Curingpolymer chemistry and process engineering, curing refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation or heat. In rubbers, the curing process is also called vulcanization.
In food preparation, curing refers to various preservation and flavoring processes, especially of meat or fish, by the addition of a combination of salt, sugar and either nitrate or nitrite. Many curing processes also involve smoking.
Curing with salt and sugar may be called salting, salt-curing, sugar-curing or honey-curing. The application of pellets of salt, called "corns", is often called corning. Curing in a water solution or brine is called wet-curing or pickling or brining. The curing of fish is sometimes called kippering.
Salt and sugar inhibit the growth of microorganisms by drawning water out of microbial cells by osmosis. Concentrations of salt up to 20% are required to kill most species of bacteria. Smoking adds chemicals that reduce the concentration of salt required.
Nitrates and nitrites (found in nearly all processed meats) not only help kill bacteria, but also produce a characteristic flavor, and give meat a pink or red color. The use of nitrates and nitrites in food is controversial. (see: Nitrite curing)