Curing and Smoking Meats for Home Food Preservation
Literature Review and Critical Preservation Points
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2. Curing Foods
Curing is the addition to meats of some combination of salt, sugar, nitrite
and/or nitrate for the purposes of preservation, flavor and color. Some publications
distinguish the use of salt alone as salting, corning or salt curingand reserve
the word curing for the use of salt with nitrates/nitrites. The cure ingredients
can be rubbed on to the food surface, mixed into foods dry (dry curing), or
dissolved in water (brine, wet, or pickle curing). In the latter processes,
the food is submerged in the brine until completely covered. With large cuts
of meat, brine may also be injected into the muscle. The term pickle in curing
has been used to mean any brine solution or a brine cure solution that has sugar
2.1. Salting / Corning
Salt inhibits microbial growth by plasmolysis. In other words,
water is drawn out of the microbial cell by osmosis due to the higher
concentration of salt outside the cell. A cell loses water until
it reaches a state first where it cannot grow and cannot survive
any longer. The concentration of salt outside of a microorganism
needed to inhibit growth by plasmolysis depends on the genus and
species of the microorganism. The growth of some bacteria is inhibited
by salt concentrations as low as 3%, e.g., Salmonella,
whereas other types are able to survive in much higher salt concentrations,
e.g., up to 20% salt for Staphylococcus or up to 12% salt
for Listeria monocytogenes (Table 5.3.). Fortunately the
growth of many undesirable organisms normally found in cured meat
and poultry products is inhibited at relatively low concentrations
of salt (USDA FSIS 1997a).
Salting can be accomplished by adding salt dry or in brine to meats. Dry salting,
also called corning originated in Anglo-Saxon cultures. Meat was dry-cured with
coarse "corns" or pellets of salt. Corned beef of Irish fame is made
from a beef brisket, although any cut of meat can be corned. Salt brine curing
involves the creation of brine containing salt, water and other ingredients
such as sugar, erythorbate, or nitrites. Age-old tradition was to add salt to
the brine until it floated an egg. Today, however, it is preferred to use a
hydrometer or to carefully mix measured ingredients from a reliable recipe.
Once mixed and placed into a suitable container, the food is submerged in the
salt brine. Brine curing usually produces an end product that is less salty
compared to dry curing. Injection of brine into the meat can also speed the
2.2. Nitrate/ Nitrite Curing
Most salt cures do not contain sufficient levels of salt to preserve
meats at room temperature and Clostridium botulinum spores
can survive. In the early 1800's it was realized that saltpeter
(NaNO3 or KNO3) present in some impure curing
salt mixtures would result in pink colored meat rather than the
typical gray color attained with a plain salt cure. This nitrate/nitrite
in the curing process was found to inhibit growth of Clostridium.
Recent evidence indicates that they may also inhibit E. coli,
Salmonella, and Campylobacter if in sufficient
quantities (Condon 1999,
Several published studies indicated that N-nitrosoamines were considered carcinogenic
in animals. For this reason, nitrate is prohibited in bacon and
the nitrite concentration is limited in other cured meats. In other
cured foods, there is insufficient scientific evidence for N-nitrosamine
formation and a link to cancer (Pariza
For more information, please refer to the following resources:
- Examination of Dietary Recommendations for
Salt-Cured, Smoked, and Nitrite-Preserved Foods (Pariza
- Nitrite in Meat (Epley
- Safety of Cured Pork Products (Cassens
2.3. Cure Mixtures
For the home food preserver, measuring small batches of cure for
nitrites or nitrates would require an analytical scale that few
consumers have access to. Therefore, some manufacturers sell premixed
salt and nitrate/nitrite curing mixes for easy home use. Caution
is needed when using pure saltpeter instead of commercially prepared
mixes, since accidental substitution of saltpeter for table salt
in recipes can result in lethal toxic levels (Borchert
and Cassens 1998).
Some examples of commercially prepared cures include:
2.3.1. Prague Powder #1, Insta Cure, or Modern Cure.
This cure contains sodium nitrite (6.25%) mixed with salt (93.75%). Consumers
are recommended to use 1 oz. for every 25 lb. of meat or one level teaspoon
of cure for 5 lb. of meat.
2.3.2. Prague Powder #2
This mix is used for dry cured meats that require long (weeks to months) cures.
