[Iliff Ave]

It seems that whenever I brew a style with significant amount of roasted malt (which is not very often), I perceive a sourdough type tanginess in the finished product which I don't really care fore. I don't think it is an off flavor and would be a coincidence since I have only noticed it in darker beers. The beers overall aren't bad but just seem to have this odd note to them. My most recent porter had this flavor as did a friends recent sweet stout which I thought was strange. I haven't had many commercial style stouts or porters recently so I am not sure if I detect it in general...

Could this be related more to my water? Maybe it is a palate thing?

I did treat my water with a small amount of gypsum and calcium chloride but don't have the specifics. If I recall correctly, my mash pH was 5.2

Can you pick anything out here that could contribute to this?

6.25# Pale Ale Malt (great western)
3.75# Munich (great western)
1# Brown Malt (Thomas Fawcett?)
12 oz Chocolate Malt (Briess)
12 oz Crystal 80 (Briess?)

Fermented with S04 yeast in the low 60s

[kramerog]

Generally, roasted malts are more acidic than other malts.  Are you doing anything to adjust your mash pH?

[erockrph]

What was your pH? Roasted malts are acidic and will drive your pH down. I usually shoot for a mash pH of about 5.5-5.6 on porters & stouts, and that makes a big difference.

[HoosierBrew]

To me, it sounds like a pH thing.  Dark roasted malts are acidic, and will sometimes drive your pH below good levels. The tanginess you're getting is likely your pH being too low. I use baking soda to raise pH in my dark beers to ~ 5.5.

[Iliff Ave]

Generally, roasted malts are more acidic than other malts.  Are you doing anything to adjust your mash pH?

I just edited that above:
"I did treat my water with a small amount of gypsum and calcium chloride but don't have the specifics. If I recall correctly, my mash pH was 5.2"

I thought that maybe I added some baking soda as well due to mash acidification.

[Iliff Ave]

I am not positive that my mash pH was 5.2 but that seems to be correct. If so, that could very well explain it. I will adjust accordingly next time I brew something similar. Thanks!

My friend who lives nearby does not treat his water so that could explain why I tasted it in his stout as well.

[kramerog]

Generally, roasted malts are more acidic than other malts.  Are you doing anything to adjust your mash pH?

I just edited that above:
"I did treat my water with a small amount of gypsum and calcium chloride but don't have the specifics. If I recall correctly, my mash pH was 5.2"

I thought that maybe I added some baking soda as well due to mash acidification.

Like the others said, I think you will be happier with a mash pH of 5.5.  Calcium chloride lowers the pH so you should probably eliminate that.  Also gypsum increases the sourness in the finish so you can eliminate that.  You could replace the gypsum and calcium chloride with pickling lime if you need to add calcium and raise the pH but as I mentioned in another thread it is easy to overdose on the pickling lime unless your scale can read in 0.1 g increments.

In other words, it is a water thing.

[Iliff Ave]

I got caught up in trying to create a 'black balanced' profile by using gypsum and calcium chloride and didn't pay too much attention to pH as long at it was in the acceptable range. I will have to look at my notes but I believe I added some baking soda to counteract some of the acidity. Now I know...

[dmtaylor]

20% dark roasted malts and crystal malts will get your post-boil pH down pretty low.  For that reason, I add just a tiny sprinkle (like 1/2 teaspoon) baking soda to all my dark beers in the boil, and have never experienced the dark roasted tang since I started doing this.

[erockrph]

20% dark roasted malts and crystal malts will get your post-boil pH down pretty low.  For that reason, I add just a tiny sprinkle (like 1/2 teaspoon) baking soda to all my dark beers in the boil, and have never experienced the dark roasted tang since I started doing this.

And to take it one step further, since this is more of a flavor adjustment than mash chemistry adjustment, a bit of baking soda can be added at any step in the brewing process to adjust this. That includes post-fermentation. If you have any of the off-tasting batch still laying around, you can simply dose it with a bit of baking soda to see if the flavor improves. If it does, it's safe to say that you've isolated the issue.

[Hooper]

Great answers...I've had the same question about my last two dark beers. I will adjust PH up for the next one.

[dmtaylor]

I should also mention.... do not use more than just a touch of baking soda.  If you were to use a full teaspoon or more in 5 gallons, the beer can taste really nasty.  Baking soda does not taste very yummy.

[majorvices]

I like to use calcium carbonate to adjust my mash pH to the 5.5 - 5.6 range on my dark beer. As the other folks have mentioned, makes all the difference.