products, including light cream and sour
cream, can’t actually be cooked to make a
sauce; they must be added as a last-minute
enrichment. The exceptions are heavy cream
and crème fraîche, which contain so little
casein that its curdling simply isn’t noticeable
(p. 29).
Reduced Cream When heavy cream is added
to another liquid to enrich and thicken it — to
a meat sauce, or deglazing liquid, or a
vegetable puree — then of course its fat
globules are diluted and its consistency thins
down. In order to make cream a more
effective thickener, cooks concentrate it even
further by boiling off water from the
continuous phase. When the volume of cream
is reduced by a third, the globule
concentration reaches 55% and the
consistency is like that of a light
starchthickened sauce; when reduced by half,
the globules take up 75% of the volume and