Jerry Avins wrote:
...
> Thanks, Val. I learned a good bit. Oat flour and rice (I have less
> experience with it) flour have some of the nice keeping qualities of
> arrowroot without the gloss. I'll review what McGee* has to say.
>
> Jerry
> __________________________________
> * "On Food and Cooking" ISBN 0-684-84328-5
This is from McGee:
*Flour and Cornstarch*
Wheat flour is the thickener most often used in European and
American cooking, and cornstarch is preferred in Oriental cuisines,
though it sometimes substitutes for Flour in Western recipes. cornstarch
is purified by soaking the whole grain, milling it coarsely to remove
the germ and hull, and grinding, sieving, ans centrifuging the remainder
to separate the seed proteins. The resulting starch is washed, dried,
and reground into a fine powder consisting of single granules or small
aggregates.
Wheat starch will begin to thicken at a somewhat lower temperature
than cornstarch. More im****tant, flour contains a significant amount of
protein, about 10% by weight, while cornstarch is relatively pure and so
thickens more efficiently. Cookbooks vary in their advice, with either
1.5 or 2 tablespoons given as the equivalent of 1 tablespoon of
cornstarch. Perhaps the most immediate difference between these two
thickeners is a visual one. A flour sol will remain mostly opaque, while
a cornstarch-based sauce becomes translucent and gives a glossy finish
to foods it is poured on. Again, the key is flour proteins. gluten
proteins are not soluble and, when mixed with water, form clumps that
will not break up with cooking. Light that may pass right through the
starch-water mesh is scattered by the gluten bloblets, producing a
milky, impenetrable appearance. Some authorities consider translucence
and gloss to be absolute virtues. The classic French brown sauce is
clarified by skimming the protein off the surface during hours of slow
cooking, and Escoffier as we have seen, looked forward to purified
starches precisely to avoid this long procedure. Others, however, think
of flour sauces as less flashy, more honest and "traditional" than
cornstarch-based sauces. This is clearly a matter of taste. Do remember,
though, that the two materials are not equal in thickening power, so
that some juggling of pro****tions is necessary when substituting one for
the other.
*Root Starches*
Both flour and cornstarch are made from seeds, and seed starches
have two general characteristics: short amylose chains, which means
relatively low thickening power for the amount used, and a noticeable
"cereal" taste. One of the reasons for making a roux, or cooking the
flour in butter before adding it to the the liquid, is to get rid if
this raw flavor. the less commonly used root starches, on the other
hand, have little taste at all and relatively long amylose chains. That
is, they do not need to be precooked and will do an equivalent amount of
thickening in smaller quantities. Root starches also gelatinize at lower
temperatures. Potato starch was the first commercially im****tant refined
starch and is still quite popular in Europe. In the United States,
arrowroot, refined from a West Indian plant /(Maranta arundinacea)/ is
commonly available.The properties of root starches make them especially
useful for last-minute corrections, as we shall see.
(Next, there is a short section about tapioca and modified starches.)
Jerry
--
Engineering is the art of making what you want from things you can get.
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