There are several types of stocks. Although they are all made from a combination of bones, vegetables, seasonings and liquids, each type uses specific procedures to give it distinctive characteristics.

A white stock is made by simmering chicken, veal or beef bones in water with vegetables and seasonings. The stock remains relatively colorless during the cooking process.

A brown stock is made from chicken, veal, beef or game bones and vegetables, all of which are caramelized before being simmered in water with seasonings. The stock has a rich, dark color.

Both a fish stock and a fumet are made by slowly cooking fish bones ( crustacean shells and vegetables without coloring them, then simmering the in water with seasonings for a short time. For a fumet, wine and lemon juice are also added. The resulting stock or fumet is a strongly flavored, relatively colorless liquid.

A court bouillon is made by simmering vegetables and seasonings water and an acidic liquid such as vinegar or wine. It is used to poach fish or vegetables.

Ingredients

The basic ingredients of any stock are bones, a vegetable mixture known as a mirepoix, seasonings and water.

Bones

Bones are the most important ingredient; they add flavor, richness and cola to the stock. Traditionally, the kitchen or butcher shop saved the day’s bones  to make stock.

But because many meats and poultry’ items are now purchased pre cut or portioned, food service operations often purchase bones specifically stock making.

Different bones release their flavor at different rates. Even though the bones cut into 3- to 4-inch (8- to 10-cm) pieces, a stock made entirely of beef or veal bones requires six to eight hours of cooking time, while a stock made entirely from chicken bones requires only five to six hours.

Beef and Veal Bones

The best bones for beef and veal stock are from younger animals. They contain a higher percentage of cartilage and other connective tissue than do bones from more mature animals.

Connective tissue has a high collagen contents. Through the cooking process, the collagen is converted into gelatin and water.

The gelatin adds richness and body to the finished stock. The best beef and veal bones are back, neck and shank bones as they have high collagen contents. Beef and veal bones should be cut with a meat saw small pieces, approximately 3 to 4 inches (8 to 10 cm) long so that they release as much flavor as possible while the stock cooks

Chicken Bones

The best bones for chicken stock are from the neck and back. If a whole chicken carcass is used, it can be cut up for easier handling.

Fish Bones

The best bones for fish stock are from lean fish such as sole, flounder, whit-or turbot. Bones from fatty fish (for example, salmon, tuna and swordfish) not produce good stock because of their high fat content and distinctive flavors. The entire fish carcass can be used, but it should be cut up with a cleaver or heavy knife for easy handling and even extraction of flavors. After cutting the pieces should be rinsed in cold water to remove blood, loose scales and other impurities.

Other Bones

Limb, turkey, game and ham bones can also be used for white or brown stocks. Although mixing bones is generally acceptable, be careful of blending strongly flavored bones, such as those from lamb or game, with beef, veal or chicken bones. The former’s strong flavors may not be appropriate or desirable in the finished product.

Mirepoix

Mirepoix is a mixture of onions, carrots and celery added to a stock to enhance its flavor and aroma. Although chefs differ on the ratio of vegetables, generally a mixture of 50% onions, 25% carrots and 25% celery, by weight, is used.

For a brown stock, onion skins may be used to add color. It is not necessary to peel the carrots or celery because flavor, not aesthetics, is important.

The size in which the mirepoix is chopped is determined by the stock’s cook-time: The shorter the cooking time, the smaller the vegetables must be chopped to ensure that all possible flavor is extracted. For white or brown stocks from beef or veal bones, the vegetables should be coarsely chopped into , 1- to 2-inch (2 1/2- to 5-cm) pieces.

For chicken and fish stocks, the vegetables should be more finely chopped into 1/2-inch (1 1/4-cm) pieces. A white mirepoix is made by replacing the carrots in a standard mirepoix parsnips and adding mushrooms and leeks. Some chefs prefer to use a white mirepoix when making a white stock, as it produces a lighter product.

Seasonings

Principal stock seasonings are peppercorns, bay leaves, thyme, parsley stems, and optionally, garlic. These seasonings generally can be left whole. A stock is cooked long enough for all of their flavors to be extracted so there is no rea­son to chop or grind them. Seasonings generally are added to the stock at the start of cooking.

Some chefs do not add seasonings to beef or veal stock until midway through the cooking process, however, because of the extended cook­ing times. Seasonings can be added as a sachet d’epices or a bouquet garni.

Salt, an otherwise important seasoning, is not added to stock. Because a stock has a variety of uses, it is impossible for the chef to know how much salt to add when preparing it. If, for example, the stock was seasoned to taste with salt, the chef could not reduce it later; salt is not lost through re­duction, and the concentrated product would taste too salty.

Similarly, sea­soning the stock to taste with salt could prevent the chef from adding other: ingredients that are high in salt when finishing a recipe. Unlike many sea­sonings whose flavors must be incorporated into a product through lengthy cooking periods, salt can be added at any time during the cooking process with the same effect.