Need Input...High FG...What am I not seeing?

[hafmpty]

I hate asking this question because I realize there are many different reasons why my gravity could be finishing high. I'm hoping you can help me narrow down the particular reasons in this instance. Here's what I've got...

I brewed Monday, January 12. It was a big grain bill and my MLT was full to the brim. I figure my water/grain ratio was around 1-1.15 qt/lb. It was thick.

I recirculated through the entire mash with a target mash temp of 150F but the recirculation was really slow. I'm going to loosen up my crush to allow a faster flow. The temperature is constantly monitored as it exits the MLT. I know it wasn't overheated. At the end of the mash I checked temperatures and realized that the temp on right side of the grain bed was much lower than the side the recirculating wort was flowing onto. The right side was down around 130F, the left side, closer to 150F. It was like this during the entire 60min mash. I ramped to 168F for mash out. I checked for starch conversion and conversion was complete.

When I sparged I missed my target pre-boil gravity and added 3lbs of DME to bring the OG up to the 1.077.

Boiled for 90min, chilled, etc. The OG was 1.084. It is a Baltic Porter and the gravity is currently 1.030. I pitched a MASSIVE starter of WLP830 and fermented at 53F for 5 days. Then I ramped the ambient temp 3F every 12 hours until I was at 68F. It's been there ever since. It's a version of Tasty's Fast Lager Fermentation.

BTW I did a forced fermentation test and the gravity only got down to 1.024 (target is 1.018).

WHAT AM I MISSING?
WHAT AM I DOING WRONG?

Also, I brewed a Bock on the same system and with much the same process (except I did a double decoction) and it finished very high too. WTF?

 

[Pappers_]

First off, I really have no idea, and am interested in hearing what others have to say.

I'm going to guess that its something related to your mash. I do simple, single infusion into a cooler mashes, so am not speaking from experience, but the recirculating should not give you a 20 degree difference in your mash tun, which can't be good. Now, its low, which would make you think the problem would be too high a fermentability, but in any case, it seems messed up.

The other issue could be that your gravity readings are off for some reason, but I don't see that from what you described. Your fermentation regime, as described, sounds fine for this beer and this yeast.

I'm guessing that someone who knows more than I do is going to figure out that your mash is messed up. Maybe for your next beer, do an experiment and don't recirculate the mash, do a simple single infusion mash and see if you have the same problem. If your FG is closer to what you expect, at least you've narrowed down the problem. If your FG is still too high, well, then I was wrong

 

[Wolfbayte]

1. How do you know it's finished? Take another gravity read in 3 days and see if it's lower.

2. What is your recipe. Run the entire recipe, including DME through a brew calculator. Normally a lower mash temp gives you more fermentables and a lower FG, so maybe your mash was higher than you thought.

3. How big was your big starter?

Personally, I'd wait another week or two and measure again.

Best,
Wolf

 

[grathan]

I'll put my thoughts in order. For what it's worth I've never measured FG, but just thoughts from what I've read and not experience.

1.) lack of aeration and yeast nutrients
2.) cheap DME
3.)How long did mash out step-up take?, perhaps test for conversion before this step. Perhaps there was unconverted starch and it converted at the higher temp during mash-out ramp-up.
4.)You can't measure FG accurately? this is remote possibility because you can't measure mash correctly so there is a chance you can't measure FG correctly either.

 

[hafmpty]

1. How do you know it's finished? Take another gravity read in 3 days and see if it's lower.

It dropped 50% of the way to FG in 5 days. Since then it's just been trickling along. It still is bubbling but only very slowly. I know it's not "finished" but it's damn near close. Certainly not going to drop another 12 points.

2. What is your recipe. Run the entire recipe, including DME through a brew calculator. Normally a lower mash temp gives you more fermentables and a lower FG, so maybe your mash was higher than you thought.

I used a Thermapen to take my measurements and an RTD that is highly accurate too. It was calibrated using the Thermapen as a reference so I imagine it's pretty accurate.

3. How big was your big starter?

3 Vials pitched into a 1.6L stepped to 2.8L stepped to 5L then pitched. Estimated number of cells was the 2 million cells per mL per degree plato (via BrewersFriend.com Yeast Calculator).

Personally, I'd wait another week or two and measure again.

That's what I'm going to do and hopefully it'll get down to drinkable.

