Help me identify off flavor - "autumn leaves" (?)

[QuercusMax]

In several of my German beers I've noticed a subtle off flavor that bothers me quite a lot (mostly because I don't know how to get rid of it!).

I've detected this in my Vienn-Ale (Jamil's Vienna, fermented with US05), Helles, and Maibock. The helles and maibock were fermented with WLP838. All of these use Durst malts (Pilsner, Vienna, and Dark Munich, in varying proportions), and Mount Hood hops.

This flavor most reminds me of old oak leaves in fall. It's possible it might be a tannin thing? It's extremely subtle, but in the oldest one (the Vienn-Ale) it has become more prominent, at least to me.

Any ideas? I'm using Cleveland Ohio water with no treatments. I haven't noticed this in my british or American beers, but those are either fairly hoppy or estery.

I'm planning on entering some of these in a local contest, in the hopes I can get some better feedback.

 

[estricklin]

The idea of oak leaves does kind of suggest tannins doesn't it? Maybe check your sparge temps, or your ph during the last half the sparge? I've read those can pull tannins out.

I also read somewhere, that older grain can cause some strange subtle flavors in beer, that suggest phenols, but more like wood or grass.

Maybe someone will jump in here with mroe experience.

 

[QuercusMax]

I do a modified BIAB, so my sparge is very fast (I mash at 1.25qt/lb in a kettle, then transfer to a bucket and drain with paint strainer bag, then do a single sparge). Total lautering time is <10 minutes. I'm going to rebrew my helles in a week, and I'll check my ph and possibly add some sauermalz.

When I've checked my mash ph on recent brews (just got test strips recently), they have been 5.0-5.2 for an ESB and a Mild, both of which have a decent percentage of crystal or dark malts.

I definitely have no problems with conversion or attenuation, both of which would be high ph symptoms.

It's possible this is just a "grainy" taste from the Durst? I've cold-aged (at ~33F) all of these for a month after primary, then bottle conditioned.

 

[zzARzz]

If there is a bit of a cheek drying sensation in the aftertaste then it is likely a tannin issue. Often they become an issue when sparging at too high a temperature (for AG batches), squeezing the specialty grain bag for extract and partial mash batches or if the pH is too high when mashing. I suppose your water source could also be a possible cause, so you could try some bottled water for your next batch and see if the flavor is still there.

For my water I made a filter for $10-$15 by getting an inline refrigerator water filter from Home Depot and attaching a couple of piece of 3/8" braided tubing to it with hose clamps and a hose adapter to attach it to my stationary tub faucet. I run the water through it slowly and it makes a huge difference in my brew water quality compared to the regular tap water.

 

[QuercusMax]

That's the funny thing; I wouldn't necessarily describe it as astringent, but perhaps that's due to it being so subtle.

I might try using half distilled water for my next light lager and see how that goes. My wife loves the helles and has no complaint, so I make it mostly for her, so if it doesn't fix the issue it's no big loss.

 

[QuercusMax]

Oh, one other data point: I've made 2 session saisons (OG ~1.035) using 84% pils/16% Vienna / Munich without this flavor showing up. Same process, but with WLP565.

 

[beersk]

squeezing the specialty grain bag for extract and partial mash batches or if the pH is too high when mashing.

Not true. There are plenty of brew in a baggers that squeeze, including myself, without tannin issues.
This is likely a pH issue. pH strips are said to show inconsistent readings, usually .3 lower than it actually is. And if your mild and ESB were reading 5.2, with specialty grains, something like a helles, with almost nothing other than pils malt, will read several points higher. I know that with RO water and with all pils malt, the pH in Bru'n water, still predicts to be in the 5.6 or 5.7 range. Acid malt or some kind of acid to bring pH down is nearly always necessary.
Are you treating your water for chlorine/chloramines? That may not be it, but if you aren't, you should be.

 

[QuercusMax]

If the ph strips really read .3 low, that would explain a lot. I'll try using the acid malt. Any idea how much I might need? I was thinking I would start with 2 oz.

 

[beersk]

Check out Bru'n water to work out your additions (if you know what's in your water), but the rule of thumb is 1% acid malt to bring your pH down .1. Not sure if that's empirically true or not, but it's a start. I think it's been shown that you can use up to 8% acid malt before you start getting a lactic taste.

 

[zzARzz]

Not true. There are plenty of brew in a baggers that squeeze, including myself, without tannin issues.

I've read articles/threads that say squeezing is fine and others of the "don't do it" variety, but I agree that pH and mash/sparge temps are the biggest factors in tannin extraction, so that was an err on the side of caution statement.

 

[QuercusMax]

I do squeeze my bag, but I don't think that's the cause. pH seems more likely. I've read that decoction drops pH - I may try that as well. Maybe do 3 gallons of helles with acid malt, and 3 gallons decocted. I have done a double decoction for a gluten free (millet malt) beer, so the process doesn't scare me. Since I mash on the stovetop anyway, it's not that much extra work, aside from the constant stirring.

 

[FarmerTed]

Send the worst offender to a competition, or maybe just take a sample to a local homebrew shop. I'm gonna guess that it's DMS. I had issues with it in a couple of beers, and fortunately it was picked out in a competition. To me, it didn't taste at all like cooked corn, and didn't smell sulfury (I'm a chemist, and have worked with DMS, and in the beer, it didn't smell at all the way I would have expected). Rather, it was sort of earthy, and had a sharp flavor to it that became more apparent as the beer warmed. I could definitely see someone saying that it reminded them of leaves.

How lond did you boil? Do you normally use pilsner malt? Maybe just the colder lager fermentation is leaving more dms in your beer than ale fermentations with similar grain-bills.

 

[Malric]

DMS can also occur if you don't have a vigorous enough boil.

 

[QuercusMax]

I always do 90 minute boils with pils malt. The one this is worst in is a vienna I did with US05, with only about 30% pils. It's also the oldest. So it might be some type of oxidation byproduct?

 

[QuercusMax]

So it's been a month and a half since I last posted in this thread, and I decided to toss as many of my lagers as I could into my spare fridge.

The clarity of all of them has improved massively, and it seems this off flavor is pretty much gone as well. My Oktoberfest and Helles are crystal-fricking-clear, and taste fantastic.

My theory is that either A) it was caused by tannins, and lagering them has caused the tannins to drop out, or B) I had a cold for most of September and October and that was causing my taste buds to be wacked out.