December 1998 -- Cover Story
By: Ann Juttelstad
Even the most jaded food scientists can find that scanning grocery-store prepared-foods aisles showcases an astonishing number of meat snacks, lunch options and entrees. In-store delis are bursting with luncheon loaves, roast beef, turkey breast, pork roasts, fish patties, surimi sticks, ham loaf and chicken. All are formed, pressed, rolled and shaped to ease preparation for foodservice workers and improve eating for consumers. Even high-end products, such as duck and veal, are using restructuring technology to improve cost-effectiveness.
Away from the deli aisle, restructured meats are found in the sausage and sliced lunch-meat section. Bacon - flavored, formed and sliced from restructured chicken - resides in the breakfast case. The snack rack holds jerkies, meat sticks and smoked-fish offerings. Even the pet-food aisle offers an array of semisoft, formed treats for four-legged eaters.
The reason for these offerings is the simple fact that busy consumers are maintaining their demand for quick-and-easy meal solutions. Foodservice personnel are equally demanding in their requests for cost-effective, easy-to-handle products requiring little preparation. Gone are the days when the vagaries of a whole ham or the oddities of a natural turkey breast would be tolerated. Consumers, delicatessen operators and restaurateurs insist that products be easily sliced, have the ability to be reheated, provide an attractive appearance, and offer flexibility of use. Plus, they want gourmet-quality eatability.
With the gauntlet thrown to the meat-processing industry, the reaction has been to take the challenge in hand. While the initial response might have been a desire to breed boneless chickens and raise pigs that yielded perfectly rounded hams, the reality is that the industry is forming these picture-perfect meat products themselves.
In fact, the technique of using bits and pieces of meats to form a solid loaf has existed for as long as there have been butchers. Every farm wife had a recipe for using up those bits of meat left over after a butchering, says Susan Brewer, associate professor at the University of Illinois, Champaign-Urbana. These meat pieces were generally mixed with spices and flavorings, and mixed by hand for long periods of time. The mixing process forced the proteins in the meat to gradually be brought to the surface, and the meat pieces started sticking together. The product was then formed into a loaf and baked, frozen or canned to preserve it. The result: a sliceable meat product for sandwiches and entrees.
The technique remains much the same today, but with a decidedly modern twist.
Stability and value
Use of meat trimmings doesn't necessarily mean meats are of inferior quality. Trimmings often are just small pieces of high-quality material, lean and flavorful, says Brewer, and can produce product valuable to manufacturer and consumer. Most lower-quality meat goes into ground meats, not into value-added product.
Improvements in meat quality, ingredients and technology have allowed processors to produce a vast array of products, many that are undetectable from their natural cousins. Most sandwich meats used in today's restaurants come from restructured meats, Brewer explains, and the consumer is totally unaware. This is because natural-product texture and flavor now can be reproduced using pieces and chunks of meat, fish or poultry bound together using an arsenal of new ingredients and application systems.
Twenty years ago, attempts were made to "stick these products together with additives like egg white or vegetable proteins" Brewer says, "but it didn't work." Many of these earlier techniques used to mimic the protein bonds produced when meat proteins are mechanically forced into contact with each other have been cast aside for more modern methods.
"All food proteins do not stick together like a zipper, like we would like them to" Brewer explains, "but meat proteins are used for muscle contraction in all species and, therefore, all meats are fairly similar." Most often, these products rely on the protein-to-protein bond produced by tumbling the ingredients in a mixer. Mixing brings these proteins to the surface where they form a coherent chemical bond. Proteins in wheat and soy form somewhat less powerful bonds. Even gelatin doesn't form the type of structure that the physical mixing of meat proteins produces. However, nonmeat ingredients can provide necessary characteristics to the finished product, including flavor enhancement and color stabilization.
