The Best of the WurstThe Best of the Wurst

The Best of the Wurst
May 1999 -- Design Elements

By: Ann Juttelstad
Associate Technical Editor

    For millennia, butchers have ground together scraps of meat and fat, seasoned it with spices and herbs, stuffed it into animal intestines and produced sausage. Some early examples of the sausage maker's craft come from ancient China, where the first documentation of sausage production dates back 2000 years. Early sausage production was a small-scale industry, with many sausage makers depending on a specific bacterial monoculture to flavor and preserve their distinctive products. Eventually, European settlers brought sausage-making to America, where the process was used to preserve meats, especially those of a lesser quality.

  The United States is now home to 21,000 sausage makers, who produce more than 6.3 billion pounds of sausage per year, according to The Dictionary of American Food and Drink.

  Sausages can be loosely classified into five categories, although each category supports a wide variety of sausage types. Cooked and cooked-smoked sausages include frankfurters and bologna. Luncheon loaves and specialty sausages include olive loaf, head cheese and pimento loaf. Fresh and fresh-smoked sausages, which must typically be cooked before serving, include varieties such as pork breakfast sausage and bratwurst. The cooked, gelled-type category contains products such as liverwurst. Fermented sausages are classified as being either dry, such as pepperoni and salami, or semi-dry, such as thuringer and summer sausage.

Simple sausage

  Sausages generally are emulsions of meat and fat particles, salt, curing agents (nitrates, nitrites) and spices that are stuffed into a casing. These can be sold raw, smoked or cooked. Fermented sausages incorporate fermentation organisms, and are ripened and dried. Many fermented sausages are stable at ambient temperatures.

  All sausage production shares a basic technology, starting with the preparation of ingredients. The mix starts with 50% to 70% lean meat. The meat can be derived from a wide variety of sources - from the more common beef, pork and poultry, to the more exotic salmon or emu. Typically, skeletal meat is used, but "variety" or "by-product" meats, such as hearts, lips and livers, can also be used. In fact, some of these alternatives are considered essential ingredients in specialty sausages - liver sausage or head cheese, for example.

  Whatever the choice, one meat characteristic essential for sausages is binding. This refers to the ability of the meat to bind water to itself and form a cohesive mass. Meats from different sources have different binding capacities. For example, lean beef skeletal muscle and skinless poultry rank fairly high in binding, while meat with high levels of connective tissue or organ meats exhibit this characteristic to a significantly lesser degree. Meats also have differing emulsification capabilities, moisture levels and even flavor, so the choice of meats in the formulation must take account of all of these factors.

  The meats are chopped with fat, then combined with salt, curing agents and flavorings. The mixture is stuffed into casings. The casings can be "natural" or "manufactured." Natural casings come from hog, sheep or cow intestines and are largely made of collagen. They are processed via drying and smoking, which hardens them and makes them less permeable. These casings are fairly elastic and shrinkable, and remain in contact with the meat throughout the process. Natural casings are edible.

  Manufactured casings can be derived from cellulose, edible or inedible collagen and plastic. Cellulose casings possess stretch and shrink characteristics similar to natural versions, but tend to be more uniform in size, are stronger, and have a lower microbial load. Collagen also possesses strength and uniformity, and edible versions can remain on the product for consumption. Plastic casings also exhibit high strength, but they are impermeable to smoke and moisture, and therefore are not used for smoked sausage or those processed in hot water.

  The high fat content in finished products means that the fat used must have a high melting point and be low in unsaturated fatty acids, particularly in fermented products. Pork back fat is often used in sausage production, as it has a low level of linoleic and linolenic acids, which makes it less prone to autoxidation. Antioxidants, including TBHQ (tertiary butylhydroquinone) and BHA (butylated hydroxyanisole), are sometimes used. Natural oxidation inhibitors, such as rosemary, garlic and mace, also can extend shelf life, as does ascorbic acid, which also preserves the color in the finished product.

  A sufficient level of salt lowers water activity. Salt levels of 2.5% to 3.0% are common, but some sausage types may contain as much as 8% salt in the final product. Salt, in combination with sodium nitrite (up to 150 mg/kg), inhibits development of food-spoilage microorganisms. Salt also helps solubilize proteins in the meat, which then form a sticky film around the fat and meat particles, forming a stable emulsion and inhibiting oxidation.

