and when it’s old The Healthfulness of Fish Oils Why should fish and not Angus steers provide the highly unsaturated fats that turn out to be good for us? Because oceanic waters are colder than pastures and barns, and most fish are cold-blooded Throw a beefsteak in the ocean and it congeals; its cells are designed to operate at the animal’s usual body temperature, around 100ºF/40ºC The cell membranes and energy stores of ocean fish and the plankton they eat must remain fluid and workable at temperatures that approach 32ºF/0ºC Their fatty acids are therefore very long and irregular in structure (p 801), and don’t solidify into orderly crystals until the temperature gets very low indeed The Perishability of Fish and Shellfish 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, coldwater species, especially fatty ones, spoil faster than tropical ones Where refrigerated beef will keep and even improve for weeks, ... 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.. .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... 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, coldwater species, especially fatty ones, spoil faster than tropical ones Where refrigerated