Oxidised bottles in batch

[daggermark]

A first for me, I've had a couple of oxidised bottles in a batch. They don't seem to be related in terms of first/last bottles in the batch.

I use swing-top bottles and the seals are pretty new.

Can't quite work out how this has happened. I syphoned the batch onto sugar solution already in the bucket, and used a bottling wand from there. All bottles were taken directly out of a starsan bucket and emptied before filling with beer. Lids were immediately closed.

Two weeks later, two of the bottles were dark coloured, vinegary, and uncarbonated. The rest (so far) have been fine. Any ideas?

 

[jschein]

Vinegar usually means acetobacter infection.

 

[IslandLizard]

Uncarbonated points to a leaky seal/gasket.

The new fliptop gaskets are a fairly hard/dense plastic now, not the medium compressible rubber they were in the past.

If you're reusing the gaskets, I noticed it helps to flip them before each filling. After flipping, if there's still a deep indentation left, better replace those with new ones. And don't store the empties clamped down.

 

[daggermark]

Vinegar usually means acetobacter infection.

Where could this come from? The hops? I am very very careful on sanitation throughout so I doubt it could come from equipment or mishandling.

Uncarbonated points to a leaky seal/gasket.

The new fliptop gaskets are a fairly hard/dense plastic now, not the medium compressible rubber they were in the past.

If you're reusing the gaskets, I noticed it helps to flip them before each filling. After flipping, if there's still a deep indentation left, better replace those with new ones. And don't store the empties clamped down.

This was my first thought, but the gaskets are quite new and compress nicely. In fact, some of those bottles have only been used once. I've stupidly forgotten which bottles had the 'bad' beer by mixing them up, but all the gaskets look identical to me. I'll flip them all and do another brew and see what happens.

 

[IslandLizard]

Where could this come from? The hops? I am very very careful on sanitation throughout so I doubt it could come from equipment or mishandling.

This was my first thought, but the gaskets are quite new and compress nicely. In fact, some of those bottles have only been used once. I've stupidly forgotten which bottles had the 'bad' beer by mixing them up, but all the gaskets look identical to me. I'll flip them all and do another brew and see what happens.

Aside from the gasket flip/check, also check the bails for having sufficient tension. The sheer force needed to close (and reopen) is an indication of gasket compression and indirectly of making a seal.

Flipping the gasket over before reuse will expose a fresh surface, while giving the other side time to relax and spring back to some degree. They can be reused many times, just keep an eye and feel on them. Maybe you have gotten better gaskets, there's some real hard plastic crap out there.

I doubt the hops are a vector of infection, they're antibacterial. For instance they prevent growth of lacto strains when above 15-20 IBU. Beside, if that were the case, your other bottles would be infected as well.
Air that gets inside the bottles oxidizes your beer, and also the alcohol, turning it into vinegar. Like beer that's been sitting out in a glass or bottle overnight.

 

[myelo]

Where could this come from?

If it's truly just a few bottles, the most likely source of infection is the bottles themselves. Star San is a surface sanitizer so if there is a bit of gunk somewhere in the bottle or cap, it won't get sanitized.

 

[daggermark]

One of the bails is very slightly less tense than the others, but still quite tight.

I'm going to swap a few seals around, and give everything a good scrub in oxy before the star san next time.

 

[daggermark]

Noticed as well today that carbonation across the bottles is inconsistent. The one I just sunk had basically zero head and very little fizz. I wonder if this one was close to being spoilt but just about survived. I racked my beer onto the sugar solution in my bottling bucket so I believe distribution should have been fairly even.

 

[rburrelli]

Noticed as well today that carbonation across the bottles is inconsistent. The one I just sunk had basically zero head and very little fizz. I wonder if this one was close to being spoilt but just about survived. I racked my beer onto the sugar solution in my bottling bucket so I believe distribution should have been fairly even.

A gentle stir before bottling might help with better distribution of the priming sugars. I think your issue is with this and the swing top bottles together.

 

[ncbrewer]

Air that gets inside the bottles oxidizes your beer, and also the alcohol, turning it into vinegar. Like beer that's been sitting out in a glass or bottle overnight.

I've never heard this (about oxidation turning it to vinegar) before. I'd like to read about it if you could share a link.

 

[IslandLizard]

I've never heard this (about oxidation turning it to vinegar) before. I'd like to read about it if you could share a link.

That wasn't phrased right. With Acetic Acid bacteria (Acetobacter), such as from fruit flies.