Whole-muscle products use the same chemical principle as ground or chunked products to form the protein bond, says Stuart Ensor, senior application scientist, Penford Food Ingredients, Englewood, CO. In a turkey-breast product, for example, usually two or three muscles are bound together to form natural-looking meat. To accomplish this, turkey breasts are brined in a solution of water, salt, phosphates, dextrose, starch and flavors. The brining medium is agitated to keep the insoluble material in suspension. The breast meat is injected with the brine solution and then tumbled in a drum "like a big cement mixer with baffles on the inside." This provides the physical action needed to bring the proteins to the surface of the product, and alsoevenly distributes the brine throughout the muscle. The product is then put into an impermeable plastic sleeve, a vacuum is drawn, and the package is further shrink-wrapped. The product is then cooked and cooled. The result is a consistent turkey-breast product of uniform size, weight and color that slices easily, but still has the visual and textural characteristics of a natural breast product.
Similar techniques produce chicken products that can have unique applications. Gemini Food Industries, Sturbridge, MA, makes a restructured chicken breast for the foodservice industry. The finished product is designed to be thinly sliced and served with sautéed green peppers, onions and cheese on a hoagie roll for a "chicken Philly steak," says Warren Kenniston, senior vice president, Gemini. By taking an inexpensive piece of poultry, and processing it this way, says Kenniston, "you can provide consumers with a product that is a perceived healthy alternative to beef that tastes great." The restructuring of the chicken meat allows the company to produce a product that can be sliced paper thin, an option unavailable for a natural chicken piece. Furthermore, the product is freezer-stable, offering potential in meal-replacement development and as a pizza topping. The process allows Gemini to use lower-cost cuts of meat (trim and pieces), and form them to make one piece of meat. The new technology is being used to bind the meat together with ingredients such as glutamates.
"Sometimes, you take a full piece of meat that needs to be cut down," Kenniston explains. "The trimmings have less value to food processors, so the basic raw material cost is considerably less than a full piece."
Restaurant owners also are demanding that food safety, quality, cost and portion control all be addressed by suppliers. "A natural 4 oz. chicken breast can range from 3.75 oz. to 4.25 oz.," Kenniston says. "With these products, 4 oz. is 4 oz., each and every time." Food-safety concerns in the foodservice sector favor restructured meats as a way for getting precooked entrees with a consistent shelf life that can withstand the rigors of handling and the abuses of untrained labor. Pre-formed, pre-cooked meat portions take the guesswork out of food preparation.
It's not just the meat that's crucial to restructured meat product flavor, texture and stability. A product with consistent weight, color and flavor, and that is resistant to purge (the syneresis of the product that produces watery pockets inside the packaging and a drier finished product) relies on several ingredients.
Ties that bind
A pivotal part of meat restructuring is the ingredients used to add flavor, improve texture, impart mouthfeel, increase shelf life and aid eye appeal. Many ingredients have been used over time, but some seem to do a better job than others.
Blood plasma has been shown to be an effective binding material, Brewer says, but it tends to darken product color (making it unsuitable for light-colored meats) and possesses a metallic flavor. Its appearance on label statements might prompt a negative reaction as well. These factors have made it unacceptable to some U.S. consumers. Labeling standards require that blood plasma be labeled as such in the United States, but European regulations allow the label of blood products as meat byproduct or beef protein.
However, recent research has found new uses for blood plasma in restructured foods. Used as an emulsifier in sausage-making, its gelling action is largely unaffected by salt concentration or pH. Low-salt sausage formulas retain their firmness when blood plasma is used as the emulsifying agent. It also can increase sausage yields approximately 4% to 5%. Research conducted by Jae W. Park, Ph.D., associate professor of food science and technology, Oregon State University's seafood laboratory, Astoria, has found that adding blood plasma to Alaskan pollock surimi mix has a significantly positive effect. Blood-plasma proteins act as very functional binders, offering processors one more option in developing new surimi products. However, most surimi products still are formulated with egg white, starch, stabilizers and polyphosphates. Phosphates are widely used as food additives. Mono- and polyphosphates act as buffering agents, emulsifiers and sequestering agents in restructured foods. Salts and phosphates suck the proteins to the surface of the meats," says Brewer, by changing product pH, facilitating the binding process.
