Bubble Gum Flavor...Again

[frankjconway]

So I brewed an IPA (from the LHBS, using a single vial of WLP001, no starter) a couple months ago and it had a distinct bubble gum flavor. It seemed to get worse after a month or so. I read up on the bubble gum flavor and it seemed the comments pointed to the yeast.

I did a Pliny clone from Austin HBS (pitching two smack packs of Wyeast 1056) and it came out wonderful. Gave half the batch to my brother, drank or gave away most of my half and saved one. It's been bottled for about 2 months and I just opened the last one and it has a very similar bubble gum flavor.

In both cases, the fermentation temps were in the mid 60's for most of the time, with the exception of the IPA, which got down to 59/60 for a day before I brought it back upstairs. The IPA stuck at 1.020 and (at the recommendation of the LHBS) I added Amalyse extract, which brought it down to 1.010. I thought that may have been responsible for the off flavor since reading that a lot of people don't try that.

Not quite sure what is going on here. Both were partial boil with steeped grains. Neither used a starter. I think that may be my next step in the brewing process for future batches. Any suggestions or ideas would be appreciated. All I can really find on bubble gum flavor is "the yeast".... but nothing tells me anything real specific. Nothing I've found indicates that flavor is a result of contamination. I was under the impression that the WLP001/1056 yeast is pretty clean, so I would imagine it is a flaw somewhere in my process. Any ideas?

 

[marubozo]

As you have found, bubble gum flavors almost always come from warm fermentation temps. But the temps you listed don't really back that up. But, at what temp did you actually pitch the yeast? Did you get the wort down to say 75, pitch, and then stick it in a 65 degree room after that? Even if you pitched at say, 70, the yeast could have begun fermenting very quickly before the beer had a chance to cool down to ambient temps, even raising the beer a bit warmer to the mid-70 range and completely ferment out in a day before subsiding to the mid-60 range you saw.

Making a starter is a good next step because one vial/smack pack is underpitching and going to stress the yeast a bit more than you want, and depending on the OG of your Pliny even pitching two packs may have been underpitching.

So I'd start with that, but I'd also make sure you are pitching your yeast at a lower temp than your target fermentation temp so that when fermentation raises the temp of the beer it's still near your target. For example, if I'm looking to have a beer ferment at about 65 I always cool my wort down to about 61-62 before pitching and then by the next morning when it's actively fermenting the beer temp is usually reading 65-66.

Or maybe the flavor you're experiencing isn't really a typical bubblegum flavor because that often subsides over time instead of getting worse

 

[frankjconway]

Good point. I pitched (as the instructions recommended, if I recall) when the wort was 75-80 and then put it in a room that was (I would guess) 62-64. I do remember (now that I think of it) transferring the IPA down to the cellar because the next day (after fermentation was going good) it was still about 70. A few days later (I had put it on the floor of the cellar) it was down to 59-60 so I brought it upstairs where it sat at about 64 or so until bottling. I do have about 6 IPA's left that I'm going to let sit for a few months and see if it does lessen. I swear it got worse over a few weeks, though, but that may have been my imagination because I was looking for the bubble gum flavor.