[hang5lngbd]

My recent batches have all had a vinegar flavor to them. From my research so far I gather that they are probably getting contaminated. However, this last batch was so clean I don't see how it could be so.

Equipment that touches the wort:
Glass carboy - old but well sanitized
Copper coil wort chiller - sanitized and put in at 20min on the boil
Plastic Funnel. - Bought a new one and sanitized it
Metal aerator - Well sanitized

If anybody can think of something causing this problem it would be much appreciated.

Gaffer

[tygo]

What exactly is the metal aerator?  Are you talking about a stainless steel diffusion stone or a mix-stir or something else?

[AmandaK]

From my research so far I gather that they are probably getting contaminated. However, this last batch was so clean I don't see how it could be so.

So was the last batch unaffected by the vinegar?

Either way, vinegar usually comes from acetobacter. Acetobacter is a bacteria that thrives on oxygen and uncleanliness. Can you go into more detail on your process?

[hang5lngbd]

From my research so far I gather that they are probably getting contaminated. However, this last batch was so clean I don't see how it could be so.

So was the last batch unaffected by the vinegar?

Either way, vinegar usually comes from acetobacter. Acetobacter is a bacteria that thrives on oxygen and uncleanliness. Can you go into more detail on your process?

My last batch smells / tastes terrible - vinegary as well.

After the beer has cooled I put my aerator into the carboy before pitching the yeast. I use an oxygen canister connected to a diffusion stone like device and the beer is aerated in 20seconds or so. I cleaned it well enough I think.

Just for kicks, I'll not aerate today and report back.

[denny]

So, what about your cleaning process?  You can't sanitize something that isn't clean.

[tygo]

I use an oxygen canister connected to a diffusion stone like device and the beer is aerated in 20seconds or so. I cleaned it well enough I think.

Might want to try boiling the diffusion stone for 20 minutes or so. 

[In The Sand]

+1 I boil and then StarSan my diffusion stones.

[Joe Sr.]

+1 I boil and then StarSan my diffusion stones.

I've never boiled the stone and never had an issue.  Star san before and after use.  I run O2 through it after use while it's in the star san.

[hang5lngbd]

I use an oxygen canister connected to a diffusion stone like device and the beer is aerated in 20seconds or so. I cleaned it well enough I think.

Might want to try boiling the diffusion stone for 20 minutes or so.

Boil the stone with the wort?

[redbeerman]

I use an oxygen canister connected to a diffusion stone like device and the beer is aerated in 20seconds or so. I cleaned it well enough I think.

Might want to try boiling the diffusion stone for 20 minutes or so.

Boil the stone with the wort?

Boil it in water.  If nasty little guys have taken up residence in the sintered holes, you need to either boil them or heat them in the oven until dead.  You should do this between uses as a matter of procedure.  Joe's way seems to work as well, but I would feel more comfortable with heat.

[Joe Sr.]

Joe's way seems to work as well, but I would feel more comfortable with heat.

I'm certainly not saying don't boil it.  Particularly since you have an infection.  Can't be too careful.

I've just never needed to.  And I'm lazy.

[hang5lngbd]

I use an oxygen canister connected to a diffusion stone like device and the beer is aerated in 20seconds or so. I cleaned it well enough I think.

Might want to try boiling the diffusion stone for 20 minutes or so.

I boiled and sanitized the diffusion stone and that seemed to have fixed the issue. Current batch is clean and ready for kegging.

[In The Sand]

Great! Maybe that fixed it.