Help a begginer brewer with high FG

[vsoares]

Hi everyone,

I am in my fourth batch now, but in my first two I forgot to measure the OG, so they dont contribute any data to the problem that I am about to describe. I am brewing purelly all grain (here in Brazil we have no option, cause there are no malt extracts available).

The problem I have, as indicated in the title, is too high FGs. In our third batch, we got OG of 1.074 and FG of 1.026 (it was supposed to be a porter of OG 1.065sh). In our fourth batch, we made a paulaner clone (from clone brews) and got a OG of 1.069 (again, it was supposed to be around 1.054), FG of 1.024 (though the beer is stil in primary, has been there for 10 days now, but it has been several days since the activity stopped). As you can see above, there is not really just one problem, but at least a couple:

1) I cannot hit the desired OG. I believe the recipes available around there usually consider a extraction efficiency of around 70~75%. Apparently we are hitting for higher efficiency then that (around 85~87% for the fourth batch, for example). We do top of stove mashes, and we sparge continuosly;

2) The attenuation efficiency is quite low, in the 65~67% range. After reading literally thousands of threads in this forum, I am suspecting either of two: we are underpitching the wort; we are mashing in too high temperatures. Because our stove flame in very powerfull, we usually get higher temperatures in the begging of the mash than we would like, and I am suspecting we might be denaturing part of the enzymes right away, which is making the wort less fermentable. Does that make sense, considering how high our extraction efficiency seems to be? Shouldnt the denaturization (is that even a word?) of the enzymes make the extraction efficiency go down?

How can I decide for sure if I am underpitching or not? We do 6.6 gallon (25L) batches, and in all our batches we have dumped only one sachet of dry yeast on top of the fermenter (in the first 3 batches we used Safale US05, and in the last one we used Mangrove's Jack Bavarian Wheat). Because our OG is far higher than expected, I am thinking we might be severelly underpitching the wort. Is there a easy way I can tell if I am underpitching or not? I was thinking about taking a small sample of the beer, oxygenating it vigorously, adding a lot of yeast mud to it and then waiting to see if it attenuates further. Should that work? Is there any problem in that line of reasoning?

I am asking you guys these questions because it might take me a lot of trial and error before I can definitely say what the cause of my high FG and low attenuation is, and maybe your experience can make the task easier for me!

 

[RM-MN]

Hi everyone,

I am in my fourth batch now, but in my first two I forgot to measure the OG, so they dont contribute any data to the problem that I am about to describe. I am brewing purelly all grain (here in Brazil we have no option, cause there are no malt extracts available).

The problem I have, as indicated in the title, is too high FGs. In our third batch, we got OG of 1.074 and FG of 1.026 (it was supposed to be a porter of OG 1.065sh). In our fourth batch, we made a paulaner clone (from clone brews) and got a OG of 1.069 (again, it was supposed to be around 1.054), FG of 1.024 (though the beer is stil in primary, has been there for 10 days now, but it has been several days since the activity stopped). As you can see above, there is not really just one problem, but at least a couple:

1) I cannot hit the desired OG. I believe the recipes available around there usually consider a extraction efficiency of around 70~75%. Apparently we are hitting for higher efficiency then that (around 85~87% for the fourth batch, for example). We do top of stove mashes, and we sparge continuosly;

2) The attenuation efficiency is quite low, in the 65~67% range. After reading literally thousands of threads in this forum, I am suspecting either of two: we are underpitching the wort; we are mashing in too high temperatures. Because our stove flame in very powerfull, we usually get higher temperatures in the begging of the mash than we would like, and I am suspecting we might be denaturing part of the enzymes right away, which is making the wort less fermentable. Does that make sense, considering how high our extraction efficiency seems to be? Shouldnt the denaturization (is that even a word?) of the enzymes make the extraction efficiency go down?

