Today's entry is about cooking with water (H2O, get it?), but using a fairly obscure method known as crimping.
I will suppress the geek in me and just say that protein changes (denatures) when it reaches a certain temperature. Surprisingly, proteins can denature at temperatures as low as about 107 degrees fairenheit (which is why fevers up around 105 are pretty serious and it's important to get the body temperature down). The geek in me wants to blurt out that the major structual protein in muscle (myosin) denatures from 113-131 degrees, while egg whites denature at about 160 degrees.
Poaching (subjecting them to a temperature of 212 degrees) for a sufficient length of time guarantees that denaturing occurs; the problem is that other components of food also change permanently when certain temperatures are reached. This is really important when you cook oily fish such as salmon whose fats have really low volatilty points - that's why salmon gives off its distinctive odors when cooked at higher heats and stinks up your kitchen.
The solution - crimping. I believe it's a french term, but when i googled it, it only came up after 4-5 pages due to the number of entries about crimping pie crusts.
More geek stuff - specific heat - defined as the amount of heat required (per unit mass) to raise the temperature one degree celsius. Water has the highest specific heat than any other common substance, which makes it a great choice for temperature regulation (like in a radiator - the problem is water's relatively high freezing point, which is why we have to use antifreeze in colder climates).
The bottom line is to heat water to a certain temperature and then let the water transfer its heat to the object immersed in the water. The immersed object can not reach a temperature above the temperature of the water, while the water temperature gradually decreases as heat is transferred to the immersed object.
Practical application: cooking salmon
Use a pan of sufficient size to allow one to lay the salmon flat in the pan - and add enough liquid to ensure that when the salmon is added, it will be covered by about 3/4" or so. (Note: it doesn't have to be just water, for salmon, I like to use a 1/2 dry white wine, 1/2 water combination, with a pinch of tarragon.). Heat the liquid in the pan until the water just starts to bubble, (assuming you are at sea level) which is the start of simmering temperature at about 185 degrees, Add the salmon to the pan. The initial addition of the fish to the pan absorbs a significant amount of specific heat, so keep the pan over the medium heat for about a minute, then remove the pan from the heat, and cover the pan and let it sit for about 20 minutes. That's it!
It's foolproof - the salmon never gets subjected to a temperature higher than about 180 degrees, and cooks gently until the temperature of the fish reaches the temperature of the water. And while that's all going on, you are free to devote yourself to the preparation of the remainder of the meal - or entertaining your guests.
If you want to be fancier, you can prepare a court bouillon by including aromatics such as onion, carrot in the liquid, etc, and let the liquid simmer for a bit before letting it cool, straining the liquid and reheating, but if you have a quality piece of fish, let it do all the heavy lifting in terms of flavor.
Either way, the cooking liquid will be full of flavor and shouldn't go to waste. You can make a very simple sauce for the fish by removing the liquid from the pan (save half for later), and add 1 TBLS (tablespoon - which is THREE (3) teaspoons (TSP), NOT two (2)) each of butter and flour, and make a roux by heating gently and stirring for about a minute. Add the cooking liquid a little at a time, stirring to ensure a smooth consistency. Or even simpler, remove half the liquid, and then reduce the remaining liquid (heating so that liquid evaporates, concentrating the flavor) to half it's original volume, then melt a little butter into the reduction. Add a little lemon juice or balsamic vinegar to taste.
This technique works for just about any type of fish/seafood, although a little common sense is required; a single scallop into 5 quarts of liquid is definitely overkill, and fish that's dense like swordfish is going to need a longer period over heat after adding the fish (but if you do choose to experiment with swordfish, try grapefruit juice as part of the cooking liquid).
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and since i'm still here - you can ensure perfectly cooked "hard boiled" eggs by employing the same concept - as I mentioned before, egg white denatures at about 160 degrees, but at higher temperatures, that ugly green tint forms around the yolk. so for a perfectly cooked egg with a lovely yellow yet fully cooked yolk:
place eggs in *cold* (keeps eggs from cracking) water in saucepan, with enough water to keep eggs immersed. over medium heat, heat until water begins to simmer (bubbles forming). immediately remove from heat, cover, and let sit for 20-30 minutes. remove eggs and place in cold water (which facilitates removing the shell without sticking).
