Kitchen Science question- "gravy" thickening, crock potting, etc...
- e_bone Jul 28, 2010 12:26 PM
So last night I made some VERY good Colorado/Denver style Green Chile. I like the "gravy" style we make here in Denver as it stays inside a breakfast burrito better.
I've used a dozen different techniques over the years and have never been THRILLED with my resutls but I think I'm close now. I browned and removed my unseasoned, un-floured pork in vegetable oil. I think threw in what I call the Mexican Mirepoix: onions, garlic and finely chopped serrano peppers. I sweated these in the same fat with salt until they had given up some liquid and were beginning to color. Okay.. time to roux it up... I added flour and stirred to mix... I moved this around for a few minutes until I figured the flour taste was gone and then whisked in my hot stock. Classic soup techniques everyone knows, loves, uses and thanks the French for, right? As this thickened I added my green chiles... then my reserved pork... then some other "stuff"... and let it return to barely a simmer and stewed it for just a bit to make sure I had my consistency down correctly. All was good... rich, glossy gravy!
So.. into the crock pot for slow cooking to finish the pork. I let it stew on WARM (not low, not high, just warm) until morning (about 8 hours). The pork was fabulous- fall apart.. but I've lost 50% of my "Graviness"! Much of the fat broke from sauce and was sitting on top.. the gravy had become much more watery...
What happened? How do you keep a roux-based sauce together during long, low, slow cooking? Is it impossible? If not- did I have too much fat to flour ratio? I know I didn't overcook my roux (ie: from cajun food experience I know a dark roux will not thicken nearly as well as a blonde one).
It is impossible to prevent to my knowledge. The longer a starch like flour is cooked, no matter what color stage it is at when you add liquid, the more the starch proteins break down. That's why a very dark roux does not thicken as well as a light roux as you stated. The same thing happened in your dish because of the length of time the flour cooked even though you did not achieve a dark roux at the beginning. You didn't do anything wrong, you just expected too much. :-)
In the future you can thicken at the end with a cornstarch slurry or tapioca if you feel the need, but my instincts tell me you already know that. The result will be slightly different as cornstarch and tapioca tend to be glossy and for lack of a better term, thicker and smoother, but it might give you what you want.
You are getting inconsistent results because of the length of time the flour is being cooked. The thickening power of the flour starts breaking down after 4-5 hours. If you want to put in flour early, Cook's Illustrated suggests using tapioca flour instead of wheat flour with a slow cooker.
Another way you could do it is to thicken the sauce at the end of cooking with a slurry of flour and water or corn starch and water. This gives the advantage of being able to defat the sauce before thickening it. You are cooking pork, there is going to be a lot of fat that probably should be removed.
I suppose I really should have read Shaw Olivers post before posting my own but I added a tiny bit more info.
By the way, here is a link to "The Cook's Thesaurus" reference on starch thickeners. http://www.foodsubs.com/ThickenStarch...
Here is one on all around thickeners. http://www.foodsubs.com/Thicken.html
re: Hank Hanover
Good explanations and resource links. Thanks much! Makes perfect sense.... I suppose I was confused by my knowledge of restaurants that make a chowder and then leave it on a steam table all day... it turns into paste as all the water evaporates and the thickening is compounded... thought my gravy should do the same thing but the crock pot I suppose is *not* a steam table as the temp is probably much higher than the ~200 deg a steam table creates?
The juice from your pork is leaching into your gravy.
Cook your pork in the original mirepoix and stock. Reduce and thicken with roux at the end.
Wondra flour is good to keep on hand for slurries, since it will not clump when mixed with milk, water, broth, etc., and makes a smooth gravy. If you thicken with cornstarch don't use really high heat to reheat, which will destroy its thickening power. You could also try instant mashed potato flakes, which thicken well and seem to hold better.