Abstract:
A system and method to tenderize and sterilize meat provides for uninterrupted processing of batches of meat and avoids delays and possibility of contamination of the meat. A conveyer belt carries batches of meat through liquid in a container. First and second arrays of electro-mechanical transducers are disposed in the liquid. The first array of electro-mechanical transducers is arranged facing one side of the conveyer belt and batch of meat, and the second array of electromechanical transducers is arranged facing the other side of the conveyer belt and meat. The first and second arrays of electro-mechanical transducers are oriented and controlled to simultaneously project converging shock waves of energy to and into the batch of meat. Other batches of meat are placed on and picked up from the conveyer belt by feeder and pick-up conveyers to provide for continuous tenderizing and/or sterilizing without introducing contaminations.

Description:
STATEMENTS OF GOVERNMENT INTEREST 
     The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
     BACKGROUND OF THE INVENTION 
     This invention relates to meat processing. In particular, this invention relates to a method and system for tenderizing and sterilizing meat using electro-mechanical transducers to project opposing planar shock waves in meat. 
     Meat is an important source of nutrition in most balanced diets. Generally speaking, more desirable cuts of meat are in greater demand since they typically have higher fat content and are more tender than tougher cuts. However, consumers are becoming increasingly aware that excessive fat consumption is unhealthy, and they are looking for alternatives. Less-desirable cuts that are leaner and lower in fat content may be beneficial to health conscious buyers but the toughness of these cuts still makes them unattractive. In fact, many of these buyers indicate that leaner meats that are lower in fat content would be preferable if they were not so tough. 
     In addition to the health advantages of eating tougher, low fat meats, serving these cuts also is economically advantageous since tougher meat generally is less expensive than tender meat. Cost cutting in food procurements makes large scale purchases of low fat meat more attractive to large institutional and governmental buyers. However, the toughness of some cost effective cuts makes some of them substandard, or at least, less palatable, and serving such food is likely to have a demoralizing effect on workers. Since maintaining high moral is a significant factor toward high performance in the workplace and among personnel in the armed services, food should be tender and more palatable. 
     Meat has been tenderized by many different methods for years. The most common is simple mechanical pounding; however, pounding breaks the meat fibers, and changes the texture of the meat and its appearance. For example, pounding sirloin steak gives it an appearance and texture more akin to cheap hamburger than soft, tasty and more expensive sirloin. Lesser expensive cuts that are pounded also make this unappealing transition. Additionally, pounding is labor and mechanically intensive, prone to structural failure over relatively short operational cycles, and is slow. 
     Meat has been tenderized by aging. However, aging involves storing meat at controlled temperatures for three or four weeks. This is expensive since massive refrigerated storage space is required, and the flavor of the aged meat may be altered. 
     Chemical treatment of meats has also been used. By immersing the meat in a bath of enzymes or other chemicals over a period of time, meat can be tenderized. This method also takes some time but cuts aging time from three or four weeks down to around 10 days in a controlled refrigerated space. This method is also expensive due to the time and cost of refrigeration and constant replenishment of chemicals and enzymes. This method also changes the color, texture and flavor of the meat. 
     Other methods using ultrasonic massaging in water have been attempted and have proven largely ineffective due to the low power of the ultrasonic source and the low pressure waves produced. Essentially, low pressure waves from an ultrasonic source do not behave like shock waves, and as a result, low pressure waves fail to achieve the minimal levels of density of energy and power needed to effect the structural damage needed to tenderize. 
     Tenderizing has been attempted using shock waves generated by explosive charges. Explosive charges generate a spherical (point charge) shock wave in water to act upon a batch of meat. This batch method which has shown some promise but no positive commercial result is disclosed in U.S. Pat. Nos. 5,273,766 and 5,328,403. This batch method has numerous disadvantages: the use of explosives is dangerous and produces several direct and indirect products that are environmentally and commercially unacceptable. For this reason, meats have to be wrapped in airtight plastic bags prior to immersion into the water that fills the explosive chamber, and an inspection and decontamination procedure needs to be performed after detonation to ensure consumer health safety. In accordance with the process disclosed in these patents, detonation of the explosive charge sends a shock wave through the meat; but, since the meat is nearly the same relative density as water, the shock wave passes through yielding only marginal interaction with some meat fibers. Tests of this method have shown that detonation of explosives in a closed water-filled