"Tank" <[email hidden]> wrote in message news:<[email hidden]>...
Quoted message said:What chemical action makes a roux function? What causes it to create a lovely smooth sauce or
gravy when you add the broth or other liquid? Why does it work better than using a thickener after
making the sauce, such as corn starch or flour & water?
Okay, my answer may not be exactly right, but I have an OK knowledge of food science, so I suppose
that you could call this an "educated guess".
I am willing to bet that the chemical action that makes a roux function is the same as any other
starch thickener (liason): the starch absorbs the liquid. However, the more that flour is cooked,
the less thickening power it has. So, by cooking it with fat for a period of time, it weakens the
thickening ability and gives a smooth, rich sauce rather than a gummy or gluey one.
What do you mean by "work better"? I would say that this one depends on the recipe. For example, I
use cornstarch and water to thicken a stir-fry sauce, beurre manie (raw butter and flour kneaded
together) for coq au vin, dark roux for jambalaya, medium roux for gravy, tapioca or arrowroot for
fruit pies, etc...
HTH, Erica