Source of off-flavor?

[mopowers]

I've been brewing all grain for a little over a year now and my brews seem to all have a common flavor that starts to develops after a couple weeks or so after kegging.

My taste buds aren't too refined, but the flavor is almost a sharp bitterness and seems to become more pronounced as the beer ages in the keg.

I've noticed it almost all of my brews, be it my IPAs, reds, browns, etc.

I know it's pretty much impossible to diagnose these types of issues online without tasting or seeing my process, but does anyone have any ideas what may be causing this issue?

The beers are still very drinkable for me and my friends, but I'd like to figure out what I'm potentially doing wrong.

Thank you!

 

[Carolina_Matt]

You can start by reading this and seeing if any of them align with your taste.

https://learn.kegerator.com/off-flavors-in-beer/

But I agree with you - whenever I have an off-flavor, I have a hard time pinpointing what it is. 'Wet cardboard' and stuff like that, it's not something that I'd necessarily recognize. I almost wish there was a sampler pack of crappy beer with known off flavors so that I can go down the line and actually taste everything that goes wrong.

 

[JONNYROTTEN]

If its with all beer and you dont seem to have an infection I would try different water. THe water is the common denominator in all the beers. I was getting a metallic bite in my beers. I tried Poland Spring bottle water and it went away.

I would try some bottled water on the next batch and see what happens. Cost a few bucks more than free tap water but its worth it

 

[mongoose33]

In addition to looking at water--worth doing regardless--the fact that this shows up later almost suggests an infection of some sort. Since there's a delay...

What is your cleaning regimen? What's your equipment setup? Are there any places where you may not be adequately cleaning?

How about the kegs. How do you clean them? Sanitizing?

 

[TechFanMD]

1. What do you sanitize with?
2. Have you tried different water?
3. How hot is your mash/sparge? Do you have more than 1 thermometer to check (thinking astringency here, and this wouldnt necessarily develop with age anyway)

 

[Bigdaddyale]

What I did to try and troubleshoot and find an off flavor in my HB was to brew a clone of a commercially available beer and do a side by side taste test. I picked SNPA. Turns out what I thought was a flaw in my HB was also in the original beer ( Hop bitterness on the back of the tongue). I also found that the PVC hose on the hot side was adding an off flavor (Chemical taste).

 

[mopowers]

Thanks for all of your helps guys!

After chatting with an avid homebrewer, he's thinking it may just be from oxygen exposure from kegging. The beers have tasted great for the first couple weeks, but tend to slowly degrade in aroma and hoppy flavor after that - almost developing a malty bitterness. They even tend to darken in color slightly

Is this O2 exposure?

I usually have starsan in the keg and simply push it out with CO2 and a picnic tap. Once empty, I fill the keg with beer, hook up the CO2 at about 25lbs and purge the headspace twice. Then I set it to 20-ish for a few days to carbonate. Is this process inadequate?

In addition to looking at water--worth doing regardless--the fact that this shows up later almost suggests an infection of some sort. Since there's a delay...

What is your cleaning regimen? What's your equipment setup? Are there any places where you may not be adequately cleaning?

How about the kegs. How do you clean them? Sanitizing?

I'm cleaning everything with Oxy and sanitizing with starsan. My brew partner (girlfriend) is an ER nurse, so I'm pretty confident we're sanitary. The kegs are disassembled, cleaned, and sanitized after every use. I ferment in glass carboys and rack into the kegs with a auto siphon.

1. What do you sanitize with?
2. Have you tried different water?
3. How hot is your mash/sparge? Do you have more than 1 thermometer to check (thinking astringency here, and this wouldnt necessarily develop with age anyway)

1. Starsan
2. Not yet. I've been using carbon filtered tap water with additions as prescribed by several water chemistry calculators.
3. I've mashed anywhere from 148-156 (according to one thermometer) with the same issue. I should certainly check with a different thermometer.

 

[TechFanMD]

Sounds like you're doing a lot of things right. I would be surprised if it is oxidation in that amount of time given your regimen....it's pretty solid. I've had accidents or been a bit sloppy (equipment failure mid-process) and introduced oxygen and it didn't come through as hugely noticeable that fast.

Carbon filtering doesn't remove any of the stuff that we look for in brewing water....so when you add based on a water chemistry calculator, you may actually be adding more of something that is already there - maybe even in amounts that are already too high. I would get some RO or distilled, do your water chemistry, and try that.

