Off Flavor from an experienced homebrewer

[ekjohns]

I have been brewing all grain for about 6 years now. I have been trying to get everything perfect but still have this "off flavor" I have yet to nail down (more on that later). First I would like to give you my set up to clarify how I brew:

Grain
On a brew day, I grind my grain using a monster mill set with the recommended gap size (not significantly shredding grain). I grind the malt which has been stored cool and air tight slowly.

mashing.
I use an eBIAB and do 3 gal batches in a SS pot. Temperature is controlled by a controller and I mash with constant recirculation so temp is spot on. Water is 100% RO with added salts to give me water close for a pilsner. I add lactic acid to get pH to be about 5.4. Mash for 60 min with grain/water ratio ~1lb/2qts. After mash I remove the grain bag (let drain it separate pot) and bring to a boil.

Boil
I boil for 60 min then quickly cool with CFC (copper, boil to 70C) in about 15 min.

Fermentation
Wort is aerated with 100% oxygen for 1 min @ 1 lpm. I then pitch a big yeast starter grown up on a stirplate at room temperature. Fermentation is controlled in a minifridge with adjustable thermostat. I let all my beer sit for at least 1 month in primary. I ferment in 5 gal cornies.

Serving
After 1 month of fermentation beer is moved to a new keg and allowed to mature for 2-5 months before it gets moved to the kegerator. Beer is served at 36F with 12 psi.

Okay so now for off flavor. In almost all my beers I get a flavor that is a bit metallic/astringent/acidic. I taste this in A LOT of homebrew from others as well but not commercial beers. It almost comes across as dilute lactic acid but I got this before I used lactic acid and I only add about 1 ml/ 3 gal so I don't think it is that. I also get this flavor in any beer that is not dark (wheat, american ale, IPA, etc).

I have been thinking that it might come from the wort not being filtered through the grain bed since I do BIAB, although i got this before I did BIAB and was using a cooler. I was thinking about either moving the wort after it has sat in the primary fermentor for a few hours (before pitching) to a new keg to get it off the hot/cold break or possibly moving it to secondary after 7 days in the chance it might be due to the break material. Has anyone come across this flavor before and figured it out? I am beginning to think it is just a "homebrew flavor" but why don't commercial beers have this? I live in St. Louis and would be happy to give out a bottle to anyone that thinks they could help.

 

[Yooper]

It sounds like a mash pH issue, but what salts are you adding to the water for a pilsner? 100% RO water is actually ideal, with a mash pH of 5.3 or so. Do you check your mash pH with a meter?

 

[schematix]

I'm in Chesterfield... probably opposite side of town from you.

Have you boiled your aeration stone recently? My first few brews were like what you described until I did that every single time.

 

[rabeb25]

Edit, never mind.

 

[ekjohns]

yooper - I have been following a thread of yours about RO water so I use the 1/2 tsp CaCl2 (per 3 gallons). I also add 1/2 tsp of MgCl2. I check pH with a meter (after bringing everything to same temp)

Schematix - I have not boiled by aeration stone but it does soak in StarSan before use and I have never had a contamination. I will boil it non the less on the next batch.


One thing I have noticed is the flavor is not as strong before kegging and carbonation. I wonder if I have a sensitivity to StarSans

 

[schematix]

Oxidation perhaps? You are storing for a rather long time before consumption.

 

[khillian]

How are you dealing with pressure during the fermentation? Spunding valve or a special lid with airlock? Have you tried a different fermentation vessel ever?

Just my two cents

 

[ntempleton]

It sounds like a mash pH issue, but what salts are you adding to the water for a pilsner? 100% RO water is actually ideal, with a mash pH of 5.3 or so. Do you check your mash pH with a meter?

I'm with Yooper, I'm thinking pH or water - that's the only thing consist between all batches. I'm not a big fan of RO water either unless you're 100% right with your treatments. Have you considered a batch using filtered water?

 

[wmilas]

Questions to Consider:

1) How are you making your RO water? Is it fresh made, or is it sitting around in a plastic container that could be leaching into the water? For instance I have a RO water tower above my brew setup with a 20 gallon tank. That tank has a plastic bladder. I can taste that bladder unless its carbon filtered before entering my HLT.

2) Your starter. I assuming its room temp stir-plate. Are you dumping 1-5 liters of that nasty fermented wort into your fermentation vessel or are you cold crashing and decanting?

3) Fermentation vessel. Is it passivated? You said its stainless. I'd throw some acid in that puppy.

4) You add Mg in your salt schedule. That stuff is pretty harsh and people don't realize just how far a few grams goes. Take a few grams, dissolve it in a gallon of ro water and take a taste. Is that what you are tasting? Its metallic in flavor.

5) Lastly, PH. I know people already chimed in, but tanics are metallic tasting. Calibrate your ph and temp meters, and make sure you stay under 5.4 (or 5.6 if you are adventurous) and 168F or under.

My system is highly efficient and I struggle with tannins all the time. I hate teh taste of them, as I've become super sensitive. I can taste it in many home brews, and even some craft brews now that I'm constantly looking for it. In low amounts its not puckering or dry, its just metallic to me. To figure out if this is it, make an all DME/LME batch and see if you still taste it. If you do, its not tannins.

 

[ekjohns]

wmilas, First thanks for the suggestions I will be looking into a few particularly 4 & 5

1. The RO water is obtained from the grocery store at one of the glacial water filling stations into 5 gal bottle usually a day or 2 before brew day. Drinking the water does not have in off flavor.

2. I crash cool the starter and pour off all but about 200 mL

3. SS 5 gal corny cleaned with StarSans. Reciently I have been fermenting under pressure starting out at 0 psi then increasing to 5 psi slowly over 2 weeks.

4. I do add Mg (about 2 grams for 3 gall batch). I will leave it out.

5. I am going to buy new standards as my others were starting to get old.