IPA lack of aroma / off flavors - kegging nightmare

[Andy1968]

Hi,

I am really really frustrated with my kegging results and I have not been able to find any solution to the issue.

Ever since I moved to kegging and carbing w/o sugar, I have not been able to produce a single solid beer from a keg. I have read and studied and followed all the various tuttorials, articles, and videos you can find online. Being located in Germany, our homebrew community is not as dense so there is no one to ask around where I live.

Here is the thing: I brew full-grain and the result is super nice until after secondary. Until 6 months ago, I used to add sugar and bottle from secondary - guess the way to usually start. The IPAs' hop flavour was super nice and stayed a long time. Every bottle was exactly how I planned it to turn out.

Six months ago I started kegging for obvious reasons (bottle nightmare, brewing larger batches, wanting to make the next step and so on...). I clean and sanitize the keg, I purge with CO2, I am super careful not to pick up oxygen on the way into the keg. Once done, I use a CO2 calculator to determine the right amount of CO2 for carbing. Usually, I put 30psi for a number of days to carb to the right level at given temperature. Once the pressure is balanced, I put the keg to the fridge. This is usually after a week or so.

And here is the thing: when I test after secondary right before kegging, the smell and the taste is exactly the way it should be for a green beer. I smell and taste the different hop combos making me super happy. BUT - after 2-3 weeks, when I pour a glass from the fridge, the hop aroma is completely gone and instead the flavor is strange. Not sure whether it is cardboard, or any of the other often quoted off aromas and flavors. It simply is not right and not how an IPA should smell and taste. In some batches I see quite a darkening which is likely to be due to oxidation.

I have NO clue what to do and after reading tons of articles online, I am close to getting back to bottling and carbing with sugar or at least carbing with sugar in the keg. It is completely frustrating since not one batch turned out the way I wanted it to be and I have tried to eliminate all possible causes of oxidation / infection which I digged up online.

Anyone gone through that same thing? Is it oxidation/ carb bite / anything else?

helphelphelp please. thx.

 

[day_trippr]

[...]I clean and sanitize the keg, I purge with CO2, I am super careful not to pick up oxygen on the way into the keg. [...]

The symptoms certainly point to oxidation.

Purging a keg with CO2 is a sketchy proposition (@doug293cz could show just how sketchy) and is not the best option by far.

Better is to completely fill the keg with a sanitizer solution, getting every bit of "air" out, then sealing the keg and pushing all the sanitizer solution out via the long dip tube using CO2 pressure. Once the keg is emptied of sanitizer the keg is filled through the long dip tube using CO2 pressure in the fermentation vessel while the keg PRV is latched open (or better, an "exhaust" line is run from the gas post to a bucket of water).

Beyond that and working backward, avoid cold-crashing your fermentor without providing some method of avoiding oxygen uptake; and avoid using a "secondary" fermentation vessel entirely if possible...

Cheers!

 

[micraftbeer]

I had similar experiences, and to be honest, I'm not sure what I did to solve it. Looking back at what changed in my process, I no longer secondary. I cold crash in the primary, where head space is already filled with co2 from fermentation process.

I don't do the fancy fill keg with co2, it there sanitizer thing, but I am pleased with my IPA hops. So maybe it was just about the secondary, and/or cold crashing in primary where I knew I had no oxygen in headspace.

 

[madscientist451]

Hi,


Once the pressure is balanced, I put the keg to the fridge. This is usually after a week or so.

Why store the keg warm? Do you cold crash the beer before transferring to the keg?
Once you cold crash and transfer to the keg, why not keep it cold?
I don't know if this will help your issues or not.
How are you transferring from the fermenter to the keg?

 

[bkboiler]

i stopped kegging when i moved to smaller batches but had similar issues which i believe were due to
1. volatile hop aromas escaping into open volume in keg the further i drank the beer down
2. keg tap gunking up due to being in hot garage

 

[micraftbeer]

2. keg tap gunking up due to being in hot garage

In hindsight, that would be another thing that changed for me from the period of disappointing draft beers, is my taps. I changed from the standard taps with the slider/piston in them to the forward sealing Perlick or Intertap style faucet. I had a hard time believing that made a difference, but it was one of the things I changed to over that time period.

