Help Eliminating An Off-Flavor

[Hinezer]

I've been doing all-grain batches for a couple years and haven't had any huge problems with off-flavors until my last two batches.

I recently upgraded to a bigger system and started doing advanced techniques. The first two batches turned out good but the last two have a noticeable off flavor. I'm having a hard time pinpointing it, but I'm pretty sure it's an astringent taste.

The one difference between the batches was that I started milling my own grain. The first batch I had a terrible crush...really didn't get the grain cracked at all. The latest batch I got the mill working better and i had what appeared to be a 'good crush'. Both batches had the same off-flavor.

In researching the issue, I found that over crushing can cause astringency due to the tannins. That could be the answer for the second bad batch but the first batch there was no way that I over crushed it.

The next area I've looked at was the mash pH. Could that change from milling your own grain? I haven't done anything differently with my sparging or remember anything going wrong the last two times.

Has anyone else gone through this issue and fixed it? Could it be something else like the yeast or my fermenters? The two beers completely different styles - wit vs IPA. Please help! I want to get back to making drinkable beer!

 

[Ozarks Mountain Brewery]

your going to have to tell us the flavor

 

[RachmaelBenApplebaum]

What kind of crusher are you using? how fine was your crush when the batches went bad? Did you change your process at all between stepping up your batch sizes? that's where I would start. Identify what hasn't changed since stepping up to a bigger volume and eliminate any possibilities.

 

[Hinezer]

The off flavor comes from astringency, I think. It tastes grainy, bitter and overpowers any of the regular flavors in the beer.

On the changes I've done since stepping up my batches - pretty much everything. I was doing 5 gallon batches using the typical starter kit, boiling in large kettles, mashing with a converted cooler and fermenting in buckets using an ice bath.

Now I have 10 gallon Brutis 10 system with converted kegs. Other changes that I did:
-use big mouth bubblers with spigots for fermenter
-use a temperature controlled freezer for fermentation
-switched from immersion chiller to a plate chiller
-use a hop spider instead of hop bags
-use a sparge arm instead of gradually sprinkling using a colander
-making yeast starters
-buying hops in bulk and freezing after vacuum sealing

All of these changes happened prior to the first two batches which went well. The only change I've made between the good batches and the bad batches was that I started milling my own grain.

I use the cereal killer mill. The first bad batch I didn't have much of a crush at all. The second bad batch, I set the mill gap at approximately 0.037.

 

[day_trippr]

Experienced BiaB folks often use way tighter crushes than the .038" gap setting I use for my 3 vessel system and don't have astringency issues.

Two things worth looking into: your brewing water, and the mash ph...

Cheers!

 

[doug293cz]

Over crushing does not cause tannin extraction or astringency. Many commercial brewers use hammer mills to pulverize their grains to flour (they then have to lauter with a filter press, because a traditional grain bed made of flour would never drain.) The most common cause of astringency is sparging with water having a pH greater than about 5.8 - 6.0. You also need sparge water hot enough to raise the grain bed temp over about 170˚F. If any part of the grain bed gets above pH about 5.8 - 6.0 and 170˚F, you can start extracting tannins.

I would look at acidifying your sparge water to a pH of 5.6 - 5.8, then you shouldn't have to worry about tannins (you should also be treating your strike water to achieve a mash pH of 5.4 - 5.5.)

Brew on

 

[brewkinger]

Over crushing does not cause tannin extraction or astringency. Many commercial brewers use hammer mills to pulverize their grains to flour (they then have to lauter with a filter press, because a traditional grain bed made of flour would never drain.) The most common cause of astringency is sparging with water having a pH greater than about 5.8 - 6.0. You also need sparge water hot enough to raise the grain bed temp over about 170˚F. If any part of the grain bed gets above pH about 5.8 - 6.0 and 170˚F, you can start extracting tannins.

I would look at acidifying your sparge water to a pH of 5.6 - 5.8, then you shouldn't have to worry about tannins (you should also be treating your strike water to achieve a mash pH of 5.4 - 5.5.)

Brew on

This is where I would start as well.

Every recipe has a different grain bill and different mash characteristics.
Tannin extraction is a temperature and pH related phenomenon.

 

[Ozarks Mountain Brewery]

on the safe side I would boil your new system and discard the water, any cleaner residue could be contributing to off flavors

 

[Hinezer]

Thanks for all the suggestions! Mash pH is what I'm going to focus on. But I'll run some boiling water through everything just to cover everything.