Keg coupler causing off flavours?

[hebbstar]

Hi All

Ive been having issues with my kegging recently. I'm trying to brew in the spring and keg into 50l Crusader kegs. When Summer comes around the plan was to rack from these in to corney kegs so to fit in a Keggerator.

The last two batches have had to be thrown because of a strange flavour that been left in both beers. It's affected both a Summer Lightening and a Bass clone in the same way, a lemony stringent taste that lasts a short while on the tip if the tongue before it disappears leaving some of the background flavours of the beer.

This kind of flavour has affected a number of brews over the past few years. I don't get this issue with corneys.

On closer inspection of the keg coupler it doesn't look like it is stainless steel. It looks as though it was just a coating of stainless but copper underneath.

On reflection the taste does seem to be a bit metallic, but this could be a trick of the mind given I think it's copper exposure!

I'm going to change it as I think it could be the cause...

Would extended periods of exposure to copper be a cause of these flavours?

Cheers

Paul

[Kev888]

Copper coated with stainless seems unlikely, but I've had chrome-plated brass couplers so perhaps thats what you're seeing.

I haven't had this effect, but then nor have I left the coupler itself full of beer for extended periods (just whilst the keg is 'on', dispensing). Are you really leaving the coupler coupled between spring and summer (i.e. instead of letting the keg seal), or have I misunderstood?

TBH I'm not sure it would be the cause though. Unfortunately its extremely hard both to identify flavours and to convey them in words, so its hard to guess over a forum. For me, the main lemon-like contributors are certain hops, but there could also be sourness thats lemon-like in that respect (perhaps in combo with fuity esters or something).

[hebbstar]

Keg

The coupler is left in just for carbonation and the odd sampling which can be up to a week.

It does look like it's copper with a chrome coating.

As mentioned I get the same flavours with very different hop bills.
I could be transferring an infection between the kegs I suppose?

I've left the kegs with a VWP solution to soak for a few weeks until I get the chance to brew again. It gets too hot to boil when the weather is like this, not complaining though, just running out of beer!

Thanks for the response.

Cheers

Paul

[Kev888]

Hmm, I wonder if your cleaning process might have a bearing on things, if not the lemon flavour, then at least the coupler.

If you still think it looks like copper beneath then thats not impossible, but it could also be brass with some of the zinc component dissolved away, leaving just copper on show (copper being the other main component of brass). But either way, it seems fairly clear that the coating at least has been eroded by something.

I'd also hesitate to leave VWP soaking stainless kegs for weeks. Properly diluted chlorine-based cleaners aren't too bad for good quality stainless with normal or short contact times, and (whilst I have my reservations) VWP is claimed to be acceptable for that. But 'weeks' is really quite a long time..

So its just a guess, but is it possible that you're generally over-doing the cleaning, combined with slightly risky chemicals?

[hebbstar]

Kev

Good shout. I'll drain the VWP (quite weak solution) today and give it a good rinse with water via my keg washer.

All my other keg couplers a definitely stainless steel just this one that's a bit dodgy. Unfortunately the dodgy one is the only one with a PRV so I may still have to use it when removing the spear.

Thanks again for the feedback.

Cheers

Paul