1.) lack of aeration and yeast nutrients

I used yeast nutrients in the starter wort I used for my yeast starters and I put it in the boil. I aerated for 1 minute at 1L per minute. I also RE-AERATED per Jamil Z's advice on big gravity beers. I did this at the 18 hour mark for 1 minute at 1L per minute.

2.) cheap DME

It was Briess.

3.)How long did mash out step-up take?, perhaps test for conversion before this step. Perhaps there was unconverted starch and it converted at the higher temp during mash-out ramp-up.

I thought about that too actually. It took probably 20 minutes to get to 168F and then I sat there for 10 minutes. I'm pretty sure I took a conversion test before I ramped though.

4.)You can't measure FG accurately? this is remote possibility because you can't measure mash correctly so there is a chance you can't measure FG correctly either.

Could be. I use a refractometer and stir vigorously before taking a reading each time. I don't use a refractometer now though since there's alcohol. I use my hydrometer. It's calibrated.

Thanks guys for the feedback. I might try this advice and see what happens.

Maybe for your next beer, do an experiment and don't recirculate the mash, do a simple single infusion mash and see if you have the same problem. If your FG is closer to what you expect, at least you've narrowed down the problem. If your FG is still too high, well, then I was wrong

 

[grathan]

It sounds like you've thought a lot of stuff through. Perhaps it is just the amount of unfermentables in the recipe. Certainly Bock and Baltic Porter would contain quite a few. You shouldn't base your expectations upon White Labs highest projected attenuation percentage, because this strain is only "medium" alcohol tolerance and your recipe probably contains quite a bit of unfermentables. I wonder if a software program like Beersmith wouldn't have projected a more accurate FG for you.

 

[FirstAidBrewing]

Was there a reason that the mash was so thick? Thicker mashes lead to more body and fewer fermentables. Perhaps adjust next time to > 1.5 qt /lb If possible, I know you said that your MLT was full but this is a definite thing to consider

 

[grathan]

...

 

[olotti]

Based on what ur saying it looks like the thicker mash didn't lead to complete conversion and also like others have said maybe u had a lot of unfermentable grains. My thinking on this is that ur preboil gravity was so low so something happened in the mash even though u tested it something is off u shouldn't have to add 3lbs of dme to get to ur pre boil gravity, that's a lot. Did u plan on adding dme to boost ur gravity I had to do that for my ris but that was during the boil. If not did u figure ur pre boil without the dme?

 

[hafmpty]

Was there a reason that the mash was so thick? Thicker mashes lead to more body and fewer fermentables. Perhaps adjust next time to > 1.5 qt /lb If possible, I know you said that your MLT was full but this is a definite thing to consider

I normally shoot for 1.5qt/lb but my MLT was literally MAXED OUT for the 10gal batch I was brewing. I thought I had the room based on my calculations, but apparently not. I'm working through my profiles in BeerAlchemy (the brewing calculator I use) to see if I missed something. I'm also checking my calculations for volumes, etc.

Based on what ur saying it looks like the thicker mash didn't lead to complete conversion and also like others have said maybe u had a lot of unfermentable grains.

I'll post the recipe below. This could be part of it...don't know.

My thinking on this is that ur preboil gravity was so low so something happened in the mash even though u tested it something is off u shouldn't have to add 3lbs of dme to get to ur pre boil gravity, that's a lot. Did u plan on adding dme to boost ur gravity I had to do that for my ris but that was during the boil. If not did u figure ur pre boil without the dme?

No I didn't plan on adding the DME. I added it because my pre-boil gravity came in so low.

HERE'S THE RECIPE:
22lb 2oz of German Munich Malt
12lb 14oz of Belgian Pilsen Malt
14.75 oz of US Caramel 60L Malt
14.75 oz of Belgian Special B
11.06 oz of German Carafa II
7.37 oz of UK Chocolate Malt
1lb Rice Hulls
150F for 60 minutes

 

[danath34]

1) maybe the yeast have hit their alcohol tolerance? At this point a more attenuating yeast won't have much of a flavor effect so you could pitch something like CBC-1 and see if it comes down more

2) I would personally verify the thermapen and rtd in boiling and ice water.

3) when was the hydrometer calibrated? The paper could have moved since then.

