Infection or something else

[Shoit]

I brewed a porter 5 weeks ago which has been in a corny keg for the last 4 weeks. The beer tasted fine straight out of the FV, fermentation was controlled at 19 degrees and FG was 1010. However, after approx 2 weeks in the keg i noticed a slight aftertaste which I can only describe as 'stale'. 3 weeks later it definitely doesn't taste right. The taste doesn't seem to be getting more prominent however something is definitely not right.

The brew day and my sanitisation procedures were unchanged from previous brews. I have not used this keg before, it was brought from Norm. I did not strip it down but did clean it, then sterilise it with chlorine based steriliser, rinse then use starsan.

I'm really not sure what's gone wrong - any suggestions gratefully recieved?

Kevin

[trucker5774]

When I think of infection I think of vinegar, rather like a cask ale which has been tapped way too long and oxidised with a sour taste.............there are other infection tastes of course. Is this a recipe you have done before and are the ingredients from a known or new batch? Could it just be a new taste? My money, for peace of mind, would be to see how this one goes then strip the cornie and clean and sanitise as you always do.

[Dr. Dextrin]

I've been experimenting with various kegging arrangements recently and have experienced something rather similar, maybe because I've not been following a routine and therefore been less careful.

I'm not exactly sure, but I think it might be due to not purging all the air out when the keg is filled. What I think happened is that the top layers of the beer have staled through oxidation. The first stuff tastes fine (from the bottom) - then you start drinking the staled stuff, but it doesn't get any worse because all the oxygen has been used up by then. I've left one of my kegs for quite a while now just to ensure it doesn't get any worse - and it doesn't, so I don't think it's an infection problem (plus the stuff I bottled is fine).

That's just a hypothesis, mind, but it might be relevant to your problem.

[gnorwebthgimi]

I take it that the beer is still drinkable but not enjoyable? (which makes infection less likely).

I had a similar issue, which I believe was hot side aeration but could also be an off flavour from the yeast. The taste I have is slightly sour but mostly just void of any malt flavour. Basically just "past it's best" at 2 weeks after fermenting.

Does this sound similar to your issue? If not my only suggestion is you take a part the tap and see if there is any "gunk".

Here is a link to the discussion: viewtopic.php?f=2&t=35444

How did you do the mash?

Did you aerate the wort (EG by dropping it into the fermenter) and what temperature was the aeration?

And did you use the s04 yeast?

Did the beer get splashed around when you transferred it to the keg or were any bubbles of air taken through a siphon into the beer?

I will know if hot side aeration is my problem in a few days and will add to my post.

[Shoit]

Thanks for all the replies, ill try and answer all the questions. It is a new recipe but the beer tastes different since it went in the keg. The wort was transferred into the FV at 20 degrees and was dropped into the FV via the tap from about 3ft. I am sure the tap was clean but i didn't run boiling wort through it before transferring into the FV, although i did sterilise the pipe.

I did have a problem when transferring into the keg as the syphon stopped, I tried not to let any air bubble through what was already in the keg but can't be sure.

I did use S04 yeast, the beer is still drinkable at this stage but I will need to wait and see if it gets any worse. I'll just sit on it and see what happens.

Any other suggestions greatly recieved, the only real difference in my process has been using a new keg and using star san which was several weeks old but not cloudy. I'm gutted to have had my first problem in 10 brews

Kev

[gnorwebthgimi]

Hi Shoit

Your answers are interesting. (I am assuming the taste is the same as I described).

Because your mash was normal (right?) and you have never had this issue before, it is unlikely to be HSA.

Your issue does SEEM to be oxidation from using the new barrel/equipment but it could be due to the siphoning issue.

You could try blanketing the keg with CO2 before siphoning the beer in to reduce the amount of oxygen in the barrel. Was there a lot of dead space in the keg when the beer was added (would mean more oxygen)?

[Shoit]

It's always difficult to describe tastes, it's definitely not sour or vinegary. It's just a stale taste. I purged the keg after filling with CO2 and refilled, the keg is also holding pressure ok.

