Repitching yeast to a stuck ferment

[dillz2003]

When repitching yeast made with a starter, do you pitch the liquid or just the yeast?

I am trying to make a chocolate stout OG 1.098 that is only down to 1.038 after nearly 3 weeks and I want it down to about 1.029. The yeast is Wyeast 1318. I have already tried a rehydrated US05 with some wort, but it hasn't worked, so am going to bring in the big guns, Wyeast 3711.

I will overbuild a starter on a stir plate so I can at least use the yeast again, but when doing this, should I tip in the liquid as well or decant it and just use the yeast?

 

[Dutto]

I chuck the lot in, as well as aerating the wort.

This is probably the wrong thing to do but it works for me!

 

[jceg316]

I'm in a very similar situation and posted a similar thread here. I was gonna pitch a rehydrated pack of US-05 but ended up using it for something else. I found a jar of Wyeast 2112 California Common which I'm just building up now and will pitch.

 

[dillz2003]

Thanks for the replies. I'm a bit nervous about aerating the wort to be honest, although yeast obviously needs some oxygen to get it going. If the beer was going to be consumed quite quickly I would probably just throw caution to the wind, but the wort is up to 8% already and the plan for this brew is to bottle age it until next winter. 3711 also has a reputation apparently for coping well with high alcohol, low oxygen environments and is specifically promoted by Wyeast for use on a stuck fermentation. We shall see!

https://wyeastlab.com/yeast-strain/french-saison

The yeast arrives tomorrow, so I'm going to get a dme starter on the go for 24 hours. I'm not going to make a starter with the existing wort because I doubt there is that much fermentable sugar left in it and I think DME will give the yeast the best head start. I only want to bring the gravity down about 10 points or so. Hopefully an aerated starter isn't going to do any harm to the 17 litres of wort even if I add the liquid as well.

When you aerated your wort prior to repitching, out of interest what ABV was it up to, and did you have any problems with the finished beer? I might still have to give it a good shake as a last resort!

If 3711 works I'll report back.

Of course my next brew will now be a Saison, as it's the only way I could justify spending so much on yeast!

 

[foxy]

Thanks for the replies. I'm a bit nervous about aerating the wort to be honest, although yeast obviously needs some oxygen to get it going. If the beer was going to be consumed quite quickly I would probably just throw caution to the wind, but the wort is up to 8% already and the plan for this brew is to bottle age it until next winter. 3711 also has a reputation apparently for coping well with high alcohol, low oxygen environments and is specifically promoted by Wyeast for use on a stuck fermentation. We shall see!

https://wyeastlab.com/yeast-strain/french-saison

The yeast arrives tomorrow, so I'm going to get a dme starter on the go for 24 hours. I'm not going to make a starter with the existing wort because I doubt there is that much fermentable sugar left in it and I think DME will give the yeast the best head start. I only want to bring the gravity down about 10 points or so. Hopefully an aerated starter isn't going to do any harm to the 17 litres of wort even if I add the liquid as well.

When you aerated your wort prior to repitching, out of interest what ABV was it up to, and did you have any problems with the finished beer? I might still have to give it a good shake as a last resort!

If 3711 works I'll report back.

Of course my next brew will now be a Saison, as it's the only way I could justify spending so much on yeast!

Aerate the yeast in the Erlenmeyer flask, don't go stirring up the wort.
The hazards of respiration: As a further testament to its flexibility, yeast is also diauxic, meaning the cells can use more than one carbon source for their energy needs. Under certain circumstances, yeast can respire ethanol as well as glucose, producing acetic acid (vinegar) as a by-product. This process can occur only in the presence of oxygen when no alternative energy source (that is, no fermentable sugar) is available. Fortunately, our yeast does not normally get the chance to oxidize ethanol to acetic acid because by the time all the sugar is gone and ethanol is available for respiration, no dissolved oxygen is left in solution.

Therefore, one reason brewers try to avoid aeration after fermentation has begun is to prevent their beer from turning sour. Another hazard of aeration in the brewhouse at this stage is that it can also promote chemical oxidation reactions (yielding nasty aldehydes like trans-2-nonenal), which cause staling of the finished beer.

I should emphasize that although yeast is capable of performing respiration, this pathway is irrelevant for brewers because respiration does not normally occur in the production of beer.

 

[foxy]

Just to be clear, I don't mean you to use an air stone and oxygen, that will kill the yeast, just a stir plate or shaking.

 

[Dutto]

I'm beginning to wonder about all this fear attached to oxidation.

Back in 2018 I brewed a Robust Porter (ABV +/- 6%) for a mate who was ill with cancer. It was bottled so that I could take a couple of bottles over to him whenever I visited; which was about once a month.

Personally, I don't particularly like strong brews like Guinness so when he died (not from drinking the brew I might add!) I needed the bottles and put the remainder (about 18 litres) into a King Keg with a few grams of sugar; and there it stayed until this Monday, with only a few litres being removed by myself and the occasional visitor. It still tasted okay!

I hate waste, so on Monday I decided that I would move the Porter over to a Wilko Keg because I needed the King Keg to take to France in April with a newly brewed Bitter.

The Porter didn't smell or taste "off" (bearing in mind that I don't particularly like the stuff), so I displaced the air in the Wilko Keg with CO2, pressurised the King Keg with CO2, transferred the Porter over and pressurised the Wilko Keg to 5psi.

I am fairly confident that the reming Porter will still taste okay for the next three to six months at least, so I'm beginning to wonder what all the fuss is about.

Maybe it's a case of "Too many chemists spoil the brew?"