  Nitrites, both sodium nitrite and potassium nitrite, help stabilize the finished product, particularly in semi-dry sausages, which contain a high level of water. They are sometimes added in the form of nitrates, which must undergo reduction to nitrites to have an effect. Nitrites provide a more attractive pink or red tone to the finished product by reacting with the meat's myoglobin to form nitrosyl hemochrome. They also contribute a characteristic "cured meat" flavor, and help to inhibit the growth of Clostridium botulinum.

  The addition of nitrites has fueled concern over carcinogenicity through the potential formation of nitrosamines. This reaction is fostered during high-heat processes, such as frying. As a result, food processors should limit the use of nitrates to the level necessary to inhibitC. botulinum, approximately 100 to 200 ppm. Indeed, a 1997 report released by the Council for Agricultural Science and Technology, "Examination of Dietary Recommendations for Salt-Cured, Smoked and Nitrite-Preserved Foods," reports that: "The food processing industry has decreased the residual levels of nitrites in modern nitrite-cured meats five-fold over the last twenty years." The report also notes that the use of ascorbate or erythorbate - compounds that inhibit the formation of nitrosamines - has also had a beneficial effect.

Born to ferment

  For fermented sausage, the mixture is stuffed into casings and inoculated with the fermentation organism. Common species of lactic acid bacteria used for this process are Lactobacillus plantarum, L. bavaricus, L. curvatus and L. sake. Pediococcus as a secondary fermentor is also common, with P. damnosus or P. cerevisiae most often associated with sausage production.

  Whichever strain is used, the sausages are generally inoculated and allowed to ferment - 60° to 80°F for 24 to 72 hours for dry sausages, and 85° to 100°F for 14 to 72 hours for semi-dry sausages. During fermentation, the bacteria form lactic acid in the sausage, which lowers the pH. This lowered pH reduces the water-holding capacity of the meat, and aids in drying.

  Starter cultures in fermented sausage help control the lactic acid fermentation process. This process not only lowers the pH, but also forms compounds that influence the flavor of the finished product. In formulations that use potassium nitrate as the sole nitrite source in the formula, nitrate-reducing strains of Micrococcus or Staphylococcus may be used. Carbohydrates can also be introduced into the meat mixture to jump-start the fermentation process.

  Adding acidulants quickly reduces the pH of the mixture at the start of fermentation. Glucono-delta-lactone (GDL), added at levels of up to 0.5%, is the preferred acidulant for many manufacturers of semi-dry sausages. However, because it is thought to interfere with nitrite reduction and aroma formation in dry sausages, GDL is not as commonly used in those products.

  During fermentation and drying, the environment is controlled to maintain the relative humidity at approximately 10% below that of the sausage. Drying the sausages proceeds to the desired end point, and the sausages continue to develop flavor, color and aroma characteristics.

Extra elements

  Spices and seasonings in sausage manufacture take many forms. In hot dogs, particulate spices are undesirable, so spice extractives are used. "People don't want little specks in their hot dogs; they'll think something is wrong with it," says Ruth Kaan, product development manager, SpiceTec, Ltd., Carol Stream, IL. However, she notes that products such as Italian sausage or Polish sausage rely on traditional seasonings such as fennel and black pepper, and consumers expect to see particulates in these products. Beef sticks and jerky products, which are more dehydrated than other types of sausage, may or may not have whole spices in the formula, or they may have a combination of spice extractives and whole or ground spices.

  Encapsulated spices can be used in high-heat applications, though most sausages do not fall into that category, says Kaan. "Most sausage products are cooked to an internal temperature of around 160°F," she says, and most spices are not affected at these temperatures. However, in a high-heat formulation, encapsulated products ensure that flavor release comes at just the right moment, and that the flavor will not break down under the stresses of processing.

  A new ingredient in sausage manufacture is dried plum puree, used in hot dogs and beef- and pork-sausage toppings for pizzas. Dried plum puree at 5% by weight in a pizza topping can drop the calories from fat to below 30%, as compared to traditional toppings that often derive 30% to 50% of their calories from fat, according to the California Prune Board, Pleasanton, CA. In flavor studies conducted by the Board in Florida elementary and high schools, almost 82% of the kindergarten through fifth-grade students, and 92% of the high schoolers, rated the dried-plum/sausage blend "terrific," or would at least try the product again. This is good news for school foodservice providers who are looking for ways to improve the nutritional quality of school lunches, as well as for processors seeking ways to reduce the caloric impact of sausage-bearing formulas.

