curing Meats|meat preservatives

Tips For Curing Meat Meat

Long before packing establishments were developed, it had been found that cuts of meat could be preserved by treating them with a salt solution or by packing them in dry salt. Salt inhibited spoilage by reducing the amount of water available for microbial growth. However, it was found that high concentrations of salt could promote the formation of an unattractive gray color within the lean muscle. Consequently, the use of nitrate to "fix" the red color evolved.

The use of nitrate most likely evolved by accident, because potassium nitrate (saltpeter) was most likely present as an impurity in the salt. From this, early meat processors learned that when nitrate is present, the meat developed a bright reddish color. It is from these meager beginnings that the cured meat industry evolved.
Cure - To add salt or salt brine, with or without sugar, spices, nitrites and other ingredients, to a meat or poultry product.
Pickle - Any brine, vinegar or spicy solution used to preserve or flavor food. A curing solution.
Cure Accelerators - An ingredient that accelerates the conversion of nitrite to nitric oxide, which is necessary for proper color development to occur in cured meat and poultry products.
Myoglobin - A protein within the muscle that gives it its characteristic color. A muscle pigment.
Water Activity - The vapor pressure of the food divided by the vapor pressure of pure water. The water activity of fresh meat is 0.99 or higher, and is near optimum for the growth of many microorganisms.

Curing Process
As the process of meat curing developed, the meat industry emphasized four factors: preservation, flavor, color, and tenderness. In recent years a fifth factor, yield, has come into the forefront. This factor has been stimulated by a highly competitive industry and consumer acceptance of water-added product.
The following are descriptions of each factor as they apply to meat curing.
Preservation To preserve meat and poultry, the undesirable microorganisms on the meat surfaces that cause spoilage and food borne illnesses must be inactivated and destroyed. There are many steps that help in this process, including smoking, cooking, drying, chilling, and addition of cure ingredients.

One of the most effective means of accomplishing this is by introducing salt into the meat. The resistance of bacteria to salt varies widely among different types of bacteria. 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., Staphylococcus.
Fortunately the growth of many undesirable organisms normally found in cured meat and poultry products is inhibited at low concentrations of salt.

The temperature of the curing process must be carefully controlled. It must be warm enough to allow the salt to penetrate the meat, but cold enough (less than 41ºf) to prevent decomposition.

Flavor Flavor is another factor that is of great concern to the packer. The flavor of cured meats is thought to be a composite result of the flavors of the curing agents and those developed by bacterial and enzymatic action. For example, the tangy flavor observed in dry fermented sausages, such as pepperoni, is the result of bacterial fermentation. However, because of the amount of salt used in most curing processes, the salt flavor is the most predominant.

Sugar is a flavoring ingredient added to many cured products; however, it is a minor part of the composite flavor.
Bacon may be the exception, in that after frying, bacon has a distinctly sweet taste. More importantly, because of the tremendous amount of salt used, sugar serves to reduce the harshness of the salt in cured meat and poultry. Sugar also plays an important role as food for the flavor-producing bacteria of meat during long curing processes.

The process of smoking gives the product the characteristic smoke flavor that can be varied slightly with cure and types of smoke. In addition to exposing various products to smoke generated from hardwoods or liquid smoke, it has been an industry practice in the past to spray a smoke flavoring solution onto meat food products. This is done to impart a smoke characteristic to the products during the cooking process.

Color The next factor to consider is that of color. The development and maintenance of a stable red color is very important in cured and smoked meat operations. Sodium or potassium nitrate or nitrite is the cure agent used to process cured meats. Curing agents are responsible for the development of the characteristically red stable color in meat. Nitrate is used as a source of nitrite.
The further reduction of nitrite to nitric oxide, which reacts with myoglobin (muscle pigment) to produce the cured color, is affected by several environmental conditions such as temperature, moisture content, salt content, and pH. 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.
The time required for a cured color to develop may be shortened with the use of cure accelerators.

Examples would be ascorbic acid, erythorbic acid, or their derivatives, sodium ascorbate and sodium erythorbate. Cure accelerators tend to speed up chemical conversion of nitrous acid to nitric oxide. They also serve as oxygen scavengers, which prevent the fading of the cured meat color in the presence of sunlight and oxygen.

