To RE-USE or NOT RE-USE yeast slurry from "stalled" batch?

[hafmpty]

I brewed a Baltic Porter on Monday, January 12 (Zek's Porter from Brewing Classic Styles). I had some issues during the brew day that I THINK (I don't know) affected the beer's final gravity. It was supposed to attenuate to 1.018 and right now it's stuck at 1.030 and has been for a week (down from 1.087ish).

Basically what happened is that I had a VERY THICK mash that I recirculated for 60min with a target mash temp of 150F. The thick mash and full MLT along with too tight of a crush meant my recirculation was really slow. At the end of the mash I checked temps and the left side of the grain bed where the recirculation liquid was coming out was 150F but the right side was WAY LOW around 130F. I imagine there was quite a bit of variation throughout the MLT. It was like this during the entire 60min mash.

When I sparged I missed my target pre-boil gravity (estimated 75% efficiency and got 69% instead). So I added 3lbs of DME to bring the pre-boil gravity up to 1.077 (target 1.079).

Brew day proceeded normally from there. I oxygenated for 1min at 1L per minute and then pitched a MASSIVE 3-step starter of WLP830 and fermented at 53F for 5 days. 18hrs after initial pitch, I also re-oxygenated for 1min at 1L per minute. 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. It's stuck and stopped at 1.030. For reference I did a forced fermentation test and the FG of the test was only 1.024, still 6 points high from target F.G.

Anway, I say that to give background because I'm about to dump 10 gallons of beer because I screwed up. I am however going to brew the exact same beer (only 7.5 gallons this time) and make a few changes that I think messed things up. I'm going to loosen my grain mill, use a 1.5qt/lb water to grain ratio, recirculate faster, and monitor mash temps for consistency throughout the MLT, etc.

But here's my question. Should I use some yeast slurry from the current batch for this next one?

I'm hoping that the high finishing gravity is a WORT issue and not a YEAST issue. I think it is, but I'm not 100% certain. Reusing the yeast would obviously save me from doing another big starter and also save me from buying more yeast. Obviously the risk I run is having another 7.5 gallons of beer that I end up dumping because of a high finishing gravity. I'll be brewing on Feb. 9 and will harvest the yeast during the Thursday prior to brew day.

What do you guys think?

 

[porterpounder]

Use it. The yeast should be healthy. it still ate through a good amount of sugar. The DME is probably the culprit.

 

[flars]

I have read, no first hand experience, yeast from high OG beers has been over stressed and will not be in good condition to perform reliably in another ferment.
Would a starter made with some of this yeast perform well, no writer has addressed this. Perhaps not, if the yeast itself, is not reliable anymore despite propagation of new cells.

 

[opiate82]

General rule would be that if the yeast didn't perform the way you wanted/expected it to you should not reuse it. If you are POSITIVE it is a wort issue you might be alright but I personally wouldn't risk it and would buy a fresh pack and build a new starter. This is what you really need to ask, are you willing to risk another batch on this yeast?

 

[blizz81]

I would also add that if the temperature range in your mash was off trending towards the low side (and there weren't spots that were noticeably hotter than your 150*F degrees), I would expect this to lead to a more fermentable wort, not the opposite.

 

[hafmpty]

I was just looking through my recipe and realized that I used DARK MUNICH MALT when I should have used LIGHT MUNICH MALT. Could that have been part of the reason for the low pre-boil gravity and lack of fermentation? Here's the recipe brewed for reference:

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

 

[opiate82]

I was just looking through my recipe and realized that I used DARK MUNICH MALT when I should have used LIGHT MUNICH MALT. Could that have been part of the reason for the low pre-boil gravity and lack of fermentation?

I find an extract potential % for Dark Munich to be 80-83 and Light Munich to be 78-83. Seems pretty close to me, not enough to be the cause of your low gravity issues.

 

[NYShooterGuy]

When in doubt...

But then again I agree that the yeast ate through a HUGE amount of wort and was healthy enough to do that. You could always re-pitch the old yeast with new packets.

 

[WoodlandBrew]

I would suspect that it is fine, but you could do a small test fermentation with a little DME to see if it preforms as you would expect.

 

[hafmpty]

I would suspect that it is fine, but you could do a small test fermentation with a little DME to see if it preforms as you would expect.

Would you do something with a gravity similar to what I'll be brewing (1.089) to see where it lands?

 

[WoodlandBrew]

Would you do something with a gravity similar to what I'll be brewing (1.089) to see where it lands?

Yes, that's exactly what I would do. If you don't mind holding off on your brew day I would do the same pitch rate as well, but if you just want to know if the yeast can handle the gravity, alcohol and ferment maltose then you could increase the pitch rate to get faster results.

 

[hafmpty]

I had to order a sack of Munich malt and that'll take a couple weeks to come into the LHBS so I think I'm going to try this. We will see what happens.

 

[porterpounder]

I have read, no first hand experience, yeast from high OG beers has been over stressed and will not be in good condition to perform reliably in another ferment.
Would a starter made with some of this yeast perform well, no writer has addressed this. Perhaps not, if the yeast itself, is not reliable anymore despite propagation of new cells.

There have been a couple interviews with Mitch Steele at Stone where he states that their healthiest re-pitches come from Stone IPA, both strong and hoppy. That seriously calls into question the high-gravity yeast health belief.