 

[opercularia]

Once the keg is emptied of sanitizer the keg is filled through the long dip tube using CO2 pressure in the fermentation vessel while the keg PRV is latched open (or better, an "exhaust" line is run from the gas post to a bucket of water).

Like he said. But I don't bother with CO2 pressurized transfer. I use my auto-syphon with a keg connector to the "keg out" connection. I brew long, so I overflow the keg from the CO2 port into a 2 L pop bottle, which I refrigerate and then carbonate with a carb cap for an early tasting. I prop the keg while filling so that the CO2 port is slightly lower than the "keg out" port. This prevents overfilling. I don't worry about air getting into my fermenter during the transfer, because the time is so short and I'm not stirring the beer. Saves on CO2.

I don't brew particularly hoppy beers, but I don't notice a drop in hop flavor and the cardboard flavor is gone.

 

[opercularia]

Better is to completely fill the keg with a sanitizer solution,

As day_tripper said, completely fill the keg with sanitizer. I keep my keg sanitizer in a spare keg. I transfer it to clean kegs with CO2. I prop the keg with the CO2 port high and fill through the "keg out" port. I usually save up until I have several kegs to clean and sanitize, so I connect the CO2 port of the keg I am sanitizing to the "keg out" port of the next one with a jumper.

If you are just doing one keg, either use the pressure relief of a ball-lock without propping (could get messy), or on a pin-lock keg, prop and use a CO2 connector on the CO2 port and direct it to waste.

 

[thehaze]

Something must be definitely wrong if you are kegging and the beer is not good after 3 weeks. I still bottle and continue to do so and my IPAs are good even after the first month.

I have a friend and he kegs, but he is complaining about the quality of CO2 he can get locally. Much of it is not as pure as it should be and this affects aroma, flavour and the longevity of the beer, or lack thereof in this case. Do you now how good / pure is your CO2? Where do you buy it from?

 

[divrack]

Second the liquid purge. It's astounding how little O2 can spoil a hoppy beer.
Alternatively you could prime your serving keg with sugar or kreausen thereby letting the yeast scavenge any regaining oxygen.

Or brew in space

 

[Andy1968]

Thank you all. First of all, I am relieved that this seems to be a more common challenge than I thought. Gives me some more confidence to solve it.

It is seems very likely to be oxidation as most of you confirmed. Less likely to be any other infection since I tend to over-sanitize all of my equipment.

When I moved to kegging, I simply changed too many things which in the end could lead to oxidation. So it is hard to find the one reason.

Avoiding secondary or reducing to one vessel: Even when I was regularly priming with sugar and bottling after secondary, I used different conicals for primary and secondary so the chances are low that this is one cause. Not rouling it out but quite unlikely.

Originally, I did not cold crash. I tried it for clarification and realized that I reached the same effects on the clarity of the beer when storing at cellar temps for a few days once fermentation / dry hopping had come to an end. In the meantime I am using a temp control unit during primary fermentation. Toward the end of it, I reduce the temperature to 14Celsius and the yeast settles nicely without completely going to sleep. From there I go for dryhopping directly into the second conical (avoiding splashing) which has been laid with CO2 before. Will cold crashing reduce the risk of oxygen update?

I have not used closed system transfers so far but this certainly is something I will need to try. Not sure you can do that with non-pressurized containers but there should be a way.

What I'll do next is to what @divrack suggests in order to elimate oxygen intake and work backwards. I will prime with sugar in the keg and not carb with CO2. The CO2 quality could be another issue even though it is labeled food-grade and I am confident of the source. It could be a reason.

When the sugar primed keg turns out allright, I know that the issue must be in the CO2 keg carbonization. I will then try the "keg completely filled with sanitizer".

