Metallic taste from hand pump

[BlackRegent]

Calling the resident beer engine experts @peebee @Dads_Ale et al

I've had my Angram CQ up and running for a few months now. Something I have noticed is that pints pulled through it often suffer from a sharp metallic taste, which normally dissipates after a few minutes.

I'm assuming it's carbonic bite rather than a taint from any of the equipment the beer passes through.

I keep the kegs pressurised by topping up the CO2 after a session using a sodastream cylinder connected to the gas in and I try to keep it at around 5psi (this may seem high, although I think I spoiled a keg of bitter by letting the keg depressurise too far and the seals failed so 5psi seemed like the lowest pressure that would guarantee a proper seal).

Does a pressure of 5psi seem the likely culprit for the metallic taste or could it be something else? Do I need to go down the path of installing a low pressure regulator?

Also, why does beer from the kegerator (which typically dispenses at 15psi) not show any metallic taste at all? Because it's served colder? Because it's masked by the style of beer?

 

[johncrobinson]

I used to be a bar manager and as such was responsible for the cellar.
I can honestly say that with beers/lagers at all sorts of pressures and gas mixtures i never had any taste problems. Certainly never anything that could be described as "metallic"

I would suspect a metal contamination somewhere in your brewing chain.

 

[BlackRegent]

@johncrobinson Thanks for the reply. The reason I don't think it's contamination is because the taste disappears after a few minutes. I would have thought that a taint caused by contamination would be present throughout. Also, all the brews I've done and put in the kegerator (but brewed using exactly the same equipment) don't display any metallic taste at all. It only seems to appear when I pull it through the beer engine. My pressure control of the kegs connected to the beer engine isn't very precise so I wondered if it was creating carbonic acid somehow.

 

[peebee]

Can't say I've experienced "metallic" tastes from a hand-pump. But you could be on the right thinking believing it to be CO2? I do know CO2 is accused of causing such tastes (metals often aren't the culprit, I believe one contaminant - iron - creates off-tastes of blood). The turbulent flow through a hand-pump might do something as excess CO2 is forced out of solution?

Having said that, I've a porter on hand-pump (1850 Whitbread recipe) that often hovers about 6-10PSI (perpetual secondary ferment) and no hint of metallic flavour (although not a good example - it is strongly flavourer anyway).

Keeping low CO2 pressure is virtually impossible with most regulators. Get a "secondary" variable LPG regulator (e.g. 50-150mbar Cleese), they're not expensive (£12-15). Just avoid getting stuck with POL connectors.

 

[Dads_Ale]

I must say I have not noticed this from my hand pump and I initially carb to 10psi and then reduce to about 3-5psi for storage during sessions.
The only things I could find for giving a metallic taste are leaching from metal parts or old malt.
I have noticed on some beers the foam/froth can be a bit bitter/metallic. Do you serve through a sparkler or get foam on your poured pints?

 

[BlackRegent]

Thanks for the responses. It's all a bit of a mystery then. @Dads_Ale I think you're right that it seems to occur when there is foam on the beer. It's a 4 flight Angram CQ and I've had the issue on beer pulled through a sparkler (a Banks' Bitter clone), but also without a sparkler (a plum porter). When I bought the pumps they hadn't been used for several years (the guy I bought them off had picked them up from a pub renovation and he only had them for display). I stripped everything down and soaked in sodium percarbonate. I also flushed everything through with Pipeline and did a thorough rinse afterwards. Everything that comes into contact with the beer is either glass, plastic or stainless steel so I can't imagine it is metal contamination. As I say, the taste goes away which doesn't seem to be consistent with contamination either.