On Food and Cooking

California  halibut Paralichthys    californicus

The Effects of Rigor Mortis and Time

We sometimes eat fish and shellfish very
fresh indeed, just minutes or hours after their
death, and before they pass through the
chemical and physical changes of rigor mortis
(p. 143). This stiffening of the muscles may
begin immediately after death in a fish
already depleted by struggling, or many hours
later in a fat-farmed salmon. It “resolves”
after a few hours or days when the muscle
fibers begin to separate from each other and
from the connective-tissue sheets. Fish and
shellfish cooked and eaten before rigor has set
in are therefore somewhat chewier than those
that have passed through rigor. Some Japanese
enjoy slices of raw fish that are so fresh that
they’re still twitching (ikizukuri); Norwegians
prize cod held in tanks at the market and
killed to order just before cooking (blodfersk,