SECTION II. METHODS OF PRESERVATION--ADDITION OF CHEMICALS
METHODS OF PRESERVATION
The basic methods utilized by the food industry to preserve foods are:
a. Addition of chemicals (food additives).
b. Thermal methods, such as refrigeration, freezing, canning, drying, irradiation,
c. A combination of the above methods.
The United States Food, Drug, and Cosmetic Act of 1938 contain certain rigid
restrictions on the use of certain preservatives. Some of the preservatives that may be
legally added to food are sodium benzoate, sulfur dioxide, lactic acid, acetic acid, and
sodium nitrate. Some of the preservatives that may not be legally added to food are
boric acid, formaldehyde, and salicylic acid. An illegal preservative is one that tends to
prevent or retard deterioration, but this would not exclude the use of salt, sugars,
vinegars, spices, or substances added to food by direct exposure to wood smoke. A
legal preservative must be harmless to health and must not make possible the
employment of careless methods or unfit raw materials.
PRESERVATION BY SALT
a. The Preservative Action of Salt. Salt is one of our oldest preservatives and
is still a widely used preservative. Salt in concentrations in which it is normally used in
preservation is not a bactericide, but rather inhibits many species of bacteria. Salt
exerts its preservative action by dehydration, direct effect of the chloride ion, removal of
oxygen from the medium, sensitization of the organisms to carbon dioxide, and
b. The Brine Concentration Formula. The effectiveness of salt is based upon
the amount of moisture in the tissues. The ratio of salt to water is expressed as brine
concentration. The brine concentration is arrived at by dividing the percentage of salt
by the sum of the salt plus the moisture. This figure is then multiplied by 100.
Luncheon meat containing 3.5 percent salt and 59 percent moisture would have a brine
concentration of 5.60 percent. Let us apply our formula to the foregoing figures: