Cut the bones into pieces, 3–4 inches (8–10 cm) long.
This exposes more surface area and helps extraction. A meat saw is used to cut heavy veal and beef bones. Fish and chicken bones don’t need to be cut, but whole carcasses should be chopped for more convenient handling.
Rinse the bones in cold water. (If desired, chicken, veal, or beef bones may be blanched.)
This removes some impurities that cloud the stock or, if the bones are old, give an off taste.
Place the bones in a stockpot or steam-jacketed kettle and add cold water to cover.
Starting in cold water speeds extraction. Starting in hot water delays it because many proteins are soluble in cold water but not in hot.
Bring water to a boil, and then reduce to a simmer. Skim the scum that comes to the surface, using a skimmer or perforated spoon.
Skimming is important for a clear stock because the scum (which is fat and coagulated protein) will cloud the stock if it is broken up and mixed back into the liquid.
Add the chopped mirepoix and the herbs and spices.
Remember, the size to which you cut mirepoix depends on how long it is to be cooked.
Do not let the stock boil. Keep it at a low simmer.
Boiling makes the stock cloudy because it breaks solids into tiny particles that get mixed into the liquid.
Skim the surface as often as necessary during cooking.
Keep the water level above the bones. Add more water if the stock reduces below this level.
Bones cooked while exposed to air will turn dark and thus darken or discolor the stock. Also, they do not release flavor into the water if the water doesn’t touch them.
Simmer for the recommended length of time:
| Beef bones—8 to 10 hours |
Chicken bones—3 to 4 hours |
| Veal bones—6 to 8 hours |
Fish bones—30 to 45 minutes |
Most modern chefs do not simmer stocks as long as earlier generations of chefs did. It is true that longer cooking extracts more gelatin, but gelatin isn’t the only factor in a good stock. Flavors begin to break down or degenerate over time. The above times are felt to be the best for obtaining full flavor while still getting a good portion of gelatin into the stock.
Skim the surface and strain off the stock through a china cap lined with several layers of cheesecloth.
Adding a little cold water to the stock before skimming stops the cooking and brings more fat and impurities to the surface.
Cool the stock as quickly as possible, as follows:
- Set the pot in a sink with blocks, a rack, or some other object under it. This is called venting. It allows cold water to flow under the pot as well as around it.
- Run cold water into the sink, but not higher than the level of the stock, or the pot will become unsteady. An overflow pipe keeps the water level right and allows for constant circulation of cold water (see image).
- Stir the pot occasionally so all the stock cools evenly. Hang a ladle in the pot so you can give it a quick stir whenever you pass the sink without actually taking extra time to do it.
Cooling stock quickly and properly is important. Improperly cooled stock can spoil in 6–8 hours because it is a good breeding ground for bacteria that cause food-borne disease and spoilage.
Do not set the hot stock in the walk-in or, worse yet, the reach-in. All that heat and steam will overload the refrigerator and may damage other perishables as well as the equipment. Refer to food safety guidelines for cooling.
Evaluate the quality of the finished stock.
When cool, refrigerate the stock in covered containers. Stock will keep 2–3 days if properly refrigerated. Stock can also be frozen and will keep for several months.
