Blanching is the process of cooking foods superficially in water or steam. It's a widely used technique in both commercial and home kitchens, especially to prepare vegetables for freezing or later use. However, blanching can also be used to good effect with meats. This is less common in home kitchens, but a familiar practice in restaurants.
Many chefs, wanting the clearest possible broth or stock, begin the process by blanching the meat and bones they're using. This means bringing them to a simmer and stirring them once or twice to ensure all surfaces are exposed to the water. Proteins from the meat's surface and juices cook out and coagulate, making the familiar gray foam you'll often see forming in a soup pot. The chef drains the pot and rinses the meat, washing away these proteins, and then begins making the stock. With these proteins gone, the stock will be clearer and require less skimming and straining.
The same principle applies to some stews and sauced dishes, such as the classic veal stew known as "blanquette de veau." The veal is blanched before preparing the stew, in part to keep the sauce clear, and in part to lend the veal a delicate pale appearance. When completed, the stew combines various shades of white, ivory and tan in a dish of understated elegance.
Moderating Strong Flavors
Another reason some meats are blanched is to moderate their strong flavors. This is often done with salted or smoked meats, for example, to prevent them from overpowering other ingredients with their bold flavors. It's also commonly used with strongly flavored variety meats, or offal, such as beef kidney. After being halved and blanched, their distinctive flavor and aroma is reduced significantly. This makes them palatable to a wider range of diners.
Firming the Texture
Some meats, especially delicate variety meats, such as sweetbreads or brains, are simply too soft to be handled easily in their natural state. The classic technique for dealing with them is to blanch them in simmering water or court-bouillon, which is water that's heavily seasoned for poaching meats, skin them, shape them, and press them to arrive at the correct texture and appearance.