Beer flavor total change in a day

I kegged a stout on Friday. I've been tasting the beer every day to check the progression. Regardless, it's tasted really good every day, just low on carb. Today, however, as soon as I pulled the tap handle I knew the carb today was perfect. Great head, bubbles throughout. Excited, right?

Then I go I taste it and in less than 24 hours, the flavor profile has completely changed. The first and overwhelming taste is metal. It fades to a nice roastiness, but every mouthful is dominated by metal. There wasn't even the faintest hint of this yesterday and today it smacks me in the face. To me, it's weird that this flavor appears the exact day as the perfect carb level (yesterday when pouring, there was a slight fizz, but no head).

My impression is that the metallic taste disappears as the pint progresses (perhaps either the flavor is in the foam or I get accustomed to the taste).

Ideas?

 

I'd guess you overcarbed it. You are probably tasting carbonic acid

 

OK, ill not discount carbonic acid, but I set the psi at 14 like I do for most of my beers. I didn't power charge the keg. It's not overly foamy and has the right amount of co2 "bite."

A) How or why does carbonic acid form? I know you say over carbing can cause it, but as this taste is new for me and I've carbed my kegs the same way for a few years, that doesn't seem to be the process culprit here.

B) After another pint I determined the metallic taste is not noticeable except in the head. Does carbonic acid only present in the head?

C) can I assume what's done is done and I can't remedy?

Thanks for the feedback!

 

First off, I wouldn't say that there is a perfect setting for all beers. Perhaps how you have it set is just too much for this particular beer. What kind of stout is it? If it's a low gravity British/Irish style, then I'd say overcarbing is a definite possibility.

The amount of CO2 in solution is a product of psi AND temperature. At a given psi, as temperature decreases, the amount of carbonation in solution will increase. Have you recently changed the temp settings on your kegerator.

I don't know that carbonic acid would be called a metallic flavor, but I'd say it could be very similar.

Finally, no, what's done is not done. If it is overcarbed, simply take your keg off the gas and occasionally burp the keg to let some of the CO2 out. Might take a while to get where you want it.

 

I know there isn't a perfect setting for all beers. I've found that setting around 15psi has given me more or less a good result from most of my brews. I up that number for my wheats, for example.

This is a dry stout, but it is a fairly high gravity (accidentally great efficiency that brew day) for a dry stout, ringing in at about 6.5%. My kegerator temp hasn't changed from the 48* I set it at ages ago.

If carbonic acid isn't really a metallic taste, I'm not sure what it could be. When I say metallic, I truly mean it tastes like liquid pennies in the head. When the head dissipates, the taste goes away by about 95%. Does that sound familiar at all to anybody?

 

This is exactly what it sounds like to me as well. I've had that metallic taste in my kegged beer. At first I thought it was the keg, but after purging and reducing the PSI, letting the keg sit for about a week and re-adjusting the PSI, it faded away. Other than that, I've heard of people with oxidized beer saying it tastes that way...people saying that PBW made it that way...using non-oxidized aluminum BK, the list goes on...

 

I said that I could see thinking that carbonic acid was metallic.

15psi at 48 would be 2.38 volumes of CO2. I'd say that's high for a dry stout. All you can do is reduce it and see if it fixes it.

Pour a glass and whisk some of the CO2 out of solution and see how that is.

 

I'll dial back the co2. Thanks all.

Here's my last question. I've run dozens of kegs through this system on more or less identical settings. 48*, 15psi... This is the very first time this has happened.

Are certain grains more susceptible to carbonic acid? Certain styles? Thanks!

 

I have the exact same problem. The problem seems to be CO2 level, but it doesn't take much for the head to taste metal... If anyone has any input, it would be appreciated.