Dextrinization and Gelatinization in Sauce Making

[chefmeryl]

Hello,

I hope someone can answer some questions I have had regarding the technical details of roux and white sauces made from them.

Before writing, I have consulted a lot of books including Culinary Institute of American and Cordon Bleu books.

1. Regarding the dextrinization of the flour, many books say cooking the starch in fat reduces "starchiness" and increasdes "nuttiness". But if I understand it correctly at least for a white or blond roux, dextrinization will not be complete and so most of the starch will still be there. So does the nuttiness from dextrinization partially mask the starch flavor of the remaining starch or is something else happening at a chemical level which actually changes the starch flavor and aroma of all the starch molecules?

2. Other books I have read say that in sauces made from rouxs, gelatinization further reduces starchiness by spreading the starch molecules around but I haven't read anywhere that it changes them chemically. So does the spreading around of the molecules reduce starchiness by effectively "diluting" their starch flavor? Or does it not change starch flavor at all, just the texture?

3. Some books mention that when making a bechamel, you should whisk and simmer (for up to 30 minutes) to reduce starchiness . I have had pretty good luck simmering at low heat and whisking only several minutes following gelatinization. Doesn't oversimmering of dairy-based sauces begin to produce off-flavors from cooking the milk proteins?

4. Finally, many books seem to specify adding a hot roux to a cold liquid (or vice-versa). But does this matter if you add only small amounts of liquid to the roux? My method for 1 to 3 cups of bechamel has been to add only a couple tablespoons of liquid to the roux in the beginning (without regard to what is hot or cold), mix till no lumps, than add slighly more liquid. I don't usually have any lumps.

Thanks so much,

Meryl

[cape chef]

Originally Posted by chefmeryl

Hello,

I hope someone can answer some questions I have had regarding the technical details of roux and white sauces made from them.

Before writing, I have consulted a lot of books including Culinary Institute of American and Cordon Bleu books.

1. Regarding the dextrinization of the flour, many books say cooking the starch in fat reduces "starchiness" and increasdes "nuttiness". But if I understand it correctly at least for a white or blond roux, dextrinization will not be complete and so most of the starch will still be there. So does the nuttiness from dextrinization partially mask the starch flavor of the remaining starch or is something else happening at a chemical level which actually changes the starch flavor and aroma of all the starch molecules?

(dextrinization is a term having to do with making the starch in roux more stable and dispersible in a sauce. So the nuttiness you refere to does not (and should not)be part of a white roux. As far as a "chemical level" it's all abouut molecules and how they react to heat and how large or small they become (larger being stronger) smaller ones are not as effective in thickening, but offer the "nuttiness". You would have to add more dark stock per volume of liquid then a white stock)2. Other books I have read say that in sauces made from rouxs, gelatinization further reduces starchiness by spreading the starch molecules around but I haven't read anywhere that it changes them chemically. So does the spreading around of the molecules reduce starchiness by effectively "diluting" their starch flavor? Or does it not change starch flavor at all, just the texture?

(As I said above, the starch molecules become shorter (weaker) by heating them, this is not so much a chemical change, but perhapes a "makeover" of the molecule.)

3. Some books mention that when making a bechamel, you should whisk and simmer (for up to 30 minutes) to reduce starchiness . I have had pretty good luck simmering at low heat and whisking only several minutes following gelatinization. Doesn't oversimmering of dairy-based sauces begin to produce off-flavors from cooking the milk proteins?

(Yes and no, of course we are dealing with pasturized dairy in the US that makes a difference. But letting it cook out a bit not only lessens the "starchy" flavor and mouthfeel, it also creates a more creamy sauce by binding the protiens in the milk with the fat in the roux and dairy, this proceess takes a little time.)

4. Finally, many books seem to specify adding a hot roux to a cold liquid (or vice-versa). But does this matter if you add only small amounts of liquid to the roux? My method for 1 to 3 cups of bechamel has been to add only a couple tablespoons of liquid to the roux in the beginning (without regard to what is hot or cold), mix till no lumps, than add slighly more liquid. I don't usually have any lumps.

(Being at differnt temps,hot/cold-cold/hot each has the time to "warm up" to each others temputure and give the fats and starches a chance to bind together as thet become the same temp.)

(I don't know if this helped, but great questions)

Thanks so much,

Meryl

I think I may have messed up your post by trying to quote you, sorry

I put my responses in parenthisis because after previewing my reply, you could not tell where and what I said

[chefmeryl]

Hi all,

I didn't think this was going to be a tough one! Maybe cause I was hoping for a chemist's response. Anyway, I'm rephrasing my question a bit so maybe someone can help:

During the early part of making a roux one tries to get rid of the starchy taste in the flour. I have always assumed it was dextrinization which did that. But as I think about it, dextrinization is never complete unless you make a dark roux. So I am wondering.... Is there some other chemical process besides dextrinization which removes the starchy taste from roux or is the partial-dextrinization producing enough flavor to mask the flavors of remaining starch which hasn't undergone dextrinization?

Thanks so much,

Meryl

[cape chef]

Hi Merly,

If you look at the quote I highlighted, you will find that I did my best to answer your questions.I used commas on my replies.

[chefmeryl]

Cape Chef,

Your reply was really helpful. I'm sorry if I implied something else. It was just me hoping for numbers and formula, etc..

Have a great day.