Stuff it

  Blending techniques for sausage ingredients are important - overmixing can cause stickiness and difficulty stuffing the mixture into casings. Additionally, manufacturing processes must be carefully controlled. Any delay on production lines also affects handling qualities of the meat, because the meat's now-broken molecular structure can cause the mixture to re-form and coalesce, making it stiff and harder to handle. Encapsulated ingredients, such as GDL and organic acids, help to prevent premature re-forming of the protein structure, and add a measure of control to the process. Temperature control is also important. Keeping the mixing and stuffing rooms cool prevents the fat from becoming warm and sticky, which would make the mixture more difficult to stuff into the casings.

  Casings used for fermented products may be either natural or synthetic. Natural casings have been shown to promote greater colonization and penetration by Penicillium organisms, as well as increased growth of yeasts in the product. This faster growth ensures that the fermentation process gets started quickly, inhibiting the growth of undesirable microbes. This ease of penetration, however, may have the opposite effect if the product is exposed to spoilage microorganisms, and artificial casings can help to inhibit the growth of such organisms. The casing must allow the sausage mixture to expire moisture during drying, while conforming to the shrinking shape of the sausage.

  Inoculating sausages with molds on the outside of the casing helps develop aroma and flavor. As in ancient times, many modern sausage manufacturers maintain in-house mold strains that are specific monocultures exclusive to the company. These highly developed strains can give a sausage manufacturer's products unique identifiable flavor characteristics. However, there is an unpredictability that comes with relying on ambient microorganisms to inoculate the product. Commercially produced mold cultures, such as Penicillium nalgiovense, P. expansum and P. chrysogenum, can be used as an inoculum for the fermentation.

Let's be frank

  Cooked, smoked-emulsion sausages, such as hot dogs and bologna, are manufactured in a much simpler way, but with no less attention to detail. With seven billion hot dogs consumed in the United States between Memorial Day and Labor Day, according to the National Hot Dog and Sausage Council, Washington, D.C., the frank, or wiener, is one of the most ubiquitous menu items in locations from back yards to ballparks.

  Most major manufacturers - whose products account for 70% to 80% of all hot-dog sales in this country - use the continuous method of frankfurter production, which can take advantage of efficiencies in operation.

  In this method, hot dogs are prepared by grinding the meat, chopping in salt and spices, stuffing the mixture into casings, applying smoke, cooking, peeling the casing away and packaging. The USDA requires that no more than 30% fat be present in frankfurters, with added water at 10%. Additives include salt, dextrose, corn syrup solids, microground mustard and seasonings. The USDA also allows a 3.5% addition of cereal, soy flour, soy concentrate, non-fat dry milk and 2% soy protein isolate. Skeletal meat ingredients may include beef, pork, lamb, mutton or goat. Meat by-products such as tongue, lips and tripe may be also be included.

  Frankfurter ingredients are of great importance, because they determine the product's final flavor, color and consistency. Aside from the use of various meats, by-products and binders, smoke and spices can give hot dogs a distinctive character.

  "Most people don't realize that hot dogs are a smoked product," says Patrick Moeller, vice president of research and development, Hickory Specialties, Inc., Brentwood, TN. "In most cases, smoke is a surface application, which makes it a processing aid, rather than an ingredient." Liquid smoke is applied to the stuffed (cased) hot dog prior to cooking. The links are either sprayed, using an atomizer system, or, in high-speed production, they are "drenched" in a liquid-smoke solution. Excess solution can then be recycled and reused throughout the operation.

  Drenching results in only an approximately 1/8-inch-deep smoke penetration into the product. Therefore, a product of a smaller diameter, such as the hot dog, receives maximum effect from smoke flavor. Larger-diameter sausages, such as bologna, may require smoke as an ingredient, as well as a processing aid, to achieve the desired flavor. Smoke flavoring is GRAS, and can be labeled as a natural flavor.

  Smoking provides three characteristics to the final product, says Moeller. First, it adds flavor, even though it may only be slight. Without smoke, the flavor of the frank would be too mild. Secondly, the smoke adds color. An unsmoked link would be very pale, which is unacceptable to most consumers. Thirdly, smoking enhances the skin texture, or bite, of the hot dog.

  Smoke solutions on a hot dog's surface also increase acidity on the outer skin, which makes it give up water, tightening it and providing the right bite. The smoking step must be tightly controlled, says Moeller, as the de-watering process also results in a loss of yield. There is a fine line between too little bite and too little yield. Most large manufacturers peel their product after the cooking process, resulting in the traditional "skinless" frank.