chamber produces a spherical shock wave that passes through the meat. A steel plate at the bottom of the closed, water filled chamber reflects the spherical shock wave back through the meat a second time after it passes through the meat a first time. In each pass, the shock wave is in the form of a spherical wave that only marginally interacts with some meat fibers. This process is difficult to control and lacks uniformity of tenderizing. In addition, there are obvious operational and liability risks of using chemical explosives, dealing with the noxious residue of each chemical explosion, and potentially contaminating the meat. The geometrical arrangement of the chamber disclosed in the above referenced patent is inefficient. The generation of destructive interferences of shock waves within the meat is indeterminable since spherical shock waves generated by the explosive charge rebound and reverberate off the steel walls of the container and the bottom plate hopefully where intended. This questionable effectiveness has further negated the potential value of the disclosed method of these patents. Furthermore, due to this inefficiency, large amounts of explosive must be used in order to get marginal improvement in tenderness. In addition, a large lid having associated shock absorbers and dampers must be used to contain the large detonation in the chamber. Any tenderizing by the explosive methods of processing batches usually is the result of brute force application of plenty of explosives in a single shot that must be reloaded after each shot. Thus, batch processing by detonating explosives is substantially more labor intensive than the efficient use of mechanically generated shock waves in the continuous process of this invention. 
     Thermal sterilization and high pressure sterilization methods are discussed in U.S. Pat. No. 5,588,357. Historically, some thermal sterilization methods and high-pressure sterilization methods have been used for sterilizing some kinds of food. In the thermal sterilization method, food is heated at a predetermined temperature through thermal conduction so that the food can be sterilized. Unfortunately, the thermal sterilization method results in degeneration of protein in food because of heating. In addition, thermally sterilized food sometimes emits a smell unique to thermal sterilization. In the high-pressure sterilization method, food is subjected to a high pressure, typically hundreds to thousands times atmospheric pressure to be sterilized. A conventional apparatus for the high-pressure sterilization method is large, and its sterilizing ability is poor since the apparatus is incapable of performing successive sterilizations. 
     The shockwave sterilizer of the &#39;357 patent has an elastic container for containing food, a shock wave source which is disposed to face the elastic container, and a pressure transfer medium which is interposed between the shock wave source and the elastic container. A spherical shock wave emitted from the shock wave source is transferred to the elastic container through the pressure transfer medium. The shock wave is first applied onto food contained in the container and an expansion wave is next applied onto the food after a small time delay. When the shock wave and the expansion wave are applied, differences in the shock impedance of materials (of each individual cell of bacteria) create differences in the pressure change within each cell of bacteria. This in turn creates non-equilibrium force in each cell, and as a result, the cell is destroyed and the food is sterilized. The time required for radiating the shock wave is only a few hundred microseconds so that there will be no chemical change due to a high temperature or a change in the pressure such as thermal degeneration of protein or the like. Therefore, food can be sterilized at a normal temperature, and reliable sterilization is possible without any large scale and complex apparatus. This approach also requires overcoming the problem of bacterial contamination of the shock wave sterilizer, and is done in &#39;357 by using a vaporizing electrode. But, the vaporizing electrode might be a source of meat contamination unless an elastic (plastic) barrier is used. The elastic barrier is included to withstand the peak impulse shock wave of the vaporizing electrode which may reach 6,000 psi, without rupturing. Because of this high peak impulse shock wave of the vaporizing electrode, it is conceivable that the plastic container will leak. This may require an expensive quality assurance process to ensure high confidence levels that the plastic container will not leak under all operational conditions. 
     Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for an acceptable method of and means for tenderizing and sterilizing meat while maintaining its nutritional value. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to providing a system and method to tenderize and sterilize batches of meat. A conveyer belt carries batches of meat through liquid in a container, and first and second arrays of electro-mechanical transducers are disposed in the liquid. The first array of electro-mechanical transducers is arranged facing one side of the conveyer belt and batch of meat, and the second array of electro-mechanical transducers is arranged facing the other side of the conveyer belt and meat. The first and second arrays of electro-mechanical transducers are oriented and controlled to simultaneously project converging shock waves of energy to and into the batch of meat. Other batches of meat are placed on and picked up from the conveyer belt by feeder and pick up conveyers to provide for continuous tenderizing and/or sterilizing without introducing contaminations. 