Tenderness of the product is also a processor’s concern. Tenderness is more of a problem with certain beef cuts than with pork cuts. Consequently, more emphasis is being placed on tenderness in beef. With the original methods of curing, which involved long periods of time, both pork and beef were excessively salty and tough. This toughness was probably due to the continued action of the salt dehydrating the meat fibers. With the advent of artery pumping, quick curing, and high temperature smoking, the retail establishment can produce meats that are definitely more tender.

Yield This brings us to the fifth and final factor, yield. The packer by necessity is very much concerned with yield in cured meat and poultry products.
Factors Affecting Yield

Phosphates - The primary purpose for the use of phosphates is to reduce excessive shrinkage or "purge" (cook out) when product is cooked. Phosphates also increase water holding capacity of the available protein, without increasing the apparent saltiness of the product.

Other Factors - Other factors that affect yield are smoking and cooking time, humidity, and the type of casing used, either pervious or impervious.
The addition of protein materials such as hydrolyzed plant protein, hydrolyzed vegetable protein, and monosodium glutamate will also help bind water within the product.

Massaging - More recently the process of massaging is being used to increase yield. Massaging is the process of subjecting meat chunks to mechanical treatment in order to facilitate protein extraction. This is accomplished by placing the product in a vat with an agitator or a tumbler for varying periods of time.
The results of this treatment on the meat are muscle fiber disruption with a corresponding release of salt-soluble protein, which in turn coats the muscle.
The protein is then heat-coagulated by cooking to form a matrix between muscle chunks, thus giving the product an intact muscle appearance.

Examples of products produced using this procedure are formed roasts, boneless hams, and poultry rolls.

Curing Methods
There are three general methods of curing with a number of modifications for each method. These methods are pickle curing, dry curing, and dry salt curing.

Pickle Curing or Curing Solution
A pickle cure could include:
Water and salt (plain or salt pickle)
Water, salt, nitrate, and/or nitrite
Water, salt, nitrate, and/or nitrite to which sugar has been added (sweet pickle). Other ingredients could be added to enhance flavor.

Dry Curing
Dry curing includes:
Salt alone
Salt, nitrate, and/or nitrite
Salt, nitrate, and/or nitrite with sugar.
This method is frequently used in the production of salt pork in which fatbacks, heavy jowls, and occasionally, heavy sowbellies are rubbed with dry salt.

Dry Salt Curing
One modification of the dry curing method is commonly referred to in the industry as dry salt curing. This includes the same mixtures as in dry curing, except that the product may be injected with cure solution. Just prior to being covered with the dry mix a product may be momentarily moistened to facilitate penetration of the salt.

Variations of Curing Processes
A variation on dry and dry salt curing involves a process of curing (in some cases fermentation) and then drying. Dry sausages, dry fermented sausages, and jerky products fall into this category.
Over the years more and more retail processors have entered this market. As the market for these products increased, concern has risen as to their microbiological safety. Many of these products are ready-to-eat (RTE) without further treatment by the consumer. In an effort to better assure that these products are microbiologically safe, the Food Safety and Inspection Service (FSIS) within the United States Department of Agriculture is currently reviewing these processes. FSIS is focusing on two factors within a process: 1) lethality; and 2) shelf stability.

The following are guidelines for processors to follow. At this time they are only recommendations and are not FSIS requirements.
Lethality - FSIS has determined that all processes should contain a kill step that is sufficiently lethal to pathogenic microorganisms. To be considered a RTE product the process should achieve a 5-decimal log reduction of E. coli 0157:H7 for dry, semi-dry, and dry fermented sausages, such as, hard salami, summer sausage, and pepperoni. A 5-decimal log reduction of Salmonella is advisable for other types of RTE products, such as jerky, cooked corned beef, and ham.
An example of a kill step would be a heating step within a jerky production process. It has been found that: 1) cooking the meat to 160° F before drying; or 2) drying whole beef strips at 140° F for 10 hours, will achieve a 5-decimal log reduction of Salmonella. However, this does not mean that all RTE processes must have a kill step involving heat. Combinations of fermenting, acidifying, curing, drying, and heating may be sufficient.

Shelf Stability-To be considered shelf stable a process should result in the condition in which microorganisms are inhibited from growing in product at non-refrigerated temperatures of storage (extended periods over 41° F).
One way to achieve this is to reduce the water activity of the product. It has been shown that the lowest water activity value at which a food borne illness organism will grow is 0.86. Consequently, the Food and Drug Administration (FDA) and FSIS consider foods with a water activity value of 0.85 or below not to be potentially hazardous.

