Black layer of beer in fermenter.

[Bernie678]

I hope this is the right forum:

I was getting ready to bottle my latest batch and found it had done something I have never seen or heard about: there is a three-inch layer of beer at the top of the fermenter has a black tint.

It actually looks like a black and tan. It doesn’t taste like one. I sampled the clear black layer and the cloudy golden layer separately. Both have a sour taste and smell, more pronounced in the black layer.

Details:
This is a simple extract-based Kolsch recipe I’ve made successfully at four times this year. About 6 pounds of Pilsen Light DME with about 2 pounds milled grain (Wheat, Victory & Pils).
Steeped milled grains for 20 mins 3-gals water.
Then brought to a boil and added DME. Boiled for an hour adding hops along the way.
Moved to primary fermenter and added 2 gals of cold water. Added yeast.
Fermented two weeks in cool dark room until fermenting definitely stopped.
Transferred to carboy and moved to a large ice cooler to cold crash & clarify for 3 days. Added gelatin on second day.

Original SG 1.042, final 1.005

I sanitized everything properly as far as I can tell.

My notes reminded that I had a temperature issue while steeping the grains. It hit a high around 180F for a bit but I brought it back down to 160F. That is the only thing I can think of that seems wrong or bad.

Otherwise, I am assuming some sort of contamination.

I’ll have to write this one off but trying to figure out what exactly happened.

Any feedback appreciated.

 

[Jag75]

Is your fv a newer stainless? Could be oils from manufacturer. You definitely got oxidation there as well. Stay away from transferring to a secondary. Also unless you have the proper set up for cold crashing your introducing O2.

BTW, welcome to HBT!

 

[rburrelli]

A Kolsch should not be that dark even in the lighter area of the fermenter. Did your other attempts look that dark?

 

[Bernie678]

A Kolsch should not be that dark even in the lighter area of the fermenter. Did your other attempts look that dark?

It actually appears darker and redder in the picture. It is a golden color in real life similar to what I've made before still cloudy so no clarification going on.

 

[Bernie678]

Is your fv a newer stainless? Could be oils from manufacturer. You definitely got oxidation there as well. Stay away from transferring to a secondary. Also unless you have the proper set up for cold crashing your introducing O2.

BTW, welcome to HBT!

No stainless involved. Plastic primary and glass carboy.

Are you saying the oxidation caused the black layer?

I've been using the same cold crash method for 5 batches (well, 4 good ones and now this.) Started using the secondary on the last three. I may need to be more meticulous in my process.

Thanks.

 

[hotbeer]

What's it look like when you shine a light through the other side?

I'm sort of thinking that maybe the actual beer is all the same color and you just have a clean... but dark layer on top and the bottom has a lot of yeast and trub in suspension still.

 

[Jag75]

No stainless involved. Plastic primary and glass carboy.

Are you saying the oxidation caused the black layer?

I've been using the same cold crash method for 5 batches (well, 4 good ones and now this.) Started using the secondary on the last three. I may need to be more meticulous in my process.

Thanks.

Oxidation causes the beer to darken. Not sure about the black layer. But if it taste sour , some unwelcomed bugs got to it.

 

[Kickass]

I think hotbeer has it nailed. What you’re seeing is yeast dropping out. The top is not as “cream” colored/hazy because yeast is flocculating. The bottom only appears lighter in color because the presence of yeast.

And extract is darker than suggested 99.9% of the time. It’s virtually impossible to brew a light extract beer. Even with all the tricks.

 

[BrewnWKopperKat]

FWIW, beer color isn't measured when it is in the carboy.

It’s virtually impossible to brew a light extract beer. Even with all the tricks.

Back in May 2021, there was a topic that discussed how to brew light colored extract-based beer.

The "tricks" are the same "tricks" that all-grain brewers use (fresh ingredients and oxygen pickup mitigation).

 

[Beermeister32]

If it is sour, you have a bacteria infection picked up somewhere. Might have happened with your topping up water or process.

 

[passedpawn]

What's it look like when you shine a light through the other side?

I'm sort of thinking that maybe the actual beer is all the same color and you just have a clean... but dark layer on top and the bottom has a lot of yeast and trub in suspension still.

^^ that's your answer. As the yeast settles to the bottom, you'll see that exact effect. The clear beer at top appears dark because there is no suspended yeast to reflect the light.

Sour is bad, but it's possible you're just tasting the yeast in there. I work at getting all the yeast out of my beer before kegging - don't like the taste of it. Kolsch yeast (and others) can produce a sufur-y flavor, especially when fermenting in cold temps. That will go away with a bit of time at room temp.

 

[camonick]

Transferred to carboy and moved to a large ice cooler

I think the others above that mention that the lighter colored beer still has yeast in suspension are on to something. There is a ton of debate about the advantages/disadvantages of using a secondary, but one thing that is absolutely necessary if you do use one is that it needs to be the same size as your batch, ie. 5 gallon batch— 5 gallon carboy (filled as full as possible with very tiny headspace).

 

[Bernie678]

What's it look like when you shine a light through the other side?

I'm sort of thinking that maybe the actual beer is all the same color and you just have a clean... but dark layer on top and the bottom has a lot of yeast and trub in suspension still.

Thanks for the response. The beer isn't the same color. As mentioned, I sampled both layers. I've attached pix of both in the glass. I guess I should have added these pix to original post but didn't think it was necessary.

The "black" layer is definitely darker than I have seen in previous batches of the same recipe.

