On Food and Cooking

are neither very immature nor fully ripe:
immature eggs are small and hard and have
little flavor; eggs ready for spawning are soft,
easily crushed, and quick to develop off-
flavors. Roes consist of separate eggs barely
held together in a dilute protein solution and
enclosed in a thin, fragile membrane. They
can be easier to handle in the kitchen if
they’re first briefly poached to coagulate the
protein solution and give them a firmer
consistency.
Male fish accumulate sperm to release into
the water when the females release their eggs.
The sperm mass is called white roe, milt, or
laitance, and is creamy rather than granular
(the sperm cells suspended in the
proteinaceous fluid are microscopic). Sea
bream and cod milts are prized in Japan,
where they’re cooked gently to a delicate
custard-like consistency.