Attenuation Clarification

[Logan Epps]

Hello all!,

Can someone clarify to me Attenuation yeast count and FG. I just did a Saison with 1.046 OG. I pitched a pack of Wyeast 3726 and one pack of 3724. Wyeast says they will do 80% attenuation. My FG was 1.002, which comes in at 98% apparent attenuation. Is this due to the cell count? I'm more curious for recipe building. If I want to end a certain FG, assuming you have the right amount of fermentable sugars, is it just a matter of building starters to get the appropriate cell count?

 

[brownni5]

No, has very little to do with cell count, and more about the fermentability of the wort and the yeast used. In this case, you used a Saison yeast and likely a fermentable (read: low and or long mash time). The two of those together will lead to very high apparent attenuation. The yeast manufacturers may report in "actual" attenuation, which would be lower. What we measure is apparent attenuation - because alcohol is less dense than water, we cannot get a true sense of how much of the sugar was consumed by the yeast.

Want to estimate FG? I say either 1) don't bother - what's the point; or 2) do a forced ferment test - save some wort, pitch a lot of yeast into it on a stir plate and see where it finishes.

With more experience from individual yeast strains, you'll get a better idea of where they finish. I can't think of a Saison I've brewed that didn't finish after at least 90% AA. If you want a Saison to finish at 1.012 or higher, I'd say "you don't like Saisons, do you?"

 

[Logan Epps]

Interesting. The beer finished where I wanted it to. I was just curious how that was possible according to the manufacturer. The only reason I say I would want to estimate FG is for different types of beer needing to be more dry. I guess that is done more with mash temps and adjuncts, like you said. I just got a little confused when I was building the recipe in brew father and it kept telling me it was going to finish at 1.008 and I felt that was too high for a Saison.

 

[brownni5]

I feel people put too much stock in what yeast companies say is the expected attenuation and what their software says the FG will be. There's far too much variability with the process to try to estimate that.

It really bugs me when a yeast company says expected attenuation is 80% and then say "oh by the way, this is a diastatic yeast." That's not doing the brewer any favors, especially if it's their first time using that strain.

 

[Logan Epps]

Diastatic yeast has the ability to turn non-fermentable sugars into fermentable sugars?

 

[Jag75]

Diastatic yeast has the ability to turn non-fermentable sugars into fermentable sugars?

I believe it produces glucoamylyse, which breaks down dextrins to fermentable sugars . I thought I had an issue with that in a pumpkin ale I made . This thing was way over attenuated . I hadn't used a diastaticus yeast before but it could have been wild . Then someone told me if you brew using things in the squash family the squash enzymes can be broken down to fermentable sugars . Yeast is definitely an interesting thing for sure .

 

[brownni5]

I think the above is right, or at least mostly so. Rarely will a strain labeled "Saison" or Belgian not be diastatic.

Diastatic = high attenuation.

 

[ncbrewer]

Diastatic = high attenuation.

Over a long period of time - and possibly leading to bottle bombs if bottling.

 

[brownni5]

Over a long period of time - and possibly leading to bottle bombs if bottling.

Ugh, no! Diastatic yeast don't necessarily take a long time to ferment out. I really need to post my diatribe on the Boogeyman that is the bottle bomb. I ferment with diastatic yeast a lot, probably 3/4 of my beers, and bottle a lot, probably 3/4 of my beers. My saisons and Belgians are done after 2-3 weeks (maybe sooner) and I don't have problems with bottle bombs or simple over-attenuation in the bottle!

Diastatic yeast is a problem when the brewer a) doesn't know it's there, primarily due to poor sanitation; or 2) says "well, my brewing software arbitrarily tells me it's done fermenting - time to package."

 

[ncbrewer]

Ugh, no! Diastatic yeast don't necessarily take a long time to ferment out. I really need to post my diatribe on the Boogeyman that is the bottle bomb. I ferment with diastatic yeast a lot, probably 3/4 of my beers, and bottle a lot, probably 3/4 of my beers. My saisons and Belgians are done after 2-3 weeks (maybe sooner) and I don't have problems with bottle bombs or simple over-attenuation in the bottle!

