Oily Scum

[reformed99]

Just having a look at a toucan of coopers lager I put down 4 weeks ago. Tasted OK when I was bottling it but it seems to have an oily scum on the surface of the beer in the bottle.


Its sort of hard to see in the picture but is it normal?

 

[Adamt]

Crack one (over a sink just to be careful), pour into a glass, smell and taste. You'll soon know if there's something wrong with it.

 

[newguy]

The "gospel" in the homebrewing literature is that this is a sign of infection, but I haven't noticed a correlation. As a matter of fact, I've had many infected beers that didn't have the ring around the neck/oily scum.

As Adam said, open one and see. Do it near a sink just in case it gushes.

 

[reformed99]

Just cracked one open. No gushing and it smells like beer to me. Had a taste and it has a fairly "harsh" bitterness, but I think thats just cause the toucan would be pretty bitter anyway.

If it was infected what would it smell like? Off milk? Varnish? Or something else?

 

[Adamt]

It can be a variety of things, vinegar is a pretty common one (acetobacter infection). You can also get sourness/acidity (lactobacillus), sweatiness/horseyness (brettanomyces) or medicinal/plastic/smokey/ham (phenols).

Long story short, you'll know pretty quickly if something is wrong

 

[lobo]

adam, is phenols an infection?

Lobo

 

[Adamt]

Excess phenolics can be a sign of infection, especially if the yeast pitched was a clean ale or lager yeast. However it wouldn't just spring up in the bottle if it tasted find out of the fermenter.

 

[Adamt]

Another thing reformed... how did you prepare your bottles? The scum could be from residual sanitising chemicals.

 

[jayse]

This is a fairly common infection, it'll proberly have some white colour to it or white spots, even white clumps floating in the beer if disturbed. It'll stick to the sides of the bottle like a slime too.

Anyway its not all bad news though as it can be slow acting in a bottle of beer and the beer may remain drinkable for months.

 

[reformed99]

Another thing reformed... how did you prepare your bottles? The scum could be from residual sanitising chemicals.

Yeah thats what I was thinking too. Soaked them in sodium percarbonate for a week, rinsed them out with the hose then put them in the dishwasher. Just before bottling put some starsan in and then tipped it out. No rinsing afterwards

This is a fairly common infection, it'll proberly have some white colour to it or white spots, even white clumps floating in the beer if disturbed. It'll stick to the sides of the bottle like a slime too.

No white spots or slime so maybe it is just something left over from the cleaning/sanitising. I just had another one and there is no strong or unsual taste, just the bitterness at the end.

 

[reformed99]

Feeling a lot better now. After a bit more reading it seems a few people get this on the odd occasion without it being an infection. Theory that it is a. hop oil or b. surfectant in the starsan.