So now I know what diacetyl smells like...

[DDHIPA]

I recently finished my first all grain brew with a good friend of mine using a G30 grainfather. The recipe we brewed was the American IPA by John Finch recipe kit from The Malt Miller.

Fermentation went well with plenty of activity for 10/14 days (although a smaller krausen then expected) and it was fermented at 18c for the total 14 days before racking and bottling.

I took samples for the last three days which all came in at 1012 (OG of 1060) which gave me the go ahead to bottle seeing as fermentation seemed to have finished. Now.... tasting the three samples through off no warning signals about there being an issue of buttery diacetyl however once racked into a bucket for priming the smell of popcorn was definitely noticeable, not overpowering but it was definitely there and when sampling for a final time when bottling the taste was also now noticeable.

the beer is beautifully clear and we take sanitisation and cleaning as the absolute more important part of brewing so I am pretty confident that the issue is not down to contamination but instead down to fermenting at too low a temperature and not performing a diacetyl rest at the end of fermentation.

I would very much appreciate anyone’s advice on ways to avoid this happening in the future (I am due to brew a Sussex best bitter clone this weekend to convince the father in law that all grain brewing is better than extract brewing...)

thank you in advance and sorry for all the waffle!

 

[PhilBrew]

Hi DDHIPA, and welcome to the forum

... I am pretty confident that the issue is not down to contamination but instead down to fermenting at too low a temperature and not performing a diacetyl rest at the end of fermentation.

I would very much appreciate anyone’s advice on ways to avoid this happening in the future ...

... for a "newbie" it looks to me like you're already pretty good at answering your own questions ... but yes, making sure you ferment at a warm enough temperature and performing a diacetyl rest at end of fermentation should help with those problems

You don't say whether you were controlling fermentation temperature (if so, you may want to check your controller against another thermometer) or relying on ambient being at 18c (if so, you need to remember these things change when you're not looking at them (like overnight)) but working out why this may have happened is the start of solving the problem

Cheers, PhilB

 

[DDHIPA]

Hi DDHIPA, and welcome to the forum

... for a "newbie" it looks to me like you're already pretty good at answering your own questions ... but yes, making sure you ferment at a warm enough temperature and performing a diacetyl rest at end of fermentation should help with those problems

You don't say whether you were controlling fermentation temperature (if so, you may want to check your controller against another thermometer) or relying on ambient being at 18c (if so, you need to remember these things change when you're not looking at them (like overnight)) but working out why this may have happened is the start of solving the problem

Cheers, PhilB

Thanks for replying! Haha, yes sometimes it's a blessing and sometimes its a curse! I do try to resolve my own questions usually but given the time a brew takes from grain to glass AND the cost of ingredients I am bowing to the greater know how of more experienced brewers :)

I was fermenting in a fridge in the garage hooked up to an inkbird with a heatpad underneath the carboy, and I had a second temperature probe taped (hanging) from the top (inside) of the fridge so that i had a reading of the ambient temperature inside the fridge as well as that of the fermenter. I never saw it drift more than 0.3c away from the 18c mark, it usually drifted higher as its been fairly warm during the days.

I think for the sussex I will ferment at 20c and raise a degree or two for the final few days and fingers crossed this will help. Although I will double check what the WLP001 yeast reccomends as well (the American IPA was US-05 yeast). It was definitely a mistake to follow the fermentation schedule on the grainfather recipe guide as having looked into it more closely, every recipe seems to say 14days at 18c... I will be paying closer attention to the specific requirements of individual yeasts in the future for sure.

I am going to leave the buttery brew a good 8 weeks to condition so it will be interesting to see how/if this improves the flavour!

 

[PhilBrew]

Hi

I am going to leave the buttery brew a good 8 weeks to condition so it will be interesting to see how/if this improves the flavour!

