Acetaldehyde?

[Elijah Hutchinson]

Ok, so I consistently get acetaldehyde flavor in my beer. I ferment with an airlock in primary for 3 weeks and then bottle with carbonation tabs from Mangrove Jacks. I bottle carb for a couple of weeks at room temperature and that's it. Could it be that I don't use enough hops? I read that acetaldehyde is a carcinogen so I'm not really wanting to drink my cider-like beer. This is clearly operator error of some sort and I would like to make beer without cider-y flavor. Any thoughts?

 

[Gnomebrewer]

What temperature are you fermenting at and which yeast?

 

[Elijah Hutchinson]

What temperature are you fermenting at and which yeast?

Im fermenting at room temp and with Safale s04

 

[dmtaylor]

Acetaldehyde is not very common these days. Are you sure that's your problem? Could it be apple esters from the yeast?

Acetaldehyde is caused by unusual stresses on the yeast, like if you severely underpitch a lager with unhealthy yeast and then keep it cold so it can't take off fast, something like that.

Apple esters also can be caused by stresses on the yeast, or also by fermenting too hot.

If these aren't what's going on, maybe you can have your beer tasted by a local club member or competition to help diagnose? I really don't think it has anything to do with carb tabs or hops or anything like that. It's most likely a yeast thing.

EDIT: I see now you are fermenting at room temperature. I think that's likely too hot. What is room temperature for you? 68 F? 70 F? 72 F? All kind of high for that yeast. Cool it down to like 65 F if you can. Or try a different yeast! Maybe you just don't like S-04! Try Notty or US-05 instead maybe.

 

[beermanpete]

The suggested fermenting temperature range for the Safale S-04 is cooler than the S-05. Since it seems you are not using any temperature control S-05 might perform better for you.

 

[Elijah Hutchinson]

Acetaldehyde is not very common these days. Are you sure that's your problem? Could it be apple esters from the yeast?

Acetaldehyde is caused by unusual stresses on the yeast, like if you severely underpitch a lager with unhealthy yeast and then keep it cold so it can't take off fast, something like that.

Apple esters also can be caused by stresses on the yeast, or also by fermenting too hot.

If these aren't what's going on, maybe you can have your beer tasted by a local club member or competition to help diagnose? I really don't think it has anything to do with carb tabs or hops or anything like that. It's most likely a yeast thing.

EDIT: I see now you are fermenting at room temperature. I think that's likely too hot. What is room temperature for you? 68 F? 70 F? 72 F? All kind of high for that yeast. Cool it down to like 65 F if you can. Or try a different yeast! Maybe you just don't like S-04! Try Notty or US-05 instead maybe.

It doesn't taste bad at all. Just very apple-y. Fermenting in around the upper 70s. I should definitely take it to my home brew store or something. Would acetaldehyde be noticeably bad?

 

[Gnomebrewer]

S-04 in the upper 70s is likely to be very estery. I'd be surprised if it's acetaldehyde though. Acetaldehyde doesn't come from stress on the yeast, it normally comes from incomplete fermentation when the yeast give up before it can be converted into ethanol (the final stage of ethanol production). Yeast actually like higher temperatures than we normally ferment at, so incomplete fermentation is not likely (but they will produce lots of strange esters and higher alcohols at high ferment temps). If it is acetaldehyde that you're tasting, it's more likely from oxygenation post-ferment - oxygenation of ethanol can also lead to production of acetaldehyde (even though oxygen levels of both are the same).

 

[seatazzz]

+1 on trying different yeast. Nottingham has a temperature range of 50 to 75, it's my go-to for ales. Never had the apple-y off flavor with it.

 

[ericbw]

S-04 is nasty over 70 degrees. Weird fruitiness.

 

[parrothead64]

Fermenting beer is going to be about 7 degrees higher than ambient so upper 70,s is way too hot

 

[BrianDorry55]

I would take measures to lower your fermentation temperatures. A swamp cooler is cheap and easy. If you can’t do that for some reason, use a yeast that tolerates high temps. I haven’t tried it yet but Omega’s Hothead is touted as a neutral strain that can ferment up into the 90s without becoming estery.

Do you fermentation’s seem healthy/very active? Are you reaching intended final gravity?

 

[Elijah Hutchinson]

Thank you guys for your help. My fermentation temperature is way too high for sure. Still not sure if its yeast esters or acetaldehyde that I'm tasting. Just called the local HBS and I'm going to take it in today for an expert opinion. I'll let y'all know what the verdict is.

 

[SoCal-Doug]

Keep in mind however that this whole temp thing is very yeast dependent and you should not get locked into a temp for everything. There are some yeasts that you want to ferment hotter (saison's and some Belgian's), and some should be very much colder (lager's and cleaner ale types). It's way too common for people to hold a specific temp for any and all yeasts and that is definitely not proper. In some cases, ferment temp defines the flavors you wish to achieve (like wheats for the clove to banana thing). I have a hell of a time getting correct Saison temps in the winter because (imo) the best flavors from some yeasts, come from punching it into the low 90's.

 

[Elijah Hutchinson]

Keep in mind however that this whole temp thing is very yeast dependent and you should not get locked into a temp for everything. There are some yeasts that you want to ferment hotter (saison's and some Belgian's), and some should be very much colder (lager's and cleaner ale types). It's way too common for people to hold a specific temp for any and all yeasts and that is definitely not proper. In some cases, ferment temp defines the flavors you wish to achieve (like wheats for the clove to banana thing). I have a hell of a time getting correct Saison temps in the winter because (imo) the best flavors from some yeasts, come from punching it into the low 90's.

This might be a dumb question, but when y'all are talking about fermentation temperature, are you referring to the ambient temperature of the room or the temperature of the fermenting wort? Also, which one tends to be warmer?

 

[SoCal-Doug]

The temperature of the fermenting wort is what matters. Fermentation has a natural rise in heat of a few degrees while the yeast are having their party.

 

[Elijah Hutchinson]

So I took my brew to the local HBS for an expert taste test and the guy running the place thinks that the apple flavor is probably not acetaldehyde. He thinks that it is a result of three things. 1) Pitching s04 dry, without rehydrating it properly first. 2) Fermenting in the 70s with that yeast. 3) Fermenting with an English ale yeast that specifically bred to produce fruity flavors. He recommended trying US-05 for a cleaner ferment and keeping the fermentation temp a bit lower. I got a temperature strip and stuck it on my fermenter that is currently going to see what temperature I have been fermenting at and it read 72 but it's almost done. I assume it was probably going at around 74-76ish before.

 

[Gnomebrewer]

1) Pitching s04 dry, without rehydrating it properly first. 2) Fermenting in the 70s with that yeast. 3) Fermenting with an English ale yeast that specifically bred to produce fruity flavors.

I do rehydrate my yeast (because it's so easy to do), but enough brewers don't that I wouldn't think it contributed to the fruitiness. S04 is a quite estery yeast even at lower temperatures - the yeast strain and temperature are the more likely culprits.

 

[chris000]

before you get started changing everything (which is not necessarily a bad thing), I wonder what temperature you pitch your yeast;
the wort should be slightly cooler than the choosen fermentation temperature (don't pitch hot and wait for it too cool).
if that's not the issue, change the yeast to something cleaner, rehydrate it, keep it at the coolest spot to keep it at the lower end of the optimum (it will warm up during fermentation anyway).
and before you know it, you'll make starters and have a temperature controlled incubator - welcome to the club!