For $30, you could get it tested.
https://oregonbrewlab.com/products/#offflavor
If it’s really driving you nuts, it might be worth it.
That’s worth the price IMO!
Dana does amazing work.
Several of the previous suggestions were oxidation and questioning the CO2 purity. This would pretty much eliminate those from consideration.
If I already know a certain off-flavor is in my beer, then wouldn’t these off-flavor tests just be telling me what I already know?
Here is a reason to make sure your Keg is purged and the CO2 is as pure as you can get - when alcohol oxidizes it becomes acetaldehyde. Just saying.
Analysis of a beer for acetaldehyde would remove doubt. Why do I say this? Some yeasts produce apple esters. Not green apple, but ripe red Apple. We think apple=acetaldehyde, and that is not always true.
A test would say how much acetaldehyde is there. All beer has acetaldehyde, the goal is for it to be below human threshold.
Right. It seems odd to me that you’re having acetaldehyde issues across so many beers. All of the explanations I’ve seen so far really seem like a bit of a stretch. Acetaldehyde isn’t typically a common problem. I think that if you’re having issues with multiple beers, then either you’re a supertaster for acetaldehyde, or it’s probably something else.
Any chance you could have a low level infection somewhere in your system? Maybe some microbe is producing another flavor compound that is coming across as apple?
Does the flavor present itself with other yeast strains? What about ferment temps? If you are only controlling ambient ferment chamber temperature without monitoring actual wort temp, you may be fermenting way warmer than you think.
Whats the “proper rate”?
Has this rate been verified with a scope and a count? If using a online calculator, I have found them from mildly to wildly inaccurate (but not one right). This is from scoping and actually counting.
I disagree with this. It’s one of the more common problems, especially in lagers. I think if it is a problem with process it becomes more evident in delicate lagers as opposed to stronger flavored lager.
Don’t mean to set everyone barking up the wrong tree with the Co2 impurity comment either. Just the OP says he only noticed it after the beer was kegged and carbbed. Of course it seems like lots of off flavors work that way.
I see the tests as confirming that what you think you know is correct.
I’ve found the MR Malty calculator to be actually pretty accurate compared to cell counts I did in my brewery. In fact I had a new lab guy at one point in time who had horrible math and I used to the Mr Malty to double check his calculations. Obviously you can’t tell viability but if you know the yeast is healthy and fresh you should get pretty close.
Sounds like oxidation to me. I’d check o2 exposure when cold crashing in regards to suck back. Also, when kegging - do a closed transfer if you can. If you can’t, purge the keg with co2, then siphon in the beer (with the lid open) while pushing co2 in the gas post at a very low psi - close it up, and purge 3 more times.
One of the things I have been doing to avoid “suck back” is to fill a collapsable bag with Co2 and attaching it to the blow off. Theoretically you should be able to attach it like a blow off to capture Co2. Then, when the beer cold crashes it just sucks back in the Co2 from the bag.
Here’s the bag I have ben using (they have 1 gallon sized bags too)
Here’s the valve that works on them
I use the Grainfather pressure kit to pressurize the fermenter when I cold crash. But I only have one of those. If I have more than one going, I simply seal the other fermenters.