Solutions to Difficulties of Home Curing Pork
N. G. Marriott and P. P. Graham*
REVISED 2000 PUBLICATION 458-872
Virginia Cooperative Extension
VIRGINIA POLYTECHNIC INSTITUTE
AND STATE UNIVERSITY VIRGINIA STATE UNIVERSITY
Virginia Cooperative Extension programs and employment are
open to all, regardless of race, color, religion, sex, age, veteran status,
national origin, disability, or political affiliation. An equal
opportunity/affirmative action employer. Issued in furtherance of
Cooperative Extension work, Virginia Polytechnic Institute
and State University, Virginia State University, and the U.S. Department of
Agriculture cooperating. J. David Barrett, Director, Virginia Cooperative
Extension, Virginia Tech, Blacksburg;
Lorenza W. Lyons, Administrator, 1890 Extension Program,
Virginia State, Petersburg.
For centuries, meat has been preserved by drying, salting
and smoking. Chinese ancestors have used salt to cure and preserve meat since
the 13th Century B.C. Preservation by smoking is believed to have been
developed inadvertently by primitive tribes who lived in caves and burned fires
for warmth and to discourage predatory animals. The American Indian preserved
meat prior to settlement by Europeans through hanging it in the top of a tepee
to maximize contact with campfire smoke. During the past, meats have been cured
to reduce spoilage. These meats were unevenly cured or dried and were
frequently salty or too heavily smoked. After the development of refrigeration
systems, meat has been cured primarily for the development of color and flavor
desired by many consumers.
Curing is the addition of salt, sugar, nitrates, nitrites
and sometimes phosphates and ascorbates to meats for preservation, color
development, and flavor enhancement. The functions of each ingredient used in
- Provides a characteristic flavor to impart a cured meat
- Acts as a preservative through growth inhibition and
destruction of microorganisms.
- Enhances the transport of other cure ingredients throughout
the muscle by osmotic movement of salt itself.
- Dehydrates meat tissue to reduce bacterial growth.
- Provides a characteristic flavor to impart a cured meat
- Counteracts the harshness of salt.
- Provides an energy source for microorganisms which convert
nitrate to nitrite during a long term cure.
- Provides a surface color characteristic of aged ham if
caramelized sugar is used.
Nitrates and Nitrites:
- Contribute to the characteristic cured flavor.
- Contribute the characteristic reddish-pink color of cured
- Prevent growth of a food poisoning microorganism known as Clostridium
botulinum which can occur in foods that require heat processing.
- Retard the development of oxidative rancidity and rancid
- Prevent warmed-over flavor in reheated products.
- (This ingredient should be used only for those meats cured with a liquid cure known as a pickle.)
- Reduce rancidity development and shrinking during curing and
smoking of meat by use of a pickle (cure ingredients dissolved in water) that
is injected into the muscle tissues.
- Reduce cooking loss of the cured product.
- Speed the curing reaction by faster color development
through more rapid reduction of nitrates and nitrites to nitrous acid and
ultimately nitric oxide that combines with myoglobin (a muscle pigment) to fix
the cured color.
- Reduce oxidation and subsequent off flavor and color.
II. Why Dry Cure?
Dry curing was the original method of preserving meat
through a dry rub method of cure application. This method, which was brought
forward from early civilization to the 21st century, involves mixing the cure
adjuncts and subsequently rubbing the mixture on the external surfaces of the
meat to be cured. Penetration of cure adjuncts primarily from the lean surfaces
occurs via osmosis (created by salt). Therefore, this method involves long
periods of storage with one or two additional applications of curing
ingredients (a process known as “overhauling”). Although this cure method
requires 1-2 months (or longer) for larger pork cuts such as hams and involves
a large amount of shrinkage, it is considered a popular method for curing hams
in Virginia. In fact, the Virginia Style Cured Ham was one of the first agricultural
products exported from North America and continues to be exported every year.
The Virginia ham is distinguished as a product with a distinct and unique
flavor preferred by many throughout the world. The distinct advantages of a
country cured ham by introduction of a dry rub cure are:
- Unsurpassed flavor and texture for a specialty product.
