Peter Aitken wrote:

> "Bob Pastorio" > wrote in message
> ...
>
>>AzuReBlue wrote:
>>
>>
>>>I was wondering what the difference is between using cornstarch to
>>>thicken something vs. flour. Is there any? Can I use cornstarch
>>>in place of flour with no noticeable effect?
>>
>>Depends on what you're doing and how you're doing it.
>>
>>Cornstarch is a pure starch with no protein or other ingredients. When
>>it gelatinizes, it's clear.
>>
>>Flour has quite a few other things in it besides starch including
>>protein. When it gelatinizes, it's opaque because of the "impurities"
>>in it.
>>
>>If you're making roux or slurries, they'll each behave differently.
>>
>>What are you doing? How are you doing it? More info from you gets more
>>info.
>>
>>Pastorio
>>
> Making a roux with cornstarch is new to me - can you please elucidate?

Escoffier thought it was a good idea about a century ago. He talked
about arrowroot, but as starches, they're essentially interchangeable.
He said:
"A Roux made from a pure starch such as arrowroot would give the same
result as one made from flour, the only difference being that it is
necessary to take into account the other substances contained in flour
which would mean that a smaller amount of pure starch is required."

He suggested making the roux from clarified butter and arrowroot. We
used to do it in my restaurants for several reasons: No long simmering
necessary as starches gelatinize before the full boil is reached. No
skimming because the other ingredients are missing from both the
butter and the starch. It could be adjusted immediately rather than
having to wait for full thickening as is the case with a full butter
and flour roux.

We used to use the butter and starch volume for volume. Cup for cup or
tablespoon for tablespoon.

Pastorio