# What is the thickening power of different types of roux?

I often take the easy way out and work with white roux, usually mixing it 1:10 for a sauce, and using the warm liquid into hot roux method. Tonight I needed a more toasted taste. I was afraid to try dark roux outright, and went for brown roux. "The professional chef" gives a bechamel recipe with 1:10 (white roux to milk) and an espagnole recipe at 1:8.5 (white roux to stock), so I thought I'd be on the safe side with 1:7.2 (brown roux to stock). The result was much thinner than I expected, I had to emergency-bind it with arrowroot.

So, I would like to know, what is the correct ratio for roux? Let's assume that I am thickening the same liquid (e.g. beef stock), and I know how thick a 1:10 mix of white roux and liquid gets. What ratio of blonde, brown and dark roux to liquid creates the same viscosity as 1:10 white roux?

• 1:72? Not 1:7.2?
– Cascabel
Feb 14, 2012 at 4:13
• Sorry, had forgotten the decimal point.
– rumtscho
Mar 18, 2012 at 17:35

My understanding is that the ratio shifts from 10:1 (liquid to roux) for a pale roux, up to about 5:1 for a nutty brown roux, with a somewhat linear relationship between the two extremes. A dark brown roux has very little thickening power, mostly they are used for flavor more than actual work-a-day thickening.

The problem may not so much in the roux ratios, but in other ingredient variations. For instance, if you are using a traditional 3:2 flour:fat roux, and your fat is butter, make sure you are using clarified butter, or that you are allowing most of the water to cook out of the butter before adding the flour - excess water in the roux will break down some of the starches and reduce the thickening strength.

Finally, there will be some variation no matter what - you can always make a little extra roux in a second pan to integrate if necessary.

• If you're paranoid that you might need more roux, you can always make a larger batch, then remove some to add back in later. (I've held extra in the fridge for a few days; another question mentions freezing it)
– Joe
Sep 16, 2014 at 22:43

I don't know if it's possible to give a very accurate roux:liquid ratio as a function of color because it can be hard to accurately and repeatably judge the color. Your best bet is to add some of the liquid -- maybe half or so of what you expect to need eventually, whisk until smooth, and bring it to a boil. It should thicken up at that point, and then you can start adding more of the liquid until you get to the consistency you want. Remember that the sauce will thicken a bit more as you cook it due to evaporation, and it also seems to thicken a bit as it cools. So if you start with it just a touch on the thin side, it'll probably be perfect at serving time.

Maybe there does exist a roux color chart that can help, or maybe you're not looking for super accurate numbers. After checking "Cooking" (Peterson), "The New Professional Chef" (Culinary Institute of America), "On Food and Cooking" (McGee), and "Cookwise" (Corriher), the only guideline on ratio I found was from Shirly Corriher, who tells us that you want 1 tablespoon of flour per cup of liquid for a thin sauce, 2 tablespoons per cup for a medium sauce, and 3 tablespoons per cup for a thick sauce. There's a discussion of why darker roux thickens less, of course, but no attempt to quantify that effect. Corriher goes on to point out other variables: age of the flour, protein content (higher protein flour thickens less), and other ingredients (salt, sugar, acid).

Perhaps because there are so many variables that are hard to quantify and control, this is one of those areas where most cooks rely on a little experience and a lot of observation.

• I'm all for just trying things, but rumtscho did explicitly ask for actual ratios. Your first sentence confuses me - I'm not sure why the fact that dark roux is different from white roux would make it impossible to measure anything with dark roux. You could, for example, thicken something with 1:10 white roux, then do exactly as you say, gradually adding measured amounts of liquid until it comes to the same consistency, and then you'd know.
– Cascabel
Feb 14, 2012 at 4:15
• @Jefromi I mean that without a reliable way to judge how far the roux has cooked, you can't accurately know the degree to which it will thicken. The human eye is very good at comparing two colors side by side, but not so good at measuring color in an absolute sense; what looks "medium brown" on different days, in different lighting conditions, and especially to different people, will vary a lot. So the right ratio might be 1:7 one day, and 1:8 the next. I'm not saying "just try it," but rather "sneak up on the thickness you want, because you can always thin the sauce more." Feb 14, 2012 at 4:26
• Maybe your first sentence would have been better stated "...because you can't accurately measure the darkness of the roux." And yes, I understood what you meant by gradually adding liquid ("just try it") but it's not necessarily useful if you're trying to make a given amount of sauce, not to use up a given amount of roux.
– Cascabel
Feb 14, 2012 at 4:29
• @Jefromi I've updated the first sentence as well as most of the second paragraph -- see what you think. My objection to "just try it" is that it sounds haphazard, whereas what I'm talking about is quite methodical. Once you've made the roux, you've basically established the final volume of sauce (unless you do as Sam Ley suggests and keep some extra roux on hand). The desired texture of the sauce is usually more important than the quantity, so thin it until you're satisfied. Feb 14, 2012 at 5:27

Although this doesn't specifically answer the question, it does include a comparative colour chart for roux, which will be most helpful in gaining a consistent thickening power.

From there I'd be tempted to make a batch of sauce as suggested above, using a given quantity of roux at the correct colour & adding stock to derive a known quantity of stock to roux. Thereby giving the ratio you'll use later.

Once noted down it should be easy to derive a ratio and make-up the rest of the sauce with a new roux, and you'll know your numbers for next time. :)

• I have the whole book at home, but it doesn't say anything about the ratio. I know I could check for myself, but I hoped to learn it from somebody who has already done it, there is no need to reinvent the wheel once per kitchen.
– rumtscho
Dec 2, 2014 at 21:31