Recently I have been making white sauce by:

  • heating the milk in a pan until nearly boiling
  • mixing corn flour with a small amount of cold milk
  • removing milk from stove
  • add corn flour mix to hot milk
  • stir until thick.

This is very fast and never produces lumps, but what are the disadvantages versus using the traditional roux approach?

  • 2
    I am not certain why your are looking for "disadvantage"? if it works for you and in the recipes you make, then it is a good substitute for a roux.
    – Max
    Mar 13, 2016 at 22:33
  • My suggestion is that you try making a sauce with a blonde roux and your own white sauce and comparing the two for yourself, side by side. Mar 13, 2016 at 23:27
  • I'm surprised there are no real downsides. If so, why do all recipes i read call for a roux?
    – Tim Galvin
    Mar 15, 2016 at 18:56
  • 1
    The technique you're using is called a 'slurry' (mixing the starch with a cold liquid before adding it to the hot liquid). I want to say that I've seen this technique used for gravy, so went looking for cream gravy w/ slurry ... but wasn't having much luck in recipes (a few people saying it could be used, but most were still using wheat flour). I did find some cons to cornstarch -- besides the stability issue that Hmmm mentioned, they also said it doesn't take well to freezing (if you make a lasagne & freeze it), and it can lose thickness if over-heated.
    – Joe
    Sep 28, 2016 at 21:54
  • 1
    In the end, what you are doing is the exact same thing as making a custard sauce from an eggless custard powder, sans the vanilla flavoring and colorant (cornstarch, coloring, flavouring, that's all what is in custard powder). Sep 29, 2016 at 8:22

2 Answers 2


If it works for you (you like the results), there really isn't a disadvantage unless you have leftovers. Cornstarch (cornflour) thickened sauces tend to thin upon reheating more than roux thickened sauces. Depending upon what you are making, you may or may not notice it much if at all.


I saw this on another search and I will quickly add my 2 cents. Cornflour (corn starch) doesn't hold it's thickness as well over long periods of time in a warmer (think restaurant). The sauce breaks with long-term heating or reheating, however I feel it is far smoother than a roux is. I can taste the grittiness of AP Flour in a roux.

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