It contains 1 oz. of sodium nitrite and 0.64 oz. of sodium nitrate. It is recommended
that this cure be combined with each 1 lb. of salt and for products that do
not require cooking, smoking, or refrigeration. This cure, which contains sodium
nitrate, acts like a time-release cure, slowly breaking down into sodium nitrite,
then into nitric oxide. The manufacturer recommends using 1 oz. of cure for
25 lbs. of meat or one level teaspoon of cure for 5 lbs. of meat.
Many individual manufacturers and commercial sausage makers produce curing mixtures,
often combining sugar and spices with the salt and nitrite/nitrates. It is important
that consumers follow manufacturer directions carefully.
For more information, please refer to the following products,
companies, and available resources:
- Morton Salt Meat Curing Products
(Morton Salt Co. 2001).
Their products include Tender Quick, Sugar Cure, and Smoke Flavored
- Curing Products (Mandeville
Co. 2001). Their products include Poultry Cure, Quick Cure,
Golden Cure, Complete Cure, Maple Flavor Cure, and Myco Pickle.
2.3.4. Saltpeter, Sodium or Potassium Nitrate
Commercially, nitrate is no longer allowed for use in curing of smoked and
cooked meats, non-smoked and cooked meats, or sausages (US
FDA 1999). However, nitrate is still allowed in small amounts
in the making of dry cured uncooked products. Home food preservers
should avoid the direct use of this chemical and opt for the mixtures
2.4. Combination Curing
Some current recipes for curing have vinegar, citrus juice, or alcohol as ingredients
for flavor. Addition of these chemicals in sufficient quantities can contribute
to the preservation of the food being cured.
2.5. Flavor of Cured Meats
Besides preservation, the process of curing introduces both a desired flavor
and color. Cured meat flavor is thought to be a composite result of the flavors
of the curing agents and those developed by bacterial and enzymatic action.
Because of the amount of salt used in most curing processes, the salt flavor
is the most predominant.
Sugar is a minor part of the composite flavor, with bacon being an exception.
Because of the tremendous amount of salt used, sugar serves to reduce the harshness
of the salt in cured meat and enhance the sweetness of the product (ie. Sweet
Lebanon Bologna). Sugar also serves as a nutrient source for the flavor-producing
bacteria of meat during long curing processes.
2.5.3. Spices and Flavor Enhancers
Spices add characteristic flavors to the meats. Recent studies have suggested
that some spices can have added preservative effects (Doyle
1999). However, the quantities of spice needed to achieve these
effects may be well beyond the reasonable quantities of use.
Nitrites and nitrate conversion to nitrite provide the characteristic cured
flavor and color (see below).
The tangy flavor observed in dry fermented sausages, such as pepperoni,
is the result of bacterial fermentation or the addition of chemicals
such as glucono-δ(delta)-lactone.
The process of smoking gives the product the characteristic smoky flavor that
can be varied slightly with cure recipes and types of smoke used.
2.6. Color of Cured Meats
A high concentration of salt promotes the formation of an unattractive gray
color within some meat. Nitrate when used for some dry-cured, non-cooked meats
is reduced to nitrite then to nitric oxide, which reacts with myoglobin (muscle
pigment) to produce the red or pink cured color. If nitrite is used as the curing
agent, there is no need for the nitrate reduction step, and the development
of the cure color is much more rapid.
Generation of Nitric Oxide (NO):
- Sodium nitrate is reduced to sodium nitrite
by microorganisms such as Micrococcus spp. present on
- Sodium nitrite is reduced to nitrous acid in
the presence of an acidic environment (e.g., by fermentation or
by addition of glucono-δ(delta)-lactone).
- Nitrous acid forms nitric oxide. Nitric oxide
reacts with myoglobin (meat pigments) to form a red color.
The time required for a cured color to develop may be shortened
with the use of cure accelerators, e.g., ascorbic acid, erythorbic
acid, or their derivatives. Cure accelerators tend to speed up chemical
conversion of nitric acid to nitric oxide. They also serve as oxygen
scavengers, which slow the fading of the cured meat color in the
presence of sunlight and oxygen. Some studies have indicated that
cure accelerators have antimicrobial properties, especially for
the newly emerging pathogens like E. coli O157:H7 and Listeria
monocytogenes (Doyle 1999).
Since cure accelerators are rarely used in home curing, this information
needs further review or research to determine what benefits home
curing would have by using certain cure accelerators.
Document Use | Preface | Table
of Contents | References