Restructuring technologies allow meat processors to use lower valued trim to produce more consistent, higher quality, value-added products. Use of chemically set or cold-set binder technologies further allows companies to market value-added, reduced-salt restructured or formed products in a raw, unfrozen state. Cold-set binders including calcium alginate, transglutaminase and fibrinogen/thrombin systems may be used in unique ways to restructure and improve returns on lower valued muscles, trimmings and smaller lean muscle pieces usually relegated to minced or ground meat. The functionality and acceptability of these products are dependent upon the binder used as well as the starting material. Information in this chapter will address how cold-set binders function, suitable raw materials for restructuring, differences in these binding systems, and methods to manipulate final texture.
11.1 Introduction
Over the years the meat industry has been known as an industry with a very low profit margin. This has led processors to make use of everything within the carcass and has led to such phrases as ‘using everything but the squeal’. Traditionally, consumers have always enjoyed steaks and chops and demand for middle and prime cuts, from which steaks and chops are fabricated (Secrist, 1987) continues to be high. Unfortunately, approximately only 25% of a beef carcass is composed of cuts that are suitable for steaks that can be cooked rapidly with dry heat. The remainder of the carcass is composed of many diverse muscles that vary widely in preparation for optimal eating characteristics. Fabrication of carcasses into retail portions results in the production of smaller or odd pieces.
11.2 Meat source
The meat source will define the amount of binder used and the amount of prior trimming and processing needed. Tougher cuts may be processed to either remove the connective tissue or physically disrupt the structure through blade tenderization or even grinding. Using binders on high-valued products such as tenderloin can result in reduced portioning losses. As an example, two tenderloins may be bonded in a head to tail fashion, resulting in a tube-shaped log that can be cut into consistent portions. In this method the tails which are normally salvaged for trim value are incorporated into the full portion, maintaining their value.
The cold-set binders that are available commercially can be used on any type of meat product including poultry, fish and seafood (Ruiz et al., 1993; Kuraishi et al., 1997; Boles and Shand, 1999; Beltrán-Lugo et al., 2005; Moreno et al., 2008). However local regulations should be checked to determine what can be used in the market and what the label requirements will be. Some minor modifications to procedures are needed to accommodate different characteristics of the raw products. For example, aged beef products are typically more difficult to bind using cold binding systems.
Recent work in alternative beef fabrication methods in the United States has classified individual muscles based on tenderness, flavor and other characteristics (Bovine Myology and Muscle Profiling), to increase the value of traditionally lower valued wholesale cuts. The altered cutting procedures result in new sources of more consistent meat, raw materials that can be used either directly for portioned steak products or as raw material for bonded items. This is especially true for smaller, odd-shaped muscles such as the teres major or petite tender. Researchers have also studied the use of specific muscles or muscle groups in restructured meat products. Ruiz et al. (1993) excised infraspinatus, triceps brachii, biceps brachii and supraspinatus for use in restructured meat products. The researchers reported that the infraspinatus and the supraspinatus were the easiest muscls to excise and distinguish because of their location on top of the scapula. Furthermore, consumers did not score restructured steaks differently for tenderness, flavor or overall acceptability from the four muscle groups. Boles and Shand (1999) reported that meat cut had no effect on raw or cooked bind of steaks and sensory scores for texture acceptability were higher for steaks made with clod (primarily infraspinatus and deltoideus muscles) and tri-tip (primarily tensor fasciae latae muscle) than steaks made with chuck tender (primarily supraspinatus muscle), or inside round (primarily semimembranousus and gracilis muscles).
Furthermore, Boles and Shand (1999) reported that steaks made from chuck clod were lighter in color than those made from chuck tender or inside round but were not different from steaks made from tri-tip. Ruiz reported that removal of the epimysium along with cutting muscles into 2.5 × 2.5 × 5 cm3 chunks before manufacture of restructured steaks negated any difference in tenderness associated with specific muscles. Recio et al. (1986) also found that intermediate or extensive trimming of muscles found in the chuck clod prior to manufacture of restructured steaks improved overall tenderness and palatability. This indicates that steaks can be made from lower end cuts as long as it is cost effective to remove the heavy connective tissue and the particle sizes are reduced.
11.2.2 Fresh vs. frozen vs. pre-rigor meat
Previously frozen meat does not have a detrimental effect on the chemical reactions of cold-set binders. It is important to note that unlike conventionally restructured meat products where meat chunks can still be slightly frozen when processed, cold-set products must be completely thawed before the binder is added to the meat. Excess purge from the meat can interfere with the binders and can often be the source of failed binding. Boles and Shand (1999) reported the use of previously frozen meat had no effect on raw or cooked bind or dimensional changes of restructured steaks. Utilizing previously frozen meat, however, did result in lighter and less red steaks than product made from unfrozen meat.
It is therefore feasible to collect high end trimmings from portion cutting operations, vacuum package and freeze these trimmings for later use in the preparation of cold-set bonded products. Pre-rigor meat has many improved functional properties when manufacturing conventionally restructured products such as hams than post-rigor meat. Farouk et al. (2005) reported that restructured rolls bound with alginate or Activa made with pre-rigor meat had higher bind strength than those made from post-rigor meat. Schaake et al. (1993), however, found no difference in raw bind strength of steaks made with either hot- or cold boned meat when utilizing alginate as the binder. Use of pre-rigor meat did impact color. Restructured steaks manufactured with cold-boned meat were redder and darker than steaks manufactured with hot-boned electrically stimulated meat (Schaake et al., 1993). The difference in redness, however, disappeared after allowing steaks to bloom for a longer period of time. This is not unexpected as pre-rigor meat often has a higher pH which can result in slower oxygenation and a slower appearance of bright red color. Schaake et al. (1993) also found that when steaks were manufactured with cold-boned beef (boned and frozen within 120 hours), steaks were scored more tender by the sensory panel compared to steaks made with hot-boned beef.
11.3 Traditional restructured meat products
The technology used in manufacture of processed meats and more specifically the use of salt in preservation dates back many centuries. More recent developments have been with phosphates, refined gums, starches and vegetable proteins. In some ways restructuring technology has been around for thousands of years especially when products like sausages are considered. A good example of how restructuring technology evolved to the present was in the manufacture of the boneless ham, or ‘section and formed ham’ as it is sometimes called.
The original process involved separating muscles to remove connective tissue and intermuscular fat or seamfat. These muscles were then subjected to protein extraction via salt, phosphate and mechanical action. The muscles were recombined via a form, casing or mold and cooked, causing the protein exudates to heat-set acting to bond the muscles together. The resulting end product was a boneless version of the original which had advantages of allowing use of smaller or by-product muscles to make a traditional product with the added benefits of lighter shipping weights because of bone removal, less plate waste and greater convenience.
