"Meating" Design Challenges

"Meating" Design Challenges
October 1996 -- Applications

By: Lynn A. Kuntz
Editor

    As in other segments of the food industry, those who develop meat products must address important health issues that drive consumer demand. Two of the most significant concerns for today's consumers are nutrition and safety. To this end, food designers have had to rely on new technologies to create more healthful meat products.

The fat of the land

  In the bad old days, high-fat meat meant high quality. In fact, more fat typically brought a higher quality grade within the U.S. Department of Agriculture's (USDA) grading system. Unfortunately, over-consumption of animal fat also leads to serious health problems. Many American consumers have shifted from mammal-based "red" meats to lower saturated fat and lower cholesterol poultry and seafood.

  Meat (meaning "mammalian" meat) contains relatively high levels of saturated fatty acids, especially palmitic and stearic. Beef fat contains approximately 54% saturated fatty acids, sheep fat about 58%, and pork fat about 45%. In contrast, chicken fat only contains about 32% saturated fatty acids. Animal fats are a significant source of cholesterol, another nutritional pariah.

  Over the last decade, the meat industry has sought to develop more healthful products. This evolution has affected both fresh and processed meats.

  Beef quality grades depend on a number of factors that influence palatability: maturity, degree of marbling (intramuscular fat), texture, and carcass conformation. Similar standards hold for veal, mutton and lamb. Pork grades depend mainly on yield factors. U.S. No. 1 pork has less back fat than U.S. No. 2, but more than pork graded "Cull."

  Current research and breeding trends have focused on developing more efficient, leaner animals. In cattle, the average carcass weights have increased, as has the ratio of lean meat to trimmable fat. The National Cattlemen's Association reports that the amount of beef produced per cow has risen from 449 lbs. in 1984 to 550 lbs. in 1994.

  In addition to breeding, other methods can increase the production of lean meat. Two compounds -- porcine somatropin (pST) and ractopamine -- enhance the conversion of feed to meat muscle and reduce the fat content in pigs. However, their use has stalled in the research stage due to many of the same concerns that have plagued the use of bovine somatropin (bST) in dairy cows.

Low-fat shuffle

  The strong demand for lower fat meat products is reflected in new product activity. This means focusing on ways to cut the fat content of traditional products.

  The FDA and USDA have provided definitions and descriptors for these products. For example, a standard, full-fat emulsified meat product such as a hot dog contains approximately 30% fat and no more than 40% added water. A "reduced-calorie" claim or "less fat" claim means 25% fewer calories than the standard. A product labeled "light" would have to cut the fat by 50%. A "lean" product requires 10% (by weight) fat or less, and "extra lean" indicates 5% or less fat. For "low-fat," meat must contain 3% or less fat.

  The easiest method for lowering fat is to use lower fat cuts of meat -- ham or loin versus pork shoulders, for example. Closely trimming visible or external fat cuts fat, but this precludes the use of more economical cuts and high-fat trim.

  More sophisticated methods can also remove fat. Some approaches require heating the meat to liquefy the fat, then separating the fat from the meat with techniques such as centrifugation. Another method, developed by CF Systems Corp., Arvada, CO, utilizes liquefied gas-solvent extraction. This process uses GRAS solvent gases that are liquid under elevated pressure. Removing the pressure causes the gases to flash off.

  "You must use ground meat particles because the food must have intimate contact with the liquefied gas," says Starnes Walker, Ph.D., vice president and managing director of CF Systems. "For this process, we need to consider surface area to volume."

  According to Walker, this process is less expensive than CO2 extraction. The temperatures required can be much lower than those used for cooked or mechanical extraction methods. Lower temperatures mean higher quality and fewer microbial problems.

  "This method could be used to create products for the national school lunch program where there is an emphasis on fat reduction. You could use it to extract the fat, but then back-blend to a standard level. It won't change the taste or modify the protein content," notes Walker.

  Merely formulating with leaner meats creates two serious problems: It raises the cost and usually affects the palatability. Although intramuscular fat is associated with tenderness, it may only be that fat acts as a lubricant during chewing. However, the fat level significantly influences the juiciness and flavor of whole muscle and processed meat products.

  "When we process meat for lower fat products, we need to dilute the fat content of that meat," says Dan Putnam, senior application scientist, Grain Processing Corp., Muscatine, IA. "Water is the most cost-effective ingredient."

