My stuck ferment...I'm going to experiment

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Alemaker

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two weeks ago, I brewed 10 gal of Orfy's Mild Mannered Ale. I overshot my gravity a bit, as it came in at 1.042. Still not a big beer by any stretch. Orfy recommends mashing at 158, but I mashed at 155 instead since I like mine a bit dryer. I pitched rehydrated Nottingham, and had active fermentation in 12 hours. I did not aerate, as rehydrated dry yeast should not need it. Especially at this gravity.

I've been stuck at 1.020 for over a week now. It may have gotten too cold, but raising the temp and rousing the yeast have had no effect. I checked my mash thermometer, and it's at least reading boiling water right on the money. I added yeast nutrient and pitched new rehydrated Nottingham 48 hours ago. I just checked the gravity, and it's still at 1.020. Didn't think that would work, but it was cheap enough to try. Other than possibly getting a little too cold, I'm really at a loss as to what could have caused this. My mash thermometer seems to be right on, and Nottingham should have eaten this beer up.

I have this split into two carboys which gives me a chance to do some experimentation with fixing a stuck fermentation. I'm thinking about doing some things that everyone warns against, but few have actually tried themselves.

I'm thinking in one carboy, I will drop in my diffuser stone and add pure O2. Now, I know what everyone's thinking. I'll oxidize the beer since it already has alcohol. Maybe, maybe not. We'll see. My thinking is that the yeast may absorb it before it does too much to the beer. Also, if oxidation is something that shows up later, I'll just have to drink it faster. It will be interesting to see if it will jump start the yeast, and if it actually has any impact on the flavor of the beer.

In the other carboy, I will add amylase enzyme. Not Beano which has other enzymes, but amylase from the LHBS. I figure I can watch the gravity and when it's down to what i want, I'll crash cool and keg.

I'll post my results as they come in.
 
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Alemaker

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OK. Amylase enzyme in one carboy. 30 seconds of pure O2 in the other.

I'll check gravity again in two days.
 

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OK. Amylase enzyme in one carboy. 30 seconds of pure O2 in the other.

I'll check gravity again in two days.
I don't like oxidized beer, so I don't get the "add o2"- but I have to ask- why? What's wrong with a 1.020 mild? I know you mentioned the "why " in your post, but it still doesn't answer the "why?" A 1.020 mild sounds fine to me. I wouldn't ruin it by oxidizing it.
 

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PS- wort always needs aerating, no matter the gravity. A starter, or rehydrating, no. But always aerating. It's good for the yeast reproduction. Not at the end, when it's oxidizing, but before pitching; the yeast will reproduce. Aerating is a good thing and never not recommended.
 
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Alemaker

Alemaker

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I don't like oxidized beer, so I don't get the "add o2"- but I have to ask- why? What's wrong with a 1.020 mild? I know you mentioned the "why " in your post, but it still doesn't answer the "why?" A 1.020 mild sounds fine to me. I wouldn't ruin it by oxidizing it.

because I want a 1.010 mild, lol. Yeah, it could ruin it, but I want to see if it actually does, rather than just relying on the conventional wisdom. I'm taking one for the team here. :)
 
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Alemaker

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PS- wort always needs aerating, no matter the gravity. A starter, or rehydrating, no. But always aerating. It's good for the yeast reproduction. Not at the end, when it's oxidizing, but before pitching; the yeast will reproduce. Aerating is a good thing and never not recommended.
I'd read that dry yeast are not necessarily in need of aeration. And I have the means to do pure O2, but was being lazy I guess.
 
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Carboy #1 with AE is definitely fermenting again.

Carboy #1 with O2 is still showing now signs of activity.
 

Gremlyn

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I'd read that dry yeast are not necessarily in need of aeration. And I have the means to do pure O2, but was being lazy I guess.
Dry yeast are probably in most need of aeration of the wort. They have the most arduous task of going from packet to fermentation and will need all the help the can get. If you did a starter, especially on a stir plate, you could probably get away without any aeration and still some out with good attenuation.
 
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Dry yeast are probably in most need of aeration of the wort. They have the most arduous task of going from packet to fermentation and will need all the help the can get. If you did a starter, especially on a stir plate, you could probably get away without any aeration and still some out with good attenuation.

I always aerate my wort when using liquid yeast. Do I need to aerate the wort before pitching dry yeast?

No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production.

If the slurry from dry yeast fermentation is re-pitched from one batch of beer to another, the wort has to be aerated as with any liquid yeast.
This is what Danstar says about it anyway.
 

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If the enzyme has kick started it, then the wort was just not as fermentable as you thought, right?