11.3.1 Ingredients in conventionally restructured meat products
Salt
One of the basic ingredients needed for conventional restructured meat products or ‘heat-set’ products is salt. Salt is used to extract myofibrillar proteins to produce a protein exudate that when heated binds muscle pieces together. Salt level is dependent on the final product characteristics: between 0.5 and 1.5% is typically used in uncured restructured products while cured products normally contain 1.5–2.5% salt in the finished product. It is important to use lower levels of salt to reduce lipid oxidation for products stored and sold in the raw state (Gray and Pearson, 1987). Higher levels of salt help improve yields for products that are cooked, packaged and then sold (Trout and Schmidt, 1986; Carballo et al., 2006; Hong et al., 2008).
Theno et al. (1978a) reported that the composition of exudates formed to bind meat pieces together was dependent on the salt and phosphate level as well as the length of time mechanical action was applied. Trout and Schmidt 1986) reported that increasing the ionic strength and pH of precooked beef rolls produced predictable, additive increases in cook yield and tensile strength of restructured meat products. The maximum cook yields and tensile strength values occurred at sodium chloride concentrations between 1.5 and 2.5%. Salt affects water-binding ability and color of meat. Salt use in restructured products improves water-binding properties (Carballo et al., 2006) as well as reducing purge after frozen storage (Raharjo et al., 1995). One drawback to using salt is it acts as a pro-oxidant and initiates discoloration as well as lipid oxidation. Huffman et al. (1981) reported that as the percent salt in the formulation increased from 0% (control) to 1.5%, thiobarbituric acid (TBA) numbers increased linearly.
Phosphates
Phosphates are added to restructured meat products to help solubilize meat proteins and increase water-holding capacity, thereby improving bind and yield of the finished product (Offer and Trinick, 1983). Phosphates also contribute to flavor stability in cooked products. Phosphates act as metal chelators that can affect the rate of off-flavor development after cooking (Boles and Parrish, 1990).
Lawrence and coworkers (2004), however, reported increased off-flavor intensity when whole beef loins had been enhanced with salt (0.2%) and phosphates (0.4%) and stored for 7 days before analysis. Increased levels of phosphate can result in off-flavor development, especially soapy flavors. Phosphates have also been shown to have metallic flavor components (like the taste of a silver spoon) especially when used near their limit (0.5% in many countries).
Seasonings and flavorings
One major advantage to conventional restructuring is that seasonings and flavorings can be added along with salt and phosphate. Specific flavor profiles for ‘Greek style’ or ‘Italian style’ are easily incorporated. Whole spices or powdered products can be used. Whole spices result in a visual impact; large pieces of pepper or whole leaves of oregano are easily seen in the product. However, large pieces of seasonings or herbs can interfere with binding between large muscle pieces. As an alternative, oleoresins or aquaresin spice extracts can be used to season restructured products to prevent these binding problems. Flavor enhancers, such as hydrolyzed vegetable protein, autolyzed yeast protein and monosodium glutamate, are sometimes added to increase the intensity of meat flavor. This is very useful in products that have a low salt content and few seasonings.
11.3.2 Mechanical action
Mechanical action is extremely important in the manufacture of conventional restructured products. One of the main features of tumbling or mixing is aiding the extraction of protein exudates from muscle fibers to form a natural binding agent. During tumbling of muscle several events occur; meat fibers become distorted, the sarcolemma ruptures, nuclei are released and perimysial spaces fill with soluble protein and fat droplets (Theno et al., 1978a). After prolonged tumbling, the myofibrils separate and meat pieces begin to lose their textural integrity. A partial breakdown of tissue integrity aids bind. Tumbling and mixing of meat increases myosin release, which removes the necessity for an added binder. Even without the addition of non-meat proteins, cook yields are improved by 8–10% or more with efficient mechanical action. Theno et al. (1978a) reported that the composition of the exudates formed during tumbling is dependent on salt and phosphate level as well as the length of time mechanical action is applied.
11.4 Cold-set binders
Cold-set binding (non-thermal gelation) has evolved as a way to improve the overall eating quality and preparation methods for more realistic restructured steak-like meat products. This improvement is centered in six areas; product appearance, product flavor, product texture, product preparation, health considerations and costs. In other words, today’s fabricated steak has to look, taste and eat like a steak while being easy to prepare, healthy and be relatively inexpensive. These are not always easy to combine into a single package. The eating experience for an intact steak or chop is very different from that of a salted and precooked item. Flavor is one of the main points of differentiation, with warmed-over flavor (WOF) predominating. Precooked, highly seasoned products can overcome some of the flavor dilemmas but the eating experience is still different. When meat is prepared directly from raw, WOF is eliminated. Traditional salt/phosphate technology also changes the texture into something more like ham than steak. In some cases a very small amount of salt or phosphate is used to improve flavor, and to a lesser extent, cooking yields but formulations must be careful to minimize the effects of these ingredients on finished product color and texture. Visual appearance with specific reference to color is probably the most difficult characteristic to control. After all we typically are starting with a raw material that has been handled and may be a by-product from another operation. Once the ability of the muscle to regenerate muscle color is depleted the color reverts to the metmyoglobin form and color remains unappealing. Lower-fat or consistent fat products are somewhat easier to manufacture using cold binding technologies so long as a suitable raw material can be manufactured. Similarly portion and convenience packaging are easy enough to design and implement.
The key comes when a price is put on the product. These items can quickly cost more than their whole muscle counterparts and consumers will generally opt for the whole muscle item unless there is some health or convenience aspect of the product they like. There are currently four cold-binding system technologies that have been successfully commercialized: Activa (transglutaminase system), Fibrimex® (blood-based system), (Kelpac, Nutrisweet Kelco) calcium alginate system, and Pearl Meat Binding systems (calcined calcium). While they all have some advantages, none seems to be the perfect solution. The effects of each of the binding systems on key characteristics will be discussed.
11.4.1 Alginate system as a cold-set meat binder
When the use of alginates as binders for restructured meats was patented by Colorado State University in 1986, the US market for restructured products was approximately 180 million kilograms. Products manufactured with alginate binders extend the opportunities to add value and create new products that meet consumer needs because they retain their form without requiring a cooking step.
The alginate system is composed of three main components: sodium alginate, a calcium source and an acidifier to aid calcium release. When the components of this system are added to a meat product during mixing they slowly gel (Means et al., 1987), resulting in a product that appears and can be handled like whole muscle. The meat/alginate mixture can be shaped via a mold or casing and allowed to react undisturbed for binding to proceed. The finished bound product can then be portioned into its final form.
