Off flavour

[JackoNZ]

Hey all, hoping you might be able to help identify an ongoing problem with some of my beers. Here's the hard facts:

Effects darker beers not light lagers.
Has cropped up in my old kits n bits beers as well as first two all grain beers.
Don't think it's yeast as it's in beers with S-04 and S-23.

It's been described as an earthy type flavour, I personally wouldn't describe it as that but I do get a flavour that is just out of place, metallic/minerally maybe??. Seems to be worse when the beer is chilled too. A mate who has tried the beer said it does seem to drop off as the beer ages.

I would say it looks like maybe the water I'm using is causing it, straight out the tap. But then if that's the case why don't I get this with lagers?

For info it's cropped up in stout, brown porter and schwarzbier.

Any ideas what could be causing this off flavour?

Cheers

[Greig McGill]

Sounds like you're describing too much chocolate malt to me - I always dislike the powdery earthy type taste that gives. It might also be sparging too hot - I have noticed more tannin extraction from darker grains than pale when doing this on a "bad practice" day. Another option, as you suggested, water. I can't explain why it wouldn't be in lagers though, my chemistry is not up to much. As a simple test, do a batch using filtered water - just borrow someone's benchtop filter, or worst case, buy some water from the supermarket. If it goes away, it was your water, and I found a huge improvement when I started filtering my water anyway - that chlorine taste was a major problem in my early beers. You might notice a benefit too, even if it doesn't fix this problem.

[JackoNZ]

Cheers Greig, not sure it's the chocolate malt, it is in all those beers but with the all grain ones it's less than 3% of the grain bill each time. My sparge water is usually around 75c. I'll give the store bought water idea a go first I think. If that does solve it how much do these benchtop filters cost, do you have a link to the kind of thing your talking about?

[Soren]

Do you get a good clear wort from the mash or does it have a lot of husk in it? Do you check the pH of your mash? low pH can extract unpleasant tannins and a darker grain bill will have a lower pH than a light one, this would explain why it doesn't affect your largers...

[JackoNZ]

I use BIAB so my wort would tend to be on the cloudier side than your traditional methods. There is no husk in there though that I can see, the bag does a good job of keeping that out. Not loked at PH or salt addittions to my water yet as it's too bloody confusing!! I thought about starting off with some ph stabiliser for the mash but then read conflicting views about it being needed. Is it worth a shot??

[Soren]

i've never used the pH stabilizers but think i heard somewhere they could give a minerally off flavor, dont quote me on that though:) i would just try and get some pH papers that were reasonably accurate in the 4-7 range and stick them in the mash to check. it's less accurate than a pH meter but much more user friendly. if your pH is of you can adjust the salts accordingly. salts and papers will set you back $25 maybe with enough for 50 brews...

[Greig McGill]

Benchtop filters vary - I use a microlene one I got from the local dealer in Hamilton. I think it set me back around $180 with $90 filter replacements once a year. Best investment I ever made though - water and temp control were the two things that made the biggest difference to my brewing quality.