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
nitrate and/or
nitrite. Many curing processes also involve
smoking. The etymology of the term is unclear, but it is thought to derive from the same Latin
cura, -ae, from which the other English meanings are also derived.
Salt inhibits the growth of spoilage, killing microorganisms by drawing water out of microbial cells through osmosis. As the unwanted bacterial population decreases, other beneficial bacteria, primarily of the Lactobacillus genus, come to the fore and generate an acidic environment (around 4.5 pH). The sugar included in the cure is used as food by the lactobacilli; generally dextrose is preferred over sucrose, or table sugar, because it seems to be more thoroughly consumed by the bacteria. This process is in fact a form of fermentation, and, in addition to reducing further the ability of the spoilage bacteria to grow, accounts for the tangy flavor of some cured products. Concentrations of salt up to 20% are required to kill most species of unwanted bacteria.
Smoking adds chemicals to the surface of an item which affect the ability of bacteria to grow, inhibit oxidation (and thus rancidity), and improve flavor.
Nitrates and nitrites not only help kill bacteria, but also produce a characteristic flavor, and give meat a pink or red color. Nitrate (NO3), in the form of either sodium nitrate or potassium nitrate, is used as a source for nitrite (NO2). The nitrite further breaks down in the meat into nitric oxide (NO), which then binds to the iron atom in the center of myoglobin's heme group, preventing oxidation.