Adding water, adding value

  "Most processors want to maintain the flavor, texture and succulence found in full-fat products," says David Stone, market segment manager, meat ingredients, FMC Corp., Philadelphia. "With most meat products, the leaner they get, the more rubbery they get. Also, spices and seasonings may be enhanced by the fat. The same seasoning used in a full-fat product may give a completely different flavor profile when you take that fat out."

  The meat industry uses a number of ingredients to bind water. Some, such as the phosphates, increase the meat's ability to hold moisture. Others are water-binding, fat-reduction ingredients. These ingredients may be used alone or they may share the duty to create the desired characteristics.

  Ingredients known in the meat industry as binders improve water-binding and promote fat emulsification. The term "fillers" refers to ingredients that merely bind additional water. If the ingredient only increases bulk or alters the composition, it is called an "extender." The use of these ingredients is regulated -- the USDA only allows a total of 3.5% binders (used singly or in combination) in emulsified meats, for example. Other labels, such as "ham and water product," may limit the use to a single binder. Products labeled "lean" or "extra lean" can contain water and extenders to achieve the target fat level.

  "If you exceed that 3.5% level in a lower fat product, the USDA will evaluate it on a case-by-case basis when you go for label approval," says Putnam. "They require a notification in the ingredient statement that the level is in excess of the standard."

  The regulatory status of these ingredients is changing -- not just levels, but the ingredients that are allowed. The regulations are under review and should be simplified in the near future.

  "USDA Policy Memo 123 says, in essence, that they recognize that there are many ingredients used to make low-fat products that have not been traditionally used in meat, and that if an ingredient has FDA clearance, the USDA will likely allow its use in meat," says Stone.

  The USDA also restricts the level of water added to a product. Formerly a product labeled "water-added" could only contain water at four times the protein level plus 10%. Lower fat products obtain some leeway in that rule.

  According to Fred Bender, manager, meat laboratory, Rhône-Poulenc Inc., Washington, PA, "As you go to low-fat systems, the systems increase to four times protein plus 20% or 30%. More water is needed to replace the fat."

Buys that bind

  Meat contains its own natural binder -- protein. This holds onto water molecules because of its negatively charged hydrophilic groups. When the pH is at the isoelectric point (pH 5 to 5.2), the protein loses some of its ability to immobilize water. The structure of the protein molecule also affects its water-binding capacity.

  The type of meat influences the degree of binding of both water and fat in an emulsified system such as bologna. Lean skeletal muscle rates high in this category, while fatty meats, hearts and tongues are considered low-binding meats.

  Alkaline phosphates and salts -- sodium chloride and potassium chloride -- help increase the pH and open the structure of protein molecules. This exposes more hydrophilic areas and increases the ability of the meat proteins to hold water. The use of phosphates is regulated by the USDA to no more than 0.5% by weight of the finished product.

  Marinades or brines for cured meats often incorporate phosphates. Sodium tripolyphosphate is frequently used, but blends of different phosphates may improve color, texture, binding properties, and fat stability.

  Food Product Design explored some of these ingredients and their methods of incorporation in the July 1996 issue in "Seasoning Meats."

  Polyphosphates solubilize protein. Therefore, in chopped and emulsified meat products, they can help fuse the meat particles and impart a firmer texture when the protein is coagulated by heat during cooking.

  Added proteins, including nonfat dry milk, whey, wheat gluten and soy proteins, often are added to increase the moisture. They can be used in comminuted products like sausages or injected into whole muscle meats. Non-meat proteins may be added at a level of 1%.

  A number of gums have found their way into the lower fat products. Carrageenan is one of the most widely used polysaccharide gums in the meat industry. It is used to bind water and decrease purge (free water released from the meat after processing).

  Carrageenan forms a strong complex with proteins when the pH of the system is below the isoelectric point of the proteins. Depending on the type and level of carrageenan, the gel strength will vary. Excessive levels often create a rubbery texture. Iota carrageenans are salt-tolerant and provide freeze/thaw stability. Carrageenan can hold approximately 20 to 30 times its weight in water.

  "Guar can reduce weep, or purge, in frankfurter formulations," suggests Bender. "Because you are looking at higher water levels in low-fat products, you need something that has the ability to hold significant levels of water."

  Konjac flour was accepted by the USDA for use as a binder in meat products in July of this year. This ingredient is derived from the tuber of the konjac plant, an ingredient that has been used in China for centuries. It contains a high-molecular-weight polysaccharide classified as a glucomannan. It forms a heat-stable gel when set with heat or alkali. This gel is stable to high levels of salt.