     An object of the invention is to provide a method of and means for tenderizing and sterilizing meat. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing continuously meat products for the commercial meat packing industry. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using planar waves that synergistically collide within the meat. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using colliding planar shock waves which are generated from axially opposed high power electro-mechanical transducers. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using colliding planar shock waves which are generated from axially opposed high power electro-mechanical transducers without producing contaminants to provide for assembly-line processing of continuously moving batches of meat. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using virtually planar shock waves which are generated from multiple axially opposed high power electro-mechanical transducers to tenderize and sterilize meat via the synergistic effect of the density of energy of colliding shock waves within the intended meat target. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using planar shock waves from two axially opposed high power electro-mechanical transducers that synergistically collide within the meat target, which is located between the two electro-mechanical transducers. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat relying on synergistic collision of two axially opposing shock waves to create an effect known as Mach Stem that generates at least one localized shearing plane (for tenderizing &amp; sterilizing) perpendicular to the path of the axially opposing shock waves. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat relying on the synergistic collision of two axially opposing shock waves to generate at least one localized shearing plane (for tenderizing &amp; sterilizing) perpendicular to the path of the axially opposing shock waves to substantially rupture muscle, sinuous fibers, and cell membranes within the meat and to simultaneously tenderize and sterilize it. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat relying on the synergistic collision of two axially opposing shock waves to generate at least one localized shearing plane each having a location of convergence that is controlled electrically (timing of the pulses) or mechanically (moving the meat through the shearing plane). 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat relying on the synergistic collision of two axially opposing shock waves to generate at least one localized shearing plane having shock wave convergence at multiple planes throughout the thickness of the meat to tenderize and sterilize the meat effectively, efficiently, uniformly, and safely. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat that effectively and efficiently solves the problem of bacterial contamination without creating any new unacceptable problems. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat relying on the synergistic effect of the energy density of colliding shock waves within the intended meat target without using a vaporization electrode. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat uniformly and reliably throughout its entire volume without the need of a protective plastic container. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using colliding shock waves from axially opposed high power electro-mechanical transducers that may be used repeatedly at high rates over long periods of time without having to be replaced. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat that can be tuned (rate of fire) and timed (firing time phasing) to provide various levels of energy to be imparted to the meat to be tenderized so as to be effective on a variety of meat types, precut or whole carcasses. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat that does not use dangerous chemicals, explosives or vaporizing electrodes and reduces the need to wrap meat to avoid product contamination with by-products produced in contemporary methods. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat that reduces the need for warehouses to store meat for chemical or environmental aging and further reduces the cost of meat by using healthier low-fat cuts. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using shock waves produced by axially opposing high power electromechanical transducer arrays to result in shock waves with longer pulse durations (positive pressure phases) than attainable with explosive devices or electrode vaporization devices. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat using shock waves produced by axially opposing high power electromechanical transducer arrays to result in shock waves with sufficient peak pressures and impulses (the time-pressure integrals) to produce tenderizing &amp; sterilizing of meats more efficiently (energy wise) than attainable with explosive devices or electrode vaporization devices. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat capable of being fabricated in a variety of sizes and including differently powered opposing high power electromechanical transducer arrays to accomplish the job at hand. 
     Another object of the invention is to provide a method of and means for tenderizing and sterilizing meat that may use alternative fluids to perform similar functions, such as being used to clean things that are difficult to clean by other conventional methods and being modified for use in lithotripsy, for examples. 