... you've also not said whether you're force carbonating or whether you've primed and will be running another (carbonating) fermentation as part of conditioning ... if the latter, getting the packaged beer somewhere warm during that second fermentation should reduce/solve the butteryness

TBH though, it's surprising to hear of anyone getting any "character" (like diacetyl) from US-05 ... but then some people are much more susceptible to detecting it when it's there, also ... but it's still probably worth dropping the probe of your inkbird into some iced water and checking it reads 0C, at least, because I wouldn't expect to be sensing diacetyl in a beer fermented with US-05 at 18C (consistently) for two weeks

Cheers, PhilB

 

[DDHIPA]

Hi
... you've also not said whether you're force carbonating or whether you've primed and will be running another (carbonating) fermentation as part of conditioning ... if the latter, getting the packaged beer somewhere warm during that second fermentation should reduce/solve the butteryness

TBH though, it's surprising to hear of anyone getting any "character" (like diacetyl) from US-05 ... but then some people are much more susceptible to detecting it when it's there, also ... but it's still probably worth dropping the probe of your inkbird into some iced water and checking it reads 0C, at least, because I wouldn't expect to be sensing diacetyl in a beer fermented with US-05 at 18C (consistently) for two weeks

Cheers, PhilB

We batch primed before bottling and its sitting at 22c ish most of the time so hopefully this seccond ferment will gobble up some of the diacetyl. I am definitely going to do the ice water test you mentioned for both of my probes, thanks for the sugestion!

 

[Pennine]

yeah I would agree that seems odd to get diacetyl with us05 at those Temps. I have done much cooler and never noticed buttery. It will likely go away so don't make process changes sampling out of the fermenter. Give it another month to decide.

 

[Edison]

I could be wrong but if there wasn't enough yeast to begin with they may not have stuck around long enough to clean up after themselves.
Was the wort cooled to fermentation temperature when you pitched the yeast? Did you add enough oxygen before pitching? Did you rehydrate the yeast? Did you add any yeast nutrient? These things should all help you start off with ideal conditions for the yeast colony to grow before it starts to get busy with turning sugar to alcohol. 1.060 is a reasonably high OG so giving the yeast ideal conditions is a good idea.
I monitor fermentation closely and as it begins to slow down (but is still actively fermenting) I gently up the temperature a few degrees to encourage the yeast to keep going. Most temperature sensitive flavours are produced in the first few days of fermentation, after that, raising the temperature a bit shouldn't have any detrimental effects.
You could do a force diacetyl test by warming up a small sample of beer in a microwave and having a smell/taste. If its buttery try gently rousing the yeast and warming it up to help it finish up before bottling.

 

[DDHIPA]

I could be wrong but if there wasn't enough yeast to begin with they may not have stuck around long enough to clean up after themselves.
Was the wort cooled to fermentation temperature when you pitched the yeast? Did you add enough oxygen before pitching? Did you rehydrate the yeast? Did you add any yeast nutrient? These things should all help you start off with ideal conditions for the yeast colony to grow before it starts to get busy with turning sugar to alcohol. 1.060 is a reasonably high OG so giving the yeast ideal conditions is a good idea.
I monitor fermentation closely and as it begins to slow down (but is still actively fermenting) I gently up the temperature a few degrees to encourage the yeast to keep going. Most temperature sensitive flavours are produced in the first few days of fermentation, after that, raising the temperature a bit shouldn't have any detrimental effects.
You could do a force diacetyl test by warming up a small sample of beer in a microwave and having a smell/taste. If its buttery try gently rousing the yeast and warming it up to help it finish up before bottling.

Yeast was chilled down to 20c before pitching the yeast but I didnt aerate the wort much (other than setting up the outlet of my counterflow chiller a foot above the fermenter to that it "splashed" in from a height before pitching and I didnt add any yeast nutrient.

Yeast health and stepping up the temps towards the end of fermentation are definitely things I am going to improve on in the next brew as this will benefit all aspects of the finished product. I won't rush to raise the overall fermentation temps as many have said US-05 tends to behave nicely at the 18c mark, plus if I do so it will make it hard to know which changes if any have in fact been beneficial.

I am also very much looking forward to trying the finished product in 7 weeks time once it has had a chance to sit and have a second fermentation