Safale s-04 and Isoamyl Acetate (bubblegum)

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mi5

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Found this thread searching for S-04 and Bubble Gum:

https://www.homebrewtalk.com/f37/safale-s-04-alc-tolerance-106048/index2.html#post6659599

But decided to start a new one as this is really a bit of a tangent.



My ferment is now giving off bubble gum aroma (this appeared during the 2nd week of primary, after I moved it from cold basement (13 C Ambient) up to another room (17 C ambient) - the move was on around day 7..and I was hoping to kick start a bit more activity and make it work further on the high OG , but I realise now that that was probably a mistak!).


Bill Notes - I used S-04, Crystal Rye, Crystal Malt, a bit of Biscuit Malt and mostly Wai-Iti hops, on top of a majority Munich MAlt bill (all grain, high gravity) - so it was always going to have a sweet + fruity balance anyway. I rehydrated in warm water for half hour with a small amount of brewers sugar, and it got pretty hard going in that jar - then Pitched into warm ort around 22 C. The ferment remained around 20 for the first few days, which I assumed was OK as the yeast packet said good between 12 and 25, and best between 15 and 22 or something,


Question 1 - Is it possible to get a bubblegum smell but not the taste? (wishful thinking)..


Question 2 - IF there is bubble gum ester (Ethyl Butyrate) is that something that may get removed a bit over another couple of weeks, whilst the yeast cleans up after itself? If so I will avoid racking into a secondary vessel and leave it go keep going.

Question 3 - assuming he temp change was to blame, I am guessing that moving it back to the colder room now 4 days later will not help much...correct?


Lesson learned: Do more research, and next time I wont move the vessel, + I will try to pitch lower and also maintain a cooler 15 /16 C temp)
 
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I believe the best practice is to avoid producing the compounds that produce off flavors, then you don't have to worry about getting the yeast to clean up the flavors later on.
It seems you have already figured this out since you have included what you'll try next time.
I suspect your method of pitching at 22c and then fermenting at 20c for the first few days may have caused your current bugglegum smell.
If you pitched at 22c, then your fermentation actually started above 20c and settled down to 20c after a while.
Next time, get the wort down to 15-16C before pitching and try to keep it below 19-20C.
Your specific questions:
1. Yes its possible, but not likely. Although it might not be that bad.
2. Yes this is possible, but depending on the taste, racking the beer might a good move. The aeration during racking could help the yeast
with the cleaning up activity.
3. No, a colder room won't help much now, the flavors were probably produced in the first few days of fermentation.
 
+1 to a lot of what he said.
there are some people pitching more like around 20 (i do), but then fermenting at around 16-17. but s-04 i believe is known for going pretty strong, which will create a lot of heat, which is why yours jumped up to 20 even though it was in an ambient temp of 13.
as you said, just do more research before you brew next time. pick your next style of brew and find out what works best for that style. some ales will want to ferment around 20. some around 15. it depends what flavor profile you're hoping to get out of the yeast.

1) often the smell will be stronger than the taste. plus, don't lose hope, as this could be a taste you find you like with this beer. it could end up mixing well with the malt flavors, especially since it's a sweeter brew.
2) time can only heal so much of a mistake. i personally wouldn't rack it, but i would just leave it in your primary until like week 3 from when you pitched your yeast.
3) the temp change wasn't what was to blame. it was having it at 20 for the first few days of vigorous ferment activity. many people move up the temp after all fermentable sugars have been consumed (aka when you've reached FG). i personally always move mine at day 9 from 17C to 21C. but, no, at this point you don't want to move it to a colder temp unless you're doing a cold crash before bottling/kegging.
 
Thanks for the above advice all, useful and informative. I'll leave it another week (to make 3 weeks in all) and then sample, take gravity etc, then decide between secondary or straight to bottle depending on how it tastes.

Not giving up hope, perhaps it will transpire to be a blessing in disguise and work well with the brew! I'll report back.
 
Minor correction: Ethyl Butyrate, not Isoamyl Acetate is the ester you're getting. The latter smells like bannana, not bubble gum.

If the beer is still fermenting, you should postpone your worry until it's done. I have rarely brewed a beer that smelled like the fermentation gasses. Yeast re-absorb and metabolize many of their byproducts, and many are volatile anyway, so they don't come out in the final beer. Do not rack the beer to another fermenter while it is still fermenting, especially if you're trying to clean it up. You want the yeast around for that job, and your beer will rely suck if it stalls because you took it off the yeast.

The best way to reduce esters is to use a clean strain. After that, cool fermentation is best, but too cool can create worse problems. High pitching rates are associated with esters, but the alternative, low rates, can create solventy alcohols that are (IMO) worse. Reducing oxygen is another path to reduced esters, but since most homebrewers are under oxygenating in the first place, that's probably not the right place to go.
 
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