Infection

[alecsf]

Hi All,

Again, thanks for the advice on past posts, and the general awesomeness of this forum.

I kegged beer a couple of weeks ago, and I think it's infected. I'm not too bothered (heresy! but wait... see extra information below). I've had a similar 'off-flavor' before after bottling with a 'hand-me-down' racking cane given to me by a UK guy leaving South China (where I am).

Last time I had this, I checked it out on both morebeer and How To Brew, but got the feeling neither of them really described what I can taste. I have a moderate exposure to wine (trading in France) and wine faults, so I think my best bet is to rely on that experience to describe this fault. It's as follows:

1 - Progression
i - Not noticeable at all at fementer-out stage (either to bottles or keg).
ii - In bottles, noticeable only after 4-5 weeks - EG one or two weeks after I start drinking
iii - In keg, noticeable after 2 weeks (see exceptions below)


2 - Characteristics
i - Nothing on the nose, at least until much later on (5-6 weeks in bottle; maybe 3-4 weeks in keg....?). Even then, very hard to describe the smell. The best I can do for smell and taste? Mean; stingy, ungenerous. Sorry; that's the wine background...
ii - First noticed at the very back of the tongue, both sides, leading to an impression of 'all the way across' the back of the tongue, although that's probably just the brain playing tricks...
iii - Slightly 'cooked' (thought not vegetal) taste. This to me points to digestion and therefore to a bug in the beer.
iv - This is the thing which really makes me think it's an infection (although, as I said, I can't find a good description of the taste, linked to an infection, anywhere:
iva - The malty 'generosity' of the beer diminishes faster than the off-flavor develops. You start off with a gorgeous IPA which makes you glad you went All-Grain, then a week later, you think: Meh. It's not watery, exactly, but where's the sweetness, mouthfeel etc.
ivb - Another week goes by and you're like: There's something kinda mean about this beer.
ivc - And then after another week, it's like: This beer is malevolent. I should bin it before it curses my house, sleeps with my wife out of spite, steals my phone and bad-mouths me to all my friends.

So I figure it's an infection partly because it seems to be removing the mouthfeel and sweetness of the original fermented liquid. It's as if something is eating the unfermentable sugars and pooping out this hard-to-describe, very slightly metallic and unavoidably 'mean' taste.

I took a gravity reading to see whether this is the case. I'm looking for a reduction in even unfermentable sugars reflected in lower gravity, right? (calculated to 20C) But it turns our my gravity went up. That said, there's still some CO2 in the beer after only 30 mins of taking the sample which might be skewing the reading. I'll leave it overnight and check again tomorrow. So far:
-- OG: 1054
-- FG: 1010
-- Current: 1012

I said I'm not too bothered about it:

Well, I'm done getting bent out of shape over beer errors. Learn and move on. And...

Extra Information
The beer which had these characteristics before was bottled just during the humid period (very humid here) in mid April, which I figure is high-risk for infection. There was a sudden rise in temp in May, and that's when it started to go off. And I used that racking cane... Which I've since binned.

The current beer... I got kegging set up and kegged it in a Corny (2nd hand), but the corny kept leaking beer and gas, so (though the beer tasted good) I poured it (not tapped or syphoned) into another Corny which has been OK (no leaks). So I figured that if it's infected, this new-ish batch, then that's (the pouring) where the infection got in. I didn't starsan the (washed) lid of the new Corny before putting it in, on order to close it. Doh. I have another beer (a Pilsener SMaSH) waiting to connect to the Sanke coupler (I've only got one gas outlet connected so far) so I'm a bit 'mamahuhu' (whatever) as we say in China about binning what's left of the IPA.

Before I do, there's yet more information...
Right now, I'm pitching in the whole deal from the boil into the fermenter, including trub. Then after 3-4 weeks, I'm syphoning off the beer to keg (previously bottle), leaving a good 1.5-2 inches of trub in the fermenter to throw out. I had two (very) good batches of IPA this way before the first 'off' one.

So, my question:
-- Anybody else had similar characteristics?
-- Can anyone confirm if it's an infection, and if so, what that specific infection might probably be?
-- Anyone think it's caused by leaving too much trub in the fermenter (even though the pre-bottling or pre-kegging beer tastes great, and two batches made this way were great too)?

Thanks in advance for your thoughts.

 

[Talgrath]

To me that doesn't sound like an infection, usually an infection is more obvious and it wouldn't bring about the flavors you describe as I understand them, you'll see odd bubbles or something similar and the beer would either taste rather sour or buttery or something similar. I honestly have no idea what those wine terms mean in terms of taste; but if it's metallic taste there could be a few culprits. First, if you use an abrasive cleaner or pad on the metal portions of your equipment that can bring out a metallic taste for obvious reasons. It's also possible there's high amounts of iron in your water, as hop flavors recede naturally the metallic taste becomes more obvious; if possible test your water for high iron concentrations. Another possibility is that hydrolysis due to poorly stored malts, depending on how you're getting your malts this might be the most obvious answer; I'm not sure many folks in China know how to properly store grains for brewing.