 

[mopowers]

Sounds like you're doing a lot of things right. I would be surprised if it is oxidation in that amount of time given your regimen....it's pretty solid. I've had accidents or been a bit sloppy (equipment failure mid-process) and introduced oxygen and it didn't come through as hugely noticeable that fast.

Carbon filtering doesn't remove any of the stuff that we look for in brewing water....so when you add based on a water chemistry calculator, you may actually be adding more of something that is already there - maybe even in amounts that are already too high. I would get some RO or distilled, do your water chemistry, and try that.

I've had my water tested (post filtering), so I use those numbers in the water chemistry calcs I use. I think for the next batch, I'll definitely use distilled as the base and see if it improves. Don't get me wrong, the beers I've made are very drinkable. They just tend to get 'bland' and develop a sharp bitterness after anymore than a month or so.

 

[mongoose33]

The way you originally described it didn't sound like oxidation which is why we all had different suggestions.

But in your last post, you added that hoppiness faded, and that does sound like oxidation.

I would say that your transferring process is....well, less than ideal.

I usually have starsan in the keg and simply push it out with CO2 and a picnic tap. Once empty, I fill the keg with beer, hook up the CO2 at about 25lbs and purge the headspace twice. Then I set it to 20-ish for a few days to carbonate. Is this process inadequate?

Do you purge the lines before transferring the beer? Do you feed CO2 back into the fermenter as you rack to the keg? Not sure why you're purging the headspace if the keg is already just full of CO2.

 

[mopowers]

The way you originally described it didn't sound like oxidation which is why we all had different suggestions.

But in your last post, you added that hoppiness faded, and that does sound like oxidation.

I would say that your transferring process is....well, less than ideal.



Do you purge the lines before transferring the beer? Do you feed CO2 back into the fermenter as you rack to the keg? Not sure why you're purging the headspace if the keg is already just full of CO2.

Thanks for your input! I do not purge the auto siphon, or hose. Not sure I'd even know how to. I do not feed CO2 back in the fermenter during transfer. I purge the headspace just as a precautionary measure.

 

[day_trippr]

Loss of hop aroma -> loss of hop flavor -> a progression towards sweetness -> and darkening, is the oxidation progression.
"Wet cardboard" and "sherry" are way down-stream of all that, and it's a shame that so many sites use those two to describe the effects of oxidation when so-afflicted beers are already well past doomed...

Cheers!

 

[mopowers]

Thanks guys!

So, what's the proper way to transfer from a carboy to a keg without introducing oxygen?

 

[mongoose33]

Thanks guys!

So, what's the proper way to transfer from a carboy to a keg without introducing oxygen?

There are probably 2 or 3 ways you might do this. Here's how I do it.

I'm racking into a keg that has a little residual CO2 pressure in it from purging it. If you look closely you'll see I have a QD on the keg connected to a line that connects to the spigot on the fermenter.

I'll connect the IN or gas side of the keg to a line that I lead back into the fermenter. Nothing holy about the airlock, it's all I had (cutting off the head) that would fit the size of tubing I had. So--when I open the spigot to rack into the keg, the displaced CO2 from the keg is the "makeup air" going back into the fermenter.

I'll run a little of the residual CO2 pressure from the keg through that line before I connect it, so I've purged any air from it.

Just before I connect that line to the spigot, I'll connect it to the keg. Residual CO2 will blow through the line, purging it, and as it reaches its last gap, I direct that into the spigot so as to clear that as well. Then connect.


Now, in your case, with a carboy, you'd need a cap with two holes in it, one in which you can insert a siphon, one in which you can insert the return line from the keg. You'd have to find a way to purge the siphon and line before racking; perhaps purge w/ the CO2 gas from the keg, and then when time to start the siphon, I'd have clamped off the return line from the keg, and maybe use a little CO2 pressure from a tank to get the siphon started, then when it's going, quickly connect the return gas line from the keg.

That's about as close to perfect as I can get.

 

[day_trippr]

Start with liquid-purging the keg leaving it full of CO2, purge your liquid line from fermentor to the Out side of the keg with CO2 before connecting it, then use CO2 top pressure on the fermentor to push the beer into the keg while venting the latter (I use a short hose on the Gas side into a small bucket of water but you can also just leave the PRV latched open)...

[edit] Here's my set-up...

Cheers!

 

[mopowers]

How much pressure can a glass carboy take? 2 psi? 5 psi?

Also, when CO2 purging the keg, how much is enough? When do you know you've eliminated all ambient air?

