Julie Dow, age 14, of Chattanooga, Tenn., for her question:
HOW ARE FISH CANNED?
Details vary in the canning of different species of fish, but the fundamental process is the same. The fish are first prepared by grading, cleaning and cutting for the filling machines or for hand packing.
After the fish are packed and seasoned, the air is exhausted from the cans, which are then sealed. The cans next move to cookers.
Some oily fishes, such as sardines and tuna, are precooked before packing. Specialty products such as fish soups require more preparation.
In the United States, about one fifth of the total fish catch is canned each year.
A large part of the catch is quick frozen at extremely low temperatures after it is graded, cleaned and packaged. The quick freezing ensures fresh flavor and texture for the fish.
A much smaller portion of the U.S. catch is cured. Curing includes drying, smoking, salting and pickling fish. Methods of drying fish by blowing warm, dry air on them have replaced sun drying in many areas.
Herring, salmon, smelt and mackerel are fishes commonly smoked. The cleaned fish is salted, washed and drained in preparation for smoking. It is then partially dried and hung in the smokehouse for curing. Salting or pickling fish is done entirely by hand and each producer develops his own characteristic flavor. The process consists of salting, draining and drying.
Processors also make breaded fish sticks and meal sized portions of breaded fish that are sold cooked or ready to cook. The quick freeze method is used with the breaded fish dishes.
Scraps and waste from fish contain much protein. Much of this waste is processed into dried meal and concentrates that are used for animal feeds.
Research is being conducted to convert some of the fish processing waste into food for human beings. Efforts are being made to develop an odorless, tasteless fish protein concentrate that could be added to foods. Scientists believe that in time this substance can be used to enrich food in parts of the world where people lack sufficient protein in their diets.
The commercial value of fish is not limited to its use as food. Various industrial products contain fish parts or fish byproducts.
Did you know that manufacturers make shoes from the skins of sharks? Also, abalone shells are made into buttons.
Menhaden, sardines, herring and sharks produce valuable oils. These oils are used in making paints and varnishes, in tanning leather and in the manufacture of linoleum and synthetic materials.
Manufacturers also use byproducts of fish to make glue. In addition, a kind of gelatin called isinglass is made from the air bladders of certain fish.