 

[stoutfan87]

To me that doesn't sound like an infection, usually an infection is more obvious and it wouldn't bring about the flavors you describe as I understand them, you'll see odd bubbles or something similar and the beer would either taste rather sour or buttery or something similar. I honestly have no idea what those wine terms mean in terms of taste; but if it's metallic taste there could be a few culprits. First, if you use an abrasive cleaner or pad on the metal portions of your equipment that can bring out a metallic taste for obvious reasons. It's also possible there's high amounts of iron in your water, as hop flavors recede naturally the metallic taste becomes more obvious; if possible test your water for high iron concentrations. Another possibility is that hydrolysis due to poorly stored malts, depending on how you're getting your malts this might be the most obvious answer; I'm not sure many folks in China know how to properly store grains for brewing.

I agree. To me it sounds like it could be a water issue. From what I have read, chlorine can give a metallic taste, but I haven't experienced that personally.

 

[WayFrae]

The way this flavor comes on over several weeks makes me think oxidation. Cardboard, paper, leather, sherry flavor are all forms of oxidation off-flavors.

 

[alecsf]

Thanks all for considered replies. Here's what I think 24 hours later:

Oversensitive? Me?
It's possible I'm just over-thinking this. I let the fridge relax a bit, and reduced the carbonation, and the 'mean' flavor seems to have dropped back a bit; or conversely, the malty richness and original bitter is coming through better. The beer as it stands definitely has a fault, but it's not (so far) bad enough for me to bin the batch. I'll see how it drinks over the next few days. For perspective, though, I wouldn't send it back in a pub in Scotland or England, but I'd switch to a different beer for my 2nd pint, and if they both had this fault, I'd go G&T or long whisky for the 3rd round.

MOLD!
While I was pouring my beer this evening, between writing paragraphs in this post, I noticed there's mold on the outside of the tap. I scraped some off, but maybe you can still see it here:

I ran starsan through the system when I got it, but I didn't dismantle it.

Here, the moldy season is over. Late March to late May, EVERYTHING gets moldy. Shoes, clothes, etc are taken out of closets in March and scrubbed. Water drips down the walls.

(Perhaps surprisingly, the malt survived in its bucket and sack. At least as far as I know...? Again, if the malt was moldy, I think I'd have noticed at the fermenter-out stage tasting, if not before.)

However, even now, the condensation on the outside of the tap is going moldy in the 30+ heat (the kegerator is, by necessity, in the lobbby; we don't do air-conditioning much in this house). There's something to think on... My fellow brewer up the road keeps a brew-room at 19C all the time with aircon. I might disconnect everything and sanitize again over the weekend. (If somebody spikes my homebrew with Adderall, or something.)

Climate
The climate here is not suited to brewing, but I knew that when I started. The hope of overcoming those challenges is part of the interest in brewing for me. Not saying I'll definitely have it cracked one day, but trying... Incidentally, I'm fermenting in another fridge at 18C; not in the sub-tropical temperatures.

Talgrath:
Maybe you're right about the metallic flavor. I have used steel wool to clean the base of my Urn (BIAB) where the element meets the base. However, the metallic taste (and it's only very slightly metallic) is absent at the fermenter-out stage. On the water, again, I don't think it's changed since I did the best batches back in Feb, March this year. On malt storage, I'm buying Weyermann direct from a reasonably reputable importer (Barthaas). I'm keeping it at room temp (now low-mid 30s) in a dry bucket. I wonder if this is not right. I'll have a look around and check it out.

"I honestly have no idea what those wine terms mean in terms of taste..."

I know what you mean. I can't find a beer 'off-flavor' which matches this either. When I worked in wine, we'd describe as 'mean' or 'stingy' a wine which was disappointing in the level of fruit flavor (sweetness mostly, and some complexity) as opposed to a 'generous' wine which gives a good fruit kick to balance the tannins, alcohol and acidity.

I'll bear this stuff in mind and thanks for the response. Appreciated.

stoutfan87:
Thanks for the 2nd opinion. The water here is high in chlorine, and I think it has also got higher recently (based on taste when brushing teeth - we don't drink the tap water here) that might be a factor. I thought chlorine boiled off, though. Do I need to boil my strike & sparge water before boiling the wort? Or am I wrong about chlorine boiling off? Or do I need to start doing water chemistry to sort out my PH? And can this be cancelled out based on the straight-from-fermenter beer being unaffected by this fault?

WayFrae:
Again, thanks for the suggestion. I don't think it's oxidation (can't detect those flavors) but I'll do some research and try to minimize unnecessary O2 in my process.

BTW, the gravity reading was 1.006 at 31C after the CO2 left the beer. That reads as 1.008 after adjusting for temp. A tiny loss of gravity maybe caused by slight ongoing fermentation in the keg...? Doesn't seem significant to me.

Thanks again. Any news, I'll post it here.

 

[Talgrath]

Well, mold could certainly produce some weird flavors, if it's that humid that could explain things quite nicely. Another thing that popped out at me is that you don't drink the water there, if the water isn't fit to drink it might not be the best stuff to brew with, water that is unpleasant to drink is probably going to be unpleasant in beer too. If possible, you may want to look at getting some other source of water, or a water filter and see if that doesn't improve things a bit.