A classic bechamel sauce is a roux and milk. Why can’t I just add the flour directly to the milk and cook till thickened, stirring vigorously to keep it from clumping?

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    I can see this is going to be a controversial question :/ – Fattie Jul 1 '20 at 14:37
  • BTW unfortunately it does seem this is a dupe.. – Fattie Jul 1 '20 at 14:37
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    Does this answer your question? What is the advantage of a roux over a raw flour slurry, in sauce? – Fattie Jul 1 '20 at 14:37
  • probably, Fattie, but members might hesitate to dup-close a question with a +52 voted answer. – JTP - Apologise to Monica Jul 3 '20 at 16:13
  • There is one way you can "just add flour to milk", which is with the milk cold, and using a blender or powered mixer to break up the lumps. This is what one does for crepe batter. Presumably such a mixture could also be cooked into a sauce, although I've never seen one. – FuzzyChef Jul 6 '20 at 5:57

You do not need to make a roux. While your proposed technique of adding flour directly to milk will almost certainly lead to clumps, there are other ways to incorporate flour, butter, and milk: namely, a beurre manié.

First, let's explore why flour clumps in hot liquid. As explained in this Seattle Times cooking advice column, flour will immediately gelatinize when added -- forming a sort of gel-like barrier that encases clumps of flour. No amount of stirring will break up these clumps. A simple fix is to use Wondra or a similar product. This flour is specially formulated to avoid clumping; I am not familiar with the details of their process, but I know that the product can be directly whisked into a sauce without clumping. It is fairly popular in America for making gravies.

But, with standard flour, the best fix is to work in fat: it works as a lubricant, keeping particles of flour separated for long enough to incorporate into the sauce. As you know, one method to accomplish this is to make a roux: flour is added to hot fat and stirred until incorporated. Only then is liquid slowly added. An alternative is to make a beurre manié: a mix of cold butter and flour that is added, uncooked, to the sauce.

Both a roux and a beurre manié provide sufficient lubrication to prevent clumps; however, many chefs prefer roux for a variety of reasons.

  • Making a roux requires less mechanical action. Working cold flour and butter requires a lot of stirring or kneading. A roux, on the other hand, can be quickly whisked together with less resistance. This is ultimately a personal preferences: you may find one or the other workflow easier.

  • Some people think a beurre manié tastes "floury". The hot butter in a roux lets you "cook out" the floury taste, some say. Not everyone agrees: this cook tried both methods, and in a taste test, saw no discernible difference. If a sauce thickened with beurre manié tastes good to you, go for it.

  • In the same vein, a roux lets you toast the flour. Dishes that use "dark roux" (like gumbos, etouffée, or Japanese curry) rely on this toasty flavor for depth, color, and balance. In this case, you cannot substitute a beurre manié without losing flavor.

The beurre manié has a bit of a bad reputation as a "shortcut" or inferior option to the roux. But, if you are struggling with roux, or just want to try a different process, I encourage you to give it a shot. If you do get some clumps, you can always just strain the sauce through a fine sieve.

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    Thank you for a great answer. Incidentally, it's interesting to observe the clumping and surface gelatinization when one heats flour with water (say in equal quantities). Okay, there's no culinary use, but flour is cheap. – Mark Wildon Jun 30 '20 at 20:05
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    @MarkWildon You're right, you can observe this directly; it is a unique texture for sure. But there is indeed a culinary use! A tangzhong or "water roux" of gelatinized flour is used in Chinese baking to retain moisture and make pillowy soft bread. Try it out!. – Benjamin Kuykendall Jun 30 '20 at 20:23
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    I don't know whether buerre manié is a "shortcut" but a sauce made w/ buerre manié is not even vaguely like bechamel. For example, say we were discussing cognac, one could say, oh, there's also champage, different technique - there's no sense at all in which method champ. is a "shortcut" to method cognac, they're totally different. {As an aside, I don't think buerre manié is particularly easier than making roux. It's incredibly difficult to get roux to turn out correctly, but then, that's true of many things.} – Fattie Jul 1 '20 at 14:24
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    I believe "cowboy roux" {why denegrate cowboys, BTW?!} is another sort of "sauce substitue".. flour and water right? – Fattie Jul 1 '20 at 14:32
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    "While your proposed technique of adding flour directly to milk will almost certainly lead to clumps" well, there is the family of deserts that is colloquially called "Pudding" in German and more correctly "Flammeri". You start by bringing part of the milk to boil and in parallel prepare a slurry of the flour (or starch) in the remaining milk. Then quickly stir the slurry in the hot milk. (compare also starch-based versions of Dutch Vla). – cbeleites unhappy with SX Jul 1 '20 at 21:50