How can I decide for sure if I am underpitching or not? We do 6.6 gallon (25L) batches, and in all our batches we have dumped only one sachet of dry yeast on top of the fermenter (in the first 3 batches we used Safale US05, and in the last one we used Mangrove's Jack Bavarian Wheat). Because our OG is far higher than expected, I am thinking we might be severelly underpitching the wort. Is there a easy way I can tell if I am underpitching or not? I was thinking about taking a small sample of the beer, oxygenating it vigorously, adding a lot of yeast mud to it and then waiting to see if it attenuates further. Should that work? Is there any problem in that line of reasoning?

I am asking you guys these questions because it might take me a lot of trial and error before I can definitely say what the cause of my high FG and low attenuation is, and maybe your experience can make the task easier for me!

Your high initial temperature may not affect the efficiency but there are two enzymes that need to work together. Alpha amylase can break down the starches fairly quickly and it isn't denatured as quickly as the beta amylase but it produces dextrines that are not fermentable. That gives you your high FG.

Beta amylase works a bit slower than alpha and it is more sensitive to the high temperatures so it won't have time enough to break down enough of the dextrines to make them into a fermentable sugar before it becomes denatured.

Because of the necessary temperature for the mash to work properly you need to learn to turn that burner down sooner. I run my burner on high at the start but turn it down as the temperature approaches my strike temp and just creep up those last few degrees so I won't exceed the strike temp.

Underpitching the yeast can lead to stressed yeast and some interesting (not necessarily in a good way) flavors and aromas in your beer but with some care it can still bring the beer to an acceptable FG. Aerate your wort very well so the yeast have the oxygen they need to make new cells. Start the ferment near the low end of the yeast's preferred range and keep it there until the ferment slows, then let it warm up to help the yeast complete the ferment.

 

[rodwha]

I'm not sure if that's under pitched enough to create a real problem like that.

Here's a great yeast pitching calculator:
http://www.mrmalty.com/calc/calc.html

 

[Qhrumphf]

Are your batch volumes correct? If you're substantially over gravity but you're ending up substantially under volume, it maybe be just overconcentration of the wort, and not an actual increase in efficiency. Or maybe you really do just have higher efficiency. I usually hit 80-85% depending on the beer (higher for session beers, lower for high gravity beers).

That said, if the OG was higher than expected, I would also expect the FG higher than expected, but not that high. As mentioned above, if you're mashing in too high, you're denaturing beta amylase rapidly but leaving alpha amylase to work, resulting in less fermentable wort. Lowering the flame earlier to dial it in properly is a good bet. You might also consider going the Saison Dupont route, and mashing cool (by mash standards) in the 90-100 degree range, and then slowly raising the temperature of the whole mash a degree or two every couple minutes, allowing maybe 90-120 minutes to go from 90-100 to 168 mash out. That may be overkill, since it'll produce the fermentability of wort you want in a Saison.

That said, your idea of aerating and overpitching a small sample is called a forced ferment test, and it's a good idea. That will certainly isolate whether it's wort problem or a yeast problem. You should expect a point or two lower in the forced ferment test regardless simply because the yeast are being given conditions they love at the expense of proper flavor, but if it's more than that, then it's probably a yeast problem you're having. If the change is minimal, then it's probably a wort problem.

 

[Qhrumphf]

Also consider rehydrating your dry yeast. That'll get you close enough to a proper pitching rate at the gravities you're talking about. If you're just sprinkling unhydrated yeast, yeah, you're underpitching.

 

[vsoares]

Thanks guys, I am glad to know there is, indeed, such a thing as a forced fermentation test and that is exactly what I was expecting would solve my problem. Sure I will be extra carefull about my mashing temperatures from now on as well!

 

[cobrem]

You may want to try a strike water calculator for mashing in (brewers friend website, for example). I mash on stovetop as well, and get pretty close to initial mash temp. If slightly high, I just dump in a bit of cool water to get it down as quickly as possible. Something to consider...

 

[gauthierk]

Are you doing a full extract, partial mash or full AG? Under pitching most of the time would lead to a slow primary fermentation but eventually the gravity would fall do the numbers you are shooting for.. I think your enzyme conversations might be stunted for some reason. It could be too hot of a boil not allowing the alpha and beta's to do their job as said earlier... I would try and give it a good protein rest.. bring your wart temp to the 150's and turn off the flame for about 20 to 30 min.. Let it rest then full boil it out...

