toffee/caramel off flavour...from bottling?

[Baksheesh]

Hello all. New to the board and first time posting.

I need some help improving.

I sometimes get a sweet burnt toffee/caramel flavour after bottling (which I don’t taste when bottling). It fades a bit with time but not sure it ever goes away.
What could it be?
Can off flavours develop in the bottle fermenting that weren't there after primary?
Any idea what I can do to avoid it?

 

[RPh_Guy]

Hi, welcome to HBT!

You're using regular corn sugar or table sugar for priming?
Do other people taste this off-flavor, without you telling them?

Could be...
Too much crystal malt
Old LME
Some kind of scorching/caramelization during mash or boil
Underattenuation
Oxidation

Might help to know more about your process/recipe/readings.

 

[Baksheesh]

Hi RPh Guy,

Thanks for the file - A lot to take in and try and understand.
My process is using a mix of LME and DME for wort and steeping grains for flavour.
Others can taste it.
It has happened 4-5 times in my 26 brews to date. Not consecutively but the last two brews have had it again.
I was tasting this one after 4 days carbonation only, still this is not usual in my early tests.


Regarding your points:
- Last batch only had 100g Crystal and 100g rolled oats so I don't think that's the problem.
- LME is purchased in the last 2 months and less than 1 year old according to can.
- The bottom of the brewpot was clean if that means anything. Also I couldn't taste the same flavour when bottling if that means anything.
- OG 1.038 - FG 1.006, 12 days in fermenter, no activity in airlock so I don't know if it underattenuation
- I don't know about oxidisation. I was always told "cardboard" flavour, which this isn't. But your presentation has a lot more stuff and I suppose it sounds closest to "Melanoidins –Natural anti-oxidants > Honey, toffee flavors (2,3-pentanedione) –cloying notes" whatever that means.

Let me know if all this helps at all or what else I can tell you about process.

 

[ESBrewer]

Maybe it is butterscotch type flavor, which means there is some diacetyl. Does it feel somewhat oily between your fingers? It's hard to imagine the crystal malt flavor would change that much at bottling stage.

 

[Baksheesh]

Maybe it is butterscotch type flavor, which means there is some diacetyl. Does it feel somewhat oily between your fingers? It's hard to imagine the crystal malt flavor would change that much at bottling stage.

Yeah I suppose it could be butterscotch/toffee/caramel are all sort of similar to me. I control fermenting temperature at 18 degrees thought and I don't taste it before bottling/priming. Could diacetyl develop in priming?

 

[ESBrewer]

The precursor alpha-acetolactate (formed during primary fermnetation) may turn to diacetyl when packaging the beer. Higher temp during bottle conditioning and oxygen that dissolves into the beer during racking/bottling may cause this conversion. This is the most likely cause, but bacteria (some lacto, pedio) can produce diacetyl, too. But these bacteria tend to produce excess co2 and make it taste sour, too.

Eventually, yeast in the bottles may take care of diacetyl, but as the amount of viable yeast can be small this may take (too) long.

What type of yeast did u use??

EDIT. Have a look at this https://byo.com/article/dealing-with-diacetyl-tips-from-the-pros/

 

[RM-MN]

Yeah I suppose it could be butterscotch/toffee/caramel are all sort of similar to me. I control fermenting temperature at 18 degrees thought and I don't taste it before bottling/priming. Could diacetyl develop in priming?

Even though you are brewing an ale, you might have better flavors if you do a "diacetyl rest" near the end of the fermentation. Control your temperature in the initial part of the ferment like you mention but after 4 to 7 days let the beer warm to the low to mid 20's C.

 

[Baksheesh]

The precursor alpha-acetolactate (formed during primary fermnetation) may turn to diacetyl when packaging the beer. Higher temp during bottle conditioning and oxygen that dissolves into the beer during racking/bottling may cause this conversion. This is the most likely cause, but bacteria (some lacto, pedio) can produce diacetyl, too. But these bacteria tend to produce excess co2 and make it taste sour, too.

Eventually, yeast in the bottles may take care of diacetyl, but as the amount of viable yeast can be small this may take (too) long.

What type of yeast did u use??

EDIT. Have a look at this https://byo.com/article/dealing-with-diacetyl-tips-from-the-pros/

This time safale-04. Bottling temp is 18-24. That’s not too high is it?

 

[Baksheesh]

I will play with temps and try a rest on next brews.