Fish stock (food)
Fish stock forms the basis of many dishes, particularly fish soups and sauces. In the West, it is usually made with fish bones and fish heads and finely chopped mirepoix. This fish stock should be cooked for 20–25 minutes—cooking any longer spoils the flavour. Concentrated fish stock is called "fish fumet".
In Japan, a fish and kelp stock called dashi is made by briefly (3–5 minutes) cooking skipjack tuna (bonito) flakes called katsuobushi in nearly boiling water. Other Japanese fish stock is made from fish that have been fried and boiled for several hours, creating a white milky broth. This has a rich feel and sweet umami taste.
Fish stock forms the basis of many dishes, particularly soups and sauces. A fish consommé is a type of clear soup made from richly flavored fish stock that has been clarified usually through a fining process involving egg protein. Fish consommés usually have too little natural gelatin, so the fish stock may be double-cooked or supplemented. Since fish gelatin melts at a lower temperature than gelatins of other meats, fish aspic is more delicate and melts more readily in the mouth. Dehydrated stock can be formed into small cubes (pictured at right) called stock cubes.
A few basic rules are commonly prescribed for preparing stock:
- The stock ingredients are simmered starting with cold water.
- Stocks are simmered gently, with bubbles just breaking the surface, and not boiled. If a stock is boiled, it will be cloudy.
- Salt is usually not added to a stock, as this causes it to become too salty, since most stocks are reduced to make soups and sauces.
- The fish is added to a stock before vegetables, and the "scum" that rises to the surface is skimmed off before further ingredients are added.
- If the cook wants to remove the fat after the stock is finished, it can be cooled in a refrigerator. The fat then floats and separates into solid globs or into a sheet like ice on a lake, and can be removed with ease.
- Stocks can be frozen and kept indefinitely but are better fresh.
Stock versus broth
Fish broth can also used as the basis for fish soups and sauces. The difference between fish stock and fish broth varies in different parts of the world. Broadly, stock is the thin liquid produced by simmering the raw ingredients with the fish bones. Then the solids are removed, leaving a thin, highly flavoured liquid to give a classic stock. Broth is produced by additionally including solid pieces of the flavouring fish, along with some vegetables. Both a fish stock and a fish broth can be made more substantial by adding starches such as rice, barley or pulses, at which point it becomes a fish soup. Fish broth by itself can be served as a basic soup.