On Food and Cooking

The cold aquatic environment is also
responsible for the notorious tendency of fish
and shellfish to spoil faster than other meats.
The cold has two different effects. First, it
requires fish to rely on the highly unsaturated
fatty acids that remain fluid at low
temperatures: and these molecules are highly
susceptible to being broken by oxygen into
stale-smelling, cardboardy fragments. More
importantly, cold water requires fish to have
enzymes that work well in the cold, and the
bacteria that live in and on the fish also thrive
at low temperatures. The enzymes and
bacteria typical of our warm-blooded meat
animals normally work at 100ºF/40ºC, and are
slowed to a crawl in a refrigerator at 40ºF/5ºC.
But the same refrigerator feels perfectly
balmy to deep-water fish enzymes and
spoilage bacteria. And among fishes, cold-
water species, especially fatty ones, spoil
faster than tropical ones. Where refrigerated
beef will keep and even improve for weeks,