Help with a Diagnosis Please

I don't equate tart/cider with sherry-like at all. You say it struck you as acetaldehyde...does it remind you of green apples?

 

Yeah, I'm not with the sherry notes...

I also don't think it's oxidized, if any, maybe a little, but shouldn't be tart.. or cider like.

 

Firstly, let’s discuss the oxidation aspect first. Since this beer was brewed just three weeks ago I would be surprised if any effects of oxidation (e.g., a cardboard flavor, sherry flavor, etc.) would be evident yet. In other words, at only 3 weeks into the brewing process unless there was a HUGE oxidation issue/exposure I would not expect to see any evidence yet.

As regards the topic of infection, the best indicator is that “no off smells” are noticed. I am uncertain what exactly would create the “tart/cidery taste” that was reported. There is a possibility that this is just an indication of a ‘green’ beer and additional conditioning is needed. I am uncertain why a “tart/cidery taste” was recognized in one bucket vs. the other if it is due to the beer being ‘green’.

When do you intend to package this beer and what is your packaging format (e.g., will you bottle condition your beers)?

Cheers!

Edit: a longshot question: @sjverla : are there any fruit flies in your homebrewery?

 

Tart / cider sounds to me either like:

1. the tail end of aceteldahyde reduction. should probably already be long gone at the 3 week point though, especially considering you are reporting that your other carboy doesn't have the off flavor.

2. the early onset of acetobacter development. If it turns from tart and acidic to vinegar like that could be the acetobacter further developing. You might also see ropy / jelly like snot strings develop as well.

3. the early onset of either a lacto or a pedio infection. Lacto would be the more likely of the two since I think pedio takes a while to develop to the point where you are beginning to taste acid. If pedio, you should eventually start getting diacetyl production along with the acid development.

So to decide btw 2 and 3, I'd assume gravity readings (as well as the visual, aroma, and flavor cue's mentioned as it develops) might provide a clue. I assume that a lacto or pedio infection could eventually drop your FG lower than the non-infected carboy, while an acetobacter infection would not. Acetobacter can metabolize some sugars, but I don't believe it metabolizes the ones that sacc. would leave behind. If it is acetobacter though, you will know soon enough as the beer will be reduced to vinegar fairly quickly.

 

It sounds like your instinct is probably correct about acetaldehyde; I would give this one some time to clean it up and take another sample in a few weeks.

I doubt it oxidized, infection is possible given the airlock being loose was the only difference between the two brews; was that the only difference between the two you can pinpoint?

The only other cause of cider or tart like off flavors that I know of is using too much corn sugar in your recipe; since only half your batch is tasting off like this; I very much doubt this also. Did you use a large amount of corn sugar per chance?

I would give it some time and see; most likely those cidery/tart flavors will go away as acetaldehyde is turned into EToH.

It does however still strike me as odd that only 1/2 your brew has the off flavor; if they both stayed at similar temps the entire time they would both likely have these off flavors- given they are the same batch split into two vessels.

The fact that the off flavor is present in the bucket that had the airlock come loose makes me think it might actually be infection.

Do you have a microscope you can look at a drop of yeast slurry under to see if it is infected?

 

Wouldn't 3 weeks be a little early to see obvious signs of infection (pellicle, snot,...)?

 

@sjverla , my recommendation is that you maintain positive thoughts and just let the beer 'ride' for another week. Hopefully it is just an issue of the beer still being 'green' (i.e., acetaldehyde) and the extra week will permit the acetaldehyde to be processed by the yeast.

Please report back how things turn out.

Cheers!

 

A standard microscope is not a good way to check for bacteria, due to the small sample size / dilution required to thin the yeast and trub out enough for viewing under typical magnification. Most breweries rely on innoculating growth media with wort samples and incubating for 5 to 7 days until any bacteria that maybe be present grows into a large enough colony to become visible to the naked eye.