  A combination of konjac and starch is available that can be used to replace visible fat in a coarse-ground sausage product. Acetylating the konjac with a base presets the gel, which can be chopped into small pieces. This produces a tough, heat-stable gel that can withstand grilling temperatures or high-heat impingement ovens.

  Other carbohydrates that bind water are useful in meats. Starches, maltodextrins, corn syrup solids, and even honey can get into the act, improving flavor, as well as binding moisture. These are relatively inexpensive ingredients that structure water and that may also provide freeze/thaw stability, depending on the properties of the added ingredient.

  "Corn syrup solids may contribute a very low level of sweetness, depending on the DE (dextrose equivalent)," says Putnam. "If you want to avoid the use of binders, you can add corn syrup solids. You are allowed a significant amount of them in most products. The major exception is frankfurters -- because it is considered a filler. In hams you have a limitation on all ingredients including water based on PFF (protein fat free), but some processors have added 5% or 6% corn syrup solids to maintain the texture."

  Maltodextrins can be used in some products. In hams they are only approved as a carrier of spices, so they could not be used at high levels.

  "We recommend a corn-based modified starch for processed meats," Putnam says. "It has an extremely low gelatinization temperature -- approximately 120°F. The advantage to a low hydration temperature is that it will begin picking up water sooner than a native starch. In that amount of time, the water could be lost in a smokehouse process."

  Typically, the internal temperature of a processed or smoked product ranges from 155° to 170°F. The starch should be fully hydrated at that temperature to be effective. A starch that is not fully hydrated has a greater tendency to lose moisture over time.

  Fiber ingredients such as beet fiber, rice bran and soy fibers can provide texture to water-based, fat-reduction systems. Oat fiber has been used extensively in reduced-fat meat applications.

  "When you are looking at replacing fat with other ingredients, you are generally looking at replacing several different functions at once," says Bender. "Normally you will have to balance the ingredients so the product is optimal."

  Mixtures of these ingredients typically achieve the desired result in lower fat meat formulas; they modify texture, influence cooking properties, meet regulatory limits, or provide a cost advantage. They can also take advantage of any functional synergies like those seen between starch and carrageenan or starch and konjac.

  "For the meat industry we sell products that are a combination of konjac and starch or konjac and carrageenan," says Stone. "It helps to control the texture and characteristics you are getting from the konjac. Using starch can give the konjac gel a white, fat-like appearance."

Taking the heat

  There are a number of considerations when choosing a particular stabilizer or mixture of ingredients. Heat and how it is applied to the product are two of the most important.

  "A hard-surface cook, like that encountered with a barbecue grill or a foodservice roller grill, is harder on a meat product," warns Stone. "And with less fat in the product to cushion the effect, it can be a problem. You need to pay very close attention to the ingredients you're using. With a low-fat product it's a matter of adding water and managing the moisture so that it mimics the succulence and juiciness of fat. The ingredient or ingredients must overcome that type of severe environment."

  Different ingredients give up moisture at different temperatures. Therefore, cook time and temperature greatly influence product design.

  "When using carrageenan in a low-fat hamburger, at about 125°F, that carrageenan starts to give up moisture," says Stone. "You can see that happen toward the end of the cook process; you can actually see a halo of moisture on the grill. The gel structure of the carrageenan begins to melt and releases the water. If you put that burger in a warming area, it would just continue to dry out. Konjac can make a stable gel that will hold up past boiling."

  Still, there must be a balance between heat stability and eating quality. Stone notes that, in general, the more heat stable a gel is, the less it tends to give up water during eating, and the less juicy it seems.

  The heat and its duration encountered by processed meats also influence the effectiveness of the binders and fillers used. Moreover, the process itself can often be changed from that used for a higher fat product. With low levels of fat, emulsion breakdown is much less of a controlling factor. This often means a shorter, higher temperature process.

  For processed meats that depend on water to replace fat, the type of casing can affect the finished product. A water-permeable casing allows moisture to escape as steam during high-heat processes.

  Another consideration in some meat products, especially fermented products, is pH. Some water-structuring ingredients, such as carrageenan, are not stable under acid conditions.

Debugging meat

  Meat is the perfect environment for microbial growth. Some specialty fermented products, such as summer sausage, have a low enough pH and water activity to functionally eliminate microbial problems. (However, if the fat were replaced with water, it could cause a serious problem.)

