Join Date: Aug 2004
Water vapor and minute water droplets seen in the air are two different things. The high-pressure steam that drives the catapults on an aircraft carrier is invisible, and under enough pressure, that blown through a pin-hole in a high pressure pipe, will cut metal. The hot droplets from a tea kettle, or boiling pot of water is also steam. Steam is also produced when frying, as the water that leaves the food is heated by the hot oil. Those bubbles you see when food is frying is superheated steam, or vapor. The bubbles release it into the air when they pop on the oil surface. It is often invisible to the eye.
The right conditions will cause visible water droplets in the air, even at very cold temperatures. We see it as clouds, or fog. It's still water, suspended in the air, and caused by external conditions on the normally invisible water vapor that's in the air.
Cullinarily, steaming food is the act of transfering heat into the food by bringing that food into contact with hot steam. There are different ways to achieve this. Most commonly, it's done by placing food into a container with myriad holes that allow steam to pass through to the food. The container with holes (steamer) is placed into a tight-fitting pan that contains boiling water. A cover is fitted to the steamer insert, trapping the hot steam. The steam transfers heat into the food, but leaves more nutrients, and color pigments in the food than does simmering, or boiling water.
Another method of steaming is achieved when food is placed on a shelf, or suspended grate in a pressure cooker. The pressure cooker uses hotter steam, as the internal pressure of the vessel allows the water to boil at a higher temperature than at normal pressure. Also, the pressure helps to further stress the food, breaking it down more quickly than is achieved in a non-pressure cooking method.
If food is placed in foil, with no added liquid, such as in a foil pouch, or en-pappiote, or even in a foil-wrapped potato, as the food heats, the water vapor that normally escapes into the air is trapped by the foil, and steams the food.
The reason that lasagna is considered a baked dish is that the liquid for the sauce, meat, and cheese simmers and cooks the noodles. Yes, steam is produced, but isn't the primary mechanism that transfers heat into the food, or hydrates the noodles.
The same is true of casseroles, pot roasts, foods made in a slow cooker, etc.
Steaming is a great way to cook many vegetables, some breads, and even a pudding. Meats are usually better when cooked by another method, at least, that's MHO.
I welcome all comments, valid corrections, and discussion. 'f I've stated something incorrectly, let me know, but have documentation to back you up.
In any case, I hope this post helps clear things up a little about what steaming is, and isn't.
Seeeeeya; Chief Longwind of the North
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