Dried yeasts and pH

[Joe Sr.]

Thanks Joe Sr. How long is ‘too long’? 

Edit: I’ve read “If less than two weeks, brewers will usually have no problem reusing yeast. Over two weeks and you may or may not have problems. After four weeks, the viability of yeast slurry is usually 50% or lower. As yeast sit in storage, they consume their glycogen reserves.”

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In all honesty, I've reused yeast stored for up to a year.  I pour the yeast from the fermenter into a sanitized container, seal it up, and put it in the fridge.  I prefer Rubbermaid type containers because they will bulge and not explode if pressure builds up.  I just kegged an O-fest that I made with last years yeast.  I was worried about the slurry, but it took off in the starter and the beer tasted great going into the fermenter.

The 5 days to two weeks "rule" is more geared towards repitching the slurry rather than growing up a starter.  At least IMO and experience.

[Robert]

The problem with dry yeast is it is contaminated with non-yeast microbes, if yeast grows faster than bacteria (lactos) there would be more of it in future generations. leaning out the effect of lower pH caused by the smaller % of lactic acid producing microbes. one possible reason.

So if this hypothesis is correct,  rehydration should result in the same 1st generation pH as direct pitching,  but making a starter might make a difference.  Experiment needed.

Not brewing this weekend but next.  Nottingham would be a reasonable choice for the planned brew,  for which I want good attenuation.  I will make a decanted starter this time, and report fermentation data here.

[Robert]

It seems that this topic been brought to the attention of Fermentis.  They reached out to me yesterday, and I've exchanged some emails, covering several issues.   

They dispute the "contamination" idea, based on the assertion that no brewing yeast,  liquid or dry, is 100% pure, nor does it need to be for brewing purposes.  Further they suggest that in triangle tests, panels cannot distinguish beers fermented with liquid or dry yeast,  but when informed that a beer is from dry yeast, will then claim to detect tartness.  All very interesting (and as I said I may be deluding myself as to the taste because I've seen the pH readings) but of course, valid or not, that's all off topic,  as what I'm curious  about is the actual measured pH value.

What is very interesting is this:

They provided an EBC paper (1997) reporting comparisons of dried yeast and second generation brewery yeast,  both prepared from the same lab culture of a lager strain, using pilot scale fermentation.   They found that rehydration vs direct pitching of dried  yeast made no significant difference in fermentation performance,  including cell count during fermentation.  There was no significant difference  between the liquid and dried yeasts in fermentation performance. They also found no significant analytic difference between the beers made with the liquid and dried yeasts,  including finished beer pH,  and tasting panels could not distinguish them.   This is a scanned image,  not a web page,  but here's a link to it on my Google Drive if anyone's interested.  https://drive.google.com/file/d/1zh2KW1pgHP-KM6CU5sxEOukTHm7uFdNM/view?usp=drivesdk

Now, this experiment involved a lager yeast.  I mentioned above in the thread that I have only one example of a dried yeast lager fermentation to offer,  and no comparison with a repitch,  but that my dried  yeast fermentation was seemingly consistent with my experience with liquid cultures of the same original strain (W-34/70.)   So also consistent with the results in the paper.   Where I have seen the low pH with first generation dried yeast is in ales, specifically Nottingham and S-04.  So it would still be interesting if the community could provide more data.  If you repitch, do you see a measured pH difference in subsequent fermentations, with either liquid or dried yeasts?  If you don't repitch, do you see such a difference between liquid and dried yeasts on a group average?  Does rehydration matter?  We may be able to do one of two things:  Either show that there is something happening that needs an explanation,  or that my observations are statistically insignificant or unreproducable.   Either would be interesting.   

(Whether I am able to do a starter with dried yeast this week will depend on my schedule.   I may direct pitch again on brew day,  either Nottingham or S-04.   Either way, it will be another data point. )

[BrewBama]

Interesting that they reached out to you. I sent them an email mid Oct to ask about the issue. I did tell them there is an ongoing topic on the AHA forum. Glad they took an interest and investigated. I rely on dry yeast and if a solution can be determined I need to know how to make my best beer with it. If it’s as simple as making a starter, decant and pitch I can do that.


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[Robert]

They said someone had emailed, leading them to read the thread.  Guess that was you, thanks for getting their attention,  BrewBama.  I did tell the representative I'd try to keep the topic alive on here and get more data.  Biggest surprise for me in all this is how few people track fermentation data.  I want to rely on dried yeast myself, as it removes the problem of diminishing viability in storage,  and is dead easy to use.  Ultimately if we find there are pH anomalies,  do they actually correspond to taste defects?   Only triangle tests would tell, and Fermentis (of course) are quite certain they know what the answer would be. 

[BrewBama]

I just put a replacement pH meter (MW101) on order so I should be able to provide additional data soon. I just never thought to test pH of a finished beer.


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[Joe Sr.]

Further they suggest that in triangle tests, panels cannot distinguish beers fermented with liquid or dry yeast,  but when informed that a beer is from dry yeast, will then claim to detect tartness.  All very interesting (and as I said I may be deluding myself as to the taste because I've seen the pH readings) but of course, valid or not, that's all off topic,  as what I'm curious  about is the actual measured pH value.