- Curing may be conducted as an easy operation without elaborate
- Needs for preservation are minimal since bacterial growth is
retarded by the salt and the final product is drier than other cured meats.
III. Curing Mechanism
When cure is administered, the salt diffuses inward, to form
a complex with the meat proteins. The slower the diffusion inward, the longer
the outflow of water and soluble proteins from the muscle. The basic mechanism
involved in meat curing involves the action of nitrates and nitrites. Although
other reactions and steps are involved in the curing mechanism, the following
sequence of events provides a simplified explanation of the process.
Nitrate is converted to nitrite by a reducing action of microorganisms that are
present within the meat tissues. Reduction of nitrite to nitrous acid and
ultimately to nitric oxide is effected either by microorganisms or by the
muscle’s own enzyme system. Nitric oxide binds to myoglobin, the meat pigment
protein, to provide the characteristic cured meat color. This cured color is fixed
by application of heat during the smoking process.
IV. Effect of Curing On the Nutritive Value
The biological value of meat proteins is not lowered by
curing and the B-complex vitamins are essentially unaffected. However, minimal
losses of water soluble vitamins can occur through weeping. During storage,
cured meats deteriorate through discoloration, oxidative rancidity, and
microbial changes. These conditions will be discussed later. Nitrates up to 3
1/2 oz. per 100 lbs. of meat are permitted in a limited quantity in dry cured
meat because of their importance in flavor, color fixation, and retardation of
bacterial growth. Since nitrates may be toxic when eaten in large quantities,
care should be exercised to use only the recommended amount as supplied in the
commercial cure to be used. Commercial cures may be purchased from farm supply
stores and some drug and food stores. A frequently used dry cure mixture
utilizes 8 pounds of salt, 2 pounds of sugar and 2 ounces of sodium nitrate
(dry cure only). These ingredients are mixed thoroughly and frequently divided
into three equal parts for application at three intervals.
V. Problems - Solutions of Home-Cured Pork
Although home curing of pork may be successfully conducted
if the proper steps are taken, certain precautions should be taken to improve
the finished product. The following problems that are discussed can frequently
occur. However, as the discussion suggests, solutions exist to maintain an
Lack of uniformity of size and shape of cured cuts - Uniformity
can be improved by selecting cuts or live hogs from a specific weight range.
Most hogs are slaughtered when their live weight ranges from 240-270 pounds.
This size hog produces uncured hams that weigh 16-20 pounds. Picnics from hogs
in this weight range weigh 8-10 pounds and the uncured belly averages 15-18
pounds. Uniformity of shape of each cut can be provided by separation of all
cuts from the same location. An example of correct fabrication procedures of
pork cuts to be cured is:
- Ham fabrication - The ham should be separated from the
carcass by cutting through the center of the hock. The ham and loin should be
separated between the 2nd and 3rd sacral vertebrae (2nd vertebra from the
juncture of the rump and back) and cut perpendicular to the long axis of the
- Belly fabrication - The belly and shoulder should be
separated from the 2nd and 3rd rib from the cranial (front) end. The belly
should be removed from the loin along a line adjacent to the tenderloin and
ventral (belly side) portion of the blade bone of the loin. The spareribs
should be removed from the belly and each end of the belly should be trimmed of
excess fat to make it a correctly shaped rectangle.
- Picnic and Boston butt fabrication - The foot should be
separated from the shoulder 11/2 inch above the knee joint. The neckbones
should be removed by cutting beneath the sternum, ribs, chine bones, and feather
bones. The brisket flap should be cut off on the inside of the shoulder and the
jowl removed parallel to the breaking line between the 2nd and 3rd ribs. The
picnic and the Boston butt are separated by cutting 1/2 inch below the exposed blade
bone and at right angles to the breaking line between the 2nd and 3rd ribs.
- Trichina infested pork- Improved management among pork producers
has been responsible for almost complete elimination of Trichinella spiralis infestation
in pork in the U.S. during the past few years. To ensure protection against
trichina, all pork should be held at 0F for 14 days or heated to 142F
during smoking and conventional cooking.