I think this will also be interesting to see how quickly and severely the oxidation takes over the beer.
 
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If the enzyme has kick started it, then the wort was just not as fermentable as you thought, right?
It appears so. I will have to re-evaluate again my mash process. My tun is direct fired, and my thermometer is placed near the top of the grain bed. It could be that I have higher temps deeper in the grain bed.

I think this will also be interesting to see how quickly and severely the oxidation takes over the beer.
Yeah, it will be interesting. Everyone says it will, but few have actually taken the risk of ruining their precious beer to find out. :) I'm hoping that all the yeast will have absorbed the O2 so quickly that it won't have had time to oxidize the beer. It may be an interesting data point on how and when beers will oxidize.
 

Gremlyn

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This is what Danstar says about it anyway.
Interesting... they must base their answer on the assumption (or maybe proven fact, I'm sure Danstar has done their research) that when they harvest and lyophilise their yeast to create the dry product, they do so at the peak of aerobic respiration and growth. This would give the yeast a good supply of the sterols and fatty acids built up so that they can come out swinging. I've never encountered a cell line that didn't need some recovery time after lyophilisation and reconstitution, though, but maybe they give you enough cells to account for viability concerns too.
 
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I'd read that amylase takes a while to work, but I sure did get a lot of activity pretty quickly. I've been reading some posts here from those who have used amylase and it seems like nobody's getting lower gravities than they wanted (unlike beano). It appears that amylase is a pretty selective enzyme and won't just convert everything. That is encouraging.
 
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The O2 half still shows no activity. I'm going to say that O2 was ineffective at restarting this fermentation.

I guess I'm convinced that I've got a mash temperature problem. This was only the second time brewing with this mash tun, so it looks like I've got some tuning to do.

If the AE half finishes at my target gravity, I'll give the O2 half the AE treatment too. Then I'll be able to do a good side by side taste test for oxidation.

I know that the oxidation of beer is well documented. What I'd like to know is how easy it is to achieve, and is it really a concern in the primary with such a large population of live yeast.
 
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Looks like fermentation is about wrapped up on the AE carboy. The gravity is reading at about 1.011. I'm thinking it will probably end up near 1.008 or 1.009. Added AE to the carboy that I oxygenated.

Interestingly, the samples tasted thinner when the beer was at 1.020.
 
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Looks like fermentation is about wrapped up on the AE carboy. The gravity is reading at about 1.011. I'm thinking it will probably end up near 1.008 or 1.009. Added AE to the carboy that I oxygenated.

Interestingly, the samples tasted thinner when the beer was at 1.020.
Is there a way to halt fermentation once you reach your target? Campden tablets perhaps? I have a Marzen (My first lager) that never got below 1030 is is way too sweet. I've thought of doing the AE treatment but just haven't. Can you explain your process and where you got the AE from?
 

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My LHBS sells AE in small pill bottle size containers.

As for the Oxidation, my bet its it will be pretty bad as the yeast only use the oxygen during the beginning of the ferm (cell formation and reproduction if I remember right), and if your ferment was already "done" (at least as far as the yeast was concerned) then the O2 has been hanging in solution since you started the experiment. If you had done the O2 and immediately added the AE I bet the yeast would have been more happy to take care of it for you, or at least created enough cO2 to displace the O2.

As for the Nottingham not needing the aeration, that's a really interesting tidbit of info. I've alway read that there was no exception to the rule. I wonder how the new yeast cells being produced create healthy cell walls then?
 
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Is there a way to halt fermentation once you reach your target? Campden tablets perhaps? I have a Marzen (My first lager) that never got below 1030 is is way too sweet. I've thought of doing the AE treatment but just haven't. Can you explain your process and where you got the AE from?
I suppose you could stop it that way, but I'm just going to ride it out until it stops dropping, which I think it pretty much already has. I just got the AE from the LHBS. One teaspoon per 5 gallons.
 
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As for the Oxidation, my bet its it will be pretty bad as the yeast only use the oxygen during the beginning of the ferm (cell formation and reproduction if I remember right), and if your ferment was already "done" (at least as far as the yeast was concerned) then the O2 has been hanging in solution since you started the experiment. If you had done the O2 and immediately added the AE I bet the yeast would have been more happy to take care of it for you, or at least created enough cO2 to displace the O2.
Well, that is what I want to find out. If it is oxidized pretty bad, I'll at least have a good reference point for what oxidized beer tastes like. I've never had any oxidized that I know of, even though I've made every mistake known to brewers over the years. The latter is what makes me curious about just how hard it is to induce oxidation in a primary fermenter.
 
