Diacetyl problems with ales and lagers

[Sadu]

Hi everyone, I bottled a 1 gallon pilsner 3 weeks ago and noticed it had an off flavour that wasn't present earlier. The best diagnosis I could come up with was diacetyl and I asked around here and that was the general vibe. I did do a diacetyl rest sor a few days before cold crashing, but since this was my first lager I put this down to a learning experience.

Then my second lager came out with the same flavour, though not as strong. This one annoyed me a bit since I had carefully started ramping up the temps well before full attenuation and given it a very good d-rest at ale temperatures. Again put it down to learning, decided to leave it a while before I do any more lagers.

Imagine my surprise when I take a gravity reading on my ESB and it also has the same flavour! I didn't even realise diacetyl was a thing with ales. This ESB was given a good healthy pitch of Wyeast 1450 Denny's favourite and took 7 days to hit FG. It's now day 16, it's been on the temp controller the whole time at 19-20c. I was planning to cold-crash it now and bottle on day 19.

The off-taste itself is subtle, less of a flavour but a strange texture in the mouth. Best I can describe it is that it feels like something coating my teeth and lips when I drink, maybe an oily / soapy feel to it. It makes the beer taste a little uncomfortable. I could have diagnosed this incorrectly, I have no other experience with diacetly to compare with.

Now this is just the gravity sample and maybe I need to RDWHAHB, and to be fair I haven't tasted the pilsner yet to see if those flavours cleared up. Sometimes things just get better after carbonation. But if there's something wrong with my process then it would be good to get it sorted before I do too many more batches. Aside from these 3 batches, other brews have come out really great.

I have been very careful with sanitation, anything touching the beer post boil gets cleaned and liberally sprayed with starsan. There is no funky residue on the top of the beer or any other signs of infection.

If anyone has any ideas I'd appreciate the input, otherwise I guess I'll bottle it and see if this goes away over time.

 

[unionrdr]

Here's a list of off flavors that should prove enlightening.
http://howtobrew.com/book/section-4/is-my-beer-ruined/common-off-flavors Your problem is process related.

 

[LLBeanJ]

Persistent problems with diacetyl, assuming that's what you have there, would have me looking for an infection. Do you have a ball valve on your kettle, by chance?

http://brulosophy.com/2014/11/13/problem-identification-or-helping-a-buddy-stay-in-the-hobby/

 

[Sadu]

Thanks for the replies. I'm really keen to diagnose whether this is infection or a temperature control issue and these batches were made on different equipment which helps with diagnosis I think. I think the only piece of equipment common to both batches is me.

I thought I'd try the pilsner to see how that came out. The pilsner was a split batch between lager and ale yeast so that will help with the diagnosis. The lager has the diacetyl flavour but otherwise tastes excellent, love the saaz character. The us-05 ale version has no diacetyl flavour but is a bit dry for my liking, slightly astringent perhaps. Choosing between these beers I would take the lager yeast version every time, even with the diacetyl flavour.

Am I correct in saying that if the diacetyl was caused by a brewday infection then I would taste the diacetyl in both versions? Since there is no diacetyl in the ale version can I rule that out as the cause and focus on fermentation sanitation and fermentation temp control (ie longer/warmer d-rest, more time in primary)?

Also if this is an infection, is this something that gets stronger over time? So if the flavour stays constant then it's more likely temperature control, if it increases then more likely an infection?

 

[LLBeanJ]

Yes, I think it would be correct to assume that both versions would show symptoms if the source were a brewday infection. It could also be that the ale is slower to show symptoms, but hopefully, it won't and you can focus on process control to solve the issue.

Not sure if it would get stronger over time if from infection, but it very well might. Hard to say. However, I believe with yeast-produced diacetyl, its presence would be there almost immediately, since it was created by the yeast and they failed to clean it up. If it takes a while to show up, then that would suggest infection to me. So, in my mind if you taste a sample, say 3-5 days after active fermentation ends and you get diacetyl, I'd be looking at my ferm process. On the other hand if the sample tasted fine at 3-5 days post-ferm and then began to show signs of diacetyl 2-3 weeks later, I'd be thinking infection.

 

[crusader1612]

Persistent problems with diacetyl, assuming that's what you have there, would have me looking for an infection. Do you have a ball valve on your kettle, by chance?

http://brulosophy.com/2014/11/13/problem-identification-or-helping-a-buddy-stay-in-the-hobby/

to be honest, an infection would the the bottom of my list for Diacetyl (A Pedio infection if you will)
but obviously, cleanliness and sanitation, are massive parts of the hobby.
so make sure its thoroughly cleaned and sanitary before you let it touch your wort/beer.

If you keg, this type of infection, can be picked up through beer lines, so could be another thing to look at.

But for me the first culprit is always fermentation.
so look at the following
* Fresh healthy yeast.
* high pitch rate.
* ensure you always do a rest, this ensures the beer finishes out, and the higher temps helps to eliminat diacetyl.
* rest much longer. i always rest early, and let it fly for the duration (2 week ferment - day 3/4 raise to d-rest and let it go for the rest NB this is for ales)

 

[LLBeanJ]

to be honest, an infection would the the bottom of my list for Diacetyl...