Phosphates provide an important function in restructuring meat products; they disassociate actin and myosin in actomyosin. Myosin holds water better than actin, and alkaline phosphates serve to "push open the proteins," says Jim Lamkey, technical manager, Meat Ingredients Unit, FMC Corporation, Philadelphia, PA. Salt draws the protein from the muscle and allows the protein to trap water in the spaces between the proteins. Salt and phosphates work synergistically, with lower levels of each substance being needed when used in conjunction with each other.
The alkaline phosphate/salt combination improves meat-product juiciness, as well as firmness, particularly in low-fat products. In addition, phosphates improve product shelf life by acting as an antioxidant for post-processed foods, Lamkey says. Phosphates sequester heavy metals in the formulas, making them unavailable to promote oxidation.
In some full-fat products, alkaline phosphates result in a "soapy" flavor when used at too high a level, Lamkey explains. A more neutral phosphate blend might reduce the soapy flavor. Acid phosphates have much the same function as akaline phosphates, but yield will be sacrificed. In this case, the alkaline phosphate is combined with an acid phosphate to control pH.
Starches help bind the moisture within the protein matrix. They produce a gel when combined with the water within the muscle, and can significantly affect texture. Starches can aid in mouthfeel, particularly when used in reduced-fat products. Starch also enhances the yield of processed meats, and can improve a meat's nutritional profile.
Processors look to starches to perform two basic functions, says Michael Augustine, director, ingredient application, A.E. Staley Manufacturing Company, Decatur, IL. One is for the water-holding capacity. Waxy maize starch is particulary well-suited for applications in which the processor wants to increase yield and decrease purge. Other types of starch function as binders, providing firmer texture, particularly in low-fat and fat-free products. Common corn starch, dent starch and potato starches represent starches that are used for their binding characteristics.
Typical consumers want all the flavor of full-fat meat products, but want to reduce their fat intake. Starches can add back some of the mouthfeel without adding those high-fat calories. Corn, wheat, potato, oat, rice, tapioca, arrowroot, konjac and other starches can be used to good result, Ensor says. The key is to use modified starches in a meat system. Other kinds of starches can collect in small pockets inside the meat, adversely affecting finished-product appearance and color. Modified starches distribute easily through a meat block. "Modifying starches improves stability and texture," Ensor explains. The modification process increases moisture control within the starch granules, and also decreases syneresis and improves structure. Additionally, modified starches improve the final product's freeze/thaw tolerance and refrigerated-storage quality.
Some specialty starches, such as a low-pasting-temperature starch that gelatinizes from 110° to 130°F, have specific applications for specialty products, says Augustine. However, he also points out that combinations of modified and unmodified starches can provide the precise functionality needed in some processes. "Look at the needs of the system," he says, "it depends on the user and the expectation of the product."
In addition to using starches, texture and mouthfeel can be improved by adding other gel-forming ingredients. Curdlan, from Takeda U.S.A., Inc., Saddlebrook, NJ, is a polysaccharide produced by the microorganism Alcaligenes faecalis var. myxogenes, that produces a strong gel that's stable in freezing and retort processing. Carrageenan, sodium alginate, pectin and gelatin have varying degrees of gelation properties, all of which improve water retention and impart specific textural attributes.
Carrageenan is stable in low-pH products (high acid), but can become mucilaginous in some formulations. Sodium alginate is soluble in both hot and cold water, and doesn't gel on cooling or coagulate on heating. It is minimally affected by pH. Sodium alginate can form gels with calcium, acid or both, and is virtually tasteless. Pectin substances form best in an acid-sugar medium and at low pH, around 2.8 to 3.4. Gels formed with pectin may be brittle. Gelatin, most commonly derived from animal hides, is a soluble protein derived from insoluble collagen, and is water-dispersible. Gelatins can display a rubbery characteristic in some formulations.