Alginate is a hydrocolloid, or gum, that is derived from several types of brown algae of the class Phaeophyceae (Means and Schmidt, 1987). Alginates are linear polysaccharide molecules composed of d-mannuronic and l-glucuronic acid units. The glucuronic acid has an affinity for divalent cations such as calcium and therefore gels can be formed by providing formation, and are typically referred to as either cold-set, chemically set or non-thermal gels. Alginate gels do not ‘melt’ on heating and thus the product remains intact during cooking. A popular way to envision the alginate gel is to imagine an egg carton with the cardboard representing the glucuronic acid and the eggs as calcium ions – the calcium ions interact with the alginate molecule to form the gel (Means and Schmidt, 1987). Similar relationships between meat proteins, calcium and glucuronic acid units have been proposed to explain the bind strength observed in alginate restructured meat products. A slow-release calcium source is a key ingredient in the alginate binder system. Proper distribution, solubility and calcium release rate are essential for successful application of the alginate binding system. Calcium carbonate is generally used in this system because it is relatively inexpensive ingredient and has a low solubility. As a chemically set gel, the alginate reacts instantly with available calcium ions so if the source was completely soluble the gel would set well before the product could be molded or shaped. Since these bonds are irreversible, the bind strength would diminish or fail as the available substrate was exhausted especially if forming was delayed. Trout (1989) reported a high calcium carbonate : alginate ratio was required to reach maximum binding of the meat pieces.
Alginate without calcium carbonate showed no binding. Other sources of calcium have been evaluated. Esguerra (1994) found no difference in bind strength of restructured steaks manufactured with alginate and encapsulated calcium lactate or alginate with calcium carbonate and encapsulated lactic acid. Moreno et al. (2008) used calcium chloride for alginate gels and found Warner Bratzler shear force values of steaks restructured with alginate were higher when samples contained 1 g kg−1 CaCl2 than when they contained 10 g kg−1 CaCl2, suggesting to these researchers calcium saturation of the alginate at the lower level.
Organic acid, usually lactic acid or glucono-delta lactone (GDL), represents the final component of the alginate binder system. The original research with the alginate process did not include an organic acid and the result was a product which was criticized for an unappealing ‘slippery mouthfeel’ (Means and Schmidt, 1986). High levels of alginate contribute to this characteristic. Commercial producers of the alginate binding system suggest the use of either encapsulated lactic acid or GDL to improve calcium solubility and therefore cohesiveness of restructured product. Means et al. (1987), however, observed no increase in cooked binding with the addition of GDL in the calcium alginate binding system.
The proportions of alginate, calcium carbonate and organic acid deserve some consideration. Experiments with various levels have demonstrated that bind strength or cohesiveness of the product is largely dependent on the total amount of binder in the formulation. The tendency is to use more binder to increase bind strength, but this is only partially effective and quickly reaches a point beyond which little improvement in strength is observed. Means and Schmidt (1986) observed that high levels of sodium alginate and low calcium carbonate levels were detrimental to cooked bind of restructured steaks.
Fortunately, rather small quantities of the binder ingredients are required for successful restructuring in this cold-set binding system. Means and Schmidt (1986) indicated that the optimum sodium alginate concentration was between 0.8 and 1.2% with a calcium carbonate level between 0.144 and 0.216%. High levels of alginate are more likely to result in off-flavors (Means et al., 1987), so these researchers suggested a reduction in alginate to reduce the possibility of off-flavors in the finished product. Other research has utilized lower levels of sodium alginate and obtained favorable bind in the raw state (Esguerra, 1994; Boles and Shand, 1998, 1999). A reasonable starting point for most processors is to utilize 0.6% sodium alginate, 0.6% organic acid and 0.2% calcium carbonate. At least 0.4% sodium alginate is required, but more than 1.0% increases the chances of off-flavors. The range of 0.1–0.3% calcium carbonate is recommended by suppliers. The acid is most variable and depends largely on pH of the raw meat material (preferred to be 5.6–5.8) and should fit in the range of 0.4–1.0%. The combination of alginate binders should total about 1.4–2.0% of the final product and this compares favorably with concentrations added to conventional restructured meat products. Reaction time is also important for the alginate system because the gel is not formed instantaneously.
If the gel forms too quickly, there is no time for stuffing, shaping or otherwise forming the product. Utilization of acidifiers and low soluble calcium sources control the release of calcium to allow time for processing before the product gels. Means and Schmidt (1987) indicated that 2 to 48 hours are necessary for the gel to set in a chilled environment (0 to 5 °C) depending on the solubility of the calcium source. After this period, the bonded meat is durable enough for normal slicing and packaging operations. An alternative is to freeze the restructured meat log and portion via conventional methods (slicing, cleaving, etc.).
Color is an important characteristic of any raw meat product. Use of alginate to restructure meat products can influence color. Trout et al. (1989) reported that metmyoglobin concentration was low in restructured steaks containing alginate and at least 0.13% calcium carbonate and was not different from restructured steaks containing salt and phosphate.
However, all restructured steaks had higher metmyoglobin concentrations than intact muscle and addition of alginate resulted in a larger percent of the steaks being discolored. Means and Schmidt (1986) also reported discoloration of alginate restructured steaks but the discoloration was less than that observed for salt and phosphate restructured steaks. One important factor to note is particle size reduction increases surface area of meat particles and incorporates oxygen and can influence the color stability. This increased oxidation rate could contribute to the reduced color observed by these researchers.