     These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic top view of the apparatus for tenderizing-sterilizing meat in accordance with this invention. 
     FIG. 2 shows shortening reduction as a function of temperature for pre-rigor chilling to 16° Celsius for 16 hours, (adapted from B. H. Locker and C. J. Hagyard&#39;s “A Cold Shortening Effect In Beef Muscle,”  Journal of the Science of Food and Agriculture , (1963). 
     FIG. 3 is a front view of a typical array of electro-mechanical transducers arranged in adjacent rows taken along line  3 — 3  in FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, tenderizer/sterilizer  10  is geared toward processing meat  100  for the commercial meat packing industry. Typically, meat  100  may be continuous batches, or commercial slabs that may weigh about 300 to 600 pounds. A smaller version of tenderizer/sterilizer  10  can be constructed based on the teachings detailed herein for home consumers to tenderize and/or sterilize smaller portions of meat  100 . Therefore, numerous sizes and capacities of tenderizer/sterilizer  10  may be made in scaled versions depending upon the particular applications. 
     Factors that make meat tender are well known and fully qualified. The following factors are well known and accepted ways to make meat tenderer: 
     1. Cause the sarcomere to be longer. 
     (a) Prevent shortening of the sarcomeres caused by cold temperatures. Meat must be refrigerated to prevent spoiling. Locker and Hagyard&#39;s article cited above, including FIG. 2 showed that the sarcomeres shorten when refrigerated. They also showed new temperature affects the sarcomeres. 
     (1) provide a thickness of subcutaneous fat equal to a thickness of about: 0.10 inches in lamb; 0.25 inches in beef. This thickness slows down temperature drop in muscle since fat is an insulator. The thicker the fat the better since the fat slows down temperature changes that occur from live to dead and from dead to refrigerated. Fatter makes the sarcomeres weaker and therefore, less prone to cold shortening 
     (2) Chill meat at high temperature before rigor mortis sets in (to about 16° C. for 16 hours immediately after slaughter, see FIG.  2 ). 
     (3) Apply electrical stimulation to meat at 550 volts, 2 to 6 amps, 15 times in one minute to cause a very rapid drop in muscle pH and much quicker onset of rigor mortis. 
     (b) Stretch the sarcomere. 
     (1) Apply Texas A&amp;M TENDERSTRETCH™ technique that has suspension by the obturator foramen. Hindleg acts as a cantilever. 
     (2) Apply Stouffer&#39;s Stretching Devices to A&amp;M&#39;s TENDERSTRETCH™ technique to include clamps and stretching rods. 
     (3) Apply the trademarked technique known as TENDERCUT™ wherein bones and connective tissues are cut around muscles to allow stretching of the tissue. 
     2. Disrupt the integrity of the myofibrils. 
     (a) Increase activity of endogenous enzymes that include: (a) calpains, which are stored in the cytosol near Z-lines and require calcium to be activated, and/or (b) cathepsins, which are stored in lysosomes. Calpains work on Z-lines while cathepsins work on actin-myosin bonds. Calpastatin regulates calpains; the higher the calpastatin levels and activity, the less breakdown of myofibrils. 
     (1) Apply aging by storing in cooler for 1 to 6 weeks at 0-30° C. 
     (2) Apply high temperature, post-rigor chilling by storing at 200° C. for 24 hours, (same effect as 20° C. for 14 days). 
     (3) Apply high temperature, pre-rigor chilling by storing at 160° C. for 16 hours. 
     (4) Apply electrical stimulation of meat by rapid pH decline to rupture lysosome and release cathepsins. 
     (5) Infuse/inject calcium chloride into meat by pre-rigor infusion or post-rigor injection of a solution of calcium chloride into muscle to cause increased activity of calpains. 
     (b) Mechanically sever myofibrils. 
     (1) Electrical stimulation causes violent contractions to tear myofibril. 
     (2) Machines have multiple blades and/or needles to penetrate meat as it passes through on a conveyor. First machine was called a Jaccard and the process “Jaccarding.” 
     (3) Scoring, dicing, cubing, grinding or chopping meat created mechanical severance. 
     (4) Placing meat in a sealed water-filled chamber and setting off an explosion in the process known under the trademarked process know as HYDRODYNE™. 
     (c) Topically add exogenous enzymes which are biochemical catalysts. Protease enzymes can break down collagen proteins that are found in skin, bone, and muscle 
     (1) Papain, present in papaya and sold as meat tenderizer; 
     (2) Bromelin, present in uncooked pineapple; and 
     (3) Ficin, present in figs. 
     (d) Marinate meats with acids (vinegar or wine) 
     3. Disrupt the integrity of the connective tissue. 
     (a) Use exogenous enzymes. 
     (1) Marinate with salt and vinegar in a 2% solution of NaCl plus acetic acid in water. 
     (2) Use fungal enzyme (rhozyme) such as  Aspergillus oryzae.    
     (3) Use tropical plant enzymes. 
     (b) Sever stromal proteins. 
     (1) Tenderize by blade or needle. 
     (2) Effect mechanical severance. 
     (c) Convert collagen to gelatin. 
     (1) Cook by moist-heat cookery for a long time with steam generation, e. g. by braising, stewing, or simmering. 
     The following table shows the relationship between tenderness and meat cuts: 
     