I'm planning to brew the next batch over the weekend. Fingers crossed.

 

[madscientist451]

. From there I go for dryhopping directly into the second conical (avoiding splashing) which has been laid with CO2 before. Will cold crashing reduce the risk of oxygen update?

There's no reason to move the beer from the primary conical. Just put your dry hops in primary.

 

[doug293cz]

It sounds like you have been doing your forced carbonation at relatively warm temperatures, rather than at serving temperature. That, combined with an inadequate protocol for keeping O2 out of the keg while filling, is probably a major cause of your oxidation problem. Page 21 of this presentation shows that 3 weeks at 65° - 70°F gives as much degradation in flavor as 4 months at refrigerated temperatures. Hoppy beers should be refrigerated ASAP, and kept cold to maximize flavor preservation. Natural carbonation can help eliminate free O2 in the keg, but isn't a guarantee, as many brewers have reported the same kind of oxidation problem when bottle conditioning.

As @day_trippr has noted, you need to purge your keg, AND keep it sealed (except for a pressure bleed) all the way thru the beer transfer process. Filling thru an open keg lid will allow too much O2 into the keg during the process, even if the keg was O2 free prior to filling. Watch the following video. It shows that Br2 completely mixes with air in about 30 minutes. Br2 is 3.6 times heavier than CO2, so CO2 will mix even faster. Later in the video, they show both Br2 and NO2. NO2 is about the same density as CO2 (46 vs. 44), and the NO2 mixes with air much faster than the Br2.

GCSE Science Revision - Diffusion of Gases - YouTube


Brew on

 

[ProblemChild]

I have actually started using my kegs as secondary fermenters.

I will rack to the keg keeping the CO2 line opened just a crack to keep a nice blanked to CO2 on top of the beer.

At the end of secondary I will:
crash in the keezer
run off trub through the "Out" line
open the lid
prime
close the lid
and purge the minimal space at the top with CO2.

Form there I naturally carbonate. If I were to force carb, the lid would remain closed.

 

[doug293cz]

I had similar experiences, and to be honest, I'm not sure what I did to solve it. Looking back at what changed in my process, I no longer secondary. I cold crash in the primary, where head space is already filled with co2 from fermentation process.

...

Yes, the headspace is pure CO2 at the end of fermentation, but when you cold crash, the pressure of the CO2 in the headspace drops, and that causes air (and O2) to be sucked back into the headspace (unless you do something to backfill with CO2 instead.) Also, over time, the colder beer will absorb some of the CO2 in the headspace, causing more air to backfill into the headspace. As we saw in the video in my previous post, CO2 does not form a protective blanket for more than a few minutes, so the O2 ends up evenly distributed throughout the headspace. I have done a detailed analysis of O2 suckback and CO2 reabsorption here.

All is not lost however, I cold crash without CO2 backfill, but only for ~2 days. I do the liquid keg purge, CO2 pressurized transfer, do multiple purges of the headspace after filling (belt and suspenders), and keep the beer cold from then on. I have not observed significant degradation of my hoppy beers over about a two month serving period.

Brew on

 

[Andy1968]

@doug293cz - this is really interesting. I checked my protocols again. As I said, I had never done a closed transfer, but I completely filled the keg with CO2 until I was able to smell CO2 at the very top (which does minimize but not really eliminate O2 intake as you say). Then I carefully filled the keg and closed immediately pressurizing with the necessary pressure to reach the right carb level at the given temperature. BUT: I carbed at cellar temps not knowing that this might have a negative effect. I was only thinking of the higher pressure I need to apply.

And - looking back, the beer tasted and smelled nice after carbing (reaching CO2 balance) but then, I put the keg in the fridge and this seems when things went bad. This certainly reduced the head pessure considerably and as you say, even a small amount of O2 would be able to cause oxidation. I thought that my keg is oxygen-free and once it is closed nothing could happen. Wrong it seems.

I should fill the keg using the closed system and cool down to serving temp before carbing this might solve it.