 

[hafmpty]

There have been a couple interviews with Mitch Steele at Stone where he states that their healthiest re-pitches come from Stone IPA, both strong and hoppy. That seriously calls into question the high-gravity yeast health belief.

I remember reading that...or hearing that...somewhere. Good to know I wasn't imagining things.

UPDATE: I will have to push my brew day back by perhaps a week or two. That will mean 5-6 week old yeast. Is it better to let the yeast sit with the beer on top of it for 5-6 weeks or should I rack off and wash the yeast and keep it in the fridge and make a smallish starter (3-4L)? Never done this before.

 

[flars]

The best environment for the yeast is under the beer. Six weeks of time, after the fermentation of the beer, will have very little effect on the viability of the yeast.

 

[WoodlandBrew]

There are a number of advantages to storing the yeast in beer as flars suggests. These include the low pH, alcohol, and hops all which are antimicrobial. The alcohol will also take it's toll on the yeast. Here is some data I collected:
http://www.woodlandbrew.com/2013/01/abv-effects-on-yeast.html

 

[hafmpty]

There are a number of advantages to storing the yeast in beer as flars suggests. These include the low pH, alcohol, and hops all which are antimicrobial. The alcohol will also take it's toll on the yeast. Here is some data I collected:

http://www.woodlandbrew.com/2013/01/abv-effects-on-yeast.html

This is great info. As far as I can tell based on my calculations I've got a 7.6% ABV beer that's been in the fermenter for 30 days (or will have been by the time AJ pitch. Your figures tell me I've got around maybe 30-35% living yeast? If that's true then I'm guess that after all the reproduction they did I'll be fine washing the yeast and pitching the entire quantity of washed yeast and I don't need to worry about over pitching. Would you agree? BTW I'm pitching this into 8gal of wort at 1.089 O.G.

 

[hafmpty]

http://www.woodlandbrew.com/2013/01/abv-effects-on-yeast.html

This is great info. As far as I can tell based on my calculations I've got a 7.6% ABV beer that's been in the fermenter for 30 days (or will have been by the time AJ pitch. Your figures tell me I've got around maybe 30-35% living yeast? If that's true then I'm guess that after all the reproduction they did I'll be fine washing the yeast and pitching the entire quantity of washed yeast and I don't need to worry about over pitching. Would you agree? BTW I'm pitching this into 8gal of wort at 1.089 O.G.

 

[WoodlandBrew]

That sounds about right. The data was collected with yeast at ambient temperature to represent aging in a fermented. If the yeast was stored cold the viability may be better.

 

[hafmpty]

I just couldn't do it guys. I couldn't justify the risk. I ended up buying a single smack pack and growing it up in a two-step starter. I was worried about the health of the yeast after sitting in 8% beer for a month and also the stalled fermentation. Call me a coward, but I had to weigh the risks. Brewing on Monday. We will see how it goes.

 

[WoodlandBrew]

That's understandable. With a $40 ingredient cost for a batch of beer an $8 for new yeast you would want to be at least 80% confident in the washed yeast to make it just economically viable. That doesn't count your lost effort and schedule from a bad batch.

 

[05m50dan]

Thats probably the best decision. Any time your yeast doesnt behave the way you expect, you shouldnt re-use that batch...even if its only been one generation. it's not worth throwing out a whole new batch of beer to save a couple bucks on new yeast.
Also, RE:Stone reusing off of their IPA, 1) not sure if thats really valid or not, 2) i dont believe that their IPA's OG is close to 1.090 so it's not valid for comparison, 3) I even if they do reuse off their IPA & it's close to 1.090, I believe i heard Mitch say they use a propriatary yeast strain for their beers. That being the case, i wouldn't use one brewery's experience over the vast experience of a majority of brewers/biologists.
I always try to make the best beer that I can with the time and money I have, and if it were me, i wouldn't do it.

 

[hafmpty]

I believe i heard Mitch say they use a propriatary yeast strain for their beers. That being the case, i wouldn't use one brewery's experience over the vast experience of a majority of brewers/biologists.

Even though I won't be able to use this yeast, I'm brewing a Bock (regular, not Dopplebock) after this. I was thinking I might harvest the yeast from this upcoming batch and reuse it, but again, after hearing from 05m50dan and others, I think reusing after such a big batch isn't wise. I'll be using the same strain, but again, not willing to risk it.

All that being said, I learned a lot (which is always good) and I found a new blog to follow:

http://www.woodlandbrew.com

On a related note...if I wanted to do some yeast counting, what microscope do you recommend? Not something fancy, but something that's "good enough" to be used for that purpose. Any recommendations? Used is fine too.

 

[05m50dan]

Here' another blog to check out. towards the bottom of the page he talks about microscopes.

https://bkyeast.wordpress.com/2012/12/17/how-to-build-a-yeast-ranch/

 

[WoodlandBrew]

if I wanted to do some yeast counting, what microscope do you recommend? Not something fancy, but something that's "good enough" to be used for that purpose. Any recommendations? Used is fine too.

Here is the one I use. I've been very happy with it:
http://www.woodlandbrew.com/2012/11/amscope-binocular-compound-microscope.html

Here is a picture I took this morning using that microscope and my cell phone. (With a dark field disk that I printed)