High attenuation numbers, trying to figure out root cause

[darkrabbit]

Hi all, I am trying to figure out my attenuation numbers and why I am getting ~85% fairly consistently which it’s screwing up my recipes a bit in Beersmith.


I use liquid yeasts only, and build my starters based on the number of cells BS estimates I’ll need. I store yeasts as well and reuse them after a thorough rinsing. BS always estimates 70-75% attenuation and I consistently hit 10-15% higher, and I don’t understand why.


I’ve recently moved to electric brewing and my mash efficiencies are no less than 90%. Sometimes 95. Again, BS calculated, but still. I’ve had the attenuation discrepancy since I started but my **** efficiency before used to balance it out. Now that my efficiency is awesome combined with my attenuation numbers I am making beers with a significant alcohol content and possibly other off flavours and I think it’s affecting the final product.

I am just trying to understand why I am getting the attenuation I am getting so I can address it and adjust my process or recipes accordingly.

Does pitch rate affect attenuation? What else does?

Thanks for any advice. I have only been brewing a year but I am trying to solidify my processes and make consistent beer so I can then experiment more from a known baseline.

 

[lowtones84]

Pitch rate can, sure. What temp are you usually mashing at?

 

[Kickass]

What yeast are you using?

 

[TheMadKing]

How many times are you reusing a single strain of yeast?

 

[couchsending]

How many of your fermenters have you used French Saison yeast in? Or any other diastaticus strain for that matter.

 

[ba-brewer]

What is your grain bill and do you add sugar?

Have you checked your hydrometer lately, are you adjusting for temperature?

 

[Comfort_Zone]

There's many questions to be asked here. What temperature do you typically mash at? Which strain(s) do you routinely use? What are your cleaning/sanitizing procedures?

 

[Qhrumphf]

90-95% efficiency into the kettle is certainly doable, but not common at the homebrew scale. Are you sure your numbers are accurate?

How sure are you on the efficacy of your mash thermometer? If your thermometer either has a wide accuracy range, or is otherwise off in mash range, that could be your problem. Accurate at freezing/boiling won't tell you enough.

Assuming there's no bigger underlying issue, you may just be mashing too low. If you mash 147-148 and use a good bit of pure O2, Chico for example will push well into the 80s for atteniation.

 

[Vale71]

Efficiency suspiciously high, attenuation suspiciously high... Sounds like your OG measurements could be consistently in error on the high side. That's the first thing I would start looking into.

 

[Home_alone1]

I always get 80-85 attention with most yeast . I mash really low and generally prefere a dryer beer. I’d say just use less malt and go from there

 

[darkrabbit]

Thanks all for the replies!

Pitch rate can, sure. What temp are you usually mashing at?

150F - 156F depending on the beer.

What yeast are you using?

WLP001, WLP300, WY1318, WLP002, WY3711, WY1335, WLP820. All of the ones I've used so far same results.

How many times are you reusing a single strain of yeast?

I think I've gone max 3 times so far. No more than that yet. And I rinse them quite well, there's almost no trub left when I am done (I use a separatory flask on my last step of the rinse).

How many of your fermenters have you used French Saison yeast in? Or any other diastaticus strain for that matter.

Interesting... I didn't know about that until you posted it. Only one. BUT my results are consistent across all fermenters including my stainless steel conical.

What is your grain bill and do you add sugar?

Have you checked your hydrometer lately, are you adjusting for temperature?

Grain bill varies a lot.... My most recent one was a Julius clone I found with 2 Row 47%, Golden Promise 35%, Carafoam 10%, Aromatic 5% and Acid malt 1% (approximately). 90% efficient mash, 86.3% attenuation (70.1% estimated by BS). London Ale III yeast (WY1318). I have only added sugar (honey) to one beer and knew my numbers were going to be screwed up there, so I am not even including it in my sample.

I should mention my mash time is usually 60 mins, then a 20 min mash out, then fly sparge.

Hydrometer is a digital Milwaukee. I actually cool my samples down if they're even on the higher end of the acceptable range to ensure I am getting the right number, and I take 3 readings for each sample.

What are your cleaning/sanitizing procedures?

I clean small parts with soap and water, non scented dish usually. Kettles get either hot water or hot water and a 70/30 Oxy / TSP90 mix. Fermenters the 70/30 mix for all parts, I clean the stainless conical with the Spike CIP ball, and once that's done I still disassemble and wash the parts.

Sanitizing is all Star San in a spray bottle for anything cool side. Hot side I do nothing.

90-95% efficiency into the kettle is certainly doable, but not common at the homebrew scale. Are you sure your numbers are accurate?

How sure are you on the efficacy of your mash thermometer? If your thermometer either has a wide accuracy range, or is otherwise off in mash range, that could be your problem. Accurate at freezing/boiling won't tell you enough.

Assuming there's no bigger underlying issue, you may just be mashing too low. If you mash 147-148 and use a good bit of pure O2, Chico for example will push well into the 80s for atteniation.

So the temp numbers are likely very close. I did a full calibration only a few months ago, and I validate the numbers during the 'activity' using a thermapen. I will verify this however during my next brew, I am already getting a thorough log put together for it so I can figure it out. I don't use O2, I use an airstone and aquarium pump to oxygenate for 20 mins prior to pitching.

My refractometer which is a digital Milwaukee, I've calibrated several times with distilled water and it's bang on. I don't use a 'manual' refractometer as it's harder to get a visible reading sometimes due to particles in the wort (blurry line). I am going to try manual and digital next brew though to try and eliminate this for sure as a source of the issue.

