photo shows a flan baked without benefit of a water bath.
of gentle versus high heat on egg proteins
a baked custard mixture, pour it into individual serving dishes,
and place all except one in a shallow pan with hot water halfway
up the sides of the custard cups. Place the remaining custard on
the oven rack beside the water bath, and bake all the custards the
same length of time. If you peek in the oven when the custards are
almost cooked, that poor lone custard will probably be boiling!
Compare this custard to one cooked in the water bath. When they're
cooled, turn each onto a plate and examine it carefully. Chances
are the custard without the benefit of the water bath is full of
little holes and oozing liquid. Taste it and you'll find the texture
is quite rubbery. That's because the egg proteins have coagulated,
then toughened, squeezing out liquid as they're exposed to prolongued
same phenomenon occurs when an egg is cooked in a sizzling frying
pan. The white gets tough and rubbery and has little holes throughout
where water has leaked from the coagulating white. Even for frying
eggs, gentle heat is preferable.
Gardiner and Sue Wilson, The Inquisitive Cook