11.4.2 Fibrin/thrombin system as a cold-set meat binder
Fibrin/thrombin is a blood-based binding system sold as a two-component system in a liquid frozen form. Originally developed in the Netherlands by Harimex, it is now marketed by both Harimex and FNA Foods in Canada. The preparation consists mostly of fibrinogen, either as a partially purified preparation of fibrinogen containing one of the blood clotting enzymes or as a fibrinogen-enriched blood plasma. The second component of the system is thrombin which functions as the activation portion. The idea for the product came from the blood clotting process. Blood clotting is a complex process that basically ends in the enzymatic conversion of fibrinogen to fibrin by thrombin. Once released the fibrin then aggregates. Inherent to the system, transglutaminase, is also activated by thrombin and converts the fibrin aggregate to an insoluble gel by forming covalent cross-links between the fibrin aggregate molecules. Although the preferred reaction is between fibrin molecules cross-links between fibrin and fibronectin and between fibrin and collagen also form thus binding meat particles together. The fibrinogen and thrombin used in restructured meat products come mostly from beef sources. In more recent years similar systems have been developed from porcine sources as the concern over bovine spongiform encephalopathy (BSE) has arisen as well as utilizing blood from young animals (under 30 months of age) to manufacture the binder. The United States has not changed the approval of Fibrimex for use as a raw meat binder but the EU Directive on Food Additives approval of using bloodbased binders in meat products was rescinded in 2010. The Parliament believed there was a clear risk that meat containing thrombin could be substituted for higher priced product in restaurants or other public establishments. When manufacturing product, the fibrinogen and thrombin are thawed and the thrombin is added to the fibrinogen. Attention must be given to the temperature of the solutions. It is important that both liquids reach 26.6°C (80 °F) before being added to the meat. The mixture is then added to the meat pieces and mixed well. The product is molded as desired and left to react. Some pressure is necessary to make sure there is intimate contact between the fibrin/thrombin binding system and the meat pieces and to remove any air pockets. Once set, the product can be taken out of the mold and distributed to the market. It should be noted that the product must be molded very quickly once the thrombin is added, as cross-linking begins immediately once the components are combined. It typically has a window of handling that lasts approximately 10–15 minutes depending on temperature and concentration of ingredients. The speed and strength of bind are dependent on the thrombin concentration and therefore a level of thrombin has to be carefully chosen which addresses both constraints. Changes in thrombin and fibrinogen ratio as well as temperature and pH of the meat can alter the time available for forming. Wijngaards and Paardekooper (1987) reported that 5 hours was the minimum amount of time needed to attain maximum gel strength. Concentration of fibrin largely determines the strength of the final fibrin gel and the overall gel to meat-surface binding (Wijngaards and Paardekooper, 1987). This is limited by the solubility of fibrin. Increasing concentrations of fibrin result in an almost linear increase in gel to meat surface binding (Wijngaards and Paardekooper, 1987). Fibrin/thrombin component is typically used at a concentration between 5–10% of the meat weight, and the fibrinogen to thrombin ratio is 10 : 1 or 20 : 1. The amount of fibrin/thrombin used depends on the quality of the meat to be bound, as well as meat particle size. For example, if the meat pieces are between 0.5 and 1.0 kg in size then 250 g of fibrin/thrombin are needed per 10 kg (or 2.5%). However, if the meat pieces are 5 to 10 g in size, 1 kg of fibrin/thrombin is needed per 10 kg (or 10%). Increased particle surface area results in the need for more fibrin/thrombin to coat the particles. Tseng et al. (2006) showed that addition of increased binding solution, 0–20% of meat weight (0.5 transglutaminase : 1 thrombin : 20 fibrinogen) resulted in increased shear values of bound product. Furthermore these researchers reported total sensory acceptability increased as the level of binder solution to meat ratio increased. The binding strength of the fibrin-to-fibrin gel is always stronger than that of the fibrin-to-meat surface binding. However, fibrin gels bind more strongly to meats with higher collagen concentrations. The strength of the bonds between meat pieces is also affected by the direction/orientation of the muscle fibers. This relates to the involvement of collagen in the binding process. Wijngaards and Paardekooper (1987) reported a doubling in bind strength when muscle fibers ran parallel to the binding area than when the fibers ran perpendicular.
11.4.3 Transglutaminase enzymes as cold-set meat binders
Transglutaminases (TGase) are a wide class of enzymes shown to have the ability to cross-link proteins, peptides, and some other primary amines (Payne, 2000). TGase have been isolated from guinea pig liver, blood (factor XIII), plants, mollusks, bacteria and other diverse places. The basic difference between most of these sources is in the specificity for a substrate and the calcium requirement for activation. Typically, sources of TGase originating in microorganisms are calcium independent while those from animal sources are calcium dependent (Payne, 2000). TGase can be obtained from animal tissues and microbes (Nielsen, 1995). Mammalian TGase has been obtained from tissues such as liver, hair follicles of guinea pigs, pig plasma and fish. Sources of commercial mammalian TGases originate from liver and blood. However, TGase obtained from tissue has limited use in industry because of the complicated separation and purification procedures, resulting in a high supply cost (Kuraishi et al., 1996). The extracelluar microbial TGases are purified from Streptoverticillium sp. primarily Streptoverticillium mobarense, while intracellular microbial TGases are derived from Bacillus subtilis (Ando et al., 1989; Zhu et al., 1995; Tsi et al., 1996).
Commercial microbial TGases can be mass produced by aerobic fermentation procedures. In addition, the purification process for microbial TGase is simpler and relatively cheaper than for mammalian TGase. A remarkable characteristic of the microbial TGase enzyme is its calcium-independent catalytic property (Kuraishi et al., 1997). Microbial TGase is stable between pH 5 to 9 (Kuraishi et al., 1996). However, even at pH 4 or 9, some enzymatic activity is expressed (Motoki and Seguro, 1998). Microbial sources of TGases are active over the temperature range about 0–60°C with an optimal activity around 50–55 °C (Motoki and Seguro, 1998). Microbial TGases have been used in patented meat products for more than 10 years (Japan patent 2079956; Nielsen, 1995). One commercial version is sold under the trade name ActivaTM as a preparation containing TGase in combination with a protein source with or without other ingredients. It is marketed under various codes based on the local regulations and the approved ingredients in the particular country. It is typically used either as a liquid slurry or as powder used to dust the surfaces to be joined. Activa TG-RM, TG-EB, and TG-B-solution type are milk protein-based while ActivaTM GS is gelatin-based dusting. Activa TG-RM, TG-EB and TG-Bsprinkle-type (among others) are generally used for powder coating applications while ActivaTM TG-GS and TG-B-solution type are generally slurried with water just before adding to the meat during processing. Many commercial blends of transglutaminase contain milk proteins and thus require labeling for the existence of an allergen. TGase is an enzyme that catalyzes an acyl-transfer between the γ-carboxyamide groups of glutamine residues in proteins or peptides with various primary amino groups. When the ε-amino group of lysine residues in proteins acts as an acyl-acceptor, both intra- and inter-molecular ε-(γ-glutamyl)lysine cross-links are formed (Kuraishi et al., 1997). TGase can cross-link most food proteins including legume globulins, wheat gluten, egg proteins, actin, myosin and milk caseins (Motoki and Seguro, 1998) to varying degrees. Enzymes from mammalian sources require calcium ions to express enzyme activity while the activity of bacterial sources is independent of calcium concentration (Motoki and Seguro, 1998). Heavy metals such as copper, zinc and lead significantly inhibit TGase activity (Motoki and Seguro, 1998).
