Two topics - fact or fiction

1) The proprietors of my LBHS assert that wide temperature changes can stress or damage the yeast in bottled - already carbonated - beer rendering it bad. Not skunk as in sun light exposure - but damaged or ruptured yeast cells leading to off flavors or worse - un-drinkable beer. This came up specifically in regards to putting cases of beer in my Virginia garage for longer term storage. Our temperature swings here can be 30-40 degrees in a 48 hour period (20 in a 24 hour period). Fact or fiction?


2) My son and I just received the results of a Porter competition. Overall the results averaged in the low 30's with some marks 27-29. A couple comments noted a phenolic flavor and "yeasty/estery" smell. The beer (Jamil's robust porter) was in primary 5 weeks and bottled directly skipping a secondary. The competition was 3 weeks to the day from bottling time. My son believes the yeasty/estery smell is due to bottle conditioning. Specifically he thinks it is related to bottle fermentation for carbonation purposes. Fact or fiction or mis-understanding?

I have no idea on #1. On #2 I just can't imagine it is related to bottle carbonation - too many folks are doing this to put up with it. If anything I would think it was related to the beer still being a bit green (although 5 weeks in primary and 3 in the bottle seems right) or the temperature of my fermentation. This beer was fermented at 69/70 degrees and stayed in that range for all 5 weeks.

Thanks in advance for the comments.

1. Fact. Yeast is best kept sealed in a cool, dark place (like the fridge). The freezer can have VERY detrimental effects without proper precaution. Likewise, summer heat can completely ruin a yeast vial/pack/bottle.

2. Hard to answer. It's more likely that your initial fermentation temperature was too high, but that doesn't rule out some funk happening after bottling. You'd have to have tasted it before and after bottling to get a definitive answer. Regardless, 69-70 is a bit high for most ales, particularly a style like porter that calls for little esters in the flavor profile. Shoot for 60-65.

Yuri_Rage said:

1. Fact. Yeast is best kept sealed in a cool, dark place (like the fridge). The freezer can have VERY detrimental effects without proper precaution. Likewise, summer heat can completely ruin a yeast vial/pack/bottle.
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Thanks for your comments. Just to confirm about #1 - this applies to beer that has been bottled & carbonated and is waiting to be consumed, right? I ask because the answer seemed more directed at a batch of yeast, not the yeast contained in bottled beer.

Applies to everything except dry yeast. Dry yeast can handle much wider temperature swings. If it's in a beer that's meant for consumption, you'll likely have flavor impacts, as well as yeast viability issues.

On one, personallly I would rather my stored beer not go through such temps changes. Don't you have a more temp stable environment? I would think that the over time this can only have a detrimental effect.

On two. No it is not the bottle conditioning. I feel very strongly that you submitted a quite green beer. Submit that same beer at 8 weeks in bottle and I bet you would have gotten an entirely different response. I love porters but I don't even taste my first sample until 6 weeks in bottle and then it is just to gauge how far it has come.

Also, with just 3 weeks in bottle on a bottle conditioned beer that yeast pack at the bottom will become roiled in handling (in getting to the judges) and provide a yeastier profile to your beer. At 8 or 10 weeks that pack will stay pretty intact and not sabotage your entry.

Watch your pitching rate for issue #2. A lag time that is to long can allow some off flavors to get hold. I would not call them phenolic always, but often that identifier works. Keep entering the comps and asking questions. I think those are signs of a concerned and dedicated brewer.