Noob has Acetaldehyde problem

Hey all. Relatively new to extract brewing, and I'm having a bit of an issue. As I processed my first batch, I noticed that it had a weird off-flavor throughout the process, but I couldn't identify it. I also failed to hit my FG, stopping at about 1.020. Not knowing any better, I bottled it anyway (doh!). The weird flavor has gotten a bit better as it has aged, but it's definitely still there.

Now my second batch is 10 days into primary, and I've got the same issue. Current SG is stuck around 1.020 (target is 1.015), and I have the same off flavor developing. After forcing myself to drink way more than I wanted to in an attempt to identify the flavor, I'm reasonably certain it's Acetaldehyde.

My temperature is fine, consistent at 69 degrees. I pitched 2 packets of dry yeast, rehydrated, so it definitely isn't under-pitching. So I'm assuming that the SG problem is related to using an LME with a high rate of unfermentability, as I understand this can be an issue. My questions are: 1) are these 2 issues likely related? And 2) what, if anything, can I do to the one I still have in primary to alleviate the issue? Thanks!

Here's a pretty good write up on it. IME it's usually due to transferring off the yeast before they've had a chance to clean things up, but this article lists some other possible causes.

https://beerandbrewing.com/VJmwUisAALkq3055/article/off-flavor-of-the-week-acetaldehyde

BTW, the 1.020 issue is fairly common with extract.

You probably will have acetaldehyde after 10 days, and it's one of the things that define "green beer". The yeast will convert it and take care of it on it's own. Let the beer sit in the primary 2-3 weeks and another couple of weeks in the bottle at your conditioning temp, at least. If you ferment only 10 days, bottle, and put them in the fridge early, the yeast can't finish up. That link above lays out what's happening if that flavor sticks around, but almost 100% of the time it's not going to.

Sweet, thanks guys!

cristoirsearlas said:

Hey all. Relatively new to extract brewing, and I'm having a bit of an issue. As I processed my first batch, I noticed that it had a weird off-flavor throughout the process, but I couldn't identify it. I also failed to hit my FG, stopping at about 1.020. Not knowing any better, I bottled it anyway (doh!). The weird flavor has gotten a bit better as it has aged, but it's definitely still there.

Now my second batch is 10 days into primary, and I've got the same issue. Current SG is stuck around 1.020 (target is 1.015), and I have the same off flavor developing. After forcing myself to drink way more than I wanted to in an attempt to identify the flavor, I'm reasonably certain it's Acetaldehyde.

My temperature is fine, consistent at 69 degrees. I pitched 2 packets of dry yeast, rehydrated, so it definitely isn't under-pitching. So I'm assuming that the SG problem is related to using an LME with a high rate of unfermentability, as I understand this can be an issue. My questions are: 1) are these 2 issues likely related? And 2) what, if anything, can I do to the one I still have in primary to alleviate the issue? Thanks!

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If the room temp is 69 you could have other issues. The yeast will drive the beer temp higher than room temp which can give you some esters that are not what you desire. If possible (everything is possible with enough money thrown at it) you should start the ferment cooler, probably in the low 60's (beer temp, not room temp) for a week, then let the beer warm to the upper 60's or low 70's to encourage the yeast to clean up the beer better. That may get you a lower FG also.

Check your hydrometer with plain water to make sure it's reading right. What do you sanitize with? I had several batches of beer get ruined by star San when I first started brewing. They say star San is no rinse but maybe my water messes it up too quickly or I used too much. The beer would taste fine but turn into a horrible chemical aftertaste. So I started rinsing it off and that aftertaste vanished

Acetaldehyde smells VERY much like green apple. It's pretty distinctive. After 10 days I would think it should be gone unless the temp dropped quite a bit and the yeasties went to sleep. I would not recommend drinking beer with acetaldehyde in it as it is toxic and will give you the hangover from hell. As pointed out above, if your ambient temp was 69, then fermentation was probably happening closer to mid 70s and that's too warm unless it's a Belgian strain. If it tastes harsh, like nail polish remover, then you have fusel alcohols. These can mellow a little with age but will never age out completely. Sounds like you need temp control