Diacetyl troubleshooting - Safale US05

[raidernixon]

Hi All,

I made a 10 gallon batch of bells oberon clone on 06 Jan 2019, and used safale us05 dry yeast. This is my first time to try US05 (or any dry yeast for that matter) so I am not sure what is "normal" or what to expect with it.

Background:
Vessel: 14 gallon unitank with cooling/heating temp control
Starting gravity: 1.057, target final gravity of 1.012
Pitched 6 packs of US05 (hydrated and 70 degrees) into oxygenated wort (carb stone) cooled to 70 degrees (I felt this pitch amount was overkill but was following the recommendations of various pitching calculators online since I haven't worked with dry yeast before - I assumed 6 billion viable cells per pack per fermentis' label)
Visible fermentation started within 8 hours, was vigorous for 3 days and began calming down on day 4. Maintained temp at 68 degrees the entire time.

Observations:
Day 4 - increased to 70 degrees, 1.014 gravity, smell of acetaldehyde, some taste of diacetyl
Day 6 - increased to 71 degrees, 1.013 gravity, some smell of acetaldehyde, stronger presence of diacetyl in taste
Day 8 - Unchanged from day 6
Day 10 - Unchanged from day 6

In each day above, the pour sample looked like orange juice - very cloudy which I suspect is yeast suspension. I placed each sample in the fridge afterwards and a small yeast cake develops at the bottom of the glass.

Overall I am trying to diagnose if something problematic is going on with the yeast, namely the strong amounts of diacetyl persisting, or if it is to be expected for this yeast to take a while to clean up. Was my intuition right that 6 packs of yeast was too high of a pitch rate? If there is a problem, I would appreciate any tips or tricks that might help get the diacetyl cleaned up.

Alternatively - I've considered that there could be an infection, but I don't really know how to diagnose that as the source of the diacetyl problem, other than the beer eventually turning sour. Right now, the beer does not taste sour, and I cannot easily look at the beer since it is in a unitank.

I appreciate any advice, suggestions, or experience stories with this yeast from you all. Thanks for any help.

 

[maisch]

Cool your fermentation temp to about 62f - 65f then ramp to 70f - 72f for cleanup.

 

[CarolinaMatt]

far from an expert, but 6 packs seems to be way too much. I just brewed a 5 gallon batch of peanut butter cup stout that had an OG of 1.080 and I only used two packs of US 05 per the recipe/kit. Do you have a method of temp control? If not, it may be leaning towards the higher temp range of the yeast if it was not temp controlled due to the exothermic heat the yeast kicks off during their party. I believe from memory the package says a range of around 55-75 degrees F, but ideal is 60-72 F give or take. Overall it is still very early so I think give it time as it is green and the yeast will come back around to clean up after themselves as things settle out. A cold crash may be in order to help the large amount of yeast fall out after the yeasts are done feasting. Curious to see what others say and let us know how things turn out!

 

[raidernixon]

far from an expert, but 6 packs seems to be way too much. I just brewed a 5 gallon batch of peanut butter cup stout that had an OG of 1.080 and I only used two packs of US 05 per the recipe/kit. Do you have a method of temp control? If not, it may be leaning towards the higher temp range of the yeast if it was not temp controlled due to the exothermic heat the yeast kicks off during their party. I believe from memory the package says a range of around 55-75 degrees F, but ideal is 60-72 F give or take. Overall it is still very early so I think give it time as it is green and the yeast will come back around to clean up after themselves as things settle out. A cold crash may be in order to help the large amount of yeast fall out after the yeasts are done feasting. Curious to see what others say and let us know how things turn out!

Thanks guys, in answer to your question this is a temperature controlled tank unit which fluctuates within +/- 1 degree of what it is set at

 

[snowtiger1987]

6 packs for 10 gallons is WAY overpitching. 2 would have been plenty. Overpitching can cause problems just as underpicthing can.

 

[millatime]

I use safale 5 all the time, 90% of the time I only use 1 packet. I also don't oxygenate it, as I have read this isn't needed most of the time with this yeast. I "sprinkle it on top of the wort" as it says on the packet.

6 packs does sound like way too much. I'm sure there would be unwanted affects to this, unfortunately I'm not the most experienced so I cant help you there

Also, I use this yeast in my cream ale and does have that "butter" taste which is prob contributed somewhat from this yeast as well as the grain bill.

 

[Qhrumphf]

Usually a severe overpitch results in fusels and autolytic notes, not diacetyl. I've never have a problem with any of the Chico variants kicking off noticeable diacetyl apart from hop creep issues (and that's only with age).

A Pediococcus infection will almost always produce some diacetyl, but as you've said if you're not getting lactic acid, that doesn't really make sense either. Usually lactic acid AND diacetyl makes me think Pedio.

Perhaps the overpitch (and you certainly did) is responsible. I use Chico a lot (between WLP001, WY1056, and a smaller lab's version), but I haven't used US-05 in YEARS.

 

[raidernixon]

Hey Everybody,

Firstly, thanks for all of the input and advice.

I wanted to issue an update here for the knowledge base.

As of today (3 weeks exactly from brew date), the gravity has dropped a little further from 1.013 to 1.011; and within the past 2 days, the detectable diacetyl has dramatically dropped off and the beer is now tasting quite nice.

The only thing I changed was increase the unitank vessel temp from 71 to 72 degrees about 1 week ago. Not sure if that truly had any impact overall, but I am certainly glad that it seems to have cleaned up. In the five years I've been messing with homebrew I've never had a diacetyl issue, so this was my first "scare" if you will. I'm glad to see that others agree that this may have been a sever yeast overpitch situation - I really felt this was the case but ignored my gut. lesson learned, but maybe it didnt matter too much in the long run if it still yielded good beer.

My plan forward is to let is sit for another week, see how it tastes, then carb and cold crash/condition for a few more weeks it if all good. I'll issue a few more updates just to confirm the final product results.

Robby

 

[Northern_Brewer]

FWIW those Fermentis packs are typically 20-24 billion cells when reasonably fresh, the 6 billion number is just for the lawyers. So for <1.060 worts, one pack per 5 US gallons is fine. You massively overpitched

Current Fermentis advice is that rehydration isn't necessary.

As mentioned above, dry yeast don't need as much aeration as liquid yeast, as they already contain most of the sterols needed for cell multiplication.

It's up to you, personally I'd start fermentation a touch cooler than 70F.

 

[couchsending]

Yeah a massive overpitch was most likely your issue. A slight over pitch isn’t going to cause issues but a massive overpitch can cause some serious yeast health issues.

You could probably pitch less than half and have a much different result.

As it’s been said, no o2 needed for dry yeast.