Very confused! Imp. Stout, stuck? and tastes great at 1.050

[hlmbrwng]

I'm really at a loss here. I wanted to brew a big imperial stout. I did an all-grain batch with an OG of 1.100. My intent was to feed it a little bit of sugar at a time toward the end of fermentation to get a running OG of close to 1.130. I'm sure I under-pitched with only two packs of San Diego Super Yeast without a start (I forgot up until brew day to make a starter). It really slow down around 1.054 and over the course of about 9 days it went down to a 1.050. Now, in those 9 days I did the following: pitched a Imperial Gravity that I got from my LHBS. One guy said that although it is expired, it tore through his high gravity beer in 36 hours...pitching without a starter. I tried that and nothing. Then I purchased another pack of San Diego Super Yeast and made a 2L starter. I chilled, decanted and pitched yeast (there was about 5 times as much yeast as was in the pack originally). I added some super yeast nutrient and and oxygenated once again (a couple of minutes). After about 2 days it still is at 1.050 with only about 1 bubble in the blowoff tube per 5-10 minutes.

Okay, here is the crazy part. At 1.050 this beer tastes really good. It is not very sweet and in fact it is kinda dry!!! I made sure my hydrometer was fine (1.000 in water). I even used the refractometer and compensated for alcohol...comes out to be quite high no matter which equations and which correction factor for the hydrometer.

How on earth could this be? I would like to move on to the next phase and start adding sugar and see what happens. But I am just really really confused right now.

edit: I am going to post the grain bill shortly

 

[BeardedBrews]

If it tastes good seems like the only course of action would be to package it up, carbonate it, and drink it.

 

[MaxStout]

Strange. Even if you mashed high, it should have dropped down at least another 20 points or so. Your hydro is spot on and you've repitched, so I'm at a loss for ideas. But if you like the taste, then package it and rock on!

 

[hlmbrwng]

I checked a second hydrometer. Also at 1.050.
Here is the grain bill for a 6.25 gal batch.

I didn't add the sugar and dried malt extract in the recipe. That I was saving for the fermentation additions.
I did add some add the end of boil to get up to 1.100, since I was a little off target.

 

[hlmbrwng]

Strange. Even if you mashed high, it should have dropped down at least another 20 points or so. Your hydro is spot on and you've repitched, so I'm at a loss for ideas. But if you like the taste, then package it and rock on!

I would still like to make the sugar additions, but I don't know if this is too risky. In a way, there might be some answers in doing that. If it eats up those sugars, then whatever is in there right now is non-fermentable. But I would also hate to throw out this batch if adding sugar just makes it sweeter.

 

[MaxStout]

If you are certain that the beer has hit terminal gravity (a few hydro readings the same over 3 or 4 days), then you should be able to carb the beer and package it. I assume you're bottling?

 

[hlmbrwng]

I am going to keg it. Especially considering I don't know what will happen to the priming sugar...if it will be converted or not.

 

[MaxStout]

The few ounces of priming sugar will be consumed by the yeast--unless your yeast is completely dead, which I doubt.

Edit: It doesn't take much yeast to tear through the priming sugar.

 

[hlmbrwng]

The few ounces of priming sugar will be consumed by the yeast--unless your yeast is completely dead, which I doubt.

Edit: It doesn't take much yeast to tear through the priming sugar.

Is there anyway the specialty grains are the cause of it? I can't imagine there being 1.050 worth of non-fermentables.

Since I have so much yeast in there at this point, I might do what I had planned and add the sugar additions to the fermentor. I wanted to add 4 lbs of it.

 

[MaxStout]

Going through your grain bill, I don't see a huge amount of what might keep FG high. There is a good amount of crystal, and almost 3 lbs. extract, which would leave some more unfermentables. OTOH, the 2 lbs. of dextrose should knock down that gravity some. What was your measured mash temp?

Edit: Another question: what are your ferm temps? Have you bumped the temp up?

 

[flars]

It tastes good and kegging instead of bottling so there is no chance of flying glass. Maybe some over carbonation in the keg but that can be handled if fermentation does continues.