A critical concentration of the ε-(γ-Glutamyl) lysine cross-links is required before sufficient gel strength is reached (Kilic, 2003). Cross-linking is a function of the amount of enzyme added, protein type and content, and reaction time, temperature and pH. Intermolecular cross-links are more desirable than intramolecular cross-links, which tend to decrease gel strength (Nielsen, 1995). The breaking force of gels has been reported to increase with increasing TGase levels regardless of setting conditions (Tammatinna et al., 2007). Dimitrakopoulou et al. (2005) found that TGase enzyme level significantly affected the consistency and the overall acceptability of restructured cooked pork shoulder. Vácha et al. (2006) reported lowest raw hardness was observed when 0.5% TGase enzyme was used alone while best results were seen when 1% TGase enzyme and 1% salt were used to bind fish. Because TGase is active on soluble protein, ingredients such as salt and phopshate increase the binding strength as they extract soluble meat proteins this contributes to the overall binding matrix. As stated earlier, the meat-binding TGase products are generally used in one of two ways, as a liquid application or as a powder application. The type and volumes of raw material involved dictate the levels of TGase product required and generally increase as the surface area of the meat increases. These preparations can generally be used on red meat, poultry and seafood processed products but it is always best to follow the recommendations of the manufacturer as the preparations continue to evolve.
When used in the dry form, the powder is either sprinkled on the surface of the meat or the surface is dipped in the powder. The two powdered surfaces are then placed together and pressure applied by vacuum packaging, stuffing into a casing or other method and the product stored at refrigerated temperatures to allow for bind formation. Stretch wrap can also be used to apply the pressure so long as the surfaces are not separated by air bubbles. The product is then refrigerated for 4–24 hours to allow the chemical reaction to occur. The dry powder may also be adapted to current processing equipment by simply adding it to the meat product during tumbling or mixing. Care must be taken to form the product quickly before the reaction is complete, especially in the case of large batch sizes. The slurry product is used when particles are smaller or when specific or rough surfaces need to be coated. The slurry aids in even dispersion of the TGase product over the meat surface. Typically the meat is prepared for binding, then the powder is mixed with water to create a slurry and the slurry mixed into the meat. The meat mixture is then formed into a roll with a mold or casing. The product is refrigerated for 4–24 hours to allow the chemical reaction. Products can then be sliced into steaks or cubes and sold. Newer preparations have been developed that allow the enzyme activity in slurries to be suspended until the slurry comes in contact with the surface of the meat. This has made processing much easier to control and allows more effective use of the bonding agent. TGase binding results from cross-linking of myosin and actin (Téllez-Luis et al., 2002; Ramirez-Suarez and Xiong, 2003; Katayama et al., 2006; Tammatinna et al., 2007). Kilic (2003) determined that the use of sodium caseinate in combination with TGase resulted in stronger binding than when TGase was used alone. Commercial blends sometime contain TGase in combination with other ingredients that help maximize the effectiveness of the compound for a specific application. While TGase has been found to be an effective binding agent, it has also been used to improve texture or mechanical properties of products that contain soluble proteins for reaction substrates as would be the case with a sausage TGase. Kolle and Savell (2003) reported that consumers indicated fat-reduced and bonded ribeye steaks (seam fat was removed and then the seams resealed using ActivaTM as a bonding agent) were leaner than control steaks, allowing the consumer to purchase a cut with lower fat that would result in less waste on the plate after cooking.
11.4.4 Protein compounds as cold-set meat binders
Protein cold-set binders are a range of products that have been produced in Japan for many years and used in vast quantities in the Asian market, with particularly large usage in Taiwan and Korea, and more recently in the European Community, Australia and New Zealand. Chiba Flour Mills was one of the first to manufacture this type of binder but other companies have developed similar products that are currently being marketed in other countries. Chiba offers three products: Pearl Meat F, Pearl Meat MX-30 and Pearl Meat T. Pearl Meat F has proven to be a very effective binder for large muscle pieces. It works extremely well for producing stuffed rolled roasts or combining two striploins, or tenderloins to give a consistent product size throughout the cut. Pearl Meat F can also be used to keep vegetables inside products to be used on skewers with a few modifications. Pearl Meat MX-30 was developed to use on comminuted product. It is made into a solution and mixed into the meat with either a mixer or tumbler. Pearl Meat MX-30 has not been well accepted outside of Asia because it imparts an ammonia-like flavor to the product. Pearl Meat T is used for binding vegetables. Pearl binders and their competitors are made from a large array of proteins. They contain egg white, casein, lactalbumin, gelatin, hydrolyzed egg white, hydrolyzed casein, soy protein and hydrolyzed soy protein. This complex blend of proteins may contain allergens and it is important to know the ingredients of the protein binder to properly label the product for the existence of any allergens. The product also contains a large proportion of ash, mostly from calcium carbonate (ox bone and oyster shell). The reaction is not well understood but probably involves surface protein denaturation (oxidation) and possibly a form of calcium cross-linking. In at least some cases, ammonia is evolved during the reaction of these compounds (Payne, 2000). Pearl Meat F and Pearl Meat MX-30 are two commercial products that are used on meat pieces of different sizes. Pearl Meat F is sprinkled on meat surfaces that are going to be in contact with each other. The minimum amount to achieve bind should be used to prevent large ‘seams’ of binder to be seen. Pressure is then applied by either stretch wrap or vacuum packaging and the product stored at refrigerated temperatures to allow for binding. Esguerra (1994) reported large muscle pieces restructured with Pearl Meat F were most like intact steaks compared with restructured steaks made with other cold-set binders. Furthermore, meat can be marinated and then bound with Pearl F without changing handling procedures from what is expected with whole muscle product (Esguerra, 1994). Pearl Meat MX-30 is made into a slurry and then added to comminuted meat. Mechanical action helps to distribute the binding compound and products are placed in moulds or casings and stored refrigerated to all bind formation.
