Salmon's firm flesh and concentration of healthy oils makes it an unusually versatile ingredient for seafood lovers. It can stand up to any cooking method, and its mild but insistent flavor complements both subtle and boldly seasoned dishes. Some of the most delicate salmon dishes poach the fish gently in flavorful liquids, resulting in an unusually soft texture and moist mouth-feel. For best results, the temperature of the cooking liquid should be well below boiling.
Proteins and Temperature
To know why that's the case, it's important to understand how proteins react to heat. At moderate temperatures, protein chains become firm but remain somewhat soft. As temperatures rise to the boiling point of water and beyond, protein molecules contract and tighten. This causes the meat both to shrink and to toughen. It also has the effect of squeezing moisture out of the muscle fibers, just as a sponge loses moisture when you squeeze it. In short, high-temperature cooking tends to make foods tough and dry. A piece of salmon fillet has enough fat to remain juicy and pleasurable even when cooked at high temperatures, but low-temperature cooking yields a softer, more delicate texture.
Most recipes for home cooks call for the poaching liquid to be brought to a boil, then for the temperature to be reduced while the fish cooks. This ensures that the initial temperature will be high enough to kill salmonella or other bacteria that might otherwise survive at a low-temperature simmer. The ideal temperature range for poaching salmon is between 160 and 180 degrees Fahrenheit, low enough to avoid any toughening of the proteins yet high enough to cook the salmon in a relatively short time.
Using a Thermometer
At those temperatures the poaching liquid will be quite still, so it's difficult to maintain the correct temperature without the aid of a thermometer. Probe thermometers are the most useful, because the probe can remain in the water and provide temperatures in real time. Some digital thermometers come with a clip for mounting onto the lip of a pot or pan, which also serves the purpose. Depending on your poaching temperature, salmon fillet portions will take 10 to 13 minutes to cook per inch of thickness. They're finished when they're opaque even in the thickest portion of the fillet.
The two traditional poaching liquids for fish are fish broth and court-bouillon, a highly flavored broth made by simmering herbs and spices with white wine, wine vinegar and water. Both add gentle flavor to salmon but don't limit your choice of sauces. You can also poach salmon in wine, beer, fruit juice, olive oil, butter sauce and many other liquids or combinations of liquids. Thick sauces have a tendency to stick and scorch on the bottom of the pan, so they should be avoided unless you're oven-poaching.
- On Food and Cooking: The Science and Lore of the Kitchen; Harold McGee
- The Washington Post: The Gentle Art of Poaching
- Photo Credit Eising/Photodisc/Getty Images