Diastatic yeast is a problem when the brewer a) doesn't know it's there, primarily due to poor sanitation; or 2) says "well, my brewing software arbitrarily tells me it's done fermenting - time to package."

I've never used a diastatic yeast - just going by what I've read. According to this podcast https://www.masterbrewerspodcast.com/069-diastaticus-part-2 (The link no longer works), it has been found to take anywhere from a few days to 3 - 4 months to over attenuate. I'll wait and see how it shakes out.

 

[brownni5]

has been found to take anywhere from a few days to 3 - 4 months to over attenuate.

Right, when it is a contaminant. Totally different when it's used as the primary strain, like the OP did.

 

[ncbrewer]

I don't have a transcript of the podcast, but here is the introduction:

Over-carbonation. Exploding bottles. Lawsuits. Super-attenuation caused by diastaticus contamination is a hot topic in the brewing industry. We bring you interviews with brewers, yeast suppliers, and independent microbiologists to talk about detection, prevention, and more. Whether your strategy is to keep diastaticus out of your brewery altogether or to manage it alongside other Saccharomyces cerevisiae strains lacking the STA gene, you're guaranteed to learn something from these interviews.​

 

[brownni5]

Right, as an contaminant. Probably was posted shortly after the Left Hand vs. White Labs deal.

With good cleaning and sanitation, there is no reason to be afraid of diastatic yeast - believe me, I'd know.

 

[ncbrewer]

I got a chance to look over my notes from the podcast. You're right - the problems seem to be associated with diataticus contamination rather than using it as the primary yeast. Some of the findings make it look risky, especially the statement that there is no acceptable threshhold - even one cell can be a problem. Below are my notes from the two parts of the podcast (again, the links no longer work):



PART 1 - http://masterbrewerspodcast.com/068-diastaticus-part-1

• Breaks down dextrin and causes bottle bombs
  
  
• Can be in the yeast (intentionally) or in the air
  
  
• There is no acceptable threshold - one cell can be a problem
  
  
• In 3 - 4 months, excessive carbonation. Another lab said within 2 weeks. Another tested bottles stored at 80F - went from 2.6 volumes to 3.7 volumes in 3 days
  
  
• Once in your brewery, it is everywhere
  
  
• Keep it at bay with good sanitation (apparently, this is for accidental contamination)
  
  
• If contamination, can tell within 2 weeks, or sometimes 1 - 2 months depending on how it is stored
  
  
• Be suspicious of any very high attenuationg yeast - it might include diastaticus
  
  
• What is it? - Any Saccharamyces that has one of the three specific genes. It is not a bacteria
  
  
• It is affecting many small breweries
  
  
• One brewery using a French Saison yeast. Extreme attenuator, down to 1.002. Found it has diastaticus
  
  
• Tested some bottles. Stored at 80F. In three days it went from 2.6 volumes to 3.7 volumes.
  
  
• Wort generally has 20% - 30% dextrin. Any yeast claiming over 75 - 80% attenuation must have diastaticus
  
  
• Cannot break down 1-6 bonds in dextrins, so always leave a little sugar
  
  
• Pasteurizing distaticus beer - Does not deactivate it. Yeast is dead, but enzyme is still there. No further attenuation, but sugars are changed.
  

PART 2 - http://masterbrewerspodcast.com/069-diastaticus-part-2

• Might take 3 - 4 months to show up as over carbonation
  
  
• Diastaticus comes with some yeasts, but can also be in the environment. Less in the winter
  
  
• There are many different strains
  
  
• There is no instrument capable of detecting it at the extremely low levels - (that would still cause problems)
  
  
• Very low levels sometimes don't cause any problems initially, but cell levels build up after re-pitching.
  
  
• Can't differentiate it with a microscope
  

I understand that you have had good success with it, and probably many others have as well, but not everybody has. Brewers should be aware of the risks.