The only reason I know that Nottingham tastes tart is because when I've detected tartness I've gone back to check my records.  So, my single data point is that I noticed the flavor before I knew the yeast.

I'm no help on the pH, though.

[denny]

Further they suggest that in triangle tests, panels cannot distinguish beers fermented with liquid or dry yeast,  but when informed that a beer is from dry yeast, will then claim to detect tartness.  All very interesting (and as I said I may be deluding myself as to the taste because I've seen the pH readings) but of course, valid or not, that's all off topic,  as what I'm curious  about is the actual measured pH value.

The only reason I know that Nottingham tastes tart is because when I've detected tartness I've gone back to check my records.  So, my single data point is that I noticed the flavor before I knew the yeast.

I'm no help on the pH, though.

I quit using Nottinghamk maybe 15 years ago because of the tartness I detected.  No confirmation bias there.

[jeffy]

Further they suggest that in triangle tests, panels cannot distinguish beers fermented with liquid or dry yeast,  but when informed that a beer is from dry yeast, will then claim to detect tartness.  All very interesting (and as I said I may be deluding myself as to the taste because I've seen the pH readings) but of course, valid or not, that's all off topic,  as what I'm curious  about is the actual measured pH value.

The only reason I know that Nottingham tastes tart is because when I've detected tartness I've gone back to check my records.  So, my single data point is that I noticed the flavor before I knew the yeast.

I'm no help on the pH, though.

I quit using Nottinghamk maybe 15 years ago because of the tartness I detected.  No confirmation bias there.

Me too.  I always thought of that yeast as if it were the generic package they always gave you in a basic beginner kit beer.

[Robert]

I tapped my direct pitched Nottingham batch this weekend.   It is definitely tart.  Bah!  I'll probably drink it, but I'll grumble and gripe every time I do.  This one read pH 3.8 post fermentation,  but now I can absolutely say it's not confirmation bias in my case either.  Hope the repitch, pH 4.2, lacks the tartness.  Or I'll have to wait till the batch after that for something decent to drink.   So no Notty for now.  It's either a starter with S-04 or just repitch last week's WY1318 next weekend.  I'd like something more attenuative than 1318, so maybe the S-04.  But it's my Christmas beer, so I'm not keen on taking chances....  Beer is supposed to make me happy!


EDIT Not taking chances.  Stopped by LHBS for a nice, fresh WLP007.  Which I originally had in mind.   So the starter from S-04 experiment will have to wait a bit longer.   Though allegedly these are originally the same strain,  so comparison of a couple of generations of each would be interesting.

[Joe Sr.]

Yes.  I expected you would get tartness.  I think there are enough varied reports of tartness to confirm it is actually there.

Good luck with the repitch.  Please let us know how it turns out.

[ynotbrusum]

I just kegged a dry stout fermented with Notty, where a slight tartness may be a good thing.  I will be checking on it soon and will report back on this, too, for another data point.  FWIW, it was a 10 gallon batch that I split into two fermenters - one was rehydrates and one was just sprinkled on the wort.  Both were whipped with a wine degasser, IIRC.

I will have to take pH measurements on the finished beer, but I didn’t take measurement of pH anywhere along the way pre-fermentation.

[Chino Brews]

For the record, Fermentis recommends you direct pitch all of their brewing strains of active dry yeast under their Easy2Use campaign. They just completed a multi-year study and showed that direct pitchyng had equal or better performance than rehydrating under every pitching temp in a wide range and in every starting gravity within a very wide range. The direct pitched yeast performed better in terms of attenuation, abv tolerance, and ester production.

One of the technical reps at Fermentis was kind enough at Homebrew Con 2018 in Portland to fire up his laptop and spend 45 minutes going through proprietary data with me. I can't remember if beer pH was one of those highlighted metrics (being Homebrew Con, I had had a few).

I was a devout rehydrater and active proselytizer for rehydration. I have undergone a complete conversion and now I direct sprinkle my active dry yeast.

[BrewBama]

I tapped my direct pitched Nottingham batch this weekend.   It is definitely tart.  Bah!  I'll probably drink it, but I'll grumble and gripe every time I do.  This one read pH 3.8 post fermentation,  but now I can absolutely say it's not confirmation bias in my case either.  Hope the repitch, pH 4.2, lacks the tartness.  Or I'll have to wait till the batch after that for something decent to drink.   So no Notty for now.  It's either a starter with S-04 or just repitch last week's WY1318 next weekend.  I'd like something more attenuative than 1318, so maybe the S-04.  But it's my Christmas beer, so I'm not keen on taking chances....  Beer is supposed to make me happy!


EDIT Not taking chances.  Stopped by LHBS for a nice, fresh WLP007.  Which I originally had in mind.   So the starter from S-04 experiment will have to wait a bit longer.   Though allegedly these are originally the same strain,  so comparison of a couple of generations of each would be interesting.

Add a pinch of baking soda to raise the pH/reduce tartness?


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[dmtaylor]

Add a pinch of baking soda to raise the pH/reduce tartness?

I'm actually considering the same thing.  Next time I encounter an odd tartness prior to packaging, add baking soda to bring pH up a bit.  And can experiment in the glass with just a tiny pinch of like 1/64 teaspoon or whatever (and yes I actually have spoons to measure this).