Red apple flavor with european ale yeasts

[hardrain]

I've brewed several batches with european ale yeasts lately -- WL007, WL013, WL011

I've also gotten it with a Cal Common yeast and, strangely, WLP815 Belgian Lager Yeast.

I've not gotten it with: WL 830, 023, 003, 001, 565, WY1332 (in a porter).

It's very much the same flavor, a friend with a good pallet vocabulary (which I don't have) called it red apple, apple skin, brown apple. For me, I get a dry bitterness as soon as the beer leaves my tongue, and agree with my friend's description.

I've been told by others it's not diacetyl, which I'll confess to not knowing or previously experiencing. I'm not getting any green apple, which I'm told is the best comparable. Plus we're talking ales and I'm not rushing the beers.

In terms of brewing process:
-All grain, in all cases above mashing at 150F but not holding temp well, so could be dropping into mid 140s after an hour (always hit right around 75% eff.). My water is incredibly alkaline and so mash ph has often been high -- 5.5 to 5.7. (Fixing this slowly)

I always gradually increase the temp, about a degree every two days. For all of these batches I've done a 2L starter, cold crashed starter for 1-10 days (depending on my schedule), and pitches after letting it warm during brew day, decanting most of the liquid. Oxygen stone (~45 seconds). Fermenting on the cooler side of all recommended ranges in a chest freezer set +/- 1 target temp. Sanitizing very well. Two week minimum in carboy before kegging.

Only two theories:

1. My well water is insanely alkaline and high mineral, I know this because of how much acid in tests it was taking to lower ph, actual water test pending). I usually mash with bottled water, but was still often in the 5.7 range (high). I've been mashing with bottled water (still getting high ph numbers, but often using lighter grain bills, so slowly learning to use acids to fix). I sparge with half bottled, half well water. Could something about the water be stressing or affecting the yeast to crease more of these fruit flavors? And often the same flavor?


2. I ferment in a chest freezer set to temp, with the probe taped to the side under a cotton ball. Could I be way underestimating the heat of fermentation and over relying on the ability of the chest freezer to conduct the colder temp, thus creating a spike in temp after the yeast picks up and stressing the yeast? If this one is true I'd suspect is's a very common issue for homebrewers. And would that spike lead to the same taste impact despite different yeasts? I'm never getting fusel alcohol flavors.

I haven't bought new buckets or siphons in a while, but this isn't a bateria-related issue as far as I can tell, and it doesn't get worse as the keg sits.

Other than that I'm clueless. Anyone experienced this flavor before?

 

[friarsmith]

Any time I hear "apple flavor," whether green, red, or crab apple, I think about yeast stress and acetaldehyde. Some yeasts are more prone to this than others.

The process you describe seems solid with oxygenation, but are you sure you're pitching at the right temp, meaning both the starter and full batch of wort are within a few degrees of each other and not too warm? Have you had your well water tested? Maybe something else is going on with the water.

A high mash pH can result in tannin extraction, leading to the perceived bitterness or sharpness you describe.

Diacetyl tastes like slick/oily butterscotch candy and smells a lot like buttery microwave popcorn. If you're leaving beer on the primary yeast cake two weeks, you shouldn't have too much trouble with diacetyl. When in doubt, pour a little of your hydrometer sample into a microwavable mug and warm to 100 degrees or so. That will bring out the butter (if it's an issue in the beer), meaning you should let the beer stay in primary a little longer and perhaps warm it up a few degrees.

 

[hardrain]

Thanks for the reply. After posting this I think I'm going to focus on three things:

-Mash pH, might be time to finally get serious with water chemistry and get my mash to 5.2 rather than the 5.5-5.7 it's been at since.

-If feel really good about pitch rate and initial temperature (I always let yeast warm on brew day, and benefit of well water is that it's very cold, so can usually wort-chill down to the right temp). However, I don't feel good about knowing the internal temp of the carboy vs what I'm reading as ambient air...as much as I hate doing this I think I might start opening the carboy from time to time and (very carefully) checking the internal temp of the liquid. Right now I'm relying mostly on the temp probe taped to the carboy, with a check from one of those temp stickers.

-"Something else" with my water. I'm using less and less well water but it might be time to cut it out 100% and see what happens, or at least until I get it tested.

Maybe it's a combo of stress from higher temps on day 2-3 when the yeast are producing heat, plus the tannins from higher mash ph?

 

[hardrain]

One other thing, I guess: my starters are all 100% well water and light DME, and I'm not regulating the temp on those starters at all (I let them run two days, sometimes in the 60s, sometimes closer to 80, depending on weather). I inferred temp didn't matter from White's book, but could swings in the starter, or a high ph starter wort stress the yeast population before pitching?