A problem with adding many starches and other gel-forming materials to a chopped meat or whole-muscle product are pockets of gelatinous material connecting the meat fibers, which consumers easily notice. These pockets can be reduced by thoroughly completing the tumbling process, and by utilizing the properties of the starches themselves. For instance, potato starch has the ability to disperse into the muscle more easily than corn starch in some applications, Ensor says. Also, meat-product mouthfeel might be compromised in some applications. Starches can produce a slick, gummy or waxy mouthfeel, while gelatins may produce a rubbery characteristic. Often, it is a systems approach to binders that gives the best overall flavor and texture profile, while improving yield and reducing purge.
Z-Trim, developed by USDA, has been used as a replacement for starches in some restructured meat applications. Made from agricultural byproducts, such as the hulls of rice, beans and peas, this dietary-fiber gel absorbs water, producing large deformable structures that can be modified to adjust a product's mouthfeel from very smooth to very textured. Z-Trim can be used as a fat replacer in reduced-fat meat applications, and is a source of insoluble dietary fiber.
Multifunctional ingredients are essential to new-product success, and research continues to reveal the diverse uses of even common ingredients. Food scientists from Clemson University, Clemson, SC, have proven that adding honey to turkey rolls creates an antioxidant compound as a result of the Maillard reaction. Concentrations of up to 15% by weight in a chopped-and-formed formula do not give the product an overly sweet taste, according to the researchers. Refrigerated studies reveal that, at that level, the honeyed turkey rolls display only 15% of the oxidation of their non-honeyed counterparts. Honey also seems to inhibit bacterial growth on meat surfaces, possibly increasing product shelf life by days or even weeks.
Adding proteins to processed meat, poultry, fish or surimi can deliver a compound benefit. Whey and soy proteins can add significant amounts of amino acids. They also contribute calcium, iron, sodium and zinc, providing a considerable nutrient boost to the finished product. Whey proteins aid in the emulsification and adhesion of the meat after chopping and blending; soy proteins contribute to mixture adhesion.
Liquid meat protein by Novo-Nordisk Biochem, Inc., Franklinton, NC, can be added to processed meats and fish to improve microbial quality, texture and protein distribution. The ingredient helps to bind muscle to form a cohesive piece from individual chunks.
It is essential in restructured meats to keep the fresh-meat color throughout a product's shelf life. Sodium erythorbate enhances color retention by inhibiting oxidation in cured meats and meat snacks. Adding coloring agents, such as caramel color, can enhance the roasted meat color in a beef loaf or boost the reddish tone in a ham loaf. Researchers at Takeda have found that adding vitamin C (ascorbic acid) to processed meats not only accelerates the development of color in hams, sausage and cured meats, it also inhibits color fading over time. Ascorbic acid speeds color development in two ways. The first is by accelerating the reduction of nitrous acid to nitrogen oxide. The second is by accelerating the reduction of nitrosometmyoglobin to nitrosomyoglobin. Fading of meat color in the deli case is caused because the denatured globin nitrosohemochrome is decomposed by light, and further oxidized to brown hemochrome. Adding ascorbic acid prevents this oxidation. Fading of deli meats also can be minimized by keeping the meat in a dark place.
The color of processed meat and poultry also is affected by product pH. "Pinking of poultry and, sometimes, red meat can be due to a high pH," Lamkey says. Pink poultry is unacceptable to consumers, who associate the coloration with underdone meat. Regulation of the pH with phosphates and glucono delta lactone can remedy the situation.
Lactates in processed meat and seafood products control pH, helping extend shelf life. Most significantly, lactates, such as sodium lactate and potassium lactate, inhibit the development of Listeria monocytogenes and Clostridium botulinum. Ascorbic acid also inhibits the development of C. botulinum.
