April 2001
Meating at the Deli
By Paula Frank
Technical Editor
A visit to the supermarket deli used to be fairly straightforward. Options included sliced turkey, roast beef, salami, bologna and ham; nowadays, the choices are far more complex. For instance, basic turkey breast has evolved into oven-roasted, or smoked or flavored with honey or pepper. Turkey also may serve as an alternative to traditional meat bases, such as pork or beef, through the use of cures or flavorings that simulate the flavors of products such as ham, pastrami or bologna.
Although luncheon meats comprise a segment of the larger processed-meats category, its products vary in composition, flavor and process. Some deli meats — typically roast beef, ham, turkey or chicken breast — are made from whole-muscle pieces or large cuts, although they also may be chunked and formed into restructured portions. Comminuted meats, such as sausages, salamis, bologna and luncheon loaves, may be either coarsely or finely chopped; cured, seasoned and/or smoked; heat-processed; or fermented and dried. The ingredients and process play a significant role in the texture and flavor of luncheon meats, and help characterize overall quality and shelf life.
Meating objectives
Some luncheon meats undergo several processing methods, for example summer sausage, which is fermented, dried and smoked, or bologna, which is cooked and smoked. Other meats are merely cooked, such as braunschweiger and certain types of salami. Luncheon loaves contain a blend of comminuted meat with seasonings and perhaps condiments such as olives, pickles and pimentos. These loaves are water- or steam-cooked in molds.
During heat processing, meat proteins denature and coagulate as they lose their solubility, causing the texture to harden. Microbial fermentation and drying actually cause similar changes to protein structure. Through the introduction of a starter culture, such as Pediococcus acetolactii — a lactic-acid-producing bacteria — the pH drops to 4.6 to 4.7. The meat undergoing fermentation must be dehydrated at refrigeration temperatures until the water activity (Aw) falls below 0.96 for microbial safety. This prevents botulism spore germination. Subsequent drying and fermentation occurs at 18° to 24°C (64° to 75°F) for dry sausages and 32° to 43°C (90° to 109°F) for semidry sausages. Flavor development and textural hardening develop throughout dehydration and aging.
Various ingredients initiate chemical reactions within processed meats that impact properties such as binding, skin formation, color and flavor development and/or flavor stability. At times, one processing method or another helps stimulate these reactions. Salt, for instance, plays a key role in solubilizing protein, which aids in meat binding. Mechanical action, such as blending or tumbling, also helps extract and solubilize protein.
Meats may be coarsely comminuted or finely ground. Bologna, for instance, is chopped to an emulsion-like batter. Once the proteins become soluble, they function as emulsifying agents and stabilize fat particles and free water within the meat’s viscous matrix. Over-mixing the batter can negatively impact the emulsifying capability of the soluble proteins because it not only increases the surface area of fat particles, but also because excessive mixing generates heat that causes protein denaturation and coagulation.
Some meats are chunked and formed, or restructured, into a solid mass. Salt and phosphates help extract and solubilize the proteins. The solubilized proteins act as a binder as the meat chunks are tumbled or packed together into a mold or casing.
Discovering the cure
Curing meats, while historically done for its preservative effect, develops and stabilizes a pinkish-red color and protects against off-flavors. Curing ingredients include salt; sodium or potassium nitrite salts; and cure accelerators, such as sodium ascorbate or sodium erythorbate. At times, sodium or potassium nitrate salts are used in combination with nitrite; however, nitrite functions more rapidly in the reaction that fixes the cure color, since nitrate first converts to nitrite before it is reduced to nitric oxide.
During the curing reaction, nitrite is reduced to nitric oxide — a reaction hastened by the addition of cure accelerators. Initially, myoglobin, the red muscle pigment, and its oxygenated bright-red form, oxymyoglobin, are oxidized to brown-colored metmyoglobin. Nitric oxide then combines with the heme, or ferric, (Fe3+) portion of metmyoglobin resulting in the formation of nitric oxide metmyoglobin, which is then reduced to nitric oxide myoglobin — an unstable, red pigment with iron reduced to the ferrous (Fe2+) state. In the final reaction, heat denatures the protein portion of myoglobin, which leaves the heme group attached to nitric oxide, forming the more stable pink pigment — nitrosyl hemochrome.