 

[kelper]

I am trying to make a chocolate stout OG 1.098 that is only down to 1.038 after nearly 3 weeks and I want it down to about 1.029. The yeast is Wyeast 1318. I have already tried a rehydrated US05 with some wort, but it hasn't worked, so am going to bring in the big guns, Wyeast 3711.

What is its temperature?

 

[strange-steve]

Aerate the yeast in the Erlenmeyer flask, don't go stirring up the wort.
The hazards of respiration: As a further testament to its flexibility, yeast is also diauxic, meaning the cells can use more than one carbon source for their energy needs. Under certain circumstances, yeast can respire ethanol as well as glucose, producing acetic acid (vinegar) as a by-product. This process can occur only in the presence of oxygen when no alternative energy source (that is, no fermentable sugar) is available. Fortunately, our yeast does not normally get the chance to oxidize ethanol to acetic acid because by the time all the sugar is gone and ethanol is available for respiration, no dissolved oxygen is left in solution.

Therefore, one reason brewers try to avoid aeration after fermentation has begun is to prevent their beer from turning sour. Another hazard of aeration in the brewhouse at this stage is that it can also promote chemical oxidation reactions (yielding nasty aldehydes like trans-2-nonenal), which cause staling of the finished beer.

I should emphasize that although yeast is capable of performing respiration, this pathway is irrelevant for brewers because respiration does not normally occur in the production of beer.

I think it's good etiquette to quote your source when you copy and paste.

 

[foxy]

Whole article was posted here one week ago, no point in posting the whole link just the paragraph about agitating wort partially fermented.
https://www.thehomebrewforum.co.uk/threads/brew-stuck-at-1020.85074/page-2

 

[dillz2003]

What is its temperature?

Originally 20c but raised it to 22 to try and get it fermenting again.

Well the 3711 arrived yesterday and is now on the stir plate. Will be interesting to see if it lives up to Wyeast's claims. I'll report back in a few days.

 

[strange-steve]

Whole article was posted here one week ago, no point in posting the whole link just the paragraph about agitating wort partially fermented.
https://www.thehomebrewforum.co.uk/threads/brew-stuck-at-1020.85074/page-2

Hmm, didn't occur to me to look in a separate thread for a reference. Wierd, right?

 

[Sadfield]

Always worth requoting the source so people can see the whole article and assess the validity of the information. For those open to learning, anyway.

 

[jceg316]

Originally 20c but raised it to 22 to try and get it fermenting again.

Well the 3711 arrived yesterday and is now on the stir plate. Will be interesting to see if it lives up to Wyeast's claims. I'll report back in a few days.

Please do keep us updated. I just realised that the yeast I was about to pitch can only handle up to 9% abv so I won't be using that. I'll buy a packet of US-05 again. I will rehydrate on a stirplate.

I would agree that if it's on a stir plate for a day or two it will give the yeast enough oxygen and there will be no need to oxygenate your beer.

 

[foxy]

I would agree that if it's on a stir plate for a day or two it will give the yeast enough oxygen and there will be no need to oxygenate your beer.

Not a good idea, re-hydrate by all means, the dried yeast does NOT need oxygen. My comments were for getting oxygen into a liquid yeast starter. Re-hydrate on the stir plate for 1/2 hour, the dried yeast has all the sterols it needs so as you wake it up it will start looking for food. Pitch at the same temperature as the wort.

 

[dillz2003]

Well, we have a winner! In my case Wyeast 3711 did live up to the promise of restarting a stuck fermentation.

I made a 1.5 litre starter of 3711 on a stir plate for 24 hours, saved half a litre in a jar for future use, then I decanted about half the liquid off the yeast and pitched the remainder in the bucket at a temp of 21c. This was last Friday and the gravity was still 1.038. After about 24 hours I was getting airlock activity every 30 seconds or so. By Monday the gravity was 1.033 and today it is 1.028. There is still some airlock activity every few minutes, so it may drop a bit more yet. Hopefully not too much more.

Interestingly I tasted the 'beer' produced from the 3711 starter, and it tasted amazing, I couldn't stop sipping it!. Dry, spicy and slightly peppery as per the description. I can't wait to brew a saison with it when my stout allows me to have my bucket and fridge back!

 

[Sadfield]

I'd be wary of packaging this too quickly now that you've introduced WY3711.

 

[dillz2003]

I think that's very good advice! Since hauling the bucket out of the fridge to get a reading I'm back to airlock activity every 30 seconds or so.

I think I've unleashed the beast!

 

[Sadfield]

Yep. Not only is your WY3711 consuming sugar, it's a diastatic variant of Saccharomyces, this means that it excretes enzymes similar to those in the mash into your wort. These break down the complex sugars into smaller, simpler sugars and it's now supper time for any of your original yeast that's still hungry.

 

[jceg316]

Well, we have a winner! In my case Wyeast 3711 did live up to the promise of restarting a stuck fermentation.

I made a 1.5 litre starter of 3711 on a stir plate for 24 hours, saved half a litre in a jar for future use, then I decanted about half the liquid off the yeast and pitched the remainder in the bucket at a temp of 21c. This was last Friday and the gravity was still 1.038. After about 24 hours I was getting airlock activity every 30 seconds or so. By Monday the gravity was 1.033 and today it is 1.028. There is still some airlock activity every few minutes, so it may drop a bit more yet. Hopefully not too much more.

Interestingly I tasted the 'beer' produced from the 3711 starter, and it tasted amazing, I couldn't stop sipping it!. Dry, spicy and slightly peppery as per the description. I can't wait to brew a saison with it when my stout allows me to have my bucket and fridge back!

Good to hear you sorted yours out! I still haven't got round to sorting mine out yet