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RTE-SS Process Familiarization

11-29-16

Ready to Eat and Shelf Stable Products

Process Familiarization

Many processors combine nonmeat ingredients and raw meat or poultry for 

further processing into Ready to Eat (RTE) or shelf stable (SS) products. This 

module reviews important process steps and factors that must be controlled to

meet standards for safety and product identity.

Objectives

1. Define Ready to Eat

2. Define Shelf Stable

3. Identify process steps that relate to the safety of fully cooked-not SS, heat 

treated-SS, and not heat treated-SS products

4. Identify factors requiring control at key process steps to meet standards 

for safety and product identity

Introduction

This module covers common processing steps for products in the following

HACCP processing categories:

1. Fully Cooked-Not Shelf Stable. This category applies to establishments 

that further process products by using primarily a full lethality heat process 

step (e.g. cooking) to achieve food safety. The finished products are not 

shelf stable and must be frozen or refrigerated for food safety purposes. 

These products also meet the definition of Ready to Eat as defined in 9

CFR 430.1.

Ready to Eat (RTE) product is a meat or poultry product that is in a form

that is edible without additional preparation to achieve food safety and

may receive additional preparation for palatability or aesthetic, epicurean,

gastronomic, or culinary purposes. RTE product is not required to bear 

safe-handling instructions or other labeling that directs that the product 

must be cooked or otherwise treated for safety, and can include frozen

meat and poultry products.

2. Heat Treated-Shelf Stable. This category applies to establishments that

further process by using a heat treatment processing step to achieve food

safety in combination with curing, drying, or fermenting processing step to

achieve food safety. The finished products are shelf stable and not 

required to be frozen or refrigerated for food safety purposes. 

Inspection Methods 32-1
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Shelf Stable (SS) product is free of microorganisms (pathogens and

spoilage) capable of growing in the product at non-refrigerated conditions 

at which the product is intended to be held during distribution and storage.

3. Not Heat Treated-Shelf Stable. This category applies to establishments 

that further process by curing, drying, or fermenting processing step as the

sole means by which product achieves food safety. Establishments in this 

category may apply a low-level heat treatment as long as the heat 

treatment is not used as means to achieve food safety. The finished

products are shelf stable and not required to be frozen or refrigerated for 

food safety purposes.

Fully Cooked-Not Shelf Stable Example: Hotdogs

One of the major product groupings under the Fully Cooked-Not Shelf Stable 

category is cooked sausages. There are many different types of cooked

sausages. Some common examples are bologna, cooked salami (a.k.a., cotto

salami), polish sausage, and hotdogs. Let’s take a closer look at hotdogs as an 

example of how these products are produced.

The first steps are meat and/or poultry, other ingredients, and packaging

materials are received and stored in the establishment until ready to use. Many

establishments carefully control the quality of the incoming ingredients through

purchasing specifications. Meat ingredients may have quality specifications such

as percent fat, moisture, and protein. These are parameters that will affect the

final quality of the product.

Raw meat ingredients used in these products will depend on the type of 

finished product desired. Not long ago, most hotdogs were either a combination

of pork and beef, or they were all beef. Today, establishments still make these

products, but many more combinations of ingredients are used. Many

formulations include at least some poultry products (turkey or chicken), and

some products are made exclusively with poultry. 

The first step in the formulation process is weighing or measuring the meat 

and/or poultry ingredients. They are ground and mixed or blended with the nonmeat ingredients. Often establishments will pre-blend, that is, they will grind and

mix the meats with water and salt, and sometimes with the nitrite, and let it stand

for a period of time in a cooler. 

Antimicrobial agents, are substances such as acetates, diacetates, and

lactates, added to an RTE product to reduce or eliminate a microorganism, 

including a pathogen such as L. monocytogenes, or suppress or limit growth of L. 

monocytogenes in the product throughout the shelf life of the product.

Inspection Methods 32-2
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Binders and extenders, such as dry milk powder, cereal flours, and soy protein, 

have a number of uses in a sausage formulation. They increase the overall yield,

improve binding qualities, and add certain flavor characteristics.

Cure. Meat is cured with the addition of nitrite or nitrate, usually sodium nitrite, 

often added in a salt and cure mixture. When nitrite is added to the meat mixture 

it combines with the meat pigment, myoglobin, to form the characteristic pink-red

color of cured meat.

Cure accelerators, such as ascorbates and erythorbates, are used to speed up

the curing process. They also stabilize the color of the final product.

Phosphates are used to improve the water-binding capacity of the meat, and

contribute to the flavor and color of the product.

Spices and flavorings are used to add flavor to the sausage. The wide range of

available spices, seasonings, and flavorings is a primary reason for the variety

available in sausages in the marketplace. 

 Spices are any aromatic vegetable substance that is intended to function as

contributing flavor to food, rather than as a nutritional substance. The active

aromatic or pungent properties of spices that contribute the most to the

flavoring effect are present in the volatile oils, resins, or oleoresins of the

spice. Spices may be used whole or ground. White pepper, paprika, and

nutmeg are common spices used to produce the characteristic flavor of the

hotdog. Because paprika also adds color and makes meat look brighter red, it 

must be listed as “paprika” on labels.

 Flavorings are substances that are extracted from a food, and contribute

flavoring, such as spice extracts. 

After the non-meat ingredients are blended with the ground meats, the mixture is 

emulsified. This is done in an emulsifier, and further reduces the size of the

meat particles to achieve a very fine texture. Fat, protein, salt, and water are

mixed and combined into a semi-fluid emulsion. The meat muscle protein,

myosin, is solubilized, or released from the muscle fibers. The solubilized

protein and water combine and surround the fat globules, and suspend the fat

particles within the mixture. 

Careful control of the amount of each ingredient is essential to the quality of the

final product. The manufacturer must select a mix of raw meat materials with the

appropriate binding characteristics. Different meats vary in their ability to bind.

Lean beef, for example, bull, cow, and shank meat, has high binding ability. 

Regular pork or beef trimmings with more fat, and poultry, have medium binding

ability. Low binding meats contain high levels of fat, such as jowls and briskets.

Organ meats have no binding qualities. 

Inspection Methods 32-3
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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After emulsification, the mixture (or “batter”) is stuffed into casings, usually

artificial plastic casings that allow moisture to cook out and smoke flavors to

penetrate. Natural casings such as sheep small intestines may also be used.

Following stuffing, the product is linked by pinching and twisting the casing to

form separate units of sausage. The sausages are still held together by the

casing. These lengths of casings are then placed on racks or trees, and are 

ready to be loaded into the smokehouse. Some establishments load trees into

individual smokehouses, however, some large volume establishments use

continuous smokehouses. 

The smokehouse parameters that must be controlled are temperature, time, and

humidity. Although other documentation can be used to support the adequacy of

the cook step, many processors follow the parameters in Appendix A. The

product must be exposed to a high enough temperature in order to produce a

fully cooked, ready-to-eat product. The temperature inside the smokehouse, and

the internal temperature of the sausage, may be monitored by the establishment 

in order to verify that the critical limits are met. Cooking is a very important step, 

because it is here that any pathogens (e.g., Salmonella) that may be in the

product will be eliminated and the numbers of spoilage bacteria will be lowered to

an acceptable level. This is called a lethality treatment.

After product has reached the final temperature desired, the cooling process 

begins. Many processors use Appendix B to support that their cooling process 

will prevent pathogen growth. This product is often showered with cold water 

inside the smokehouse. This removes some of the heat from the product, and

immediately halts the cooking process. The shower is usually not sufficient to

complete the cooling process. Usually product is moved to another chiller or 

cooler to finish cooling. Some establishments use very cold water as a chilling

medium, sometimes with salt added to lower the temperature below the normal 

freezing point of water. This is called a brine chiller. Other establishments may

use cold air, and some use a combination of methods.

The cooling process is also known as stabilization. There are two types of 

bacterial contamination that must be addressed by the stabilization process.

 Spore-forming bacteria (Clostridium perfringens and Clostridium botulinum) 

can survive cooking when in the heat-resistant spore form, and these

organisms need to be considered as the products are chilled. Growth

(sometimes referred to as “outgrowth”) of these bacteria is slowed by rapid 

cooling. Cooling rates, or time/temperature relationships, must be carefully

controlled in order to ensure that product does not remain at warm

temperatures that would support the outgrowth. Excessive dwell time in the

range of 130° to 80°F is especially hazardous, as this is the range of most

rapid growth for the Clostridia. Therefore cooling between these temperature

control points should be as rapid as possible.

Inspection Methods 32-4
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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 Recontamination with bacteria must be considered as cooked products are 

exposed to the environment, food contact surfaces, or cross-contamination

with raw product prior to final packaging. Proper chilling and cold storage

temperatures limit the growth of most pathogens. However, Listeria 

monocytogenes can grow at temperatures above 31°F. Therefore, 

establishments must follow effective sanitation programs in the post-lethality

processing environment to prevent contamination. Some establishments 

include a validated, post lethality treatment (e.g. steam pasteurization) in their

process to eliminate Listeria should contamination occur. 

After product has been chilled to the desired temperature, it is removed from the

artificial casings in a machine called a peeler. This equipment quickly runs the

sausage through a tunnel that has a tiny blade that slices the casing. Steam or 

air is then used to blow the casing away from the sausage. The sausage links 

are now separate. If you closely examine the outside of a hotdog, you might see

where the casing had been cut. This blade is a potential source of contamination, 

since it contacts every hotdog!

Sometimes a product that has partially or fully completed the production cycle is 

not salable but is still wholesome, and can be used for food. For example, the

casing of some sausages may split during the cooking or smoking cycle.

Manufacturers may reuse these edible but unsalable products by removing the

casing and adding the contents to the grinder to include in another run of the

same product. This is called rework. Since the proteins are coagulated from

cooking, rework has no bind capabilities. Of course, the ingredients of the rework 

must be compatible with the ingredients of the batch to which they are added for 

labeling purposes. 

The final steps are packaging, labeling, and storage. The product is ready for 

distribution to retail stores, restaurants, or institutions.

Inspection Methods 32-5
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Fully Cooked-Not Shelf Stable Flow Chart: Hotdogs

Receiving & Storage -

Meat 

Purchase 

Specifications, 

Sampling

Receiving &

Storage

Packaging

materials

Receiving &

Storage -

Non-meat 

ingredients

Blending

Grinding

Weighing,

Metering

Emulsification

Stuffing,

Linking

Smoking,

Cooking

Showering

Cooling

Packaging, Peeling

Labeling

Rework

Post Lethality

Treatment

Storage,

Shipping,

Distribution

 

 

 

 

 

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Inspection Methods 32-6
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Heat Treated-Shelf Stable Dried Whole Muscle Meat Snacks 

Example: Jerky

This product category consists mainly of sliced whole muscle beef jerky and

similar whole muscle meat snacks such as beef nuggets, steak tenders, or other 

such named products that consist of predominantly whole muscle tissue. FSIS

published updated jerky compliance guidelines in 2012. The new guidelines

replace all previous versions.