I've never added sugar to the fermentor so can't comment on how this would affect the SG with a high percentage of unfermentable grains in the recipe.

I would have made a large starter of the same yeast and pitched it at high krausen to restart a suspected stuck fermentation.

Leave it in the primary for a couple more weeks just to see what might happen. The beer will be more clear going into the keg even if the SG doesn't go down.

 

[hlmbrwng]

Going through your grain bill, I don't see a huge amount of what might keep FG high. There is a good amount of crystal, and almost 3 lbs. extract, which would leave some more unfermentables. OTOH, the 2 lbs. of dextrose should knock down that gravity some. What was your measured mash temp?

Edit: Another question: what are your ferm temps? Have you bumped the temp up?

I have had the temp around 70 F.

Well, I'm gonna add about 12 oz of dried malt extract to see what happens. I probably should have just used dextrose, but if this works I don't want to use only dextrose and have it too dry. My logic might be off, but I wanted to do 2 lbs DME and then 2 lbs dextrose. If the yeast doesn't ferment this addition, I'm stopping here, of course. And also in that case I will likely have ruined an okay beer.

 

[kh54s10]

So how long has it been fermenting? I see nine days. For a beer like this I would let it ferment/bulk age for a month or more before considering packaging it. You will also be tying up a keg for a very long time. After packaging I would let this one sit for at least 6 months and plan on drinking it over the period of a couple of years. I would reconsider bottling it.

Also at this point I would not aerate the beer any more for fear of oxidizing it.

 

[doug293cz]

That grain bill might have been a little light on diastatic power (enzyme content). Depending on maltster, light Munich malt can be as low as 40°L, just barely enough to convert its self. The 4 lb of 2-row might not have had enough excess diastatic power to do a good job of creating fermentable sugars from all of the 0 DP grains you used.

You might try adding some of your simple sugar to the fermenter, and see if fermentation starts up again. If it does, then you know your yeast are still hungry, and you can carry on with your sugar add schedule.

Adding alpha amylase enzyme (available at your (L)HBS) can increase the fermentability of the beer in the fermenter, by breaking down some of the non-fermentable carbohydrates. The risk with this approach, is it can sometimes make your wort too fermentable, and drop your FG too low.

Brew on

 

[hlmbrwng]

So how long has it been fermenting? I see nine days. For a beer like this I would let it ferment/bulk age for a month or more before considering packaging it. You will also be tying up a keg for a very long time. After packaging I would let this one sit for at least 6 months and plan on drinking it over the period of a couple of years. I would reconsider bottling it.

Also at this point I would not aerate the beer any more for fear of oxidizing it.

It's been 13 days. I'm not going to be bottling anytime soon. I was set on these sugar additions and that is what I've been considering. I don't know if it is stuck, if the yeast are just super slow, or if there is somehow a lot of non-fermentables. I just added 12 oz of DME to see what happens. If it eats through it, I'd say that what is there is in there now is non-fermentable (although that seems unlikely given how high the current gravity is). If nothing happens, then it may just be an environment the yeast don't like. I can't imagine it being an issue with the amount of yeast considering how much I have pitched in the past week. I'm trying to problem solve so it doesn't happen again, but I realize I might end up with something that is bad in doing so.

 

[hlmbrwng]

That grain bill might have been a little light on diastatic power (enzyme content). Depending on maltster, light Munich malt can be as low as 40°L, just barely enough to convert its self. The 4 lb of 2-row might not have had enough excess diastatic power to do a good job of creating fermentable sugars from all of the 0 DP grains you used.

You might try adding some of your simple sugar to the fermenter, and see if fermentation starts up again. If it does, then you know your yeast are still hungry, and you can carry on with your sugar add schedule.

Adding alpha amylase enzyme (available at your (L)HBS) can increase the fermentability of the beer in the fermenter, by breaking down some of the non-fermentable carbohydrates. The risk with this approach, is it can sometimes make your wort too fermentable, and drop your FG too low.

Brew on

I appreciate the suggestions. These are definitely things for me to consider.

 

[hlmbrwng]

You might try adding some of your simple sugar to the fermenter, and see if fermentation starts up again. If it does, then you know your yeast are still hungry, and you can carry on with your sugar add schedule.