  Most meat products need refrigeration. This means problems still arise through mishandling, improper storage or contamination. This also affects the design of today's meat products.

  Because the government has required meat and poultry processing facilities to adopt more stringent HACCP programs over the next three years, many processors are looking for ways to decrease the microbial load on meats.

  "In the original HACCP documents, there was a requirement for some sort of antibacterial treatment," says Patrick Moeller, vice president of research and development at Hickory Specialties Inc., Brentwood, TN. "While that is no longer a requirement, people are still interested in these treatments. There's a variety of things they can use. Organic acids are approved; phosphates are fairly widely approved. Pulsed light was also just approved."

  A number of compounds can act as antimicrobial rinses for the surface of carcasses or whole muscle meats. For example, using food-grade trisodium phosphate (TSP) breaks down the surface fatty oils that help contaminants adhere. TSP is mainly effective against gram-negative organisms such as E. coli, Salmonella, Pseudomonas and Campylobacter.

  "Assur-Rinse, a trisodium phosphate system, has been proven effective against Salmonella and E. coli 0157:H7," says Bender. "It's an alkaline product -- about pH 12. One of the strengths of 0157:H7 is that it has a notable acid-tolerance, more so than other forms of E. coli, so using an alkaline is very effective."

  The spray is applied post-evisceration, as the final rinse prior to the initial cooling. While hanging in this cooler, known as the "hot box," the carcasses receive an intermittent water spray that rinses off any residual TSP. The treatment does not negatively affect the appearance or flavor of the meat.

  The degree of effectiveness varies with the method of application, according to Bender. Factors such as the spray pressure, nozzle design, and flow rate all have an influence.

  "TSP works against bacteria only if it can get to it," Bender explains. "When the bacteria hunker down inside the beef fascia, it's as if they're in a trench. They are going to be surrounded by a film of water. If the spray pressure and the impact of the spray are not correct, the surface will look wet, but you won't get down to where the bacteria are located."

  Hickory Specialties has introduced a new antimicrobial agent that can help make meat products safer. Studies conducted at Kansas State University and the University of Georgia show that an aqueous smoke product, named Code V, can effectively slow the growth of microorganisms such as E. coli and Salmonella in meat products. According to Moeller, it has been tested across over 40 pathogenic strains. The product uses standard application methods and equipment -- atomization, drenching, brines, etc. It contributes no color and leaves only a very mild smoke flavor.

  "We noticed that regular smoke products had antibacterial properties," says Moeller. "We thought if we could maintain these properties while reducing the flavor and color contribution, we would have a product with a broad range of applications. That's what this product is. It still falls under the category of a smoke fraction and therefore is considered a natural flavor."

  According to Moeller, the level required varies since the product acts on the surface of the meat. Less would be required for a larger piece. Contact times are relatively short, approximately one minute.

  As processors look for new and unique ways to make the meat we eat better for us, we will see more and more innovative means to accomplish this end.

Home on the Range

  One trend in the meat industry is the development of other meat sources such as buffalo and rabbit, along with emu and ostrich. These meat-bearing birds have been marketed as "red" meat, making an interesting contrast to the marketing strategy used with pork -- "the other white meat."

  One commercial meat animal, the Beefalo, as a cross-breed of domestic cattle and the American bison. It has a 17% to 37.5% bison influence. According to Beefalo USA Inc., Cheyenne, WY, unlike most domestic cattle these animals have the ability to efficiently convert marginal or poor forage into meat protein.

  The meat from Beefalo has fewer calories and lower levels of both total and saturated fat that many other meats -- 6.3 grams of fat per 100 grams of cooked meat. This compares with an average of 17.4 grams of fat in 100 grams of cooked beef, or about 13 grams of fat in 100 grams of cooked chicken with skin. Obviously, this figure varies with the cut of meat and the age of the animal (older animals often have more intramuscular fat), as well as with the level of subcutaneous fat included.

Restructuring Lean Meat

  One method of creating lower cost, lower fat forms of fresh meat involves using proteins derived from bovine plasma. The process developed by TNO Foods in the Netherlands is being marketed by FNA Foods, Calgary, Alberta, Canada. The process works by coating the surface of pieces of meat with fibrinogen and thrombin enzyme. Together they form a fibrin network. The resulting structured steaks or roasts maintain the structure and integrity of a whole muscle meat while using less expensive cuts.

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