A variety of other meat snacks such as meat sticks, kippered beef, and assorted

chopped and formed or ground and formed products are manufactured similar to

sausage-type products. These can be considered a type of dried fermented or 

non-fermented sausages where manufacturing differences are particle size and

final product form (round, flat, etc.).

Shelf stable dried meat snacks have a low moisture content (22-24%) and low

water activity. A water activity limit of ≤0.85 should control growth of all bacterial 

pathogens of concern as well as mold for products stored in the presence of

oxygen; however, if the product is vacuum packaged in an oxygen impervious 

packaging (anaerobic environment), the water activity limit could be ≤0.91. These

limits are based on the growth and toxin production limits for Staphylococcus 

aureus. Product labeled as “jerky” must meet the standard of identity which 

specifies a moisture protein ratio of 0.75:1 or less.

Vacuum packaged products with a water activity level > 0.85 and ≤ 0.91 should 

be kept refrigerated once the package is opened because the product would no

longer be considered shelf-stable once it is exposed to oxygen. Unless the

establishment has support that the product is likely to be consumed in a single 

serving, these products should be labeled with a statement such as “Refrigerate

After Opening”

Whole muscle beef jerky products are manufactured by pickle curing the meat in

either the whole original piece (e.g., beef rounds) or first slicing, and then

curing/marinating the individual slices. For that latter case, the raw beef round is 

first sliced, the slices then tumbled with the brine, cure and spices (optionally

marinated slices are held overnight), and placed on screens for subsequent 

smoking, cooking and drying. This process is used more often with smaller jerky

producers. 

Larger producers of whole muscle beef jerky generally inject whole beef rounds

with brine containing the salt, cure, spices, any preservatives, and often some

percentage of ground meat. Ground meat injection is permitted up to a certain

percentage and requires special equipment. The ground beef is less expensive

and also serves for better bind and more desirable final meat texture (i.e., softer). 

After injection, the injected rounds (often 35-50% injection) are tumbled and held

Inspection Methods 32-7
 

 

 

 

 

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1, 

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for a defined period before slicing and placing on screens for smokehouse

smoking, cooking and drying. 

A typical beef jerky process would consist of first preparing the brine solution with

salt, ground beef, seasoning, and cure, followed by injection, tumbling, slicing

and smokehouse processing (with 90% relative humidity) as follows:

135°F (57.2°C) 0.5 hour

150°F (65.6°C) 0.5 hour

170°F (76.7°C) Time to reach a 160°F (71.1°C) internal temperature 

and water activity of 0.85 (or other validated aw)

Heat Treated-Shelf Stable Process Flow: Whole Muscle Jerky

Beef Rounds

Temper/Thaw

Brine:

Salt, Seasoning

Cure

Slice

Marinade / Tumble

Holding Period

12-24 Hours

Place on Racks

Smokehouse:

Cook and Dry

Package

Inspection Methods 32-8
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Heat Treated/Not Heat Treated-Shelf Stable 

Example: Dried Whole Muscle Products

Dried whole muscle products are mostly dry cured. This product category

includes the familiar dried hams, such as prosciutto, Parma and country ham, but

also other dried intact pieces of meat such as dried pork bellies (Pancetta), dried

pork shoulders (coppa), and dried beef rounds (bresaola, beef prosciutto, 

basturma). The primary considerations in producing these products are that

 Larger pieces of meat result in slower salt and cure penetration.

 It is preferable to use raw meat materials with pH < 5.8.

 Meat final pH is generally higher than with fermented products.

 Salt extraction at the surface should be minimized.

 Microbial action occurs at the surface only, as the internal tissue is sterile.

 Starter cultures are sometimes added to enhance color, flavor, and

preservation, and are mostly non-fermentative.

 Distribution of non-meat ingredients into the meat tissue is through osmosis.

An initial process for manufacturing whole muscle products consists of dry mixing

the non-meat ingredients with the meat, pickle curing by immersing the meat 

pieces in concentrated brine, or injection curing by injecting the brine. Injection

curing is less common since the water in the brine must be later removed during

drying. After the initial salting, the product is held for some period of time at 

refrigeration temperatures for salt and cure penetration (“burning” period). The

product undergoes a maturation period, air drying and smoking (if desired), and

storage. The final product is either then sliced and packaged for sale, or sold in

the whole piece form for slicing by the final customer. 

►Dry Curing

The most common salting/curing process for dried whole muscle meats is dry

curing; often this class of products is referred to as “dry cured” whole muscle

meats. The first step in the dry curing process is mixing the meat pieces with the

salt and the other curing mixture. Sometimes spices, sugars and starter cultures 

are added at this initial step or they can be added later in the re-salting process 

or immediately prior to the forming. In the very traditional Italian Prosciutto

products, no cure (nitrate or nitrite) is added. More modern processes –

particularly “American style” products – use nitrate and nitrite. During this initial 

salting of the product, it is critical to completely cover all the surface area with

salt, because the high salt level and the colder temperatures are the only

measures protecting against the growth of spoilage and pathogenic 

microorganisms. Sometimes the salting process for smaller, more uniform, meat 

pieces is completed with mechanical agitation. For larger hams the salting is 

done by hand to prevent product tissue damage. For some products the bone is 

removed prior to salting, while for others it is not. If tumbling is utilized, only a

minimal schedule is employed to minimize excessive protein extraction. For 

Inspection Methods 32-9
 

 

 

 

 

 

 

 

 

 

 

 

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most “American style” Prosciutto, the bone is removed and the product is 

tumbled for the salting process.

During dry curing, moisture migrates from inside the tissue to the surface due to

osmotic pressure with the higher salt concentration at the surface. The salt and

cure migrate into the tissue due to osmotic pressure. This is a relatively slow

process and temperatures must be below 40°F (4.4°C) to minimize microbial 

growth until the salt percentage is high enough to inhibit many of the spoilage

and pathogenic microbes. The salted meat pieces are packed in curing

containers that allow draining of the meat juices as the moisture migrates out of 

the tissues. Some products are shaped or formed at this stage, but generally this 

shaping takes place after the later salting occurs. During the salting process, the

products may be re-salted several times as the added salt migrates into the

tissue. Generally, the addition of spices occurs after the last re-salting has been

completed.

►Pickle Curing

Although most hams are dry cured as above, some products referred to as “dry

cured” do employ a concentrated liquid brine (10-20% salt) in which the meat 

pieces are immersed for some time to allow for uniform salt distribution in the

tissue. This brine can also contain the cure, spices and, possibly, a starter 

culture, or these ingredients are added after the salting stage. The principles of 

pickle curing are the same as with dry curing, except that liquid brine is used. 

The product cannot be shaped or formed, although this is not necessary at this 

stage for some products. Products such as pancetta, when brine cured instead

of dry cured, are rolled as whole pork bellies after the brining step.

►Injection Curing

Although not common for whole muscle shelf-stable meat products, this process 

injects the curing ingredients directly into the meat muscle by random injection or 

artery injection directly into the blood vessels. This artery injection process is 

most often used on very large bone-in hams. Obviously, the injection curing is a

faster, shorter process allowing for rapid salt and cure diffusion throughout the

tissue; however the water for the injection medium must be removed during the

drying cycle.

►Burning 

After the salting stage, the product enters the “burning” stage. At this stage the

product is held at low temperatures (<40°F (4.4°C)) for many days to allow for 

sufficient salt penetration and equilibration. The goal is to eventually lower the

water activity sufficiently to inhibit microorganisms to a point at which the

temperature can be elevated. This period often takes many weeks to achieve

uniform salt distribution to greater than 4.5% with a water activity below 0.96. 

Inspection Methods 32-10
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Excess surface salt may be removed during this period and only moderate air

circulation is desired to avoid surface drying. Some processors may apply a soft

fat to the cut surface of the lean tissue to avoid this drying.

►Ripening

At this stage in the process, the whole muscle product should be

microbiologically stable due to salt content and lower water activity. The ripening

stage varies widely in terms of temperature, time and optional smoking cycles.

During this stage, the products are held at elevated temperatures for drying and

flavor development. Long matured hams are held at 59-65°F (15-18.3°C), while

short matured hams can be held at 75°F (23.9°C) or higher for shorter periods. 

During these periods at higher temperatures, the humidity and air circulation is 

lowered, with further moisture loss. This final step in the process can be from 3

to 12 months in duration.

Not Heat Treated-Shelf Stable Whole Muscle Flow Diagram:

Dry Cured Ham

Receiving raw hams Receiving

Storage (cold) 

FrozenRefrigerated

Conditioning

Thawed hams

Boned hams

additives

Storage

Hams Salting

Post-salting

Drying Ripening

Boning Slicing Cutting

Finished Product 

Packaging/Labeling

Finished Product 

Storage

Shipping

 

 

 

 

 

 

 

 

 

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Inspection Methods 32-11
 

 

 

 

 

 

 

 

 

 

 

 

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Heat Treated/ Not Heat Treated-Shelf Stable Example: 

Fermented Dry Sausage

Dry and semi-dry sausages are possibly the largest category of dried meats,

particularly in the United States. These products can be further categorized as 

fermented, acidified with chemical acidulants, or non-acidified. They are, with a

few exceptions, generally cooked. 

►Fermented Dry Sausage

Fermented dry sausage basically is manufactured by tempering and breaking the

raw meat materials; formulating the meat with added cure, starter culture, salt

and seasoning mixture; stuffing the product into casings, fermenting, heating, 

smoking (optional), and drying. 

The key considerations for manufacturing fermented dry sausage are as follows:

 Sausage will require 30-40% moisture loss. 

 Fat smearing over lean tissue should be minimized to enhance moisture 

loss and product definition.

 Raw meat mix should be approximately 25-28F (-3.9 to -2.2C) when

combined. 

 Meat mix temperature at stuffing should be 25-30F (-3.9 to -1.1C).

 Meat visual defects (e.g., blood clots) should be minimized, since they are 

magnified with drying.

Formulation and Blending 

During formulation, it is important to form a “meat matrix” consisting of lean and

fat particles bound together by salt soluble meat proteins. Initially, the meat 

mixture consists of soft particles, but with the addition of salt, the salt soluble

proteins dissolve and provide the “binding” material necessary. When the

product is stuffed and fermented, the resulting acid denatures the mixture, which 

results in increased firmness. If further heating occurs after fermentation, the

added heat adds to the firmness and initially accelerates the drying process. If 

not heated above fermentation temperatures, the product proceeds to the drying

stage, which increases firmness with the corresponding moisture loss. The acid 

coagulation is an irreversible process, thus the product needs to be in the final 

shape desired prior to this denaturation. For dry sausages, this initial matrix

formation needs to occur to some limited extent, but excessive matrix formation

(excessive protein extraction) leads to fat and protein smearing. If insufficient

matrix formation occurs due to premature acidification, lack of salt, too low

temperatures and/or insufficient mixing, the resulting product will be “shorted” 

(insufficient bind, mushy texture).

Inspection Methods 32-12
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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In dried, fermented sausages the first steps in production are the size reduction

of the meat tissue and the preparation of the non-meat ingredients. The raw

meat materials often are frozen, so the meat blocks must be tempered to the

desired temperature, and then reduced in size by frozen block grinders, 

hydraflakers and/or chopping in a silent cutter. Fresh meats must also be chilled

to lower the temperature prior to size reduction; they are often used in

combination with frozen materials (or addition of carbon dioxide) to control meat 

mix temperature. 

Non-meat ingredients such as the cure mix, seasoning mix (with or without salt), 

and starter culture are either weighed according to the batch size or are provided

by the vendor in unit packs corresponding to the batch size. The starter culture

is either added directly, if using a dry culture, or diluted in water first to afford 

good distribution of a frozen culture. The sausage casings are also hydrated to

afford flexibility, if provided in flat stock, or are added to the stuffing horn directly

if shirred. Often potassium sorbate is added to inhibit mold growth. 

The initial size reduction is very coarse to afford uniform mixing or chopping with

the other ingredients, but after formulation the product is re-ground to achieve the

final fat particle size for visibility. This product definition is also dependent upon

the equipment used and meat mix temperature. Sometimes the product is final 

ground prior to formulating with the other ingredients.

Generally, prior to the addition of non-meat ingredients, the meat blend is 

analyzed for fat, and possibly moisture and protein content, to allow for adjusting

the blend to the desired formulation. The meat mix may contain various meat 

types at various temperatures to afford the desired characteristics of the final 

product and to afford the desired temperature of the total mix prior to stuffing.

If a mixer is utilized, a paddle type mixer is preferred due to less smearing of the

meat mix. After the meats are formulated, the non-meat ingredients are typically

added in the following order: the cure mix, seasoning mix, and the starter culture. 

Minimal mixing time is recommended to uniformly mix the ingredients but not to

over work the mix. Vacuum mixing is optimal but not necessary if using a

vacuum stuffer. Some smaller processors historically use a silent cutter or 

chopper for both size reduction and mixing, but this type of equipment is very

operator dependent. After mixing, the product is transferred to the stuffing

apparatus. Any product transfer should minimize piping and pumping, with a

conveyor system preferred, again to minimize “working” the product. After 

mixing, some processors may final grind the product prior to stuffing, which also 

allows use of a bone collector device.

Inspection Methods 32-13
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Stuffing 

The stuffing apparatus is usually a screw type, piston, or chamber device. 

During the stuffing phase, it is important to maintain cold temperatures and avoid 

fat and protein smearing. This is accomplished also by minimizing resistance to

the meat mix flow; for example, using the largest stuffing horn possible to fit the

casing and using flat stock casing instead of shirred casings. Usually, a vacuum

stuffer is employed, which removes oxygen, providing for better curing and

concentrating the product going into the casing. For most dried fermented

sausages, fibrous, collagen or natural casings are utilized.

At this point, the meat mix is in the casing. Excessive fat smearing will

breakdown fat, enhance oxidation and retard drying. Oxidative rancidity is

degradation associated with oxygen in the air. Oxidation occurs primarily with

unsaturated fats. Degradation of fatty acids produces volatile compounds that 

cause off-odors and flavor changes. Inadequate drying may result in high water 

activity in the finished product. Fat smearing is usually visible under the casing. 

Excessive dissolved protein smear results in meat fiber orientation and is the

major cause of “cupping” in pepperoni on a pizza.

Fermentation 

During the slaughter process, the sterile tissue is often contaminated with Gramnegative (Enterobacteriaceae, E. coli, Salmonella, and Pseudomonas) and 

Gram-positive (lactic acid bacteria, staphylococci, and micrococci) bacteria.

Uncontrolled, fresh meat spoilage is usually caused by Gram-negative, 

proteolytic bacteria that decompose the protein and produce offensive odors 

(putrid, rotten egg) and flavors. 

Salting, curing, and drying the fresh meat are effective ways to control the fresh

meat microflora and preserve the meat. Curing salts (sodium chloride, sodium 

nitrite, sodium nitrate) and proper handling methods favor the growth of Grampositive bacteria while inhibiting the growth of Gram-negative bacteria. This

change in the typical microflora that allows Gram-positive bacteria to prevail is 

called “microbial inversion.” 

Today, over 95% of fermented meat processors use commercial starter cultures.

A wide variety of starter cultures may be selected for flavor and color 

development and for stability (nitrate reduction, oxygen scavenger). Starter 

cultures may come in several forms including: frozen liquid or pellets, dry

(freeze-dried) cultures, or frozen “syrup.” Meat cultures are alive and need to be

handled appropriately to ensure they do not lose viability and activity.

After stuffing, fermentation can be accomplished in an environment that provides 

the necessary temperature and humidity (e.g., smokehouse, fermentation

chamber). At the proper temperature, the lactic acid bacteria in the starter culture

Inspection Methods 32-14
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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metabolize or ferment a source of sugar (usually dextrose) and produce lactic 

acid. This controlled method of spoilage results in a “tangy” flavor that many

consumers find pleasant to the palate. The lactic acid also lowers the pH which 

helps with drying the meat.

Growth of Staphylococcus aureus during fermentation is a hazard in dry, 

fermented sausage. It is critically important to monitor the fermentation for the

proper conditions and product pH. The fermentation process must be controlled

such that a pH of 5.3 or less is reached within a time temperature combination

that controls growth of S. aureus and development of its heat stabile enterotoxin.

Depending on the room temperature maintained during the fermentation process 

(64-100°F), the time it takes to achieve a pH of 5.3 varies (36-7 hours). As 

fermentation progresses, staphylococci gradually die off and lactic acid bacteria

prevail. This change in the microbial flora is called “microbial succession.” Any

monitoring of coagulase positive staphylococci should be done on product at the

end of the fermentation cycle and before heating. If done following heating, the

Staph organisms may be killed, but the heat stabile enterotoxin may still be

present.

Note: In order for S. aureus to cause food poisoning, it must be allowed to grow

to the level of 1 million cells per gram of meat and then produce the heat stable 

enterotoxin. Proper temperature and sanitation controls prevent the growth of S. 

aureus to this level. Once the pH reaches 5.3 or lower, S. aureus growth is 

inhibited. 

Relative humidity is extremely important to all dried meat processing because of 

its impact on the quality of the product. Relative humidity expresses the degree

of saturation of the air by vapor, expressed as a percentage. Relative humidity

describes the relation of the existing vapor pressure at a given temperature to the

maximum vapor pressure at that temperature. Air at a given temperature can

absorb water (vapor) until its saturation (100%). Although now we have humidity

monitoring devices that give a direct readout of relative humidity, historically

processors used dry and wet bulb devices. The dry bulb temperature is the

direct temperature readout, while wet bulb is a dry bulb surrounded by a wet 

sock, providing a lower temperature. The difference between the two readings is 

used to calculate the relative humidity at that temperature. Charts and on-line

calculators are available for determining the relative humidity given the wet and

dry bulb temperatures.

A relatively high humidity (85-90%) is preferred to keep the product surface

slightly moist, or “tacky,” during fermentation and prior to subsequent drying. 

This avoids premature and uneven drying at the surface and the humidity

enhances the fermentation.

Inspection Methods 32-15
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Heating and Drying 

As previously mentioned, after fermentation the product can be heated prior to

drying, or go directly into drying. If heated, the product can be heated to a variety

of temperatures depending upon specific validation parameters or desired final 

product characteristics. Intermediate heating (120-140°F, 48.9-60°C) or fully

cooking (155-160°F, 68.3-71.1°C) both provide a means of destroying pathogens 

potentially present in meat to achieve the desired destruction. Applying heat to

fermented products is not always desirable due to the resulting flavor and texture 

changes; so many processors have arrived at intermediate heating schedules 

(time/temperature) that meet both objectives for destroying potential pathogens 

while preserving desired product characteristics. U.S. processors now must 

validate their own process for the specific destruction of the relevant pathogens 

(trichinae, Salmonella, E. coli O157:H7, S. aureus, Listeria monocytogenes), 

either by use of literature studies, by conducting a challenge study, or by relying

on FSIS Appendix A: Compliance Guidelines for Meeting Lethality Performance

Standards for Certain Meat and Poultry Products.

The variables during cooking and drying are cooking time, dry bulb temperature 

(generated by gas, steam coil, or electric heat), wet bulb temperature (natural 

humidity/fresh air/exhaust, steam injection, atomized water and/or refrigeration), 

and air velocity. It is very important to maintain uniform conditions during

cooking and drying. This is dependent on cooking and drying room design, 

product loading, product shape and the drying process. 

Uniform and balanced air flow is critical. Typical values for fermentation rooms 

are 4-6 air changes per minute, and less than 2 air changes per minute for drying

chambers. Processing ovens should initially be balanced by the manufacturer 

and periodically checked for uniformity. Ovens with constant airflow from the

supply ducts to the return may have temperature variations from top to bottom, 

side to side, or front to back. Temperature distribution can be determined by

placing temperature indicating devices throughout the equipment to locate cold 

spots and hot spots. Processors must determine the location of cold and hot

spots to support product or equipment monitoring procedures. For example,

monitoring internal product temperature at the cold spots in the oven could

support that all product in the batch was adequately cooked. Not monitoring

internal product temperature at the cold spots may result in failure to identify

underprocessed product. Some ovens are designed with oscillating airflow to

provide more uniform temperature distribution.

Uneven temperature distribution in fermentation equipment may result in some

product pieces not achieving a pH low enough to prevent Staphylococcus aureus 

growth and toxin production. Fermentation rates may be slower at the equipment 

cold spots. Elevated temperatures at hot spots may inhibit or destroy the

fermentation bacteria also resulting in failure to achieve a desired pH. 

Inspection Methods 32-16
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Temperature variation in drying equipment could result in the failure to achieve

the target water activity for the finished product.

Product loading is also important to achieve uniform airflow. Uneven loading will 

result in uneven conditions around the product, regardless of the design of the

heating and drying rooms. Improper loading can affect the adequacy of cooking, 

fermenting, and drying.

Product shape will affect uniform heat transfer. Heat is transferred along the

shortest dimension, so naturally shaped products like bacon and bone-in hams 

will inherently have more temperature variation compared to casing products. 

Product should be monitored for minimum internal temperature at a

predetermined “coldest” spot in the product.

The final drying process is influenced by the previous fermentation and heating

processes. Adequate carbohydrate source, the chemical environment,

processing temperatures and humidity are the influencing factors during

fermentation. During heating after fermentation, the product initially shows fast 

drying, but subsequently can actually dry more slowly if cooked, due to surface

drying and “skin” formation. Finished core temperatures also affect final product 

texture and appearance, going from more of a “raw” taste and firm bite with

definite fat and lean differentiation (final core temperature < 90°F, 32.2°C) to a

cooked taste, hard bite, and little fat and lean definition with a fully cooked

product (final core temperature > 137°F, 58.3°C).

A cooling step may or may not be employed. A hot shower rinses any residual 

fat from the surface and can tighten casing onto the product. A following cold 

shower will quickly reduce surface temperature. Meeting the cooling

(stabilization) performance standard to control C. perfringens is not needed for 

this cooling step – the pH of the products is too low for growth at this point. The

pH is close to the limit for germination and growth by other sporeformers as well

– very limited growth could occur at this point and as the water activity drops in

the drying step, sporeformers will be fully controlled.

During the drying process in a dry room, it is very important that the rate of 

moisture migration from the product center to the surface equal the rate of 

moisture migration from the surface to the atmosphere. This is more difficult with

larger diameter products, and most dry sausages exhibit greater moisture loss at 

the surface. The controlling factors for drying are temperature, relative humidity, 

air velocity, and air distribution and direction. If product is dried too fast, case

hardening occurs. Case hardening results in voids or pockets in the interior 

which could lead to bacterial degradation/spoilage. Case hardening also impedes

moisture migration so the product may not dry to the required water activity. If

product is dried too slowly, mold growth can be a problem. Mold growth is 

desirable in some products (e.g., Italian salami) for flavor and appearance, but 

for most processors, mold growth is a problem. In addition to being visibly

Inspection Methods 32-17
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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undesirable, mold growth can increase surface pH, alter flavor and restrict 

moisture loss. If only sporadic mold growth occurs, it generally is removed at 

peeling of the casing and slicing. 

Smoking 

Smoking of the product, whether using either natural smoke or liquid smoke, can

produce desirable effects for specific products. Generally, dried meats are 

characteristically smoked (hard salami) or not smoked (Genoa salami). Smoking

provides color (carbonyls + amines + dry heat) and flavor (phenols), as well as 

antioxidant (phenols) and antimicrobial (phenols + acids) properties to the

product. Smoking should not be done while the product surface is still wet due to

the resulting dark brown or “muddy” color and potential “streaking” of the color. 

Generally, smoking is done toward the end of fermentation. Excessive smoke

application in the beginning of the fermentation cycle on small diameter product 

can inhibit the fermentation activity of the starter culture.

Quality versus Safety 

In processing dried meats, there are many formulations and processing

conditions that can be varied to balance quality and safety. For example, some

processors have elected to remove beef from some formulations that contained

pork and beef so that E. coli O157:H7 is not a consideration. The rate of pH drop

and the final pH can affect both the safety and the quality of the final product. In

general, a lower pH provides more safety, but the lower pH can adversely impact 

taste. The degree of heating (none, partial, or fully cooked) is important in safety

(more heat provides greater pathogen inactivation) but changes the

characteristics of the product. Heat may be needed to obtain appropriate

pathogen inactivation. The relative humidity during drying can also impact both

product characteristics and safety. Microorganisms have increased heat

resistance to dry heat and at lower aw. A decreased relative humidity may result 

in pathogens being exposed to a dry heat, which could increase their chance of

survival. As noted before, improper air flow can dry the surface too quickly or too

slowly, both of which can impact quality of the product.

Fermented Dry Sausage: Pepperoni Formulation and Process 

A typical example of a fermented dry sausage formulation and process would be

that of U.S.-style pepperoni. The product is formulated to about 28-32% fat 

(figuring 68-70% final yield) considering a least cost formulation, including

predominantly pork with some beef. The maximum amount of beef allowed in

product labeled as “pepperoni”, and not “beef pepperoni” is 55%. Generally, 

most processors use a minimum 60% pork, but can go to as much as 100% pork 

depending upon market meat prices and if exported. Pork and beef cheek meat 

is commonly used (lack of bind, high protein) and is allowed as “meat.” Finely

Inspection Methods 32-18
 

 

 

 

 

 

 

 

 

 

 

 

 

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textured beef and pork is also allowed and used due to price, but the desired

texture and color prevent excessive usage levels.

Non-meat ingredients include: 

Salt (bind, flavor, preservative) 2.7-3.5 lb./100 lb. meat

Dextrose (limiting, carbohydrate for starter 0.5-0.8 lb.

culture fermentation)

Spices (mustard for flavor) 0.75-1.5 lb.

