Overattenuation Issue

[Jack Arandir]

My last two brews wound up overattenuating. Does anyone have any advice for this?

Munich Helles (split batch):
OG: 1.043
Yeast strain: WLP860 Munich Helles Lager
Target FG: 1.011 - 1.013 (68-72%)
Actual FG: 1.007 (83%)

Munich Helles (split batch):
OG: 1.043
Yeast strain: WY2308 Munich Lager
Target FG: 1.011 - 1.012 (70-74%)
Actual FG: 1.010 (76%)
Note: BeerSmith projected FG 1.010, so it was dead on.

(No Tilt data on this batch, since I only have one.)

English Bitter
OG: 1.033
Yeast strain: WY1968 London ESB
Target FG: 1.009 - 1.010 (68-72%)
Actual FG: 1.007 (79%)

Fermentation profiles:
Helles: Primary at 50F until FG reached, 65F diacetyl rest, 38F cold crash. Temp changes 2-4F/day.
Bitter: Primary at 65F.

Some things I'm thinking:
* I initially thought infection, but after multiple taste tests I can't detect any.
* Helles had a protein rest and decoction mash, so may have created an especially fermentable wort.
* Bitter was single infusion, but saccharification was a few degrees low. (Target 152, actual 147. I added a second infusion to top it to 152).
* WLP860 was a 5L starter because the yeast was past expiration. The starter was vigorous, so it was likely an overpitch.
* WY2308 and WY1968 were fresh smack packs. For the bitter it was probably an overpitch given the low OG.
* Munich w 860 and Bitter were both fermented in a stainless conical (Spike CF15) while Munich with 2308 was fermented in a bucket. Can the conical affect yeast FG?

I'm not concerned, and the beers are good tasting. But I'm confused why I'm not hitting the manufacturer numbers.

 

[AlexKay]

Is this measured with a Tilt? Absolute readings on a Tilt go wonky once fermentation starts and the device gets covered with yeast. They're great for telling when fermentation has started and finished, but if you really want to know the gravity at the end, confirm with another method (refractometer or hydrometer.)

 

[Jack Arandir]

I verified the data with a hydrometer and it checked out

 

[sibelman]

Apparently, each fermentation is its own beast. The same thing happened to me with Omega pilsner yeast. I've read of similar experiences here. I'm glad the beer tastes good!

 

[RM-MN]

You are a brewer, not a magician. You create conditions for the yeast to convert sugars to alcohol but when you pitch the yeast you are no longer in control, the yeast are. If you are getting those FG's with all grain and you want the higher FG that the recipe expects, you change the mash temperature or the grain bill to get there. If you are making the beer from extract you still have a little control by adding something like carapils that introduces unfermentable sugars that can take the place of part of the malt extract.

 

[MikeCo]

Apparent attenuation stated my the manufacturer for the yeast is an approximation. You can get much higher attenuation than specified depending on the recipe. An example is a beer mashed at a low temperature with a significant amount of simple sugar. Are you using brewing software - what did the software predict for your FG based on the recipe and mash temperature? If the software predicted higher numbers, one thing to check is whether your measurement of mash temperature is accurate for the entire vessel. The lower than planned mash temp for the bitter could certainly be one factor in the low FG. You can also change mash temperatures in the software and see how it affects FG for the recipe.

 

[dmtaylor]

* Helles had a protein rest and decoction mash, so may have created an especially fermentable wort.
* Bitter was single infusion, but saccharification was a few degrees low. (Target 152, actual 147. I added a second infusion to top it to 152).

In my experience, the total mash TIME matters as much or more than the mash temperature.

If you did that decoction mash including a protein rest, I would guess that your total mash time was greater than 60 minutes? And the protein rest will tend to increase the attenuation slightly anyway. But I'd be curious to know the total mash time (I mean the main mash, prior to the liquid portion hitting >168 F).

Your bitter was mashed low at 147 F, and 152 F isn't much higher. How long was the total mash time including second infusion?

