a moderate flame help minimize scorching,
and a double boiler will prevent it (though it’s
more trouble).
Between the pan bottom and the surface,
particles of other ingredients can cause
curdling by providing surfaces to which the
milk proteins can stick and clump together.
And acid in the juices of all fruits and
vegetables and in coffee, and astringent
tannins in potatoes, coffee, and tea, make milk
proteins especially sensitive to coagulation
and curdling. Because bacteria slowly sour
milk, old milk may be acidic enough to curdle
instantly when added to hot coffee or tea. The
best insurance against curdling is fresh milk
and careful control of the burner.
Cooking Sweetened Condensed Milk Because
it contains concentrated protein and sugar,
sweetened condensed milk will “caramelize”
(actually, undergo the Maillard browning
reaction, p. 778) at temperatures as low as the