Natural flavorings (spice extracts for flavor, 0.3 lb.

color)

Starter culture (Pediococcus acidilactici for high 0.5 lb. diluted

temperature fermentation)

Antioxidant (BHA, BHT, citric acid, rosemary) in flavorings

Cure (nitrite on salt carrier, color, preservative) 0.25 lb.

Typically, the meat is tempered to about 26-28°F (-3.3 to -2.2°C) prior to mixing. 

The entire meat mix is blended with the cure, flavorings/antioxidants, salt and

starter culture. After blending and regrinding, the product is stuffed at 

temperatures not exceeding 26-28°F (-3.3 to -2.2°C). The stuffed product is 

fermented at 95-110°F (35-43.3°C), 80-90% RH, to pH < 5.0 (typically 8-12 

hours), then heated (to a temperature validated for the appropriate pathogens; 

e.g., 128°F (53.3°C) internal temperature for 1 hour), cooled and dried (50-55°F 

(10-12.8°C), 68-72% RH) until moisture/protein ratio reaches 1.6 or less (typically

12 – 14 days). The MPR is used mostly for labeling purposes and has limited

use in food safety. A more reliable measure for food safety is the aw.

►Fermented Semi-Dry Sausages

Summer sausage, Lebanon bologna and Thuringer are examples of fermented

semi-dry sausages. These products are manufactured in much the same way as 

the fermented dry sausages but with a few distinctions. In general, semi-dry

sausages, as the name implies, do not lose as much water (10-15% loss) as dry

sausages (30-40% loss). The drying occurs during fermenting and cooking, so a

specific dry room is not needed. Fat and protein smearing are not as much of an

issue due to less moisture loss, so formulation temperatures are higher, in the

range of 28-40°F (-2.2 to 4.4°C). Most semi-dry types are cooked following

fermentation and exhibit finer grind and lower pH (<4.8). A typical summer 

sausage process would include a fermentation period of 12-16 hours at 100°F 

(37.8°C), 98% RH, to a pH < 5.0, followed by a smoking/cooking cycle to a

minimum of 140°F (60°C) internal temperature. Many products are shelf-stable, 

with limiting amounts of added sugars (to prevent secondary fermentation in the

vacuum package) and fully cooked to 160-165°F (71.1-73.9°C) internal 

temperature.

Inspection Methods 32-19
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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►Chemically Acidified Sausages

Some dried meat products are formulated with chemical acidulants, rather than

starter cultures, which accelerate the process by eliminating the fermentation

period. These chemical acidulants provide a slower release of the specific acid 

(as opposed to addition of the straight acid) into the meat mix in order not to

result in premature acidulation before the meat matrix is established. These

types of acidified, product processes are direct heated and cooked following

formulation.

Chemical acidulants can be encapsulated acids or the slow release acid gluconodelta-lactone (GDL). With encapsulated acidulants, the active acid ingredient 

(e.g., lactic, citric, fumaric, GDL/gluconic acid) generally is encapsulated with fat

material that melts at varying temperatures releasing the acid. Thus, acidification

occurs during the cooking process after the meat matrix has been established. 

The rate of acid release is dependent upon the specific particle size, fat coating, 

temperature, other fats in the formulation, physical processing, and processing

temperature.

GDL is a cyclic compound that releases gluconic acid slowly when the GDL is 

hydrated with the meat moisture. When GDL is added to the meat mix, the

product must be stuffed and processed immediately, before significant acid

formation. The rate of acid generation is dependent upon moisture content and

temperature.

A typical process for chemically acidified summer sausage would consist of 

formulation, followed by heating at 115°F (46.1°C), 74% RH, and then cooking to

165°F (73.9°C) internal temperature. The entire process takes 6-7 hours versus 

a 12-18 hour fermentation process.

►Non-Acidified Dried Sausages

Some dried sausages are not fermented or acidified. This product segment

includes a portion of the dried meat snacks (meat sticks) and some larger 

diameter sausages, particularly those exported to Japan and other markets

where acidity or tang is not a popular flavor. These products have the same

general formulation process as fermented dried sausages, but no starter cultures

or acidulants are added during formulation and no fermentation period is 

required. Generally, after stuffing, the products are cooked to 146F (63.3C)

and then dried to a water activity of ≤0.85. Due to the higher pH, these products 

must be dried to a lower water activity (less moisture) than fermented products to

achieve shelf-stability. The higher pH makes the product more difficult to dry and

tight control of temperature, humidity and airflow is critical.

Inspection Methods 32-20
 

 

 

 

 

1 

f 

t t 

I I I I I I 

1 f 

____ ___ ____ _ ___ ________ ___ ___ ____ _ _________ __ ___ ___ ____ _ _________ __ ___ ___ ____

RTE-SS Process Familiarization

16 11-29-

Chart: Heat Treated/Not Heat Treated-Shelf Stable Flow

Sausage Dry Fermented

Receiving starter 

sings d ca cultures an

eat iving non m ce Re eat w m Receiving ra

ingredients

tion nta e Ferm

ing Stuff

ts ien ingred e in b m Co

process (chop, and

) /or mix dna grind

eat eigh raw m W

rozen Tempering f

meat

Storage (cold) 

rigerated Ref - Frozen

eigh W

rage Sto

Casing

res ltu rter cu Sta

n Preparatio

rage Sto

g / tin Hea

king Option o Sm

ying / Dr

ing ne Rip

Packaging/

Labeling 

Slicing/Peeling

Shipping

Finished

product storage

21 32- Inspection Methods