I know most people mash for about an hour. Personally, I only mash for 45 minutes for most beers. For me on my system, this gives the right attenuation. You might consider dialing in mash time if you want your FG and ABV to be more in line with what you expect.

 

[bracconiere]

looks like only one batch at the top is really outa wack, and even that for me is normal? are you doing a temp correction on the readings?

 

[Jack Arandir]

Helles was several hours in the mash because of the decoction and steps. Bitter was a standard 60 min mash once I hit temp, which was only a couple mins after mash in.
Tilt temperature corrects the readings, so those should be correct. I also verified with a hydrometer.

 

[Kickass]

I think you’re “in the ballpark”, could be a lot worse. I hope that doesn’t come off as marginalizing your concerns.

As stated. Lower temps and longer mashed will drive greater attenuation. If able, standardizing your temps and times might help you find trends and better hit your targets. Maybe set 45 minutes and 154 as your baseline to deviate from on your next few batches.

 

[Red over White]

How did the Helles taste? 75% of my brews are Helles and a malty, well attenuated version is the goal.

Grain brand, DP and mash time in the zone for limit dextrinase to eat is a factor for me to get there.

 

[Jack Arandir]

Helles is still young, only a week in lager. Still has fermentation aromas, but is cleaning up. The Augustiner strain has some fruit and lemon flavors with a lighter body. The Munich strain is more malty sweet with a medium body and that classic "German lager" flavor. Both need more time in lagering before I can judge. But so far both are very solid.

 

[bracconiere]

Munich Helles (split batch):
OG: 1.043
Yeast strain: WY2308 Munich Lager
Target FG: 1.011 - 1.012 (70-74%)
Actual FG: 1.010 (76%)

(No Tilt data on this batch, since I only have one.)

English Bitter
OG: 1.033
Yeast strain: WY1968 London ESB
Target FG: 1.009 - 1.010 (68-72%)
Actual FG: 1.008 (76%) and possibly still going...

i'm just saying on both these...i don't even worry about the meniscus that much..but could that be it? you are reading it at the bottom of the swell?

 

[Jack Arandir]

I do read at the bottom of the swell, but these numbers are from the Tilt hydrometer. I did verify the 1.007 number with the hydrometer because I couldn't believe it.

 

[bracconiere]

I do read at the bottom of the swell, but these numbers are from the Tilt hydrometer.

do you have refrac to compare it to?

 

[day_trippr]

Well, let's review.
The OP claimed the post-fermentation Tilt data was correlated with a hydrometer. Given the ethanol present there's pretty much no chance that "adjusted" refractometer readings would be more accurate than even reading the wrong side of the meniscus on a legit hydrometer

Cheers!

 

[Red over White]

Helles is still young, only a week in lager. Still has fermentation aromas, but is cleaning up. The Augustiner strain has some fruit and lemon flavors with a lighter body. The Munich strain is more malty sweet with a medium body and that classic "German lager" flavor. Both need more time in lagering before I can judge. But so far both are very solid.

To young to judge, but sometimes you know straight away. Some pressure during the ferment can change things to the next level, if you have the ability consider it.

 

[bracconiere]

Well, let's review.
The OP claimed the post-fermentation Tilt data was correlated with a hydrometer. Given the ethanol present there's pretty much no chance that "adjusted" refractometer readings would be more accurate than even reading the wrong side of the meniscus on a legit hydrometer

Cheers!

well on the last two brews, were talking about being off 1 point though.....most hydros come with a 2 point line chart printed..

 

[Jack Arandir]

When you put it that way, maybe I'm just being overly meticulous and should just accept that this is an inexact science. Just don't tell that to the German braumeisters!

 

[bracconiere]

don't tell that to the German braumeisters!

 

[Jack Arandir]

Update: the Bitter ticked down to 1.007. I'll update the original post.

 

[Jack Arandir]

Some pressure during the ferment can change things to the next level, if you have the ability consider it.