Brew on

Do you think the 12 oz of DME was a bad choice? I went for that instead of simple sugar. Think it'll have the same effect if the yeast are still hungry?

 

[doug293cz]

Do you think the 12 oz of DME was a bad choice? I went for that instead of simple sugar. Think it'll have the same effect if the yeast are still hungry?

Yeah, if the yeast are still healthy, the DME should ferment.

Brew on

 

[hlmbrwng]

Yeah, if the yeast are still healthy, the DME should ferment.

Brew on

Well, after about 1.5 hours there already seems to be activity.
So interesting.

 

[pocketmon]

I would try satellite fermentation test.

Pull some wort, and add a lot of yeast, and treat it as a starter.
Baker's yeast might be fine and cheaper.

One day or two, you can measure the gravity to find out if there is still non-fermentable sugar.

 

[hlmbrwng]

Things are starting to make sense. I brewed an imperial stout a couple of years ago based on the same recipe. It ended around 1.035, but my estimation was that it would be in the mid-twenties. I figured that the yeast crapped out. But the beer was not overly sweet. Perhaps in that case there wasn't enough diastatic power to convert all of the starches. The beer had such a nice mouthfeel and I was very happy with the end result. In this current batch, the roasty flavors, the bitterness, the dryness, and semi-sweetness are balancing each other out really well. Btw, I really love the willamette hops in this.

Do brewers ever intentionally stop the starch-simpler sugar conversion early in order to have more non-fermentables, with the intention of having a high final gravity beer that is not overly sweet? If I can figure out how to do this consistently, I might want to brew more beers like this.

 

[ESBrewer]

I think the reason is now obvious. There's a lot of dextrin and other longer-chained carbs around that yeast just cannot ferment away. This is caused by the composition of grain bill and/or actual mash conditions & time. If you would like to get lower in terms of gravity, these need to be changed. If you like the beer this way, I think you can repeat the exact same procedure and you will likely get the same result.

 

[couchsending]

Dark Lord finishes at 1.070 right? As long as there is balance a high FG can do wonders for mouthfeel. If it tastes great, who cares. Everett is a 7.5% beer that finishes at 1.030. Keg it and enjoy.

If you need a few more points the Amalyse enzymes work wonders. I use them all the time.

 

[hlmbrwng]

Update: I continued with the sugar addition that I planned from the start.
gravity at this point: 1.050
day 1 (starting from first sugar addition): 0.75 lbs golden light dme
day 2: 0.75 lbs golden light dme
day 3: 1 lb dextrose
day 4: 1 lb dextrose
day 6: 1 lb dextrose
day 12 gravity: 1.050

It looks like it ate through all of the additional sugars. However, it seems a bit sweeter and more syrupy than before. I figured that if the gravity got back down to 1.050, then it would appear thinner than before.

So there are some threads that talk about adding Alpha Amylase to the fermentor to get the yeast to eat up some of the non-fermentables. Some people say it works, and some assume that it won't. One thought against is that it is not at the same temperature as mash. True. It is far from ideal, but the enzymes will work much slower. I'm going to document what happens so that we can add another data point to the discussion. I have my fingers crossed that it brings it down a little bit.

Unfortunately, neither the bottle nor any brewing websites state was is in the BSG amylase enzyme formula. I'm hoping that it is not alpha glucosidase...definitely not going for a super dry beer. Does anyone know what's in the BSG product? Is it a mixture of alpha and beta amylase?

Update: 14 hours after adding enzyme formula, no apparent activity

 

[Hoppy2bmerry]

Forgive me if it was already mentioned, but when did you start this batch? The reason I ask is I have had a recent saison that was dropping a point a week at the end. Normally, I'd take a couple readings a few day apart and bottle. Had I done that, I'd have over carbed beer in the bottles. I realize the yeast is a different strain and behaves differently. If you had activity adding sugar, but it tastes sweet and you think it is done, it's not done. Give it more time.