11.5 Particle size reduction
In the preparation of any type of restructured product, it is important to realize that the meat source greatly influences the end-product characteristics. High amounts of connective tissue in the starting material require some treatment to soften (enzymes, injection, mechanical tenderization), remove or break-up connective tissue. In the case of tenderizing enzymes, these treatments can be antagonistic to the cold-binding systems as they would also dissolve the protein matrix binding the products. Using cuts from muscles identified as being more tender such as rump and loin trim allows the use of larger pieces of meat with little or no treatment for connective tissue. Lennon et al. (2006) reported enhancement of muscle pieces by injection improved tenderness of large meat pieces used in restructured beef products with no detrimental effects on bind of meat pieces when Activa was used as the binder. Reported research has shown that sensory panelist’s rate restructured steaks made from larger particle sizes to be more like whole muscle products (Berry et al., 1987). Different shapes that are created by different size reduction methods can alter the texture of the restructured products. Raharjo et al. (1995) reported restructured steaks manufactured with ‘fiberized’ meat (1.5 × 1.5 × 10–20 cm3 pieces) resulted in a more desirable steaklike texture when evaluated by a trained sensory panel. Additionally, these researchers suggested the use of combined types of particle pieces to improve tenderness of restructured steaks while maintaining acceptable texture. Other research suggests that consumer panelists prefer restructured products made from ground meat to products made with flaked or sliced meat (Boles and Shand, 1998). Particle size changes the visual impact of the restructured product. Marriott et al. (1987) reported particle size of restructured chops had no effect on the resemblance of these samples to whole muscle cuts; however, none of the samples compared looked like whole muscle cuts. Furthermore, restructured chops manufactured from larger flake particles were less tender and contained more connective tissue than those samples made from smaller particles. Some researchers have reported size of meat pieces had no affect on juiciness of the restructured product (Marriott et al., 1987; Raharjo et al., 1995). Boles and Shand (1998), however, found juiciness of steakettes made from flaked meat was liked less by consumer panelists than steakettes made from ground meat. These researchers reported no sensory panel preference for texture between the different methods (ground, sliced, flaked) of size reduction. Overall acceptability of restructured steakettes, however, tended to be higher for steakettes made from ground meat. Restructured products are often made using meat particles of varying size and random orientation. Because the meat fibers are oriented in no set direction, upon cooking the steaks can shrink in unusual directions, causing dimensional changes and cook yields to be affected. Berry et al. (1987) found distortion of steaks was greater when a combination of large and small particle sizes were used to manufacture conventionally restructured steaks. Sen and Karim (2003) found more steak distortion when smaller particles were used to manufacture mutton steaks, while Boles and Shand (1998) found no difference in diameter or thickness change of steaks when comparing type of machine used for particle size reduction and opening size used for particle size reduction. One problem with using sliced meat or large pieces is that connective tissue and any fat on the meat is present in the product as large chunks (Marriott et al., 1987). Berry et al. (1987) reported that as flake size increased, visually detected fibrousness, first bite hardness, cohesiveness of the chewed mass, number of chews required for swallowing, amount of connective tissue detected by sensory panel and shear force all increased, while uniformity of the chewed mass decreased. However, removing all fat can result in a product that does not stand up to the rigors of holding ovens used in food service establishments. One way to address this problem is to use two types of meat. One would be fully trimmed with no external fat or connective tissue and the other would have a higher fat content. The lean meat can be cubed or ground through a kidney plate while the fat meat could be ground through a 3–5 mm plate. The combination of these two meats gives a raw appearance of marbled meat, but it is very consistent because the product is formulated to have a specific fat content. Many different methods of size reduction have been used. Manual cubing of the product is the simplest but most labor intensive. Grinders, flakers, cubers and slicers can also be used to reduce the particle size and increase uniformity of particles. When using the different types of cold-set binders it is important to note that the different binders act differently to different particle sizes and shapes. For example, Boles and Shand (1998) reported when using the alginate system, flaked particles resulted in a stronger bind of cooked product than sliced or ground. Fibrimex had a stronger bind in cooked product with larger pieces (8 mm), while alginate bind between meat pieces increased as the particle size got smaller (Boles and Shand, 1989). When reducing particle size heat is generated when the meat is pushed through the plates or blades. To maintain color and minimize microbial growth, the meat should be kept as cold as possible. The knives on grinders and flakers should also be kept sharp to give clean cuts, and to prevent fat smearing during processing. This can be a real problem when finely ground fat raw materials are used to mimic marbling, especially if the product is too warm or is over mixed.
11.6 Binder comparisons
The main cold-set binders that have been compared are calcium alginate, Activa or microbial TGase enzymes and Fibrimex or fibrin\thrombin binders. The strength of raw bind varies greatly among the binders. Raw Fibrimex samples are relatively fragile when compared with ActivaTM or alginate bound product (Esguerra, 1994; Boles and Shand, 1998, 1999; Farouk et al., 2005; Flores et al., 2007). Alginate and ActivaTM have similar raw bind strength, with the major difference being the visual appearance of alginate pockets seen in the alginate restructured product and smooth surface where alginate gel fills in the holes. Cook bind values are similar when comparing alginate and Fibrimex bound product. Flores et al. (2007) reported that TGase treatments had the highest raw and cooked bind compared with conventionally prepared controls and Fibrimex bound product. Beltrán-Lugo et al. (2005) found that bind of product restructured with TGase or Fibrimex was different in two different species of scallops. Improved firmness and springiness were observed when product was restructured using TGase enzymes but interestingly the species of scallop used altered the texture of the finished product. Boles and Shand (1998) reported cook bind of alginate restructured steaks was not greatly affected by size of particles used, however, steaks made with Fibrimex showed that the largest particle size had similar bind to alginate bound steaks. Addition of Fibrimex to products containing smaller particle sizes resulted in lower cook bind. This suggests that the alteration in binder concentration or ratio of thrombin to fibrinogen is an important recipe consideration to achieve similar bind strengths when particle sizes change. Color is the first impression consumers use to buy products. Particle size reduction methods often result in product with lower color stability than that seen in whole muscle meats. Because of the different visual impact of restructured steaks (Marriott et al., 1987), it is important binders do not influence the color. Farouk et al. (2005) observed raw slices from alginate bound product were darker than those steaks made with AcitvaTM and slices bound with ActivaTM were more red and more yellow (higher Hunter a* and b* values, respectively) than slices bound with alginate. Furthermore, sensory panels found that raw slices bound with ActivaTM had better color and overall appearance than those restructured using alginates. Boles and Shand (1999) reported color change over display time was not different with the various binders tested. (alginates and Fibrimex). Steaks made with Fibrimex were generally more red and more yellow than those made with alginates. Binders can influence dimensional changes as well as cook yields of cooked restructured products. Boles and Shand (1999) reported steaks made with Fibrimex had greater dimensional changes than those made with alginate. Comparison of restructured pork chops made with Fibrimex or Activa showed the least dimensional changes when chops were bound with TGase enzymes (Flores et al., 2007). Cook yields have been reported to be higher for alginate and TGase restructured products than for those made with Fibrimex (Boles and Shand, 1998; Flores et al., 2007) and alginate restructured product had higher cook yields than TGase restructured product (Farouk et al., 2005). Addition of added liquid in the Fibrimex process may explain some of the differences seen in the cook yield. Mixed results have been reported for sensory evaluation of restructured meat products. Many of the differences are due to different panel types and different attributes evaluated. Farouk et al. (2005) reported cooked alginate structured rolls to be more tender and less chewy than rolls restructured with Activa. Flores et al. (2007) found consumer comments on texture were mostly favorable for TGase restructured chops; however, some panelists noted a ‘rubbery’ or ‘spongy’ texture. There was a distinct flavor preference for the treatments bound with TGase over the treatments bound with Fibrimex. Boles and Shand (1999) saw no difference in acceptability of flavor, juiciness, texture and overall acceptability when alginate restructured product was compared with Fibrimex restructured product. However, when Fibrimex was used with different meat cuts to manufacture steaks consumer panelists did find a difference in acceptability. Steaks manufactured from chuck clod and tri-tip were more acceptable than steaks made from the chuck tender.
