[brewchez]

I wanted to try something new with dry hopping so I dry hopped an APA in a 5 gallon corny.  I used a muslin bag with some marbles to weigh it down.  2oz galaxy hops.  I dry hopped for 4 days.

I fished out the muslin bag and started to force carbonate.  When I started pulling samples to check the carb level I was impressed with the hop aroma and pleased.  I pulled a couple more samples along the way as I tend to do normally to see how the carb level was coming along.  I was getting the normal slug of yeast and such as it continued to settle out.

Interestingly though now that the beer is fully carbed and being served the hop aroma is way down.  Not even close to what a 2 oz DH should be like and its certainly way less than the initial samples I pulled.

I was wondering if its possible that I pulled out all the super infused wort during my test samples seeing as the keg wasn't really moving or getting mixed up.  My only thought was that the bags sitting at the base of the keg infused great hoppiness but after I fished out the bags much of it was concentrated in the bottom. I find it hard to believe but I was wondering if others had a similar experience.

[kramerog]

A likely culprit is oxidation caused by you pulling the hops out of the corny.  Many of us on this forum including myself leave the hops in the keg until the keg kicks or until another addition of dry hops.

Also I find that the yeast tends to absorb a lot of oil so initial pulls on the keg are very hoppy.  The hoppiness goes down as less yeast is pulled into the beer.  The hoppiness tends to spike up when the keg is almost finished.

[zwiller]

Absolutely get the beer completely off the yeast (bright) prior to dry hop.  The logic behind this is sound and matches your experience, the hop magic is attracted to yeast and it carried some of that magic out of the keg.  I crash a week @ 30F prior to DH. 

[EnkAMania]

I dry hop in the keg at room temp for three days and then leave them in for the duration of the keg

[denny]

I think the real problem is that you took the hops out.  As you get further away from when they were in there, the hop aroma diminishes.  It's no big surprise and I really don't think it has anything to do with oxidation or yeast.

[neddles]

Absolutely get the beer completely off the yeast (bright) prior to dry hop.  The logic behind this is sound and matches your experience, the hop magic is attracted to yeast and it carried some of that magic out of the keg.  I crash a week @ 30F prior to DH.

This. Get the beer off the yeast/yeast out of the beer. Any remaining yeast that have yet to floc out will be taking hoppy goodness with them as they drop. Makes a huge difference.

[HoosierBrew]

Absolutely get the beer completely off the yeast (bright) prior to dry hop.  The logic behind this is sound and matches your experience, the hop magic is attracted to yeast and it carried some of that magic out of the keg.  I crash a week @ 30F prior to DH.

This. Get the beer off the yeast/yeast out of the beer. Any remaining yeast that have yet to floc out will be taking hoppy goodness with them as they drop. Makes a huge difference.

+2.  As for fishing out the hop bag, I leave mine in with no bad effects. Hop character is extremely easily oxidized (read:diminished greatly), so IMO the fewer times the keg is opened, the better. 

[neddles]

Absolutely get the beer completely off the yeast (bright) prior to dry hop.  The logic behind this is sound and matches your experience, the hop magic is attracted to yeast and it carried some of that magic out of the keg.  I crash a week @ 30F prior to DH.

This. Get the beer off the yeast/yeast out of the beer. Any remaining yeast that have yet to floc out will be taking hoppy goodness with them as they drop. Makes a huge difference.

+2.  As for fishing out the hop bag, I leave mine in with no bad effects. Hop character is extremely easily oxidized (read:diminished greatly), so IMO the fewer times the keg is opened, the better.

Yes, do not pull out the hop bag. Makes no difference, at least none for the better.

[brewchez]

I figured I could leave the bag in there, but I feel like I have gotten some vegetal effects from larger dry hoppings when I leave the beer on dry hops in the fermentor longer than I intended.  I can't wrap my head around why removing the bag would be an issue.  Commercial hop aroma forward beers don't come with a hop bag in the keg or bottle still.  Explanations? thoughts?

And as for yeast absorbing hop oils, yes that happens but its not an absolute.  If the yeast is absorbing that much hop oil you should be able to use more dry hops to compensate.  And if that was really the cause dry hopping in primary would result in no hop aroma because the yeast count is so large there. At least that's my impression.

[HoosierBrew]

I figured I could leave the bag in there, but I feel like I have gotten some vegetal effects from larger dry hoppings when I leave the beer on dry hops in the fermentor longer than I intended.  I can't wrap my head around why removing the bag would be an issue.  Commercial hop aroma forward beers don't come with a hop bag in the keg or bottle still.  Explanations? thoughts?

And as for yeast absorbing hop oils, yes that happens but its not an absolute.  If the yeast is absorbing that much hop oil you should be able to use more dry hops to compensate.  And if that was really the cause dry hopping in primary would result in no hop aroma because the yeast count is so large there. At least that's my impression.

Commercial breweries don't use hop bags in their kegs. Many of them get hop flavor and aroma from extended whirlpool hopping and when they dry hop, they crash and then closed transfer under CO2 off of the hop debris. Of course dry hopping in primary produces hop character - I just don't feel it lasts as long as dry hopping clear beer because yeast do absorb hop oils. Using extra hops is always an option.
Look, my methods are by no means the only way. I like to whirlpool hop American styles then dry hop in keg, but there are lots of ways to hop beers with good results. Personally, I wouldn't keg hop if my intention was to pull the hops, as air is the enemy of hop aroma.  $0.02  .