What difference would the mash have made? Im sure temps were around 66deg for the 90 mins.

Kev

[gnorwebthgimi]

I would describe my "sour" taste as an absence of any nice malt or estery flavours, with a kind of mild sourness. More noticeable for the lack of flavours than the prominence of any particular flavour.

Hot Side Aeration can be caused by exposing the mash to oxygen. EG by transferring the mash to a lauter tun or filtering the wort as it comes off the mash (which is what I did). In most cases the steam rising off the mash will drive off oxygen or a very minor amount of exposure will cause very little effect. Many brewers transfer the mash out of a mash tun and into another vessel in order to sparge with no ill effects.

If hot side aeration does occur, the oxygen bonds with proteins and lipids and slowly breaks apart from these chemicals over a period of time, which explains why the beer stales on conditioning.

I (believe I) suffered ill effects because I filtered the wort (to improve clarity), which was just dumb and unnecessary. I doubt its an issue for you unless you can think of a reason why it would be (did you splash around the mash, did you leave the wort sitting around at mash temperatures for a long time?)

If you blanketed the keg with CO2, then my only suggestion is something trapped in the tap of the keg or it was oxygen introduced due to siphoning (I would have thought the yeast could have absorbed this, but I'm paranoid about oxidation).

Other people may think water treatment, but I have doubts over this.

[Shoit]

Just looking back over my notes, I did use an older batch of starsan. I'm also not sure how much of it i left in the bottom of the keg - is this something that could cause this type of flavour?

Kev

[adm]

What was your water treatment? Did you add any "common" salt to the liquor? I had a batch of porter a while back that tasted as you describe and I put it down to too much salt. That may or may not have been the cause.....

[Shoit]

I did add common salt to the water treatment, the water treatment I added was as follows

1x campden tablet
1.1g Gypsum
13.3g Calcium Chloride
2.5g Epsom
5.7g Salt
2.4g Chalk

This was based on my water profile using the stout profile from GW water treatment calculator. I 30l of water, my water profile is
CaC03 - 12 mg/l
Mg - 2.9 mg/l
Sodium 10.5 mg/l
Sulphate 39.9 mg/l
Chloride 12.3 mg/l

Looking at those figures - I wonder whether I mucked up the water treatment?

Kev

[gnorwebthgimi]

If it was water treatment then why did the flavour develop and not present immediately and only on conditioning?

I have two more questions, is this your first dark ale? (dark grains lower mash PH, which could have an effect)
and did you use a low amount of bittering hops (hops boiled for 30 minutes or more) or hops with a low alpha acid? (If the yeast caused this flavour then higher bitterness could mask it in previous beers).

I still doubt water treatment.

[Shoit]

Its not the first dark ale i've done, it's the third - haven't had anything like this before. I checked mash PH - it was just below 5.2

I strongly suspect that it's the keg that's at fault - I can't find anything else that i've done differently. Perhaps i need to give it more time - see if the flavour gets worse. If so, ill assume its an infection. If not, I'll assume oxidation or poor cleaning of the keg.

Kevin

[adm]

I did add common salt to the water treatment, the water treatment I added was as follows

1x campden tablet
1.1g Gypsum
13.3g Calcium Chloride
2.5g Epsom
5.7g Salt
2.4g Chalk

This was based on my water profile using the stout profile from GW water treatment calculator. I 30l of water, my water profile is
CaC03 - 12 mg/l
Mg - 2.9 mg/l
Sodium 10.5 mg/l
Sulphate 39.9 mg/l
Chloride 12.3 mg/l

Looking at those figures - I wonder whether I mucked up the water treatment?

Kev

I did a couple of Porters using GW's calculator where it had said to add quite a lot of salt, and I didn't like the outcome.....I did another but eliminated the salt and I much preferred it. I'm not sure if this is in any way related to the taste you mentioned, but it might be worth trying a brew with less or no salt to it.

[gnorwebthgimi]

how is the carbonation on the beer?

Perhaps this is a gusher infection. (I'm starting to suspect this is my issue).