Kegging Issues

[CHflyfish]

Been having a lot of issues with kegging my beer. The beer has that bad butterscotch taste to it. It’s happened just about every time I’ve kegged a beer. I’ve done 1-2 bottles of the same exact beer from the fermenter and the bottles turn out great, but the kegged beer comes out crappy. I feel like I’ve tried everything and still get the same results. Any thoughts as to what I can do or why this is happening?

 

[SoCal-Doug]

Butterscotch or buttery is from diacetyl. Oxidized is commonly described as stale and like you are eating cardboard or paper.

I'll take a shot and maybe explain what you are tasting and why... Diacetyl is a byproduct of fermentation. The yeast will clean itself up and break down the diacetyl if there are live and active yeast cells and you give them the time they need. When you bottle, you are probably adding sugars for carbonation. The yeast start working (multiplying) again and clean up the diacetyl. When you keg, the yeast is done and there is nothing to do the clean up, so the diacetyl stays right where it is.

To naturally get rid of diacetyl, simple raise the fermentation temp above 65F when the fermentation is about 80% completed (still some slow bubbles). Hold it there for a couple few days and until all fermentation stops. Then crash it down to chilling temps. When fermenting... have patience, grasshoppah!

Oxidation is another story. Before fermentation you NEED oxygen for the yeast. Once the yeast is done, you don't want it at all. Most commonly oxygen gets in when racking or kegging. Don't splash the beer! Have your siphon tube all the way to the bottom of the keg. Don't do things like pour from the fermenter to the keg. It's just asking for oxygen to get into your beer and taste nasty. To be clear, oxygen has to flavor, but once it starts decomposing the stuff in your beer (oxidizing), the stale flavors appear.

 

[CHflyfish]

Oh gotcha. Sorry.

 

[SoCal-Doug]

Sorry, I accidently hit send then had to edit and finish what I was typing. Re-read my reply above. It should give you some ideas.

 

[CHflyfish]

No worries. I’ve done all of that so far. Even the sample hydrometer reading taste great when siphoning into the keg. then once it’s kegged, carbed and ready to drink it’s got that taste. I don’t get it lol

 

[SoCal-Doug]

Hmmm... Is it every batch of every type of beer (i.e. with different yeasts even)? Some yeasts throw more diacetyl than others.

If everything you brew has the same off flavor, I would start thinking contamination (thoroughly clean and sterilize everything) or cleaner/sanitizer residue. Neither should taste like butterscotch but nothing surprises me anymore If it's only a specific recipe, I would look into the ingredients and processes used for that beer.

It's a stretch, but are you sure it isn't "soapy" ? that's typically caused by leaving the beer on the yeast for too long and the fatty acids break down and essentially turn to a form of soap. It can sometimes have that same greasy or mouth-film feeling.

There's a lot of "off flavors" and causes. Hard to pinpoint without tasting it sometimes.

 

[CHflyfish]

Yeah all different batches. I’ve even siphoned a couple of bottles worn the same exact beer to the keg to see what happens and the bottles beer is fine, but the keg beer isn’t. Have done a thorough cleaning with PBW and sanitizer went through a ton of new bev lines and same thing each time. Typically will let the beer sit for no more than three weeks max before keg so I don’t think it’s that either.

 

[Vale71]

It definitely sounds like you're got a persistent infection going on in your kegerator or possibly your kegs. You should disassemble and clean thoroughly all lines and faucets and if the problem persists review your keg cleaning and sanitizing regimen.

 

[Homergah]

I really think socal hit on it right off. Yeast is being allowed to clean up a bit in the bottle with the last bit of activity. If it truly is butter/butterscotch taste. Then again it could be something as simple as a dirty beer line, faucet, or poppet harboring some bacterial mass. Before you package your next beer, perform a forced diacetyl test to make sure you're actually ready to package.

 

[Vale71]

That is actually wrong, yeast does not need sugars to clean up diacetyl (or any other by-product for that matter). Yeast has a reducing metabolism and will keep reducing all sorts of by-products long after fermentation is done in an attempt to prevent cell death for as long as possible.

One thing that could prevent that from happening though (besides premature filtration/pasteurization but that's a big brewery issue) is that silly fad currently known as "cold crashing". If the OP is suddenly cooling his kegs to 32°F in a futile attempt to get the beer to clear up faster then he might be causing the yeast to quit the job prematurely through excessive thermal shock.

 

[Homergah]

Not saying reduction of sugar is reducing diacetyl. Although I did use the word "fermentation". Changed it to "activity" for clarity. My point is with the usual practice of force carbing a keg of beer, if that beer was kegged too soon, or rather, put under pressure too soon, cell uptake of diacetyl precursors will be retarded, thus increasing diacetyl in the beer. This is all kind of foggy. It's been a long time since I've had someone who wanted to discuss it.

 

[Vale71]

One also has to take into account that refermentation will cause yeast to actually produce more diacetyl that will then need to be reuptaken and reduced. This is generally true of all fermentation by-producs so that refermentation might actually slow down maturation instead of speeding it up.

In the OP's case I think the most likely causes are either improper sanitation of the vessels or issues with temperature management caused by not having to allow for refermentation in the bottle.

 

[str1p3s]

I think it's contamination in the keg or the equipment used to rack to the keg. No one else has a consistent diacetyl problem from cold crashing, even if it's slightly early and especially on ales. Replace or clean the hell out of everything the touches the beer during kegging would be my first step.