Efficiency suspiciously high, attenuation suspiciously high... Sounds like your OG measurements could be consistently in error on the high side. That's the first thing I would start looking into.

Definitely a fair point. I am not getting why my numbers are so high. Even mash gravity, seems almost too good to be true even though the recirculation over the entire mash time works amazingly well in the electric setup. Game changing. But still...

I always get 80-85 attention with most yeast . I mash really low and generally prefere a dryer beer. I’d say just use less malt and go from there

Maybe my mash is low.... I'll have to revisit my temp controls on my control panel and make certain I am actually getting these numbers.

-J

 

[Qhrumphf]

You mentioned 3711.

How often is it used, how does the timing of that use relate to this problem?

And what is your cleaning/sanitizing regimen?

3711 is a diastaticus yeast strain. And if it's not thoroughly eradicated from your equipment, that will 100% explain your overattenuation.

Edit: you said in same post.

Try switching to Iodophor. Star-San is very effective against bacteria. It's less effective against yeast. And you may need more contact than a spray bottle will provide.

When I'm dealing with diastaticus yeast I show nearly the same deference that I do for Brett. Anything it touches gets full heat pasteurization.

 

[darkrabbit]

You mentioned 3711.

How often is it used, how does the timing of that use relate to this problem?

And what is your cleaning/sanitizing regimen?

3711 is a diastaticus yeast strain. And if it's not thoroughly eradicated from your equipment, that will 100% explain your overattenuation.

Edit: you said in same post.

Try switching to Iodophor. Star-San is very effective against bacteria. It's less effective against yeast. And you may need more contact than a spray bottle will provide.

When I'm dealing with diastaticus yeast I show nearly the same deference that I do for Brett. Anything it touches gets full heat pasteurization.

I'll definitely change my sanitization for that one then, but I've only used it once and not in my conical, just in one of my 3 fermonsters.

I think just to eliminate this as a possibility at all, even for other yeasts, I'll pick up some iodophor and use it for my next sanitation cycle. Maybe not for sanitizing anything that will touch my starter though Thanks!

-J

 

[ba-brewer]

3711 is pretty clean in the mid 60s but should still have some phenols and only a slight funk. Do you get any phenols in your beers that attenuate higher than normal?

If you got a contamination in your equipment I would think your problem would be the first pitch of yeast is OK, second maybe start to shift then the third or forth pitch the contamination might be dominant. That is what happen to me when I got a diastaticus contamination. There are places you can send your yeast/beer to be evaluated and it does not cost much(batch of beer).

 

[Velnerj]

I've gotten high attenuation before like that too. I've always attributed to higher fermentation temperature especially in the first 1-3 days... Do you have a temperature control ferm chamber? What temps are you fermenting at?

 

[Mer-man]

Have you calibrated your digital hydrometer against a known gravity of wort?

 

[darkrabbit]

I've gotten high attenuation before like that too. I've always attributed to higher fermentation temperature especially in the first 1-3 days... Do you have a temperature control ferm chamber? What temps are you fermenting at?

Yep, it's controlled on the conical and I also use a swamp box for the fermonsters. 66F usually in the fermonsters as that's the ambient temperature of standing water in my basement. I add hot or cold water when I need to though depending what I want to do.

For the conical it has a heat pad and a chilling coil controlled by an Inkbird.

Have you calibrated your digital hydrometer against a known gravity of wort?

Sort of... I've checked against a wort where I used a refractometer and the digital, same results. But I think I am going to check next brew against both my hydrometer and refractometer.

-J

 

[darkrabbit]

Ok so I brewed yesterday and triple checked all my numbers. They're dead on. This time I got a 96% mash efficiency, digital and analog refractometer recalibrated, measured each 3 times for 3 different samples (distilled water, preboil grav, OG), ensured temp was around 90F for each one. I am using a dry yeast this round but it'll be interesting to see what happens, as I haven't used dry yeast in over a year. My next brew this week is a DIPA where I'll be using WLP001.

I was much more attentive to cleaning, sanitizing, and process this time as well.

-J

 

[darkrabbit]

Update, my attenuation for the US-04 yeast is at 83% as of today. It's pretty much done fermenting, but again I am getting high numbers.

I was reading a bit more about this phenomenon, and some ppl that had this issue linked it to mash out process. Mine is:

- on mash completion, heat mash to 168F
- once done, start fly sparge with water @ 168F but HLT element is OFF so the fly sparge water SLOWLY cools over time.

I am thinking perhaps doing a longer mash out, holding at 168F for a while, and keeping the HLT element on during fly sparge to keep the water at 168F.

I'll keep looking for solutions but this seems like a good start.

-J

 

[ccous]

Maybe shorten the mash to 30-45 min. Home brewers tend to mash for far too long

 

[darkrabbit]

Maybe shorten the mash to 30-45 min. Home brewers tend to mash for far too long

Thanks, I did some more searching last night and indeed this could very well be it! It makes a lot of sense because while I mash for 60min @ 156 let's say, reality is from the moment the water hits the grain to the moment I get to 168 it's more like 90 mins.

-J

 

[ccous]

Thanks, I did some more searching last night and indeed this could very well be it! It makes a lot of sense because while I mash for 60min @ 156 let's say, reality is from the moment the water hits the grain to the moment I get to 168 it's more like 90 mins.

-J

Absolutely. And I think that, even at higher mash temps, due to our small scale you are going to end up with very fermentable wort if mash temps are held for 60-90+ mins. Most of the action is done by the first 20