tyrub42
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Hi everyone,
I just wrote to Fermentis about this, but I'd love to get your opinions as well. I have seen a few threads about US05 giving off esters, but this is a unique case, as I harvested and re-pitched the same yeast twice (three batches total, including the first batch with the fresh packet). I'm just going to paste my letter to Fermentis here, and see what you all think.
I'm preparing to start using/harvesting/reusing liquid yeast, so I have reused US05 three times in the last 6 weeks to get a feel for it. The last beer, which I bottled yesterday, shocked me a bit with the yeast profile. It has lots of banana and clove esters in it, to the point that the single-malt pale ale drinks more like a hybrid saison or a Belgian Pale Ale. This was extremely surprising for two reasons:
1. I was of course not expecting it from US05
2. There are no signs of infection, no undesirable off flavors (no diacetyl, acetaldehyde, etc), my FG was exactly on target, and the beer tastes delicious. Heck, even the NZ Orbit hops seem to really compliment the taste of the yeast.
I am excited to taste it after bottle conditioning, but more to the point, while I do enjoy this happy accident, this is the first unexpected situation I've run into in my homebrewing tenure and I would like to get your input about why it happened. I'd like to outline the way I reused the yeast, and my suspected reasons for this, and get your input on it.
The first time, I took a pint of 'slurry' (yeast cake mixed with the beer that is left after transferring, making a thick yeasty goo), and a pint of sterile water, combined them in a sterile jar, and refrigerated for 2 days until I had brewed again. The particulate settled to the bottom, and the murky water at the top. I let it adjust to room temperature, and pitched the liquid, while leaving most of the particulate behind. I fermented that batch (27-liter, 1.076og) at 16c/60f before warming to 21c/70f for the last week in primary.
The second time, I just filled a sterile 300ml jar with 'slurry', refrigerated it for 3 days, and repitched into wort on brew day. Of the 300ml, I would estimate that 150ml was beer and hop particulate, while 150 was yeast cake. I fermented this beer (26 liter, og 1.053) at 21c/70f for the whole fermentation before cold crashing and bottling.
Both times I repitched slurry, signs of fermentation were present at 10-12 hours pot pitching. Both fermented at roughly the same pace as fresh 05, finishing the bulk of active fermentation in 2-3 days, and bubbles stopped within 5 days.
It would seem that the yeast were stressed somehow, although the lack of diacetyl etc. would suggest that it wasn't too severe, right?
The three factors I can think of here that could have stressed the yeast to produce these flavors (as contamination doesn't seem to be a factor) are:
-The three generations had different fermentation temps: 18c/64f, 16c/60f, and 21c/70f respectively. Would this be a factor in stressing the yeast enough to produce these esters? The second batch did have a slight presence of peachy esters, but it was very subtle and non-invasive, and that is apparently normal for 60f-and-under fermentations with 05
-The last time I repitched, I did not let the slurry warm up to room temperature. I did take it out of the refrigerator, but it was between 41f/5c and 50f/10c going into wort that was 68f/20c. Could this have shocked the yeast enough to produce this effect?
-If there was slight contamination in the original yeast packet from another strain, could that strain have taken over the flavor over three generations?
If you can think of anything else, or have any questions, please let me know. I'd like to get to the bottom of this, in order to both reproduce this effect in the future (this beer is seriously good, and prefect for summer), and more importantly, avoid it when I don't want it. I'm glad this was a happy accident, but accidents in general are not what I want in brewing of course.
To clarify how the beer tastes, it is almost like a mix of 05 and t58, but the esters are really all banana and clove without any peppery quality. My friend who helped bottle said it was her favorite beer she's ever had, and I actually poured her an uncarbonated glass to drink, so it is a palatable beer, and thank god the yeast was healthy enough to consume any diacetyl etc, so it's actually remarkably clean, but it is a shock, and most of my homebrewing friends and professional brewer friends have basically had the same opinion as I do: something obviously happened, but not sure what it was that did it.
What do you all think?