Iron is a potential catalyst of oxidation, yet nitrosyl hemochrome prevents iron from oxidizing unsaturated fatty acids — the primary cause of warmed-over flavors. Therefore, curing not only stabilizes color, but flavor as well. In addition, nitrite helps prevent the formation of botulinum toxin by inhibiting Clostridium botulinum spore formation.
Title 9 of the Code of Federal Regulations (CFR) 318.7 lists substances approved for use as either GRAS substances, or food or color additives in the preparation of products, and specifies allowable usage levels of various ingredients, such as curing accelerators and curing agents. For instance, with the exception of bacon, sodium nitrite must be less than 200 parts per million in finished products.
Cures typically are incorporated via injection, although certain specialty products use an immersion or dry-rub method. Mechanical tumbling often follows the cure addition. Comminuted products incorporate curing ingredients into the blending process. These ingredients must be adequately distributed to avoid discoloration and the potential for areas subject to spoilage.
Although phosphates and seasonings do not factor into the above curing reaction, they often are incorporated into the cure mix, or pickle.
Phosphate philosophy
“Phosphates are often used to improve quality,” notes Gene Brotsky, technical service leader, meat applications, Rhodia Food, Cranbury, NJ. “Phosphates help retard rancidity and maintain texture during frozen storage and thawing. Yield, texture and fat level determine the type of phosphate(s) used.” For meats, such as ham and turkey, requiring higher yields, high alkaline phosphate blends, in conjunction with salt, extract soluble proteins, which increases water-binding capacity.
The mechanism behind tripoly- and pyrophosphates’ reaction with meat protein resembles the involvement of adenosine triphosphate (ATP), the energy phosphate, in live muscle contraction and relaxation. The muscle’s actomyosin interacts with the polyhosphates and partially dissociates into actin and myosin filaments, allowing free water to bind with newly available sites on the protein. In restructured meats, alkaline phosphates aid in binding meat pieces together.
Blending alkaline phosphates with acidic and neutral pH products, such as sodium acid pyrophosphate and hexametaphosphate, is better-suited for medium-yield products, such as roast beef or pastrami, because alkaline phosphates can give meats a grayish-brown color. At times, uneven injection enhanced by highly alkaline phosphates causes red and grayish-brown striations. Lowering the phosphate blend’s pH can eliminate the gray discoloration, notes Brotsky.
Ground items generally use neutral-pH phosphate blends because salt and mechanical action typically achieve most of the binding. Using an alkaline phosphate blend in a ground or emulsion-type product that already has a fair amount of binding may cause a rubbery texture, Brotsky says. For low-fat items, the phosphate-blend target usually falls between an alkaline and neutral pH because, although the meat’s released protein content may be somewhat higher, there also will be much more water to bind. “For highly extended meat items, the phosphate blend should be highly alkaline to get the maximum amount of binding,” adds Brotsky.
While injecting phosphates provides optimal contact with the meat’s internal protein structure, occasionally the goal may be adjusting the meat’s surface pH. “Rhodia developed a natural preservative extracted from bacteriological growth, that is used to treat the meat’s surface to extend its refrigerated shelf life,” says Brotsky. “Since this preservative works best when the meat’s surface pH is somewhat acidic, tumbling or immersion with an acidified phosphate blend is recommended.”
Although all polyphosphates sequester iron, which is the major source of oxidation in meats, certain phosphate products have enhanced functionality. A phosphate product with lemon-juice concentrate chemically hydrated onto tripolyphosphate has enhanced antioxidant properties, says Brotsky. Thus, phosphates not only enhance texture and sliceability, but protect luncheon meats from oxidation and off-flavors as well.
Fanning the flames
Smoke contributes both flavor and textural attributes to deli meats. “The key textural attribute is the formation of a surface skin,” notes Ray Nemunaitis, vice president of sales and marketing, Hickory Specialties Inc., Brentwood, TN. “The smoke reacts with the protein on the meat’s surface to create a skin or rind. That improves sliceability or slice yield, because you don’t get as much shattering of pieces, especially with the really thin-sliced products where there’s going to be some pressure on yield.”
