French Roux

Sauce Explained: It’s Four Varieties And How They Form The Foundation Of Dishes

What Is Roux?

At its simplest, roux (pronounced ‘roo’) is flour cooked into fat until the raw, chalky taste of the flour disappears, usually in a ratio of one part flour to one part fat by weight. The word comes from the French ‘beurre roux’, or browned butter, itself traced back to the Latin ‘russus’ for red-brown. The word's first recorded use goes back to 1793, though the underlying technique is older. 

The practice of French cooks thickening broths with fried flour dates back to at least 1651, when the chef La Varenne described a similar flour-and-lard mixture. From there, French roux sauce became the backbone of sauce-making, before travelling with French settlers and traders into Louisiana kitchens, Ottoman kitchens, and eventually East Asian ones, each adapting it to local fat and flavour.

The Four Varieties Of Roux

A French roux sauce can be roughly sorted into four stages, and the only difference between them is the time they spend on the heat:

• Light (white) roux: Cooked for 1 to 3 minutes, just long enough to lose the raw flour taste. Pale, frothy, and mild in flavour. Used for béchamel, cheese sauces and creamy soups.

• Blond roux: Cooked for 3 to 5 minutes, until it turns light tan and smells faintly nutty. The standard base for velouté and lighter gravies.

• Brown roux: Cooked for roughly 6 to 10 minutes, until it resembles peanut butter and develops a toasted aroma. Used in richer pan gravies and as the base for espagnole sauce.

• Dark roux: Cooked anywhere from 10 to 20 or more minutes, longer at a lower heat, until it turns a deep, near-chocolate brown. Prized in Cajun and Creole cooking for gumbo, étouffée and brown gravies.

Why Roux Changes Colour

Every stage of roux starts the same way, with the fat coating the starch granules in the flour, which stops them from clumping once liquid is in the pan. On low heat, those starch granules absorb liquid and swell, in a process called gelatinisation, and the actual mechanism that thickens a sauce. Keep cooking past that point, and the flour's natural sugars begin to caramelise through the Maillard reaction. This is the same browning reaction that is behind toasted bread and seared meat and turns a pale roux into a nutty, deep-brown one.

The catch is that browning breaks down some of the flour's starch chains, so a darker roux thickens less per spoonful even as it tastes more complex. Thankfully, professional chefs have already done this testing on the implications for cooking:

• A blond roux had 14% less thickening power than a white one

• A roux cooked to the colour of peanut butter had lost 26% of its thickening power

That's the reason dark-roux dishes like gumbo are so reliant on roux, or an added thickener, to make up the difference.

How To Make Each Type Of Roux

The method behind every roux recipe is identical across all four stages, and here’s how to spot the changes during cooking:

• Melt the fat (butter, oil, ghee or rendered fat) in a heavy-bottomed pan over medium-low heat.

• Add an equal weight of flour and stir it in until smooth.

• Keep stirring constantly, in a steady figure-eight motion, so it cooks evenly and doesn't catch at the bottom of the pan.

• Watch for colour rather than the clock, as pan thickness, stove strength, and volume all shift the exact timing.

• Pull it off the heat at the target stage; a roux keeps darkening for a few seconds even after it's removed from the pan.

Whole butter contains milk solids that start to scorch around 150°C, so it suits light and blond roux best. Brown and dark roux hold up better with an oil with mild to no aroma, ghee, or rendered fat that tolerates higher heat without burning. Once the colour starts to shift, you have to be vigilant, as a roux left unattended for even a few seconds can go from perfectly toasted to bitter and burnt.

The Mother Sauces And The French Roux

French roux sauce isn't just a thickener in classical French cuisine, like how a cornstarch slurry is for the typical soup in Indian homes; it's the foundation three of the five ‘mother sauces’ are built on, that is, in hundreds of famous French recipes and beyond. Chef Marie-Antoine Carême first grouped French sauces into four foundational categories in 1833; decades later, Auguste Escoffier revised the list in his 1903 ‘Guide Culinaire’, dropping one and adding two more to arrive at the five mother sauces still taught in culinary schools today.

• Béchamel uses a light roux whisked with milk.

• Velouté uses a blond roux built up with a light stock (chicken, veal or fish).

• Espagnole uses a brown roux simmered with brown stock and tomato, the base for demi-glace and other rich, dark sauces.

Tomato sauce and hollandaise round out the five mother sauces, but neither is roux-based. Tomato sauce relies on reduction, though some versions might feature a roux, and hollandaise is an egg-and-butter emulsion.

Roux Beyond France

Roux didn't stay restricted to France, and with time, travelled with 18th-century Acadian exiles into Louisiana, where it became central to Cajun and Creole cooking. Two things changed along the way: the fat, and how far cooks were willing to push the colour.

• Cajun and Creole gumbo: Cajun cooks typically push their roux to a very dark, near-black stage for maximum flavour, and lean on okra or filé powder to make up for the lost thickening power; Creole cooks more often stop at a lighter blond or medium stage, especially in seafood gumbos.

• German and Central European cooking: A roux-style thickener typically made with lard rather than butter appears under names like ‘Mehlschwitze’ or ‘Einbrenne’, used to finish soups and stews.

• Ottoman and Turkish cooking: A flour-and-fat thickener called ‘meyane’ has reportedly been used in the region's kitchens since at least the 15th century, predating the technique's association with French haute cuisine.

• Japanese curry (karē): Adapts the same idea into a solid, often store-bought block of curry powder fried into a roux of butter or oil and flour, then dissolved into stock.

Light Roux vs Dark Roux vs Everything In Between

French Roux Sauce, Simplified 

Whether you are trying a French recipe or a Cajun-style one that needs a dark roux, knowing how to make one sans burning is the first step towards perfect their recipes. French cooking is technique-heavy, and a little practice goes a long way to master the roux and, in turn, the French mother sauces and, in turn, making some dishes taste as authentic as they do in their home countries.