Best,
Tyler
I just wrote to Fermentis about this, but I'd love to get your opinions as well. I have seen a few threads about US05 giving off esters, but this is a unique case, as I harvested and re-pitched the same yeast twice (three batches total, including the first batch with the fresh packet). I'm just going to paste my letter to Fermentis here, and see what you all think.
I'm preparing to start using/harvesting/reusing liquid yeast, so I have reused US05 three times in the last 6 weeks to get a feel for it. The last beer, which I bottled yesterday, shocked me a bit with the yeast profile. It has lots of banana and clove esters in it, to the point that the single-malt pale ale drinks more like a hybrid saison or a Belgian Pale Ale. This was extremely surprising for two reasons:
1. I was of course not expecting it from US05
2. There are no signs of infection, no undesirable off flavors (no diacetyl, acetaldehyde, etc), my FG was exactly on target, and the beer tastes delicious. Heck, even the NZ Orbit hops seem to really compliment the taste of the yeast.
I am excited to taste it after bottle conditioning, but more to the point, while I do enjoy this happy accident, this is the first unexpected situation I've run into in my homebrewing tenure and I would like to get your input about why it happened. I'd like to outline the way I reused the yeast, and my suspected reasons for this, and get your input on it.
The first time, I took a pint of 'slurry' (yeast cake mixed with the beer that is left after transferring, making a thick yeasty goo), and a pint of sterile water, combined them in a sterile jar, and refrigerated for 2 days until I had brewed again. The particulate settled to the bottom, and the murky water at the top. I let it adjust to room temperature, and pitched the liquid, while leaving most of the particulate behind. I fermented that batch (27-liter, 1.076og) at 16c/60f before warming to 21c/70f for the last week in primary.
The second time, I just filled a sterile 300ml jar with 'slurry', refrigerated it for 3 days, and repitched into wort on brew day. Of the 300ml, I would estimate that 150ml was beer and hop particulate, while 150 was yeast cake. I fermented this beer (26 liter, og 1.053) at 21c/70f for the whole fermentation before cold crashing and bottling.
Both times I repitched slurry, signs of fermentation were present at 10-12 hours pot pitching. Both fermented at roughly the same pace as fresh 05, finishing the bulk of active fermentation in 2-3 days, and bubbles stopped within 5 days.
It would seem that the yeast were stressed somehow, although the lack of diacetyl etc. would suggest that it wasn't too severe, right?
The three factors I can think of here that could have stressed the yeast to produce these flavors (as contamination doesn't seem to be a factor) are:
-The three generations had different fermentation temps: 18c/64f, 16c/60f, and 21c/70f respectively. Would this be a factor in stressing the yeast enough to produce these esters? The second batch did have a slight presence of peachy esters, but it was very subtle and non-invasive, and that is apparently normal for 60f-and-under fermentations with 05
-The last time I repitched, I did not let the slurry warm up to room temperature. I did take it out of the refrigerator, but it was between 41f/5c and 50f/10c going into wort that was 68f/20c. Could this have shocked the yeast enough to produce this effect?
-If there was slight contamination in the original yeast packet from another strain, could that strain have taken over the flavor over three generations?
If you can think of anything else, or have any questions, please let me know. I'd like to get to the bottom of this, in order to both reproduce this effect in the future (this beer is seriously good, and prefect for summer), and more importantly, avoid it when I don't want it. I'm glad this was a happy accident, but accidents in general are not what I want in brewing of course.
To clarify how the beer tastes, it is almost like a mix of 05 and t58, but the esters are really all banana and clove without any peppery quality. My friend who helped bottle said it was her favorite beer she's ever had, and I actually poured her an uncarbonated glass to drink, so it is a palatable beer, and thank god the yeast was healthy enough to consume any diacetyl etc, so it's actually remarkably clean, but it is a shock, and most of my homebrewing friends and professional brewer friends have basically had the same opinion as I do: something obviously happened, but not sure what it was that did it.
What do you all think?
Best,
Tyler