Smoke usage often depends on the application at hand. Certain methods incorporate smoke, but use a separate cooking process. For instance, luncheon loaves are water-cooked and then extracted from a mold or casing. Smoke is applied only for the development of color, flavor and skin texture, says Nemunaitis. “Traditionally, luncheon loaves were knocked out of the mold and sent into a smokehouse with atomized liquid smoke, which is time-consuming and affects yield significantly compared to the newer method of using an HTST oven following a drenching or dipping process in liquid smoke,” adds Pat Moeller, executive vice president of research and development, Hickory Specialties.
Humidity and temperature control impact finished-product parameters when cooking and smoking occur simultaneously. “For summer sausage, using low temperature and high humidity at the beginning enables the fermentation process to take place,” explains Moeller. “You don’t want to create a dry shell on the outside before moisture is removed from the inside. Once the pH is down to a certain level, you apply smoke and lower the humidity so the product becomes dryer and sets up an outer shell.”
Alternatively, “with ham, you put your smoke on first to create a shell,” says Nemunaitis. “Once you’ve developed your color and your shell, you raise your humidity so you don’t lose extra moisture from the interior where you want juiciness. Once you have the smoking process done, you elevate the humidity and drive the temperature up to get a proper internal cook temperature.”
Smoke usage extends beyond flavor and textural development. “We’ve done some work with people on roast beef for those who want color without flavor impact,” says Moeller. “Not only did this product give a dark surface without caramel color, but it improved the meat’s texture for sliceability and yield. Browning occurs when the carbonyls from the smoke combine with the amino acids on the meat’s surface.” This color-contributing, flavorless product may be mixed with vegetable oil and applied to fully cooked poultry, then run through a high-temperature oven to produce a texture and appearance similar to a product that has been finish-fried. Finish-frying, a hot-oil process used to create texture and color without smoked flavor, can pose a fire and safety hazard to equipment operators.
Slicing up seasonings
Seasonings containing spices as well as other flavoring ingredients often characterize luncheon meats. “Bologna typically contains nutmeg, pimento, white pepper, mustard and sometimes coriander,” says Jennifer Morgan, senior food technologist, Heller Seasonings & Ingredients Inc., Bedford Park, IL. “Salami uses a lot of garlic, cracked pepper, and possibly coriander, dried mustard and ginger. Liverwurst may contain mace, ginger, cardamom, bay and possibly marjoram.”
Delivery of spice notes to luncheon meats occurs in one of several different methods depending on flavor and visual impact desired. “The flavor impact of whole, ground or cracked spices is a longer-lasting flavor with an earthy impact — the finer the grind, the more immediate the impact,” notes Morgan. “Since spices may contain spoilage organisms, the best method of reduction of the organisms is irradiation, which does not harm the volatile oils in the spices, and therefore produces a better shelf life in the finished product. Spice extractives, oils and oleoresins are often used to give a higher and immediate flavor impact without visual effect, except oleoresin paprika or capsicum, which give the typical ink color in finished product.”
In addition to spices, seasoning blends for luncheon meats also contain sweeteners and perhaps other flavoring ingredients. Typical sweeteners include sucrose, dextrose, corn syrup and/or corn syrup solids. Some sweeteners’ functions go beyond their sweetening capability. Sucrose and dextrose not only participate in the Maillard browning reaction for cooked products, but also play a role in the fermentation process for uncooked meats.
According to a study done by P. L. Dawson, Ph.D. and S. Mathew, Clemson University, Clemson, SC, and funded by the National Honey Board, Longmont, CO, honey provides functional properties aside from flavor and sweetness contribution in poultry meat. Honey participates in the Maillard reaction, which has been shown to produce compounds with antioxidant properties. In the study, thiobarbituric acid (TBA) values measured oxidative stability of turkey breast meat containing 0%, 5% and 15% added honey. The sample with 15% honey added produced statistically significant lower TBA values than the other variables. Results from oxidative stability instrument (OSI) readings supported the TBA test results. OSI measures the presence of oxidative compounds, such as hexanal. The results showed a negative-slope relationship between hexanal and honey levels. The 15% honey sample also exhibited a higher cook yield than the other samples.