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Top Ten “Tender” and “Tough” Cuts in Shear Force (pounds) 
               
             
          
           
               
                 “Tender” cuts 
                 Shear force 
                 “Tough” cuts 
                 Shear force 
               
               
                   
               
             
          
           
               
                 Tenderloin steak 
                 5.7 
                 Top round steak 
                 11.7 
               
               
                 Top blade steak 
                 6.7 
                 Eye of round steak 
                 10.3 
               
               
                 Top loin steak 
                 7.2 
                 Bottom round steak 
                 9.7 
               
               
                 Rib roast 
                 7.3 
                 Rump roast 
                 9.5 
               
               
                 Rib steak 
                 7.4 
                 Eye of round roast 
                 9.2 
               
               
                 Ribeye steak 
                 7.5 
                 Chuck roll steak 
                 9.2 
               
               
                 Chuck roll roast 
                 7.6 
                 Chuck tender steak 
                 9.0 
               
               
                 Clod roast 
                 7.9 
                 Top round roast 
                 9.0 
               
               
                 Round tip roast 
                 7.9 
                 Bottom round roast 
                 8.9 
               
               
                 Top sirloin steak 
                 8.0 
                 Round tip steak 
                 8.9 
               
               
                   
               
               
                 Shear force = pounds of force to shear one-half-inch cores, removed parallel to the muscle fibers, of cooked muscle from steaks and roasts.  
               
             
          
         
       
     
     The following table shows the traits of tender and tough meat: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Factor: 
                 “Tender” 
                 “Tough” 
               
               
                   
                   
               
             
             
               
                   
                 Sarcomere length 
                 3.6 μm 
                 1.8 μm 
               
               
                   
                 muscle fiber diameter 
                 40 μm 
                 80 μm 
               
               
                   
                 Sarcomere/fragment 
                 6 
                 15 
               
               
                   
                 Amount of stromal protein 
                 3 mg/g 
                 8 mg/g 
               
               
                   
                 Size of elastin fibrils 
                 0.6 μm 
                 4.0 μm 
               
               
                   
                 Collagen solubility 
                 28% 
                 6% 
               
               
                   
                 Amount of marbling 
                 7% 
                 2% 
               
               
                   
                 Distribution of marbling 
                 extensive 
                 collected 
               
               
                   
                   
               
             
          
         
       