Mine too... unless it kept coming back, as OP has described. Diacetyl is pretty easy to avoid and/or mitigate even in lagers, so if it keeps cropping up, I'd be looking at something other than the yeast. At least, I'd be looking at my equipment closely making sure I wasn't missing anything as regards sanitation. Of course, it could very well be process problem, so that needs to be thoroughly investigated, as well.

 

[unionrdr]

I've also noticed that some off flavors aren't perceived until the beer carbonates & it is then magnified through aroma &/or flavor.

 

[HopHeavy]

Maybe take a closer look at your rest? In the context of your comments concerning the pils split between lager and ale yeast... and I am assuming you split a single brew and then went with traditional temps for the respective yeasts. One has detectable diacetyl while the other does not. An infection would almost certainly be more pronounced in a beer that spends more time above 60°. So I am liking the idea you weren't warm/long enough on your diacetyl rest. Just an idea... Hope you figure it out either way!

 

[ba-brewer]

In the future you can try this test to see if you detect anything after the D-rest.
http://www.winning-homebrew.com/diacetyl-test.html

 

[Sadu]

Maybe take a closer look at your rest? In the context of your comments concerning the pils split between lager and ale yeast... and I am assuming you split a single brew and then went with traditional temps for the respective yeasts. One has detectable diacetyl while the other does not. An infection would almost certainly be more pronounced in a beer that spends more time above 60°. So I am liking the idea you weren't warm/long enough on your diacetyl rest. Just an idea... Hope you figure it out either way!

Correct. I brewed 3 growlers of lager at 12c and 1 growler with US-05 at more-or-less ale temperatures. To be honest I didn't pay much attention to the ale one, I just threw it in the closet next to the other fermenters with temp-controlled heat belts and didn't stress about temperature too much. It shows in the finished product lol. Even though FG was the same I can't believe how different these beers came out.

 

[Sadu]

This is all really helpful.

What's interesting is that both the pils and ESB were fermented quite differently, with different equipment. The pilsner lager+ale in glass growlers in a swamp cooler vs plastic fermenter buckets for the ESB. Different boil/cool gear too. For the pilsner, didn't check the gravity at all until I racked to secondary, after the d-rest. The taste at that point was excellent. Didn't get the off flavour until bottling time after a couple of weeks lagering. I'm certain the glass growlers were well scrubbed/sanitised and they weren't opened until day 14 or so which I think is good, however the lids weren't totally airtight so this could be an area of concern.

Both beers got a really good pitch of healthy yeast. Vitality starters for both, good aeration, fresh healthy yeast. I don't see this as being the issue but pitch rates are something I'm very mindful of and will continue to watch.

I think I will make a habit of ramping up the temperatures once the brew is approaching FG. I didn't realise this was necessary for ales but I don't mind making it part of my process.

 

[crusader1612]

" For the pilsner, didn't check the gravity at all until I racked to secondary, after the d-rest "
You've pretty much just answered your own question right there. Lagers, fermented both traditional ways, and using faster methods (a la Brulosophy) both require care and attention, especially when it comes to the D-Rest.

"US-05 at more-or-less ale temperatures. To be honest I didn't pay much attention to the ale one, I just threw it in the closet next to the other fermenters with temp-controlled heat belts and didn't stress about temperature too much"
When US-05 is fermented warm, you won't get much in the way of off flavours, specifically Diacetyl. at lower ferm temps, it'll throw it at you. and chances are you were fermenting in the higher range of US-05's range if not just outside of it. some people suggest they get peachy esters sometimes.

 

[Sadu]

" For the pilsner, didn't check the gravity at all until I racked to secondary, after the d-rest "
You've pretty much just answered your own question right there. Lagers, fermented both traditional ways, and using faster methods (a la Brulosophy) both require care and attention, especially when it comes to the D rest

Ok this is interesting. It would be fair to say the Pilsner had reached fg before I started the d-rest. I thought this was how it worked, maybe this is where I went wrong. With the one gallon batches I try to be a little more economical with gravity readings. You suggest this is a mistake?
So next time I should start ramping up while the main fermentation is in progress?

The second lager brew I did also has the diacetyl flavour but only very mild, this was done a la brulosophy and got the temperature raised once it hit 50% AA, like the process suggests.

 

[Sadu]

Just an update on this. These lagers cleared up completely with some time, I can't pick any weird flavours with either.

This is what I love about brewing. You screw something up, leave it a while, come back and the screwup is gone.

 

[biggmatt]

A big time for diacetyl is most often produced at the very first. Make sure to bring your brew down to temp before pitching. Also you can help get rid of diacetyl faster by racking right after your rest. So it has a chance to escape

 

[Sadu]

Yep I pitch at the temperature I will ferment at. With 1g batches getting down to pitch temps is real easy.