 

[passedpawn]

I think amylase is always alpha only. At least that's all I've ever seen. I've used it with success, but others have reported it excessively drying out beers. In theory, it should only ferment to the limit of the yeast, which would be about 80% of the soluble sugars in solution.

You might not see a krausen with it since the fermentation is going to be so slow. Slow enzymatic activity on the large sugars means slow fermentation.

If you think your ABV is high right now, you might consider pitching more yeast. Between the ABV and whatever effect the high osmotic pressure from a 1.100+ beer, the yeast you have in there might not be too healtyh.

I would NOT package a beer still at 1.050. That would be undrinkable (for me, anyway).

 

[ESBrewer]

Bsg states that it cleaves 1,4-bonds and produces mainly dextrin and small amount of maltose. So if not alpha it acts much the same way (produces a new maltose unit only when it by chance cleaves at the very end of a large molecule). At low temp it may take a long time to produce proper amount of maltose, I guess. It might get a lot quicker though, because each time it cleaves a bond it produces new free ends.

The optimum temperature is not necessarily as high as barley amylase. It could be from some other source (the enzyme exists in animals etc.). I think I've seen commercial amylases that are meant to be used around 40-50C.

 

[hlmbrwng]

Forgive me if it was already mentioned, but when did you start this batch? The reason I ask is I have had a recent saison that was dropping a point a week at the end. Normally, I'd take a couple readings a few day apart and bottle. Had I done that, I'd have over carbed beer in the bottles. I realize the yeast is a different strain and behaves differently. If you had activity adding sugar, but it tastes sweet and you think it is done, it's not done. Give it more time.

Thank you for the feedback. It may not be done, but there are probably only few more points the yeast can chew through without the help of enzymes to break the sugars down further.

I started the batch 3.5 weeks ago. I know it isn't a long time to be waiting for an imperial stout, however, it was stuck at the same gravity for days (at least no noticable change by visual reading of hydrometer). At that rate, it would probably take over a year to finish. I added 4.5 lbs of sugar after, and it chewed through that within a few days of the last sugar addition. Now it's back to the same gravity of 1.050.

If you think your ABV is high right now, you might consider pitching more yeast. Between the ABV and whatever effect the high osmotic pressure from a 1.100+ beer, the yeast you have in there might not be too healtyh.

I would NOT package a beer still at 1.050. That would be undrinkable (for me, anyway).

By process of elimination, I do believe that the yeast are fine: 1) the pitching of 2 packs straight of San Diego Super Yeast, an additional can of yeast, and then a 2L starter, along with yeast nutrient and pure oxygen, and 2) after adding all of this yeast to try to restart fermentation, it wasn't until I added simple sugars that it took off again. 3) the fermentation has slowed down again after adding (SLOWLY) 4.5 lbs of sugar at the same gravity as before I added the simple sugars (1.050)

Bsg states that it cleaves 1,4-bonds and produces mainly dextrin and small amount of maltose. So if not alpha it acts much the same way (produces a new maltose unit only when it by chance cleaves at the very end of a large molecule). At low temp it may take a long time to produce proper amount of maltose, I guess. It might get a lot quicker though, because each time it cleaves a bond it produces new free ends.

The optimum temperature is not necessarily as high as barley amylase. It could be from some other source (the enzyme exists in animals etc.). I think I've seen commercial amylases that are meant to be used around 40-50C.

Thank you for the information. I don't understand everything in your post, but hopefully I will after a bit of research. =)

 

[hlmbrwng]

After approximately 24 hours, I noticed the first bubbles coming from the blow-off tube. I was cautiously optimistic until the bubbles continued and at a slightly faster rate. It does not look like the activity is anything crazy, but it is the following day and it is still going. This is a definite change, visually, from what was going on before I added the amylase formula.

 

[doug293cz]

After approximately 24 hours, I noticed the first bubbles coming from the blow-off tube. I was cautiously optimistic until the bubbles continued and at a slightly faster rate. It does not look like the activity is anything crazy, but it is the following day and it is still going. This is a definite change, visually, from what was going on before I added the amylase formula.

The amylase is going to work slowly at fermentation temps, so be patient. Maybe check the gravity every three or four days, as everyday is too often.

Brew on