurement error somewhere, or an infection. Munich has the lowest diastatic power of any of the common base malts but is capable of making a fermentable wort. It just shouldn't attenuate much below 1.015 even if your mash is at 148F for 90 minutes.

A second idea is to run a fast-ferment experiment on a sample of your wort in parallel to your main fermentation. That will tell you what the absolute minimum final gravity should be given your yeast choice. If your main beer falls below that number achieved in the fast ferment, then its not your yeast causing the extra attenuation and must be an infection or measurement error.

I haven't noticed any off flavors. I have the owner of the homebrew shop taste most of my batches, asking for non-bias feedback, and he's not mentioned any off flavors. I wash everything with PBW when I'm done brewing, and re-wash it when I pull it out to brew. I have a bucket with starsan as well as a spray bottle that everything gets hit with.

I just took a hydrometer readingredients this morning and the Nut Brown I brewed on Saturday using 1272 yeast. Reading today was 1.012. Beersmith predicted 1.015. This is the first batch I've had in my converted freezer ferm chamber since day one. Also mashed this a little higher than in the past, 154 this time. I've been mashing at 151 and using a swamp cooler with the carboys submerged in water to just under the wort line and aquarium heaters running on a temp controller. Ambient was lower than ferm temp, so I couldn't see the wort getting to hot, but perhaps it was. I don't have thermowells yet, but plan getting a couple.