In some cases, flavoring ingredients provide functionality without any flavor contribution, depending on the application and usage level. For instance, a butter concentrate at a strength of 8:1 gives turkey luncheon meat a desirable browned-buttery note, says Bill Buhler, general manager, Butter Buds Food Ingredients, a division of Cumberland Packing Corporation, Racine, WI. On the other hand, high butter concentrate at 80:1 adds a fatty mouthfeel and provides flavor enhancement to a restructured turkey slice without any defined flavor contribution.
“Frequently, our products are used at low levels (0.25% to 0.50%) where they contribute no distinguishing flavor of their own, but bring out savory flavor or round-off harsh notes from smoke, spices, cure, or undesirable flavor from the protein source, such as cow meat or comminuted poultry,” notes Buhler. “The concentrated dairy ingredients mask off-notes from soy, oxidized notes from trimmings, warmed-over flavor in precooked meats and provide fatty notes and mouthfeel to lean luncheon meats.”
Ties that bind
Luncheon-meat formulations include functional ingredients that offer a variety of benefits. Isolated soy protein and soy protein concentrate “can be used as an alternative high-quality protein source for beef, pork and poultry products,” says Russ Egbert, director of protein applications research, Archer Daniels Midland, Decatur, IL. The amount of alternative protein product (APP), formerly called vegetable protein product (VPP), allowed in meat products for the National School Lunch Act (NSLA) recently changed from 30% to 100%. The APP must meet certain criteria as outlined in a final ruling published by the USDA’s Food and Nutrition Service in the Federal Register, Volume 65, No. 47.
Part of the ruling specifies that luncheon meats made to meet NSLA guidelines must be hydrated to 18% protein or higher — the level of protein readily available in meat and poultry. “Isolated soy protein and soy protein concentrate used at the required hydration levels result in improved sliceability and higher cooking yields,” says Egbert. Regulations also stipulate that protein quality must be at least 80% that of casein, and that protein-quality testing be done with the Protein Digestibility Corrected Amino Acid Score (PDCAAS) test, which replaces the former method using the Protein Efficiency Ratio (PER). “Isolated soy proteins especially contribute to meats within the school lunch program by improving the meat’s overall quality and tenderness and by managing cost,” says Terry Anderson, director, meat industry management, Protein Technologies International, a DuPont business, St. Louis.
Functional soy proteins have other beneficial properties, including the ability to bind water and emulsify fat, notes Egbert.
Dairy derivatives, such as nonfat dry milk (NFDM), dried whey and whey protein concentrate (WPC), also act as binders and extenders in luncheon meats. Since a significant portion of NFDM’s protein contains casein, which is bound with calcium, it does not effectively function as an emulsifying agent because calcium exhibits poor water solubility. Calcium-reduced NFDM is a viable alternative to NFDM when emulsification properties are desired.
Title 9 CFR 318.7 specifies allowable usage amounts for various binders and extenders. For instance, calcium-reduced NFDM may be used individually or in combination with other binders at a maximum of 3.5% by weight of finished product. This list also includes allowable usage levels for other binders and extenders such as modified food starch and hydrocolloids. Ingredients such as carrageenan, locust bean gum and xanthan gum may be used as a blend not to exceed 0.5% of product formulation in cured pork products to prevent purging. These gums may not be used in combination with other binders approved for use in cured pork products. As an alternative, carrageenan may be used alone or in combination with soy protein concentrate not to exceed 1.5% of product formulation.
The list of approved ingredients under Title 9 provides the product developer with several formulation options, not only for binders and extenders, but for various other ingredients, including curing agents and accelerators, flavoring ingredients and antioxidants.
While luncheon meats are easy enough to consume, the development of such products is a bit more complex — requiring knowledge of federal regulations, food-safety issues, flavor-system development and meat-protein chemistry. No baloney here — just a bit of technical know-how to sink your teeth into.
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