Also the beer was already fairly clear and uniform golden color when I moved to secondary.

I'm thinking oxidation and/or contamination when moving to secondary as others mentioned.

 

[Bernie678]

I think hotbeer has it nailed. What you’re seeing is yeast dropping out. The top is not as “cream” colored/hazy because yeast is flocculating. The bottom only appears lighter in color because the presence of yeast.

And extract is darker than suggested 99.9% of the time. It’s virtually impossible to brew a light extract beer. Even with all the tricks.

Thanks for the response. Actually I've brewed several light colored extract-based beers in the past. Especially since switching to DME.

Still not sure what happened on this batch. I am assuming I got sloppy at some step and it oxidized or got contaminated.

 

[hotbeer]

Well those didn't come from the same carboy. We weren't saying the color of the beer when in the primary was the same as the beer after transferred to the secondary.

Or if they did come from that carboy in the picture, then the same thing already mentioned, the lighter beer has more stuff suspended in it to scatter the light making it appear lighter.

There are good reasons why it may have darkened. But I'll let those more experienced run with that.

 

[Bernie678]

I think the others above that mention that the lighter colored beer still has yeast in suspension are on to something. There is a ton of debate about the advantages/disadvantages of using a secondary, but one thing that is absolutely necessary if you do use one is that it needs to be the same size as your batch, ie. 5 gallon batch— 5 gallon carboy (filled as full as possible with very tiny headspace).

Good point re the headspace. That hadn't occurred to me. I may have just gotten lucky on previous batches with so much exposed surface area. I'll try a 6 gal batch the next time.

 

[Bernie678]

Well those didn't come from the same carboy. We weren't saying the color of the beer when in the primary was the same as the beer in the secondary.

Or if they did, then the same thing already mentioned, the lighter beer has more stuff suspended in it to scatter the light making it appear lighter.

Regardless, this recipe has never produced beer this dark.

 

[hotbeer]

Well also note that in the picture, the darker beer is also more transparent and you can see the towel behind it. The lighter beer is opaque and the details of nothing behind it can be seen.

 

[Bernie678]

Well also note that in the picture, the darker beer is also more transparent and you can see the towel behind it. The lighter beer is opaque and the details of nothing behind it can be seen.

Thanks for your input but I am not really sure of the point you are trying to make. I’ve attached the picture as a reference and it seems to be clouding the issue (pun intended.)

I can assure you that the beer is indeed two different colors, you'll have to take my word. But that isn’t my question.

I have brewed this batch several times using the same recipe and methods and have never seen this before.

I am asking if anyone has suggestions as to what went wrong, particularly if anyone has seen it before.

Seems like contamination or oxidation are the likely culprits but I’d love to have a more definitive answer.

 

[hotbeer]

Seems like contamination or oxidation are the likely culprits but I’d love to have a more definitive answer.

That's my take on it too. I'm not experienced in the causes of beer darkening to give you any answer about that.

But you did seem to be wondering why the top and bottom of the beer in the fermenter were different colors in your title and in the OP. I am just suggesting reasons why the top appeared darker than the bottom.

 

[BrewnWKopperKat]

@Bernie678 : What does a secondary fermenter do? has some photos of some "side-by-side" extract-based recipes - 1 with and 1 without a transfer to a secondary container.

Also, it may be that the "steep" temperature reaching 180F had an impact on this batch. Two of the malts you listed (Wheat & Pils) need to be mashed to convert starches into sugars. If you had good temperature control during the steep for the other (good) batches - but had bad temperature control with bad results on this batch - it may be that getting to 180F had a negative impact.

 

[Kickass]

O2 exposure will darken the beer overall, which may be partially to blame. But, even with your side by side glass comparison, it very much looks like yeast in suspension in the “lighter” glass. Yeast is creamy white in color and is clearly very much present in one glass and not the other.
If it were me, I wouldn’t be worried. Try to minimize O2 pickup next time, continue to use fresh ingredients and continue to employ all the extract tricks.

 

[Bernie678]

@Bernie678 : What does a secondary fermenter do? has some photos of some "side-by-side" extract-based recipes - 1 with and 1 without a transfer to a secondary container.

Also, it may be that the "steep" temperature reaching 180F had an impact on this batch. Two of the malts you listed (Wheat & Pils) need to be mashed to convert starches into sugars. If you had good temperature control during the steep for the other (good) batches - but had bad temperature control with bad results on this batch - it may be that getting to 180F had a negative impact.

Yeah, I usually control the temperature carefully but turned my back a little too long this time. I was kicking myself for letting it get so high but at that point I figured I was in for a penny.

 

[Bernie678]

O2 exposure will darken the beer overall, which may be partially to blame. But, even with your side by side glass comparison, it very much looks like yeast in suspension in the “lighter” glass. Yeast is creamy white in color and is clearly very much present in one glass and not the other.
If it were me, I wouldn’t be worried. Try to minimize O2 pickup next time, continue to use fresh ingredients and continue to employ all the extract tricks.

Yeah, there was yeast in suspension but the color difference is much more significant than the pix suggest. It wasn’t due entirely to the yeast.

I’m not overly worried, I know bad batches happen. I’ve had good luck for quite a while so probably overdue for this to happen.

I am still curious as to what exactly went wrong but regardless, I got a couple good suggestions otherwise from the post.

I had to dump the batch but just ordered the same ingredients from my local shop and will try again this weekend.
Moving forward.