Application of Curing Solutions
There are five methods to apply curing solutions to meat and poultry cuts:

Osmosis Osmosis was the earliest method used. This method involves covering the meat cuts with dry cure or completely submerging meat cuts in a curing solution for an extended period of time.
Stitch method The stitch method is the injection of curing solution deep into the muscles with a single orifice needle. With this method, the retail establishment can quickly get deep penetration of the solution into the product.
Spray Pumping Spray pumping is a variation of the stitch method using a needle with many orifices to allow for more uniform distribution of the pickle.
Artery Pumping Artery pumping is the introduction of the curing solution into the natural circulatory system.
Machine Pumping The last method, machine pumping uses a machine with many needles for injecting product. This method is considered efficient and economical.

Final Production
After product is cured, it is usually cooked, either with or without smoke. When it has reached the proper temperature it is rapidly chilled and then packaged either whole or sliced. Labeling of these products must include identification of all ingredients used in the curing process.

Excerpts from Code of Federal Regulations Title 9, Chapter 3
[318.7(c)(4), 381.147(d)(4)]
This supplement includes information on additives and the limitations for their use in curing compounds and solutions that are to be applied in or on meat and meat food products and poultry and poultry food products.
Parts per million (ppm) of restricted curing ingredients permitted in curing solutions
Nitrate--Source of nitrite.
Dry cure--3½ oz per 100 lb. of meat.
Pickle--700 ppm.
Nitrate is converted (by bacterial action) to nitrite and is a color fixer.
(Note: Nitrate is not permitted as an ingredient in bacon.)
Nitrite--Color Fixer.
Dry cure--1 oz per 100 lb. of meat.
Pickle--200 ppm in finished product.
(Note: Nitrite is limited to 120 ppm in bacon.)
Nitrite is principally used for color development. Nitrite is highly toxic, nitrite and nitrite mixtures must be controlled by the establishment.
Ascorbic acid or erythorbic acid--color-fixing accelerator, color preservative. In pickle, 469 ppm.
(Note: Not allowed in bacon curing.)
Glucono delta-lactone—pH adjuster or acidifier (also acts as a cure accelerator).
In pickle, 5,000 ppm.
Sodium acid pyrophosphate—color-fixing accelerator.
In pickle, 5,000 ppm.
Sodium ascorbate or sodium erythorbate.
In pickle, 547 ppm.
(Note: 550 ppm in the curing of bacon)
Additives that accelerate color fixation also prolong color retention and increase shelf life by their action as oxygen scavengers.
Phosphates.
Decrease the amount of cooked-out juices.
Pickle—5000 ppm.
Only clear solutions may be injected into product.
Phosphates must be "food grade" only and this must be clearly stated as part of the printed material on the phosphate container (bag).

Binders and extenders.
Prevent purging of brine solutions.

Amounts permitted

Carrageenan—not to exceed 1.5 percent of product formulation.
Food starch modified—not to exceed 2 percent of product formulation.
Sodium caseinate—not to exceed 2 percent of product formulation.
Isolated soy protein—not to exceed 2 percent of product formulation.

The above binders are only approved for use in cured pork products labeled as "Ham, Water Added" and "Ham and Water Product –X% of Weight is Added Ingredients."

Sweeteners.

Reduces harshness of salt, affects flavor somewhat.
Amount permitted

Sugar (sucrose) or dextrose—sufficient for purpose.
Brown sugar—sufficient for purpose.

Saccharin—for bacon 0.01 percent in the finished product.
Saccharin must be identified and the label must bear the warning statement ("Use of this product may be hazardous to your health. This product contains saccharin which has been determined to cause cancer in laboratory animals.").
Salt.
Provides flavoring and preservation properties.
Amount permitted
Salt—No limit
Note: Approved salt may contain up to 2% anti-caking agents.

High protein additives.

Gelatin acts as a binder or congealer for certain meat food products. No limit
Monosodium glutamate (MSG), hydrolyzed plant protein (HPP), and hydrolyzed vegetable protein (HVP).
Flavor enhancers—No limit
Smoke.

Characteristic flavor, color.
Approved hardwoods, such as: hardwood, hardwood sawdust, corncobs, corncob meal, redwood, redwood sawdust, mesquite wood, or mesquite sawdust.
Note: If product is labeled "Hickory Smoked," certification must be provided indicating such sawdust or wood used for smoking is 100% hickory.

Controls
In-plant control of restricted ingredients:
Establishment adherence to processing procedure chart.
Accurate pre-batch measurement.