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Alemaker

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Looks like I've stopped at 1.009! Sample tastes good. It's getting kegged tomorrow. I'll have to wait a few more days for the half I oxygenated. I did taste a sample of that one, and couldn't tell much difference between the two. It's hard to tell since it's a few days behind the other. At least it wasn't revolting. :). I think it's still going to be very drinkable no matter what happens with the O2.
 
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Looks like I've stopped at 1.009! Sample tastes good. It's getting kegged tomorrow. I'll have to wait a few more days for the half I oxygenated. I did taste a sample of that one, and couldn't tell much difference between the two. It's hard to tell since it's a few days behind the other. At least it wasn't revolting. :). I think it's still going to be very drinkable no matter what happens with the O2.
Actually, adjusted for temp, the FG is closer to 1.010. That's exactly what I was shooting for.
 
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Finally got around to testing the O2 +AE batch again. Gravity was 1.010. Perfect.

The taste? Fantastic. I can't taste any cardboard or other off flavors. I actually think it's better than the other one. I'm guessing since it had some more conditioning time vs the AE only batch which went to keg pretty quickly after it hit FG. (It's a good thing too, my father in law and I have almost kicked the other keg already)

So, here are my conclusions.

1. AE was a big success. It didn't over dry the beer, and I think that's saying something when the OG was only 1.042.

2. It's hard to oxidize beer in a primary fermenter.

My guess is that this is especially true when fermentation is still active (or in my case, it was reactivated). Perhaps the yeast just sucks up the O2 too quickly.

People often wonder about oxidation during fermentation from loose bucket lids or even open fermenters, and the usual reply is the "CO2 blanket" that is heavier than air. I wonder if that is the real reason, and not just the yeast doing their thing.

Maybe oxidation off flavors will creep in as it ages, but it's just not going to age for long at my house.
 

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So the O2 batch tastes exactly the same as the no O2 batch? O2 issues could be flavors other than cardboard. It can also taste apple-like, or almost sweetish, or rusty in some cases.
 
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So the O2 batch tastes exactly the same as the no O2 batch? O2 issues could be flavors other than cardboard. It can also taste apple-like, or almost sweetish, or rusty in some cases.
Not going to be able to do a real side by side test until it's chilled and carbed. I'll do that this weekend. Didn't notice any apple or rust flavors.
 

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Not going to be able to do a real side by side test until it's chilled and carbed. I'll do that this weekend. Didn't notice any apple or rust flavors.
Ressurecting this thread: Did your oxygenated beer stick around long enough to show signs of oxidation? Any update would be appreciated.
 
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Alemaker

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It didn't last too long. We finished it off pretty quickly. I didn't notice any "bad" flavors, but I do think I ended up with two different beers. Not by much, and not in a bad way, but they were just a little different. I wouldn't call one half better than the other. I suspect that if it stuck around a month or so, it may have developed some bad flavors, but I just can't say.
 

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I'd read that dry yeast are not necessarily in need of aeration. And I have the means to do pure O2, but was being lazy I guess.
You have to be selective on what you believe when reading open forums. A lot of bad/incorrect information gets parroted as truth.

It makes no sense when thinking about it logically, why would liquid yeast need O2 and not dry yeast? Yeast goes through the same process during growth/replication/fermentation, regardless of its initial packaging form.
 
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You have to be selective on what you believe when reading open forums. A lot of bad/incorrect information gets parroted as truth.

It makes no sense when thinking about it logically, why would liquid yeast need O2 and not dry yeast? Yeast goes through the same process during growth/replication/fermentation, regardless of its initial packaging form.
Read post #9. That info came from Danstar. They know a thing or two about dry yeast.
 

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Read post #9. That info came from Danstar. They know a thing or two about dry yeast.
They also sell it, and promote what is perceived to be the most valuable aspect of dry yeast - ease of use. They also claim a very wide fermentation temperature range, which doesn't mean it is optimal.

Oxygenation is not required but always beneficial to yeast growth, whether it comes in dry or liquid form.
 

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They also sell it, and promote what is perceived to be the most valuable aspect of dry yeast - ease of use. They also claim a very wide fermentation temperature range, which doesn't mean it is optimal.

Oxygenation is not required but always beneficial to yeast growth, whether it comes in dry or liquid form.
Oh this old debate. Someone do a proper side-by-side test with pure O2 oxygenated vs simply rehydrated dry yeast. Get blind taste results from worthy judges. Otherwise this debate is sort of old and pointless. Great beer is made both ways, apparently. Pros and cons in any method. :mug:
 
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