11.7 Advantages of restructuring
• Increased market value. Restructuring transforms relatively low value cuts into added value products which lead to increased profit for the manufacturer, as well as, savings for the consumer who can buy high value meat products at a lower cost. Restructuring helps to maintain some of the value of trimmings from higher valued cuts that would normally be ground into products, yielding a salvage value for this premium raw material.
• New products and uses. In addition to the fabrication of steaks, chops and cutlets, restructured meats can be formed into cubes, sticks, nuggets, etc., of practically any shape and size desired.
• Portion control. Restructuring allows production of portion controlled steaks, chops and other products. This technology allows higher precision through control of exact portion dimensions than has ever been possible with natural products. Portion control is very important from a foodservice point of view (Smith, 1984) for controlling costs.
• Control of composition and consistency. The amount of fat and other ingredients in the product can be controlled to meet consumer demands. Intermuscular fat can be removed and the product bound back together to an extent that it resembles the natural whole muscle product. Similarly small fat particles can be dispersed throughout a product mimicking marbling and improving palatability of some cuts. Tenderizing technologies (needle tenderization, particle reduction) may also be used to ensure that restructured products are consistently tender and always a positive eating experience.
• Consumer convenience. Restructured meats require little preparation time and effort. Portion sizes may also be tailored for today’s smaller households and single parent families.
• Improved food safety. Unlike whole muscle products where bacterial contamination is limited to the product surfaces, restructuring processes distribute bacteria on surfaces that may be in the center of the meat product. However, these products can be manufactured with more precise dimensions thus ensuring uniform cooking, resulting in more effective pasteurization.
11.8 Advantages of cold-set binding
• Cold-set products can be marketed in the raw, chilled state. Some consumers prefer to buy raw, chilled meat and meat products rather than frozen or cooked products based on quality and price considerations respectively. Fresh products also aid in meal planning and speed of preparation as no thawing is necessary.
• Use of sodium chloride or phosphate is not required. The detrimental effects of sodium chloride on oxidation-mediated rancidity and discoloration (Gray and Pearson, 1987) in refrigerated unfrozen restructured products can be avoided (Hunt and Kropf, 1987). Consumer health concerns regarding the use of salt and phosphates can also be alleviated (Means and Schmidt, 1987).
• Versatility of the product. Cold-set products can be cooked and used in various ways similar to fresh cuts of meat. Specialty items, such as stuffed rolls and bound meats can be easily produced without the use of string or netting.
• No need for special equipment. The simplest use of some of the cold set binders is to sprinkle the dry powder on the meat and put the two sides together with in the presence of some pressure. Other liquid systems are also easily administered via surface brushing or spraying the products to be joined. The pressure can be applied by something as simple as overwrap or vacuum packaging to something as complex as a spring loaded mould.
• Enhanced flavor. Because the meat product can be cooked from fresh there is an elimination of WOF.
11.9 Restructured meat products quality control
When using restructuring systems, quality control regimes are critical to set up and follow. Careful formulation and ingredient control as well as selection of raw meat materials for optimum color, flavor, composition and connective tissue content are critical to making a desirable and consistent finished product. Evaluation of the texture or cohesiveness of the uncooked product is essential for demonstrating one of the key benefits of the cold-set binding system, namely that the gel allows retention of form without requiring cooking or freezing. Many problems can be avoided by considering the type of product being manufactured. A chemical process is taking place to bind meat pieces together, so anything that might change the chemical process is a potential problem. Temperature is an obvious factor that affects all chemical reactions. Warmer temperatures result in faster chemical reactions which can alter the finished product. Each binding system has optimal conditions for product manufacture and should be followed for optimal performance. In many cases manufacturers of these binding systems have several versions which may or may not work with a particular system. It is always a good idea to consult with the supplier about application and follow their recommendations on which product to use. Additional information for problem identification and rectification may be obtained from suppliers and consultants. For purposes of this discussion, it is understood that cold-set binding processes include alginates, Pearl Meat F, Fibrimex or Activa. Some references to conventional restructuring may be made and this process utilizes salts and phosphates in heat-set binding of muscle proteins. Problems with cold-set restructured products can be classified into three major categories. These categories include defects related to appearance, texture and flavor of the restructured item. Solutions for these problems and many others may require careful evaluation of the defective product and processing procedures to ensure corrective actions are successful. As coldset binding is essentially based on chemical reactions of nonmeat ingredients, it is very important that processors understand the binding process before undertaking even modest formulation changes. Surprisingly poor results are frequently encountered by even slight modifications as the chemical reactions required for cold-set binding are sensitive to imbalances.
11.9.1 Appearance
Appearance is critical for the acceptance of any meat product by consumers. Cold-set products have many of the same detracting characteristics as conventionally processed restructured products and therefore solutions to some of these problems are common to both types of product. Unattractive particle size, poor lean to fat ratio and discoloration represent some of the significant defects in the appearance of products using these technologies. Typical appearance defects related to processing can be generally attributed to particles being either too large or too small. Size reduction is accomplished by mincing, or flaking fresh or tempered meat through commonly available equipment, and is usually easily modified by choosing appropriate plates, equipment settings, or raw material temperature. A relatively common practice is to use coarsely minced lean material in combination with finely minced fat material to mimic marbling. Careful trimming of starting material is the key to successfully making these products. Unacceptable lean to fat ratio is attributed mainly to poor selection of raw materials. Within the US meat trimmings containing excess fat tend to be the most economical so they are often formulated to maximum levels. Separation of lean and fat materials, coupled with formulations of limited total fat content can be helpful. Most beef steaks contain less than 10–15% fat. When the separate meat materials are minced or flaked appropriately they can be mixed and cold-set binding can proceed. A major problem with appearance is discoloration. Conventionally processed products are highly susceptible to discoloration due to pigment oxidation and cold-set products are not exempt from this problem. Prior handling and product age also greatly influences finished product color since once the ability of the muscle to reduce myoglobin pigments is depleted the color deteriorates quickly. Selection of raw materials of highest quality and uniformity will overcome most discoloration for cold-set products. Use of similar muscles to guarantee similar color and color stability is also recommended. Some discoloration may also be attributed to the binding ingredients and the gel pockets which sometimes occur. While solutions for this problem are not evident, the size and distribution of the gel can be modified through improvements in mixing. Better mixing minimizes the size of gel pockets seen with alginates and improves distribution for a more uniform appearance. It is very important with all products to remove as much air as possible to prevent discoloration due to trapped air.