 

[day_trippr]

I never go above 2 psi and even then only to get the flow started. After that I let gravity do its thing and just have enough gas flow to back-fill the head space, less than 1 psi.

I do a "Star San Purge" of the kegs. This means filling the lidded keg totally full of sanitizer (I invert the keg near the end of filling and rock it to get the last bit of air out) then pushing the sanitizer back out through the long dip tube (important to make sure it's full length and properly located in its well at the keg bottom). At the end all of the sanitizer is pushed out and the sealed keg is full of CO2.

Then, before hooking up the liquid line from the carboy I push some CO2 through the carboy and out through the line (a spare liquid post is handy for this) so no air is introduced to the purged keg...

Cheers!

 

[Mer-man]

Gravity should be enough to rack to a purged keg, and yes set the prv open during transfer.

JUST REMEMBER TO CLOSE IT WHEN YOURE DONE RACKING.

 

[mongoose33]

I never go above 2 psi and even then only to get the flow started. After that I let gravity do its thing and just have enough gas flow to back-fill the head space, less than 1 psi.

I do a "Star San Purge" of the kegs. This means filling the lidded keg totally full of sanitizer (I invert the keg near the end of filling and rock it to get the last bit of air out) then pushing the sanitizer back out through the long dip tube (important to make sure it's full length and properly located in its well at the keg bottom). At the end all of the sanitizer is pushed out and the sealed keg is full of CO2.

Then, before hooking up the liquid line from the carboy I push some CO2 through the carboy and out through the line (a spare liquid post is handy for this) so no air is introduced to the purged keg...

Cheers!

I'm going to extend this just a bit. When purging a keg using the star-san approach, I crack the lid on the keg full of star san and then apply a little CO2 to the OUT port so it bubbles up from the bottom. This creates bubbles on top of the star-san which are filled with...CO2. I let the bubbles come out of the opening to fill the gaps on top and under the lid, then set the lid in place while it's bubbling. That way I have no headspace in the keg that hasn't been filled by the star-san and thus air is in it. BTW, don't just blast it with CO2 unless you want a fountain of Star-San erupting from the keg. Don't ask me how I know this.

There's another way that's more frugal; you can actually feed the CO2 produced during fermentation through the keg. Every 2 gravity points produces about 1 volume of CO2 (i.e., 5.5 gallons fermenting produces 5.5 gallons of CO2). If you have 1.060 wort that will do down to 1.010, that's about 25 volumes of CO2 it will produce, and run through the keg, it will produce a nearly perfectly pure CO2 purged keg.

Below you can see how I pull CO2 off the fermenter to do this--I'm just pulling CO2 out of the gas manifold and sending it into the keg. In this case I also have a keg jumper inline which is being purged by the CO2 as well, though now I simply run a little beer through it to purge it.

In this case, the PRV is opened to allow gas to escape.

In the pic below I have the fermenter covered with blankets to help keep it cool while chilling. You can see the red line coming down from the fermenter to the keg; I also ran a line from the keg up to an airlock jar so I can monitor fermentation. When bubbling slows, I bump up the temp to allow the yeast to clean up after themselves.

 

[jschein]

You can start by reading this and seeing if any of them align with your taste.

https://learn.kegerator.com/off-flavors-in-beer/

But I agree with you - whenever I have an off-flavor, I have a hard time pinpointing what it is. 'Wet cardboard' and stuff like that, it's not something that I'd necessarily recognize. I almost wish there was a sampler pack of crappy beer with known off flavors so that I can go down the line and actually taste everything that goes wrong.

I have used this sensory kit it really helps; https://www.lallemandbrewing.com/en/united-states/product-details/regular-sensory-kit/

 

[mopowers]

Thanks guys. I think I have enough ammo to modify my kegging process.

 

[mopowers]

So, I think I may have identified a source of the O2 exposure. My auto siphon seems to be sucking it tiny air bubbles during the transfer. Looks like I'll be tossing it it favor of a racking cane instead.

 

[Ninoid]

While I was using an autosiphon and I had a problem with oxidation during transfer. Since when I use the hose with my mouth I have no problem.

 

[Morgz]

Have you tried bottling a batch to help eliminate your kegging process?
I've only been doing all grain for almost a year too, but it could be something that is not getting cleaned properly. Like disassembling your keg posts for a clean and sanitise, syphon, tap etc. Something in some nook and cranny that has a spec of dirt could be causing. Not sure, my 2c. Goodluck. Let us know if you work it out.