Why does the roux separate from my gumbo? I love gumbo, and make it about once or twice a month. However, I've noticed that my roux will occasionally separate from my stew and float up to the surface. I've sampled it, just to see if it had absorbed some of the flavors, but all I got was a floury taste. 

I've had gumbo enough times to know that this shouldn't be happening - the roux should be enriching the flavor of the stew and mixing in, but it isn't.

A rough outline of what I do:


Make roux with vegetable oil and flour in a 1:1 ratio.
Mix in bell pepper, celery, and onions (aka "trinity"); stir frequently for 10-20 minutes.
Mix in garlic, cayenne pepper; stir for two minutes.
Mix in thyme, bay leaves, white wine; bring to boil.
Add chicken, andouille, shrimp, tomatoes, clam juice, chicken broth; bring to boil and simmer for 30 minutes.
Add okra; simmer for 10 minutes or until ready to serve.


Here's some thoughts on possible problems:


I usually cook it in a slow cooker once I have all the ingredients simmering. I've only cooked it the conventional way (read: in a pot) once, and it didn't separate. (When I cooked it in the pot, some of the roux was in the stew that boiled off the top of the lid; a tasting revealed that it was more flavorful than the stew).


2. I've sometimes gotten lazy or been in a rush, so I only cook the trinity for 10 minutes instead of the full 20. (I've also noticed that the trinity gets uncomfortably slimy-looking after the 10 minutes, which has prompted me to prematurely move to the next step on a few occasions.)

And finally, an error I am not making: I am not burning the roux. It may smell smoky, but it is not burned.

Given this, what could be the cause?

EDIT: I've just made it again, and it's definitely not because I'm undercooking the trinity. Based on the evidence, I'm going to go with Sobachatina's answer, until I can try it again.

SOLUTION: Forgot to update this until I got pinged about a change on this question. The slow cooker made the roux separate from the gumbo; it has never separated from the stew when cooked in a pot, likely because the starch doesn't fully gelatinize when in the slow cooker. If anyone wants to look further and try to figure out when the starch is sufficiently gelatinized, drop a comment below with your result and I'll update this solution.
Making a roux has two purposes:


Coat the flour granules with fat so they are able to dissolve into the cooking liquid without binding up.
Cook the flour to remove the raw cereal flavor.


When the cooked, fat-covered, flour is introduced to boiling liquid the starch granules swell and explode tangling up the cooking liquid. The cooking liquid is thus thickened and delicious.

If your roux is separating then the starch has not gelatinized. Because you saw this problem in the slow cooker and not in a pot I suspect that you are simply not bringing your liquid to a full enough boil to gelatinize your starch.

I have never seen a roux separate out. The roux should dissolve into the cooking liquid. You might check your ratio and make sure that you don't have too much oil in your roux. Variability in measuring your flour might account for why you see this intermittently.