11.9.2 Texture
Acceptable products can be manufactured using cold-set binders. However, there are many instances where poor cohesion or a weak binding occurs. There can be numerous causes for these defects, ranging from excessive formulation moisture to improper processing procedures. Other textural defects which can be described as poor mouthfeel include softness, mushiness, slipperiness, graininess and sponginess. In some extreme cases, toughness, rubberiness or excessive bind strength can be encountered. The latter is not usually encountered with cold-set products, but is rather common for conventionally prepared products that have been over mixed. Owing to the chemical reactions involved in the cold-set process, most instances of failure to gel properly are expressed as poor cohesiveness. The causes of such failure are numerous and may be related to imbalances of the ingredients (especially excess water) condition of the raw materials (surface pH, frozen raw materials), over-handling, inappropriate time and temperatures for bond formation, or several other processing deficiencies. Because of the wide variety of causes, it is critical that the processor keep records of all processing procedures and materials when trying to identify inconsistencies. In the case of alginate binders, pH of the meat coupled with inappropriate concentration of organic acid can result in failure because the bind developed too quickly and the ultimate gel is broken by handling, or simply fails to develop because pH remains too high and calcium is not available to create the bind. Obviously, careful balance is required to result in optimum gel formation. Many of the cold-set binders are sensitive to frozen raw materials because of released moisture during the gel formation phase when the products are generally held at temperatures above freezing. Similarly time to forming is very important to all cold-set binders. Product must be filled into molds or casings before the gel starts to form or a poor bind will result. Improper storage of sensitive ingredients or even omission of key ingredients during manufacture may also occur, emphasizing the importance of proper tracking of materials during formulation and mixing. Important control examples include the temperature of the fibrinogen and thrombin just prior to addition since activation of the enzymes occurs at 26.6 °C, it is important the liquids are held at this temperature prior to use. Additionally TGase enzyme is subject to oxidation and enzyme inactivation if opened product is stored improperly. Similarly, other process deviations can occur which are easily remedied through attention to detail.
Other challenges remain when product developers use these ingredients in combination with traditional ingredients. For example, salt and phosphate are incompatible with alginate and Pearl Meat F. If these ingredients are added they can effectively prohibit the chemical reaction which forms the binding gel. Attempts to incorporate salts, spices and other flavorings can upset the binding process especially with ingredients having oxidizing components or extremes in pH. Experiments have been performed to determine if extra ingredients can be compatible with cold-set binding, particularly with alginate binder, and most ingredients have been shown to interfere with the gelling process. Fibrimex and ActivaTM, on the other hand can be used on meat that has been marinated and the gel will still form so long as excess marinade does not dilute the matrix. Similarly frozen raw material can pose a problem with many of these systems especially if they melt during the reaction phase. Poor mouthfeel may also be a typical defect in raw restructured preparation of cold-set products. Softness or mushiness is usually correlated to either poor cohesion or poor quality meat. Instances of soft texture may be due to gelation failure or the incorporation of ingredients that tenderize the meat particles too much. Excessively comminuted meats can also be a source of soft texture. Complaints about slippery or grainy texture may be attributed to the ingredients and common sources in the presence of unreacted alginate or too much Pearl Meat F. Incomplete reaction between alginate and calcium may be due to an improper ratio of ingredients or a pH that is too high for the calcium source to become soluble. It is unusual to expect toughness in a restructured product, but a possibility that has to be considered is excessive connective tissue contributed by the raw materials or when excessive TGase is used in a formulation.
11.9.3 Flavor
The desirable flavor of meat products is essential for ensuring repeat purchases. Problems with off-flavors can repulse customers and careful investigation and identification of reported flavor defects is critical. Unfortunately, flavor is a subjective evaluation that often varies with the individual, which sometimes makes it difficult to measure the problem by objective means. This makes it nearly impossible to determine the cause and effect in a troubleshooting exercise, but it is hoped that improvement can be achieved. Raw materials and nonmeat ingredients obviously have significant roles in the type and flavor which is found in the product. Any problem due to excessive aging, spoilage, oxidation or similar reduction of quality in the raw meat will carry through to adversely impact the flavor of the restructured meat product. Selection of suitable raw materials of exceptional quality is required to make acceptable commercial products: as the adage goes, ‘garbage in, garbage out’. The development of off-flavor due to the binder ingredients is more problematic as these must be added for restructuring and do not contribute towards the meaty flavor of the product. The processor does have some control over the quantity of binder ingredients and therefore should use the minimum concentration that is effective for the restructuring process. In some cases, the quality and freshness of binder ingredients can be questioned and thus appropriate steps can be taken to prevent off-flavors due to expired ingredients. The customer may perceive a reduction in meat flavor intensity due to the cold-set binders because they tend to coat the meat in order to create adhesion, so a criticism of blandness may be reported. This can be compounded by trying to extend the product with extra water. Steps to overcome this problem are more difficult to implement as the traditional method of improving flavour is to add salts, hydrolyzed vegetable protein or other flavour enhancers (monosodium glutamate, fish sauce, soy sauce, etc.). The chemistry of the alginate cold-set binding process and Pearl Meat F would be adversely affect by incorporating ingredients containing salt and although flavor would improve, textural defects would occur. At present, recommendations for reducing blandness are to add flavorings after cold-set binding is complete especially for alginate and Pearl-F bound products. This may be accomplished by the use of a marinade, rub or other post-restructuring addition to the surface of the product. Salt and phosphate with other seasonings can be incorporated into the meat prior to using Fibrimex or Activa for restructured meat products to help minimize blandness. There are numerous considerations when deciding to utilize cold-set binding agents.
Use of the cold-set binders allows the manufacture of a raw product that works well in a portion control system. It also allows utilization of high quality trimmings (loin and tenderloin) in products that have a higher value then ground meat. To maximize the quality of the product careful consideration must be given to raw material, particle size reduction and binder to use. Each will determine what type of product will result from the process.
By J. A. Boles (Montana State University, USA) in the book 'Processed Meat: Improving Safety, Nutrition and Quality' - Woodhead Publishing Series in Food Science, Technology and Nutrition: Number 211, Woodhead Publishing Ltd., Cambridge, U.K, 2011, editors J.P.Kerry & J.F.Kerry, p. 295-320. Edited, adapted and illustrated to be posted by Leopoldo Costa
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