Keeping it fresh
"Sodium lactate has a neutral pH," says P.K. Kuipers, marketing services manager, Purac Biochem, Gorinchem, the Netherlands, "and because of its good antimicrobial properties - due to reduction in water activity and special lactate-ion effect - sodium lactate extends the shelf life and improves the safety of meat products." Glucono delta lactone, used in cured meat and frankfurter applications, controls pH and also enhances the activity of benzoates, which are used as preservatives.
Potassium lactate also has been used to replace potassium chloride in reduced-salt formulations requiring extended shelf life. Historically, potassium chloride has been the substitute of choice for low-salt formulations, but its bitter flavor limited its use. Potassium lactate provides the same shelf stability in products, but is considered more palatable.
When used in conjunction with alginates, calcium gluconate can restructure fresh-ground meat into a product mimicking whole-muscle meats. The calcium gluconate is added to the meat mixture in dry form in the same ratio as the alginate. The slurry is then mixed and cooked. The finished product, which is retort-stable, can be formed into chunks for stews or kebabs, sliced, or used as a whole piece. Calcium gluconate acts as an activator when used with alginates, forming a "calcium bridge" between protein structures, says Bob Jungk, director of marketing, PMP Fermentation Products Inc., Itasca, IL.
Forming chemical bonds between proteins is the key to the functioning of a newly available enzyme from Ajinomoto, says Robert Bursey, director, regulatory affairs, Ajinomoto U.S.A., Inc., Washington, D.C. Transglutaminase (TG) recently has been approved for use in nonstandardized meat products, says Bursey, and he expects to see the ingredient approved for use in meat products with standards of identity soon. Already GRAS for seafood, dairy products and meat analogs, TG plays a revolutionary role in restructured meats and seafoods.
"Most enzymes used in food processing function by cleaving - hydrolyzing, e.g. proteases - or modifying - isomerizing, e.g. isomerases - specific molecules found in the foods," Bursey says. Mechanically processed restructured meat products rely on the massaging of the meat as well as ingredient interactions to bring the proteins to the surface so they can bond. TG cross-links proteins in a covalent bond between two peptides. "This cross-linking makes it possible to create large polymeric protein molecules from small protein substrates," Bursey says. "This is the way it's done in nature."
TG is distributed widely in nature, but its separation and purification haven't been commercially viable until recently. It is now produced through the fermentation of the microorganism Streptoverticillum mobaraense. The process, approved in Japan for nine years, possesses decided advantages for the food-processing industry.
For example, small bay scallops, which offer marginal consumer appeal, can be bound together to form a "scallop medallion," which packs considerably more sales potential. Canned sausages of all types now can be formulated with TG, and exit the retorting process with a firm texture and pleasant "bite." It can provide hot dogs and low-fat processed meats with a definite textural advantage. In addition, TG also helps foods lose less water on cooking, and increases yield. The product imparts no flavor impact to the products in which it is used, making it ideal for mild seafood and poultry applications. TG is labeled as "enzyme" on the label statement, a designation with little adverse consumer reaction.
Bursey views TG as a boon to the foodservice industry, where a great demand exists for large, consistent cuts of meat. Bursey expects it to be used, for example, to bind two pieces of tenderloin together to form one long, perfect roast with little waste and consistent cooking qualities or to form perfect boneless hams or boneless salmon steaks that can fit exactly on a bun. Institutional applications are intriguing, says Bursey, as operators seek nutritious, consistent entrees for hospitals, nursing homes and other care facilities.
Sometimes, new products come about not by way of new ingredients, but because of the linking of ingredients with machinery.
Not mom's fish sticks
National Fish & Seafood, Gloucester, MA, was looking to expand its line of extruded seafood products to fill customer needs. Quality Control Director Kathy Scanlon looked to Kerry Ingredients, Beloit WI, to help come up with some ideas.
The result: five new products expected to debut in the beginning of 1999. The impetus, says Scanlon, was the need to use existing equipment in a novel way. In the new lineup are seafood items in the shape of rings, nuggets, fish and three-dimensional triangles. An extruded calamari ring also is in the offing.
