wierd change in aroma, any ideas?

[oliver tate]

hi,
I am wondering if anyone has any advice on the following. I brewed a heavily hopped simcoe/ galaxy beer a few weeks back. I like to drink these types of beer as fresh as possible, so kegged it in a corny last week. kept the keg at high pressure for conditioning for a couple of days, then knocked the pressure down. I sampled it when I turned the pressure down and the taste was great but I what I was most pleased with was the hop aroma. It smelt clean, fresh, very tropical and utterly mouth watering! I was 100% satisfied with the beer at this point and super pleased with it. I knew what beer I was aiming for and I had nailed it.

After leaving it for a week at serving pressure(I am saving it for a party next weekend) I sampled it again today and it is still full of hop aroma but in a very different way. It still has some tropical notes but to me there is more of a mustiness and vegetal aroma to it. In short, the aroma smells 'older' to me if that makes sense!?!. It's not unpleasant as such, but very different to how it smelt last week. The beer itself tastes great, with no off flavours, its just the aroma I am concerned about.

Now as it happens, I have another batch of it still in a fermenter which I brewed at a later date. After sampling that one today to compare I can say it is still has that lovely fresh aroma, so I know there are 2 different aromas going on here.

Is there something I am doing wrong here? the hops were all fresh, from unopened packets, the beer tastes good, but can a beer really loose that totally fresh aroma so quickly? is there anyway of keeping it for longer as I have had commercial brews from kegs and bottles which have a great fresh aroma to them but they cant all be just a couple of weeks old, can they?

[oakwell]

hi oliver, it'll be interesting to see if the brew that's still in the fermenter goes the same way. how were the hops when you opened the packs? how carefully did you check them for condition and aroma when you opened them? were they healthy, dry and did they display any vegetal aroma? maybe you could post the recipe

[bigrichlock]

Are you flushing the keg with co2 before transfer then flushing 3 or 4 times before force carbonating, my guess would be oxidation.

Cheers

Rich

[oliver tate]

hi, the simcoe hops felt fine, galaxy hops were very sticky and felt fresh

I did not flush the keg before filling, but then again I never have and not had this before. maybe something I need to do in future But I definitely purged the keg a few times once it was full. Would the beer still taste good though if it was oxidisation? I am pretty confident here it is only the aroma that has changed and not the taste

[barney]

If you left it a week has a bit of yeast settled since you racked it and first sampled and you are smelling that, which has been drawn from the bottom of the cornie. I always get a bit of yeast dropping out in the first couple of weeks. It knocks the flavour out as well. Now, if its been left a week or so, I throw a half away so that its clear round the base of the pick up tube.

[oliver tate]

thanks for the suggestion Barney, just tried the beer again after pouring a half off first and its no better.

What was an aromatic, fresh, pale has completely lost its lovely aroma and now smells completely different in under a week which is disappointing. whats more, I had a few bottles worth left over after kegging it so I thought sod it I will see what they are like......same aroma as whats in the keg

I will keg the 2nd batch tomorrow night and be ultra carefully to avoid any oxidation risks and see what happens, although I am bit stumped as to whats caused this to happen in both keg and bottles?

[barney]

hop merchants are buggers, you have to be careful with them. I have had stones the size of golf balls, big lumps of mud and twigs the size of your little finger in various packets. anything like that can introduce bacteria that can take over after a few weeks. I had one taste of sweaty socks and cheese. It was the hops.

[Mr. Dripping]

Oxidation is quite a distinctive taste, I think it's hard to mistake once you know it.
3 things spring to my mind.
Change in carbonation....which can happen in either direction for a host of reasons.
Evaporation of the more volatile aroma oils over time.
Or as barney suggests; the yeast does drag a lot of hop compounds out when it flocs out. 25% of bitterness is list through yeast interaction I recently read.

[oliver tate]

ok, thanks for replies.

I know this sounds like a daft question but what would be the easiest way to replicate an oxidised bottle beer so I can compare. All I read is that it tastes like wet cardboard but I don't find that much help!!

Does oxidation effect aroma or just taste? the reason I ask is that it is definitely the aroma that is off here, if I pour a glass of it then pour it out and stick my nose in the glass you can definitely smell the 'off' aroma that has replaced the fresh hoppyness

[Befuddler]

Probably a low level infection. How does it smell now? Rubbery? I've had a similar thing before in a really hoppy pale ale. It's heartbreaking when all the hops disappear like that.

If you want to oxidise a beer, just pour it into a glass and leave it overnight. Enjoy.