cloves, cinnamon, and apples. Although the FDA
limits the concentration of sodium benzoate as a pres-
ervative to 0.1% of the food by weight, organically
grown cranberries and prunes may contain levels of
this benzoate above this limit.
SORBATES.The sorbates are a group of antimicro-
bial food preservatives comprising sorbic acid and its
three mineral salts, potassium sorbate,calciumsor-
bate, and sodium sorbate. The name of the group
comes from the botanical name of the rowan tree,
Sorbus aucuparia, because sorbic acid was first iso-
lated from unripe rowan berries. In general, food
manufacturers prefer the three salts of sorbic acid to
the acid itself because they are easier to dissolve in
water.
The sorbates are used to prevent the growth of
molds, yeasts, and fungi in foods or beverages with a
pH below 6.5. They are generally used at concentra-
tions of 0.025 percent–0.10 percent. Potassium sor-
bate, which is made by reacting sorbic acid with
potassium hydroxide, is a mild preservative that is
often used to stabilize wine as well as to prevent the
growth of molds in cheese, yogurt, and baked goods.
Allergic reactions to the sorbates are uncommon and
limited to minor skin rashes or itching.
PROPIONATES.Propionates are salts of propionic
acid. The three propionates most commonly used as
food preservatives are calcium propionate, sodium
propionate, and potassium propionate, used to inhibit
the growth of mold in baked goods. Calcium propio-
nate is also added to animal feed to prevent milk fever
in cows. The propionates are often used instead of
benzoates in bakery products because they do not
require an acidic environment to be effective.
NITRITES.Nitrites are salts of nitrous acid that
were used more often in the past for curing meat
than they are now. The most commonly used nitrite
in food preservation is sodium nitrite. When added to
meat or smoked fish, it prevents the growth of bacte-
ria, particularlyClostridium botulinum, the bacterium
responsible for botulism, a potentially deadly disease.
Sodium nitrite also turns meat an appealing dark red
color when it interacts with myoglobin, the primary
oxygen-carrying pigment in muscle tissue.
Nitrites are being gradually phased out of food
processing for two reasons. First, they are themselves
toxic in large amounts; a lethal dose of nitrites for a
human being is 22 mg per kg of body weight. Second,
nitrites in meat can react with the breakdown products
of amino acids in the acidic environment of the human
stomach to form nitrosamines, substances that are
known to be carcinogenic. To be permitted to use
sodium nitrite to prevent the growth ofC. botulinum
in smoked fish or meat, the manufacturer must show
that the maximum amount of nitrite in the food will be
no more than 200 parts per million (ppm). Sodium
ascorbate, a salt of ascorbic acid (vitamin C), is often
added to foods containing nitrites to inhibit or prevent
the formation of nitrosamines.Antioxidants
SULFITES.The sulfites are a group of compounds
containing charged molecules of sulfur compounded
with oxygen. There are five used as antioxidant pres-
ervatives: sodium sulfite, sodium bisulfite, sodium
metabisulfite, potassium bisulfite, and potassium
metabisulfite. They are applied to foods as dips or
sprays. Sodium metabisulfite and potassium metabi-
sulfite are commonly used to stabilize wine or beer.
When added to these fluids, the sulfite compounds
release sulfur dioxide gas, which prevents oxidation
and also inhibits the growth of yeasts and fungi.
Sodium sulfite is used to preserve meats, dried potato
products, and dried fruits.
Sulfites have been used for centuries as food pres-
ervatives, since they occur naturally in almost all
wines. Of all the groups of food preservatives, how-
ever, sulfites are the most likely to produce hypersen-
sitivity reactions. Asthmatics and people with allergies
to aspirin are at an elevated risk for this type of reac-
tion to sulfites. A severe systemic reaction known as
anaphylaxis or anaphylactic shock may be fatal and
requires immediate treatment at an emergency room.
Anaphylaxis is characterized by hives, difficulty
breathing, and cardiovascular collapse.
VITAMIN E.Vitamin E(tocopherol) is a fat-soluble
vitamin that occurs as a natural antioxidant in many
foods, particularly vegetable oils, whole grains, nuts,
wheat germ, and green leafy vegetables. It may be
added to fresh-cut fruits and vegetables to slow oxida-
tion. It is also used to fortify some breakfast cereals
and pet foods.
VITAMIN C.Vitamin C (ascorbic acid) also occurs
naturally in many fruits and vegetables, particularly
citrus fruits. It is a water-soluble vitamin. The salts of
ascorbic acid—sodium ascorbate, calcium ascorbate,
and potassium ascorbate—are also water-soluble and
are often added to fresh-cut apples, peaches, and other
fruits to prevent browning. These three compounds
are not fat-soluble and cannot be used to preventfats
from going rancid. To protect fats or oils from oxida-
tion, a fat-soluble ester of ascorbic acid known as
ascorbyl palmitate must be used.Artificial preservatives