- Unsanitary pork - To ensure a sanitary product, all animals
to be slaughtered should be in a thrifty condition and free of unsound
conditions, i.e., abcesses, bruises, etc. Clean facilities and equipment are
required to reduce contamination of pork during the slaughter and fabrication
process. Proper sanitation prevents contamination by microorganisms that pose a
health concern and cause spoilage through discoloration, off-flavor and odor
development. Even though sanitary precautions are taken, bacterial growth can
still occur. Therefore, pork should be stored as close to 32F as
possible prior to curing. Certain bacteria grow about ten times as fast at 38F
as at 32F. In addition to protection from spoilage, proper chilling
after slaughter will reduce moisture loss and improve pork color and firmness.
- Pale, soft and exudative pork (PSE) - Pork that is very light
colored and lacks firmness is less desirable for curing. Pale and soft pork
experiences more loss of moisture through weeping. This condition, which is responsible
for poor cured color development, yields pale colored pork that sometimes has a
gray or green tinge after being cured. The soft appearance gives a lower
quality appearance and the exudative condition is responsible for more weight
loss during curing and makes the pork more difficult to handle due to the moist
condition. A soft muscle structure causes more muscle separation and uneven
cure penetration. Greater muscle separation may permit more microbial contamination
and insect invasion during storage. The PSE condition can be corrected by
slaughtering swine that are rugged, thrifty and with enough finish to have 0.7
inch or more of back-fat thickness over the back. Hogs that show evidence of
the PSS (porcine stress syndrome) condition are unthrifty and should not be
kept as replacement stock or used for cured pork. The PSE condition can be
minimized by proper temperature control from slaughter to curing.
- Cure penetration and equalization - To ensure proper cure
penetration, the proper cure mixture must be used and the proper application
time and method is essential. The cure mixture depends upon personal preference.
As previously mentioned, the dry cure mixture that utilizes 8 pounds of salt, 2
pounds of sugar and 2 ounces of sodium nitrate (saltpeter) for 100 pounds of
fresh meat is recommended because it yields cured ham characteristics that are
preferred by more consumers. Although it has not been proven conclusively, some
research results have suggested that nitrate and nitrite are associated with
increased cure penetration. The first part of the mixture is rubbed on all
surfaces of the meat including the shank end of the hams. A thin layer (1/8
inch) of the cure is applied over all cuts prior to stacking in the curing
room, skin side down on a table or shelf. Do not stack more than three high.
The other parts of the mixture are added on the fifth and tenth days after the
initial application. The optimal cure time for maximum cure penetration is 7
days per inch of product thickness, or 2 days per pound of product. The
preferred temperature during curing is 40F. This temperature will
increase the speed of the cure penetration and reactions and reduce microbial
spoilage. In Virginia, the best time to dry cure hams is in late December. Pork
cured with too much humidity will not have sufficient cure penetration and the
product will have too much moisture as a finished product. Dry cured meats should
lose at least 18% of the original weight and most strive for 25 - 30% loss. If
the relative humidity during curing and aging is above 80%, forced air movement
by a fan or other means should be considered to assist with lowering product
moisture content. Forced air from a furnace will also reduce moisture content.
After the cure time has expired, the cured cuts should be placed in a tub or
large container filled with clean lukewarm water (not exceeding 80F) for
approximately 3 hours to improve quality and appearance. Soaking will dissolve
most of the surface curing mix, distribute the seasoning more evenly, draw out
some of the heavy salt concentration on the surface and make the product more
receptive to smoke. After soaking, the product should be scrubbed with a stiff
bristled brush and allowed to dry for about 3 hours before smoking. These
practices will improve cure penetration and reduce the salty taste from dry-cured
- Improper smoking - Most cured pork products are smoked to
improve flavor, color and preservation. Careful attention should be given to
this operation to prevent microbial spoilage and insect infestation. Insect
infestation will be discussed later. Cuts to be smoked should be placed in a
smokehouse* with adequate space between each other and the walls to permit
smoke circulation and penetration. Tight construction and properly fitted
ventilators provide effective regulation of the air flow. An outside firebox makes
temperature control easier and reduces the hazard of fire. The combustible
material used to generate smoke is important to smoked flavor development.