If you want to make bechamel, a roux is necessary because, well, that's what bechamel is. If you use your proposed method (or anything else) then the result will not be a bechamel, per definition, and it will also taste differntly. In the first place, you will be missing all the fat, and then there are subtleties like the flour not being fried.

This doesn't have to stop you from using a flour-thickened milk, as you propose. Nobody stops you from experimenting with it, and developing recipes with it if you would like to. (I am not aware of any classic recipes which use it). Also, you may want to look into using starch instead of flour for that application - it is easier to work with than non-fried flour.

  • This is of course completely correct. You can't make sauce with "flour and milk" and more than you can make a pasta dish with "flour and water". – Fattie Jul 1 '20 at 14:33
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    @Fattie: of course you can use this to make sauces. It's just not bechamel sauce. In German its called "Mehlsoße" (literally flour sauce; or deprecatingly Becher-Mehl-Soße :-> if someone tries to pretend it's bechamel). In terms of fat, it is also possible to use a mix of milk + flour + cream, which will have more fat. – cbeleites unhappy with SX Jul 1 '20 at 21:56
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    that's great info, @cbeleitesunhappywithSX thanks, mfg – Fattie Jul 1 '20 at 22:22
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    This doesn't really answer the question, which is essentially: "what is the difference". – Neil G Jul 3 '20 at 3:50
  • @NeilG My answer says it: the difference is in the taste. In this aspect, human language is not as rich as human perception - there is no way to describe taste exactly. So it is impossible to specify it in the answer. You will have to have both sauces side-by-side to know how the taste differs. – rumtscho Jul 3 '20 at 7:43

The flour must be cooked in oil, otherwise the flour will never get hot enough to undergo the changes looked for in a roux.

The oil will easily be over 350F, but milk will never get hotter than boiling.

  • You have to wonder why this was downvoted. – Fattie Jul 1 '20 at 14:13

At the risk of heterodoxy, you can. That great British author of they-just-work recipes, Delia Smith, does exactly what you suggest: puts everything in a saucepan and whisks it. She avoids clumping by starting with everything cold, and the recipe specifically addresses the cooking-out-the-floury-taste issue others have raised. Though I personally prefer to make the roux first because, well, reasons, I've tried it, and it works; one of my sisters swears by it.

  • Unfortunately, saying that Delia Smith doe sit is basically saying it's crap. – Fattie Jul 1 '20 at 14:13
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    @Fattie we could argue that point back and forth until everyone else got bored, but why not just try it? I did. It worked for me. I don't like it, and (as I think I said) I still make a roux every time, but it does work. You, too, have a simple test easily accessible. – MadHatter Jul 1 '20 at 14:38
  • I've surely tried it, thanks! The answer is interesting and informative; I made a point in a comment. – Fattie Jul 1 '20 at 14:42
  • @Fattie I'm not sure what that point was. If you've tried it, as you say you have, and yet rated my answer as informative, as you say you did, then that suggests it worked for you. If it did, then you might need to re-examine your position that everything Delia Smith says is crap, since it appears she said one thing that wasn't. – MadHatter Jul 2 '20 at 18:23

If it's 5 minutes to go and I find I need to thicken a stew, ragout or whatever I premix the flour with maybe three times its volume of cold water by shaking them in a small jar. It's important to mix really well while adding it to the pan or it will form blobs or strands that look ... well, use your imagination.

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