 

[Trox]

Have you calibrated your hydrometer? You seem to be consistently .010 -.015 high on your OG which if it is the hydrometer would put your FG around their proper range. To calibrate the hydrometer just fill up your test tube with water (tap water is fine though some say you should use distilled) and then read what the hydrometer says. The reading should be at 1.000 after temperature correction. It really isn't uncommon for the paper inside the tube to have slipped down some. If it is off then you can either just correct for the difference, or buy a new one; I personally would get a new one if it was that much off.

 

[Qhrumphf]

Have you calibrated your hydrometer? You seem to be consistently .010 -.015 high on your OG which if it is the hydrometer would put your FG around their proper range. To calibrate the hydrometer just fill up your test tube with water (tap water is fine though some say you should use distilled) and then read what the hydrometer says. The reading should be at 1.000 after temperature correction. It really isn't uncommon for the paper inside the tube to have slipped down some. If it is off then you can either just correct for the difference, or buy a new one; I personally would get a new one if it was that much off.

This is also a good call.

For what it's worth, yes technically you should use distilled water. But ultimately amount of dissolved solids in tap water is infinitely smaller than the hydrometers we use are capable of measuring ie don't worry about it.

And I would recommend, for calibration purposes, that you don't use temperature correction, but rather actually measure at calibration temperature. Which of course, assumes you have a properly calibrated thermometer. Which is also another possible issue. I was constantly having problems with the other side- FG always too low, until I picked up a lab certified high accuracy and high quality thermometer (ThermaPen), and realized the thermometer I thought was accurate (accurate at both boiling and freezing) had such a wide tolerance that in mashing range I was actually reading 4-5 degrees lower than I thought, so when I thought I was mashing at 152 I was really mashing at 147-148. If your thermometer is reading low, and not high like mine was, and you're mashing at 156 instead of what you think is 151, that'll also have an impact, especially if you're initially even hotter than that.

 

[vsoares]

Have you calibrated your hydrometer? You seem to be consistently .010 -.015 high on your OG which if it is the hydrometer would put your FG around their proper range. To calibrate the hydrometer just fill up your test tube with water (tap water is fine though some say you should use distilled) and then read what the hydrometer says. The reading should be at 1.000 after temperature correction. It really isn't uncommon for the paper inside the tube to have slipped down some. If it is off then you can either just correct for the difference, or buy a new one; I personally would get a new one if it was that much off.

Yes the first thing I thought was that my hydrometer was off, because both reading are high (OG and FG), or maybe that my tap water had a huge amout of dissolved salts, but I have already measured the local tap water density using my hydrometer and it reads something between 1.000 and 1.001, which is pretty good I assume.

 

[vsoares]

Are you doing a full extract, partial mash or full AG? Under pitching most of the time would lead to a slow primary fermentation but eventually the gravity would fall do the numbers you are shooting for.. I think your enzyme conversations might be stunted for some reason. It could be too hot of a boil not allowing the alpha and beta's to do their job as said earlier... I would try and give it a good protein rest.. bring your wart temp to the 150's and turn off the flame for about 20 to 30 min.. Let it rest then full boil it out...

I brew all grain. The last fermetation was pretty insane, actually. We have a fermenter that holds up to 30 litters, and we put just under 25 L (actually 24L, because we got a little too high evaporation from the 90 min boil). Thankfully we use a blow off tube instead of a airlock. The thing fermented very strongly, and by the end of the fermentation the water in the blow off tube pot was all full of worty stuff (there was even some yeast in the bottom of it). The refrigerator had wort/beer spilled all over it, and the fermenter was all dirty in its outside. I dont know if that might be an indication that we really arent underpitching?

 

[vsoares]

You may want to try a strike water calculator for mashing in (brewers friend website, for example). I mash on stovetop as well, and get pretty close to initial mash temp. If slightly high, I just dump in a bit of cool water to get it down as quickly as possible. Something to consider...

Yes I think thats exactly what I will have to do! I am considering even striking for a little lower temperature, and then heating it up very slowly to get to the correct mash temperature.