Smoke from the sawdust or chips of hardwoods should be used, since the burning
of softwoods results in a sooty deposit on smoked meats and is responsible for
a bitter flavor. Hickory is the most popular wood for smoking, but maple,
apple, cherry, plum, peach, oak and ash may be successfully used. Cedar, pine,
spruce and other “needle leaf” softwoods give off resins, which are responsible
for the bitter taste and odor, and should not be used. The absorption of smoke
and the change in color of the outside surface of smoked meat is increased by higher
temperatures. A “cool” smoldering type of smoke is commonly used by firms that
dry cure in Southern Virginia. The “cool” smoke should be generated in a
smokehouse with a temperature below 90F. This smoke process is utilized
until the meat turns chestnut brown in color, which may require 3-10 days.
- Incomplete color development - The rate of the cured color
development is proportional to the concentration of nitrite up to the point
where the nitrite: color pigment (metmyoglobin) ratio is 5:1. Beyond this point
nitrite appears to inhibit cured color development. Therefore, incomplete color
development can result from too much of’ this cure ingredient (or nitrate)
being applied. Various contaminating microorganisms can impair color development.
Other deleterious effects of these microorganisms include souring and
putrefaction. Therefore, control of microbes by proper sanitation and
temperature control is imperative.
- Improper aging - The aging period is critical for dry cured
pork since it is during this time that the distinguished honey-cured flavor is
developed. Aging time is required to develop the flavor typical of home cured
pork as is time for aging of beef, cheese and wine. Home cured pork cuts should
be aged for 5 months and can be aged up to a year or longer. During aging,
cured meats should be covered with heavy paper bags (without rips or tears) to
provide a barrier between the meat and insects. (More information is available
in VCE Publication 458-223, Curing Ham Virginia Style.)
- Color fading during storage - Although the smoking process
helps fix the cured color, it is still rather unstable. The cured color will
fade due to oxidation under UV radiation and in the presence of oxygen. Thus,
cured meats should be exposed to minimal lighting since most lighting contains
some UV rays. Restriction of air by vacuum packaging or by use of other
wrapping materials impermeable to oxygen will reduce color pigment fading.
- Rancid flavor - A rancid taste is frequently associated with
home-cured pork. Many people prefer cured meats with a ripe, rancid flavor that
results from adding salt to the cure formula and long term aging. Salt
increases oxidation which causes a rancid flavor. Salt accelerates the action
of an enzyme present in muscle called lipoxidase. Smoking reduces the activity
of this enzyme but ascorbic acid, which is sometimes used in liquid cures,
increases the activity of lipoxidase. Since a rancid flavor is typical of
home-cured pork, it is considered a. trait associated with this curing method.
If a rancid flavor is not liked, a shorter curing and aging period should be
considered. Rancidity among home cured cuts can be minimized by reducing the
aging period and by not freezing the cured product. Extended storage of frozen
cured meats enhances oxidative rancidity. Under certain conditions, a change in
certain fat components (i.e., fat reversion) will cause a change in flavor. Wrapping
material that does not properly protect the cured product will contribute to
dehydration and additional oxidative rancidity. If cured meats are to be
frozen, the best grade of freezer wrapping paper available should be used to
wrap the product. The “drugstore” wrap is a possible way to protect cured meat,
but other methods that do not trap the air inside the finished package are
satisfactory. After the edges are sealed to prohibit air entry, a label and
date should be applied on each package prior to freezing at -10F or
colder. Proper protection during freezing will ensure less dehydration or
development of oxidative rancidity.
