making a dark roux

The Science of Gumbo (A Dark Roux and the Maillard Reaction)

When on holiday in the United States, we visited New Orleans. Even though I think most American cities aren’t the best for tourists (being used to European cities you can stroll through by foot), I liked New Orleans. We could wander around instead of having to use a car all the time! Nevertheless, the one thing that I remember best from New Orleans is the cooking class we had at the New Orleans school of cooking.

New Orleans is of course famous for its food. One of the most famous dishes probably is New Orleans Gumbo. Never heard of gumbo (just like me before I visited New Orleans)? I would describe it as: a dark and hearty soup packed with flavour and meats, seafood and vegetables (here’s my recipe).

During the course we took they demonstrated making a great gumbo. It’s become one of our favorite dishes to make and we actually make it quite regularly.

The main trick for making a good gumbo is to make a dark dark roux, really dark. It’s relatively simple but packs the gumbo with a lot of flavour. Skipping this dark roux really makes the dish a lot less flavourful. Since this dark roux is so important, it deserves its own post, serving as a great introduction to the Maillard reaction (you’ll read more on that later in the post).

Making a dark roux

The basis for a gumbo is definitely the dark roux. Once this has been made most of the flavour development is done, the rest is ‘easy’. Making a dark roux is not very complicated, the most important ingredient is simply patience.

The recipe for a dark roux is simple: mix fat (I prefer ghee, pure butterfat, but you can also use oil or lard) and flour in a 1:1 ratio. Place it in a pan with a thick bottom and simply heat until it has become a really nice dark dark brown. I would advise staying close to the pan, especially towards the end, and stir almost continuously to prevent burning. It is a great process to see. First you’ll see the fat and flour forming a liquidy yellow consistency. Once it’s bubbling away it will slow turn browner and start smelling more and more delicious. Take care though, once it starts getting really brown it will be very very hot, well above 100°C so use stirring tools that can handle these high temperatures.

Have a look at this simple slideshare, showing the transformation from water + ghee into the gumbo basis:

The course instructors taught us to keep up heating until it was well darker than a peanut butter colour. My experience is that you generally think it’s finished too early, so continue going just a little longer (but black definitely is too much!).

Dark roux = not thickening

Most of you are probably familiar with using a roux for thickening sauces for a pie or a lasagna. This dark roux starts very similarly, but has a very different function than the so-called white roux.

The white roux is used purely to thicken sauces, it barely contributes any flavour. This is because the flour and fat are only heat enough for the flour to thicken the water mix. Once it’s thickened up, the heat is turned off.

The dark roux though, keeps heating at this point. Because of this continued high intensity heating the flour is ‘cooked’, what’s more, the starch in the flour (which causes the thickening) will start breaking down. In other words, it cannot thicken as much anymore!

Dark roux - just started
The start of a dark roux: fat & flour, still very light in colour.

Maillard reaction: browning & flavour development

So if the dark roux doesn’t contribute to thickening it must contribute elsewhere. This is where the flavour component comes in. The proteins in the butter and the sugars in the flour will start reacting together because of the prolonged heat. This is the so-called Maillard reaction, a chemical reaction which leads to the formation of brown molecules (hence the brown dark roux) and a lot of different flavour aromas.

A Maillard reaction occurs when a protein (more specifically an amine, which can be found in proteins, peptides and amino acids, the building blocks of proteins) and a reducing sugar (for example glucose or fructose). Flour contains both proteins (one of the types is gluten) and reducing sugars (flour will always contain some sugars, even though most of the flour consists of starch). The high temperatures of the roux greatly speed up this reaction.

The Maillard reaction is a great example of chemistry in our daily lives, more specifically food chemistry. In another post I take a deep dive into the hard-core chemistry of the Maillard reaction mechanism.

How did it get its name?

The Maillard reaction, (as well as pasteurization), has gotten its name through its inventor: Louis Camille Maillard. He studied medicine and worked in the field of chemistry. In 1913 he published his dissertation on the Maillard reaction. Interestingly he wasn’t studying food but kidneys whn doing this reaction. The Maillard reaction doesn’t only occur in our daark roux and other foods but is a more general reaction mechanism.

A dark roux recipe

Ready to immerse yourselves in New Orleans flavours and see chemistry occuring right in from of you? Give this dark roux recipe a try.

Dark roux - nearly finished

Maillard reaction & Dark roux for Gumbo

Cook Time: 30 minutes
Total Time: 30 minutes


  • 100g of vegetable oil, ghee/clarified butter (do not use regular butter, it's easier to make this dark roux with pure fat)
  • 100g of plain flour
  • (change the quantities based on what you're going to make, I can make about 3-4 liter of gumbo/soup with this amount of roux, the more flavour you want, the more roux you should make)


  1. Take a pot with a thick bottom, you'll be heating this up to quite high temperatures so you want it to be able to handle it. I prefer using a pot, versus a frying pan to avoid any possible splattering. Also, you'll probably want to add the other ingredients for your dish, gumbo for instance, so make sure it's large enough. Also, make sure the pot is clean and doesn't have left over meat pieces or onions for instance, these will increase the risk of burning your roux.
  2. Add the oil and flour.
  3. Mix the two, it'll be pretty liquid still.
  4. Turn the heat up to medium/high and start heating it. Don't walk away and keep stirring gently, especially towards the end since else you might risk burning it!
  5. Keep on heating until it's a very dark brown. You should continue a lot longer that you might initially think and you'll see various colour shades coming by. When you're at peanut butter colour you're heading for the right direction but you're not there yet.
  6. Once you've reached the dark brown colour immediately add some of your other ingredients, for instance vegetables. This will cool down the mix and heat the veggies up as wel, causing for some more amazing flavour development!

What's your challenge?

Struggling with your food product or production process? Not sure where to start and what to do? Or are you struggling to find and maintain the right expertise and knowledge in your food business?

That's where I might be able to help. Fill out a quick form to request a 30 minute discovery call so we can discuss your challenges. By the end, you'll know if, and how I might be able to help.

headshot Annelie


  1. Any ideas as to why as a brown roux sits and cools, the oil tends to “ooze” or separate from the roux itself? Enough that needs to be poured off.

    • Hi William,

      Great question! Dark brown roux contains a lot of fat and there is really nothing to hold on to it, especially after the flour has lost all its thickening and holding power by being so browned. Therefore, it is almost unavoidable that some or a large part of the fat separates. However, there’s no reason to pour it off. The oil + flour contain a lot of the flavour and since you’ll be adding a lot more flavours, moisture, etc. to make a final dish from that roux, the fat will disperse throughout the rest of the dish. Fat tends to be an important carrier of flavour in dishes, so getting rid of it, will change the flavour profile.

      Hope that helps!

  2. The roux is the unhealthiest part of any “French” gumbo.

    Instead of roux, use the ingredient the dish actually takes it’s name from, Okra as a thickener. Browning the chicken (and sausage will provide all the color you need).

    Roux (flour or filé) only developed as a replacement for okra when it wasn’t available or from those who just didn’t like eating it.

    But I promise it’s much better and healthier to go back to the original meaning of gumbo (okra) derived from it’s African cousins.

  3. I bake my flour in the oven to get it dark brown. Two beers and wal – La !
    Pull roux out of oven and go on to the gumbo stage.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Skip to Recipe