I do have the ability to pressure ferment (Spike CF15 + PRV), and I had considered it. My understanding is pressure suppresses ester formation and slows yeast activity, which allows you to ferment at higher temperatures. Are there any other benefits I don't know about? Large breweries worry about too much pressure on yeast in large cylindroconical fermenters because the pressure in the cone can be quite high.

I plan to just ferment cold, which accomplishes the same as pressure ferment (suppresses esters and slows yeast activity). At this point in my brewing, I want to closely mimic the best German lager brewers and master the basics before I venture into more experimental techniques. Good suggestion though.

Eric Toft at Schönram gets very high attenuation, in the high 80%, because he wants a drier, more drinkable lager. That's what I aim for as well, so I don't object to the high attenuation, except in the Bitter where it may become watery. I'm just trying to understand why I'm overshooting the manufacturer numbers.

 

[Komodo]

Well, let's review.
The OP claimed the post-fermentation Tilt data was correlated with a hydrometer. Given the ethanol present there's pretty much no chance that "adjusted" refractometer readings would be more accurate than even reading the wrong side of the meniscus on a legit hydrometer

Cheers!

Agree. I’ve been leaning heavily on the convenience of the refractometer, as it’s very quick and takes a tiny sample. But it really inly seems to work well pre-ferment. I had some baffling numbers (corrected) on my last ferment. So for the next brew I used hydrometer and only double checked with refractometer. Pre and post boil are bang on. Once fermenting, I’m using hydrometer only from now on.

I’ve added a conical in the mix, and drawing a sample into a hydrometer tube is easy and doesn’t use that much.

 

[Red over White]

I do have the ability to pressure ferment (Spike CF15 + PRV), and I had considered it. My understanding is pressure suppresses ester formation and slows yeast activity, which allows you to ferment at higher temperatures. Are there any other benefits I don't know about? Large breweries worry about too much pressure on yeast in large cylindroconical fermenters because the pressure in the cone can be quite high.

I plan to just ferment cold, which accomplishes the same as pressure ferment (suppresses esters and slows yeast activity). At this point in my brewing, I want to closely mimic the best German lager brewers and master the basics before I venture into more experimental techniques. Good suggestion though.

Eric Toft at Schönram gets very high attenuation, in the high 80%, because he wants a drier, more drinkable lager. That's what I aim for as well, so I don't object to the high attenuation, except in the Bitter where it may become watery. I'm just trying to understand why I'm overshooting the manufacturer numbers.

Pressure is definitely a nice tool in the toolbox. You are right that most homebrewers use pressure fermentation warm to make cleaner lagers, but if you want to emulate 50-80 meter tall ccv's at your favorite brewery, pressure is key. We have to use head pressure to simulate what the large tanks do natively.

Mouthfeel is different, hop and malt character is changed and the resulting beers reach maturity so much quicker, just like their commercial beer does. When pressure is applied, pitch rate, temperature and pressure schedules all impacts the final results. These "other" tools all can be used to make exceptional lagers along side traditional German lager practices and produce beer at home much closer or almost identical to theirs. Technically, it is how their fermenters work with very little head pressure.

Doesn't Eric decoct twice with some of his beers? That will definitely help attenuation. My low oxygen brewing hack is to decoct in the mashtun first, cool with deaerated strike water and then dough in the balance of the grist, so the main mash gets to work on the newly liberated starch (in the proper order now) from 30% of the grist which definitely helps with attenuation and bumps up flavor some. It sure makes a long brew day longer, but it’s worth it for the results in the glass.

 

[ScrewyBrewer]

Update: the Bitter ticked down to 1.007. I'll update the original post.

Not sure if you plan to keg the beer; if so, you could sample the fermenting beer and then cold crash it once it is near your target gravity.

 

[dmtaylor]

Agree. I’ve been leaning heavily on the convenience of the refractometer, as it’s very quick and takes a tiny sample. But it really inly seems to work well pre-ferment. I had some baffling numbers (corrected) on my last ferment.