- Souring, putrefaction and tainting - Souring and putrefaction
are caused by contamination by microorganisms. Contamination can occur at
several steps of the process, but usually takes place between slaughter and
curing. Microbial contamination is increased by improper sanitation and storage
of the fresh product for too long (over 5 days) at a temperature too high (over
32F). Microbial spoilage can also be increased by using cure
ingredients that are contaminated and by unsanitary conditions in the cure
area, smokehouse or aging area. Improper packaging of the finished product will
also increase contamination and subsequent growth of bacteria responsible for
discoloration and flavor deterioration. Tainting will frequently occur among
dry cured meats. This condition is caused by greater difficulty of cure penetration
into the muscle tissue and by pork with a pH that is above normal. The higher
pH stimulates bacterial growth which causes the tainted condition. This
condition is normally less common if time between slaughter and cure is
- Mold growth - As with aged cheese, mold growth is common
among cured meats that are aged. Molds may be removed with a mixture of 10%
acetic acid and 90% water or other equivalent rinses. After the mold is trimmed
or removed by scrubbing and rinsing, the product is satisfactory for
consumption. Molds are common in the air and will thrive if proper temperature
and moisture conditions (as during curing and aging) exist. An effective way to
prevent molds on cured and smoked meats is to store them in a dry, well
ventilated room with a temperature range of 45 - 55F and a relative
humidity of less than 68%. Unwrapped meat should not touch other meat. This method
of holding increases dehydration, but weight loss is less expensive than loss
from trimming mold.
- Salty taste - As previously suggested, home-cured pork has a
characteristic salty taste. Saltiness can be reduced by soaking cured cuts
prior to smoking or prior to storage if smoking is not done. Increased effectiveness
from soaking is possible through changing the water at least once during the
process and by increasing the soak time up to 24 hours. If the cured meats are
still too salty, frying in a skillet that contains about 1/4 inch of water will
dilute the salt concentration and result in a less salty product.
- Insect infestation - Since meat is a good source of food for
insects, cured-meats are commonly attacked by insects during storage. Insects
that most commonly infest home-cured meat are the cheese skipper, the larder
beetle, the red-legged ham beetle, and mites. Generally, cured meats should be
placed inside one or two paper bags free of rips and tears with the top tightly
tied. Wrapped cuts should be stored in a dry, cool room that has been protected
against insects. Specific characteristics of these insects include:
- Cheese Skipper—This insect gets its name from the jumping
habit of the larvae which bore through cheese and cured meats. Meat infested
with this insect quickly rots and becomes slimy. Adult flies are two-winged and
are one-third the size of houseflies. They lay their eggs on meat and cheese and
- Larder Beetle—This insect is dark brown and has a yellowish
band across its back. The adult is about 1/3 inch long. Its larva feed on or
immediately beneath the cured meat surface, but do not rot the meat. The larvae
are fuzzy, brownish, and about 1/3 inch long at maturity.
- Red-Legged Ham Beetle—The larvae are purplish and about 1/3
inch long. They bore through the meat and cause it to dry rot. Adults are about
¼ inch long, brilliant greenish blue with red leg, and are red at the bases of
their antennae. They feed on the meat surface,
- Mites—Mites are whitish and about 1/32 inch long at
maturity. Affected parts of meat infested with mites become powdery.
Recommended precautions include pork slaughter and curing
hams during cold weather when these insects are inactive. Proper cleaning of
the aging and storage areas is essential since the cheese skipper feeds and breeds
on grease and tiny scraps of meat lodged in cracks. (Cracks should be sealed
with putty or plastic wood after cleaning. Screens should be installed to prevent
entrance - especially of flies, ants and other insects that carry mites.)
Double entry doors are recommended to reduce infestation of insects. After
cleaning and sealing cracks, a surface spray should be applied to the floor so
that the thin layer of insecticide will kill insects that crawl over the
deposit. Spray aging rooms once every three months with a pyrethrin-based spray
to reduce infestation. Follow mixing and application directions on the pesticide
label. This insecticide may be applied with a paint brush if the room is
stocked with meat. If applied as a spray, remove all meat products from the
storeroom before spraying. Allow the spray to dry before any meat is returned
to the store room. If any product becomes infested after precautions have been
taken, it should be removed from the storeroom and the infested area should be
trimmed. The trim should be deep enough to remove larvae that have penetrated
along the bone and through the fat. The un-infested portion is safe to eat, but
should be prepared and consumed promptly. The exposed lean of the trimmed areas
should be protected by greasing it with salad oil or melted fat to delay
molding or drying. Ham trimmings can be used as seasoning or incorporated in