  Smoke also inhibits microbial growth and acts as a natural antioxidant, although the cooking process is designed to eliminate pathogenic organisms. In cured sausages that are processed with low heat, smoke plays a more significant role in inhibiting microbial growth. However, says Moeller, there is growing interest in the use of low-flavor smoke products after cooking and peeling to inhibit pathogen growth, particularly Listeria monocytogenes.

  Liquid smoke has an advantage over the more traditional smokehouse, which uses sawdust and heat to produce the smoke. Traditional smoking methods must conform to strict EPA codes that regulate air quality and emissions from processing plants. Liquid smoke eliminates such worries, as well as concerns about disposal and control of the smoking process. Only small manufacturers of specialty franks continue to smoke wieners in the traditional manner, says Moeller.

The great hot dog scare  Much has been made in recent months about the contamination of hot dogs and other processed meats with the pathogen L. monocytogenes. Product recalls and public-health warnings have brought this bacterium into the public eye once again, and meat processors are rightfully concerned over the control (or lack of) that they can force on this microbe in their plants. Contamination can come from a variety of sources, including animal-to-human transmission, human-to-human transmission and conveyance via food sources. The latter, of course, is the concern for food processors.   Russell S. Flowers, Ph.D., president and CEO of Silliker Laboratories, Homewood, IL, explains the importance of this pathogen in modern meat processing. L. monocytogenes is a gram-positive, rod-shaped bacterium found widely in nature that has been found to be pathogenic in man.   Not all people are susceptible to listeriosis, the illness that L. monocytogenes produces. Pregnant women, fetuses, newborns, children and immunocompromised individuals are the most susceptible to infection. "Primary manifestations of listeriosis in humans include flu-like symptoms, meningitis, abortion and perinatal septicemia," says Flowers.   In one study, laboratory workers, office workers and pregnant women were found to have respectively 77%, 62% and 30% to 40% of their fecal samples test positive for L. monocytogenes, with no signs of illness. It is clear, says Flowers, that exposure to L. monocytogenes does not constitute disease. However, this pathogen can cause food-borne illness and death.   L. monocytogenes thrives in cool, moist places, which makes it a particular nemesis in meat, as well as cheese, ice-cream and vegetable-processing facilities. Concentrations of the microbe are often found in floor drains.   Found in both raw and processed meats, L. monocytogenes is of utmost importance to processors of RTE (ready-to-eat) meats since it is presumed that consumers cook raw meat and destroy the microbe.   In RTE meat products, 5% to 12% of products tested in 1987, and 10% to 13% of those tested in 1988, were contaminated by L. monocytogenes. Processing conditions for dry and semi-dry sausages reduce, but don't eliminate, the bacteria in the sausage. Thermally processed meats will initially be free from the bacterium - contamination in these must come from post-process handling.   "Elimination of Listeria monocytogenes from processed meats requires that the processes employed kill all L. monocytogenes present in the raw meat and other ingredients, and that post-process contamination be prevented," says Flowers. "The first goal, having a lethal process, is attainable. However, further research will be required to develop and document these processes. The second goal of eliminating post-process contamination is not attainable without dramatic changes in plant design, equipment and methods employed for further handling and packaging of cooked products. Because of the ubiquitous nature of Listeria monocytogenes, it will be virtually impossible to eliminate it from the post-process plant environment."   Furthermore, it has been shown that samples testing negative for L. monocytogenes at the plant level still contain enough of the organism to show growth upon sitting in a refrigerator case, as a product would during normal distribution. So, even testing for the microbe using approved methods may not be sufficient to eliminate it from the marketplace.   Realistically, given the wide environmental range of the organism, it seems impossible to eradicate this pathogen from the food chain. However, Flowers points out that very few cases of listeriosis have been linked to meats, and he raises the question of whether contamination by meats is in fact significant in contraction of human listeriosis.   Flowers contends that implementing HACCP programs and following the American Meat Institute guidelines for processing RTE meats should be sufficient to keep L. monocytogenes at bay. The USDA is set to publish guidelines in late April of 1999, available on its website, that are designed to help meat processors seeking advice on controlling L. monocytogenes in their plants. The USDA also offers a monitoring program for RTE-meat-processing plants.   Concerns about food safety should never go away or be swept under the table. However, total elimination of potentially harmful food products is impractical and costly. The public in general, while concerned about the quality of their food, seems to make the most sensible decisions. They trust the industry to do their best at ensuring food safety - and then they go buy a hot dog. Back to top