Refractometer works just fine but you need to know that alcohol skews the readings. Using the following conversion calculator will give you accurate results within a couple of points.

https://www.brewersfriend.com/refractometer-calculator/

 

[Komodo]

Refractometer works just fine but you need to know that alcohol skews the readings. Using the following conversion calculator will give you accurate results within a couple of points.

I’m well aware that it skews and used conversions. The readings were erroneous, and the further into the ferment the worse they were.

 

[Erik the Anglophile]

Update: the Bitter ticked down to 1.007. I'll update the original post.

Going from 1.033 to 1.007 is perfectly in line with an ordinary bitter. That they should be low attenuated is a rather American (mis)conception, actual English bitters are usually quite dry.

 

[VikeMan]

I’m well aware that it skews and used conversions. The readings were erroneous, and the further into the ferment the worse they were.

Just out of curiosity, which refractometer calculator?

 

[Jack Arandir]

Well the Bitter just ticked down to 1.006, 82% attenuation. Way more than advertised 68-72%. Something strange is going on.

 

[Kickass]

actual 147. I added a second infusion to top it to 152

That’s a pretty fermentable mash schedule, very fermentable.

Something strange is going on

Maybe. Maybe not. Continue to monitor and taste. If it tastes good, it’s likely not worth fretting over.

Sometimes yeast are just gonna yeast.

 

[micraftbeer]

I find when I mash at low temps, the FG typically comes out lower than brewing software predicts, by a couple points.

 

[Komodo]

Just out of curiosity, which refractometer calculator?

That’s a good question. I don’t remember, but knowing me I probably used a couple to cross reference if the numbers were off. I had already worked up a correction factor and everything else has been right on with mine.

I was doing a temp step fast lager, and thought it was working great. It looked like it had stalled way too early, so did a hydrometer check and was shocked it was done already. Happy, but surprised.

 

[VikeMan]

That’s a good question. I don’t remember, but knowing me I probably used a couple to cross reference if the numbers were off. I had already worked up a correction factor and everything else has been right on with mine.

The correction factor, i.e. Wort Correction Factor (WCF) accounts for the fact that the sugars/dextrins in wort are mostly not sucrose (which is the sugar that our refractometers are made for). The WCF is fairly important, but when it comes to post fermentation (or during fermentation) readings, it takes a back seat to the fact that alcohol and water have different refractive indexes. That's where using a proper refractometer calculator comes in, i.e. one where the original and final readings are entered together, and not a simple "brix to specific gravity" conversion formula, even one with a correction factor (which will most definitely give an incorrect, "stuck fermentation-like" answer).

I'm not saying that this was the case with your calculations, but since you don't remember what you used, I thought I'd mention it.

 

[dmtaylor]

The correction factor, i.e. Wort Correction Factor (WCF) accounts for the fact that the sugars/dextrins in wort are mostly not sucrose (which is the sugar that our refractometers are made for). The WCF is fairly important, but when it comes to post fermentation (or during fermentation) readings, it takes a back seat to the fact that alcohol and water have different refractive indexes. That's where using a proper refractometer calculator comes in, i.e. one where the original and final readings are entered together, and not a simple "brix to specific gravity" conversion formula, even one with a correction factor (which will most definitely give an incorrect, "stuck fermentation-like" answer).

I'm not saying that this was the case with your calculations, but since you don't remember what you used, I thought I'd mention it.

+1.

There is definitely a right way and a wrong way to use a refractometer. Unfortunately, millions of people use it the wrong way and then poo-poo it, which understandably annoys the other millions who use it the right way. We cannot know which side you are on without specific data.

 

[VikeMan]

There is definitely a right way and a wrong way to use a refractometer.

It's a very sticky/FAQ worthy topic IMO. Not that most people (me included) read sticky posts before asking/commenting anyway, but at least if they existed, folks could point to them instead of retyping ad infinitum.

 

[MicroMickey]

https://crescentcitybrewtalk.com/attenuation-2/The last sentence of this article sums it up.