4) the brewing programs don't usually take into account the fermantability of particular malts, but instead apply your yeast attenuation to the OG. In reality, roast and caramel malts contribute to OG but aren't very fermantable. If your estimated FG is coming from the software, the real FG is going to be significantly higher.

 

[hafmpty]

1) maybe the yeast have hit their alcohol tolerance? At this point a more attenuating yeast won't have much of a flavor effect so you could pitch something like CBC-1 and see if it comes down more.

Never used this yeast before. I might give it a shot.

2) I would personally verify the thermapen and rtd in boiling and ice water.

They were calibrated at mash temps and then verified at boiling temps too. I'll check again though to see if they are out of whack.

3) when was the hydrometer calibrated? The paper could have moved since then.

Good thought. I'll have to check this. I need to recalibrate my refractometer to verify accuracy so I'll so the same for the hydrometer.

4) the brewing programs don't usually take into account the fermantability of particular malts, but instead apply your yeast attenuation to the OG. In reality, roast and caramel malts contribute to OG but aren't very fermantable. If your estimated FG is coming from the software, the real FG is going to be significantly higher.

Can you explain this more?

 

[grathan]

Here is an interesting read.

https://www.homebrewtalk.com/f128/testing-fermentability-crystal-malt-208361/

 

[hafmpty]

One thing I realized with this is that I used DARK MUNICH MALT instead of Light Munich Malt. Would that have made a significant difference? Was there enough diastatic power in the Pilsner Malt to convert all that? Here's the recipe again for reference:

HERE'S THE RECIPE:
22lb 2oz of German Munich Malt
12lb 14oz of Belgian Pilsen Malt
14.75 oz of US Caramel 60L Malt
14.75 oz of Belgian Special B
11.06 oz of German Carafa II
7.37 oz of UK Chocolate Malt
1lb Rice Hulls
150F for 60 minutes

 

[danath34]

Can you explain this more?

Grathan posted a great link. From what I recall from that thread, the sugars extracted from crystal malts are only about half as fermentable as that from two-row. For example, and these numbers are just pulled out of my ass, the specifics can be found in that thread linked above. But if you had a wort of OG 1.040 from two-row, it may come down to 1.004. However, if the wort was made from crystal malt, it may only go from 1.040 to 1.022 or so. And it is pretty widely known that roast malt and roast barley do not contribute much in the way of fermentables, but they DO contribue to OG. A beer made with a lot of roast malt will finish higher than a beer with the same OF, but made with only two-row.

However, in most brewing programs, this is not taken into account. They are good at calculating OG, SRM, and IBU's, but when it calculates estimated FG, it just takes the yeast attenuation and applies it to OG, without considering each malt individually. For example, if you use a yeast attenuation value of 85%, and your OG is 1.100, its going to do ((100*(1-.85))/1000) + 1 to give you 1.015 est. FG. Which is not going to be true at all if you have a high percent of caramel/crystal or roasted malts.

 

[danath34]

One thing I realized with this is that I used DARK MUNICH MALT instead of Light Munich Malt. Would that have made a significant difference? Was there enough diastatic power in the Pilsner Malt to convert all that? Here's the recipe again for reference:

HERE'S THE RECIPE:
22lb 2oz of German Munich Malt
12lb 14oz of Belgian Pilsen Malt
14.75 oz of US Caramel 60L Malt
14.75 oz of Belgian Special B
11.06 oz of German Carafa II
7.37 oz of UK Chocolate Malt
1lb Rice Hulls
150F for 60 minutes

Yes, using dark munich will make a difference. How much? I don't know. Dark munich is something around 20L if I remember right, which should still be mostly fermentable. But it is supposed to give more of a malt flavor, which can only happen if there are undermentable malt sugars present, so it will be slightly less fermentable than regular munich. But without doing a test, I wouldn't know. And the manufacturers don't advertise fermentability, I would guess because it is also depended on the mash. I wish they would list a relative fermentability compared to standard pale two-row, so you could make better estimations, but they don't.

 

[hafmpty]

I'm going to read that article. For now though, I'm using the F.G. given in the recipe that I assume is what Jamil Z. was getting when he brewed this beer. Maybe I'm wrong, but it doesn't seem like he was just using a computer program but also experience too. I try to do both in my brewing too. Besides, seeing as it's stuck at 1.030, it seems like I did something to $%@# it up. I'm just trying to identify what are most likely the culprits.