The Kerry cold-extrusion process is key to the products' success. Designed to be three-dimensional shapes in appetizer weights, these product take advantage of fish trimmings and flakes, allowing the formulator to dictate the end result.
"We formulate a product from the inside out, not from the outside in," says Jeff Kirn, director of sales, Kerry Ingredients. This process allows the formulator to decide the consistency, flavor and mouthfeel parameters, and build them into the product from the ground up. For example, National Fish & Seafood uses a shelf-stable, flavored particulate to add flavor and color to their fish-shaped product. The honey-flavored bits maintain their integrity during processing. The pieces are available in fruit, cheese, meat and sweet variations, and can be customized to meet specific requirements. "It's just a hint of honey flavor," Scanlon says, "but it's just enough that we think kids will go for it." The honey KerryBIT also has been effectively used in honey-mustard chicken nuggets.
The calamari ring developed by the National Fish & Seafood/Kerry Ingredients collaboration takes advantage of the extrusion process to control product texture. Calamari is often tough, and fosters customer complaints, Kirn says. By controlling the formulation and the extruding process, they were able to regulate the extent of "bite," making a consistently textured product. A sodium alginate/calcium chloride system forms an invisible edible skin on the product, holding it together. The product is then par-fried to set the alginate/chloride skin, and packaged for retail or foodservice sale.
Consumer demand for quick and tasty value-added meat products often goes head-to-head with a desire to eliminate perceived harmful food additives. A segment of the population is wary of added phosphates, alginates, erythorbates or salts. Yet, these consumers also desire the taste and convenience of deli meats and luncheon loaves.
Plain and simple
New technology has been developed to give these consumers just what they want. Visionary Design, Inc., Atglen, PA, recently introduced the Slinder process, a unique process that effectively slices meat to provide the substrate for the protein-bonding process. "The process transforms underutilized, undesirable cuts of meat into slices of meat that can be immersed in hot sauces or gravies for cooked value-added products," says Slinder process inventor Eugene Gagliardi, president and CEO, Visionary Design.
The Slinder slices (rather than grinds) meat, using a patented system that utilizes parallel slits rather than the holes used in the traditional grinding process. The result: More of the meat surface area is exposed and a greater level of myosin is extracted without destroying meat fiber. These long meat strips are then mechanically mixed and the meat fibers interlock and grab one another to create the RiteBite™ process. "When the mixture is formed and fully cooked, it produces a superior restructured product with the texture, bite and appearance comparable to that of a whole-muscle product," Gagliardi says. The process can even blend denuded cartilage into the mixture with no adverse effects on finished-product quality. Gagliardi claims the process can be used on any type of meat, poultry or seafood product.
This technology currently is being used to transform surf clams - typically a tough, inedible mollusk - into a tender clam steak similar to another Gagliardi invention, the Steak-umm product, owned by the Ore-Ida division of H.J. Heinz, Inc. Gagliardi also is responsible for developing KFC's Popcorn Chicken, another value-added product using restructured-meat technology.
The future for restructured meat, poultry and seafood products looks bright as technologists continue developing ingredients, technologies and processes that take advantage of the microstructure of the protein complex.
More sophisticated items will appeal to the growing demand for convenience, flavor and texture in ready-to-serve products. Kenniston looks for new technology to make it possible to bind extra meat onto a rack of ribs, making exceptionally meaty ribs that maintain a lean and flavorful character. "Utilization of lower-end meat pieces looks very positive," he says, as technologists continue finding ways to produce more with less. The benefits of cost savings with the improved food safety of these restructured meat products will be a strong incentive for producers to keep up the research.
Ann Juttelstad is a free-lance writer with an associate's degree in food technology and a master's degree in media communications. She has worked for 15 years in quality assurance, product development, technical services, and sales and marketing in the food industry.
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