On Food and Cooking

stock-based brown and white sauces, or
espagnole and velouté; and the milk-based
béchamel. Each of these relies on a distinctive
combination of roux and liquid. Brown sauce
consists of a stock made from browned
vegetables, meat, and bones, then reduced
after thickening with a roux that is cooked
until the flour browns as well. White sauce
uses a stock made from un browned meat,
vegetables, and bones, and is bound with a
pale yellow roux. Béchamel combines milk
with a roux that is not allowed to change color
at all. From these three parent sauces, the
cook can produce scores of offspring simply
by finishing the sauce with different
seasonings and enrichments.
Once the roux has been added to the stock,
the mixture is allowed to simmer for quite a
while — two hours for velouté, and up to ten
in the case of brown sauce. During this time,
the flavor is concentrated as water evaporates,
and the starch granules dissolve and disperse