     
     The following additional important factors affect meat tenderness: 
     1. Breed type:  Bos indicus  (Brahman, Sahiwal, etc.) breeds tend to be tougher than  Bos taurus  breeds (Angus, Hereford, etc.).  Bos indicus  has greater amounts of calpastatin, a protein that interferes with postmortem degradation of muscle. 
     2. Locomotive vs. support muscles: Less connective tissue is observed in support muscles. 
     3. Quality grade effects: Prime has more marbling than choice and choice has more than select. 
     4. Degree of doneness: As some meat is cooked to more advanced degrees of doneness, it will get tougher. Marbling helps to ensure acceptable tenderness at higher levels of doneness. 
     The problem of inconsistency in meat tenderness has been identified as a major concern of the meat industry. Results of various studies have indicated that differences in the rate and extent of postmortem tenderization are the principal sources of variation in meat tenderness and, thus, are likely to be the source of inconsistency in meat tenderness at the consumer level. As a result, in accordance with this inventive concept it has been discovered that reliable and consistent tenderizing is needed. 
     Furthermore, the use of the meat sterilizing process of this invention could reduce the incidence of bacterial contamination. The following facts are clear for  E. coli  0157:H7 that is a virulent strain of the family of generic bacterial contamination: 
     According to Nov. 15, 1998 statistics from the U.S. Center for Disease Control: 
     In 1993, there were 16 outbreaks of  E. coli  0157:H7, of which seven (44 percent) were attributable to ground beef. 
     In 1994, there were 34 outbreaks of  E. coli  0157:H7, of which 13 (38 percent) were attributable to ground beef. 
     In 1995, there were 34 outbreaks of  E. coli  0157:H7, of which 12 (35 percent) were attributable to ground beef. 
     In 1996, there were 32 outbreaks of  E. coli  0157:H7, of which four (12.5 percent) were attributable to ground beef. 
     In 1997, there were 22 outbreaks of  E. coli  0157:H7, of which two (9 percent) were attributable to ground beef. 
     In 1998, preliminary data showed there were 33 outbreaks of  E. coli  0157:H7 of which seven (21 percent) were attributable to ground beef. 
     Research at Washington State University in 1993 showed that  E. coli  0157:H7 was present in 0.5 percent of fed beef cattle. 
     Additionally, special U.S. Department of Agriculture (USDA) tests show that 0.2 percent of beef carcasses tested positive  E. coli  0157:H7. 
     The Food Safety and Inspection Service (FSIS) division of the USDA began random testing for  E. coli  0157:H7 in ground beef in October 1994. As of Dec. 18, 1998, more than 25,000 ground beef samples had been analyzed.  E. coli  0157:H7 was found in 0.10 percent of the samples. 
     Those most susceptible to severe illness as a result of  E. coli  0157:H7 are the elderly, young and those with compromised immune systems. 
     Typically,  E. coli  0157:H7 related illnesses occur because the 0157:H7 serotype emits a toxin which can cause hemorrhagic colitis, a disease with symptoms of bloody diarrhea and severe abdominal pain. Approximately ten percent of these cases in children lead to hemolytic uremic syndrome (HUS), which is the leading cause of acute renal failure in children. 
     HUS may progress to thrombocytopenic purpura (TTP), a central nervous system disease, characterized by seizures and coma. Patients with TTP often develop blood clots in the brain, usually resulting in death. 
     The beef industry has invested more than $8.4 million since 1993 for applied research concerning food safety and  E. coli  0157:H7. 
     To achieve reductions in microbial contamination, the meat packing and processing industry have implemented several intervention strategies. Among these are steam pasteurization, steam vacuuming and organic acid carcass rinsing, that are each designed to kill, reduce or remove bacteria. However, these methods are not effective, and other technologies, such as irradiation and ozonation, are in various stages of development. 
     Techniques currently in use to one degree or another to achieve reductions in microbial contamination include: 
     Rinsing the carcass with high temperature water. High temperature water is sprayed on the carcass at the final point in the slaughter process, which can reduce the remaining bacteria on the carcass. However, about 10 percent of beef plants do not use this process; 
     Misting the carcass with organic acid. An acidic solution, such as vinegar and water, in the form of a fine mist, is sprayed on the carcass after the hide is removed. This prevents certain bacteria from attaching to the outside of the carcass. However, about 85 percent of beef plants do not use this process; 
     Spraying the carcass with tri-sodium phosphate. TSP is an alkaline solution that can be sprayed on a carcass to prevent certain bacteria from attaching to the outside of the carcass. Used in combination with organic acid mists, the two treatments could prevent a range of bacteria from adhering to carcasses; 
     Pasteurizing the carcass with radiation. An intense pulse of energy is emitted either from a gamma radiation source like Cobalt 60 or from an electrical source like an electron beam accelerator. The energy irradiates and penetrates the meat and destroys bacteria. The U.S. Food and Drug Administration approved irradiation of red meats in December 1997. USDA must now issue a rule establishing proper application (to kill bacteria) and labeling requirements delineating all residual risks. The beef industry is awaiting USDA action; 
     Decomposing ozone in water contacting the carcass, or ozonation. Ozonation uses water infused with ozone molecules to reduce/eliminate bacterial contamination. As the ozone molecule (three oxygen atoms) decomposes to basic oxygen (two oxygen atoms), the released atom either could destroy bacteria with which it comes into contact or may react with existing chemical compounds to create a more benign byproduct. Application of ozonation for beef carcasses has not been fully developed, and its performance is unclear, but processes could include spraying or misting carcasses with ozonated water. The use of ozone treated chilled water for poultry decontamination is not practical in some facilities; 
     Pasteurizing the carcass by steam, or steam Pasteurization. Carcasses pass through a steam cabinet which emits a short blast (less than one second) of superheated steam (approximately 350 degrees Fahrenheit). The steam effectively pasteurizes the exterior of the carcass just before it enters the cooler. At the end of 1998, nearly 50 percent of America&#39;s beef was produced by packing plants that did not use steam pasteurization technology; and 
     Vacuuming the carcass by steam to produce lower bacteria counts than what is possible with just a trimming knife. Other steam and hot water vacuums can only remove visible dirt or debris from the carcass aseptically without killing any bacteria. Although it is easy to implement this method, about 20 percent of beef plants do not use this technology. 
     Referring to FIG. 1, tenderizer/sterilizer  10  has large container  20  filled with liquid  25 . Conveyor system  30  is disposed in container  20  and immersed in liquid  25 . Container  20  may have lid  21  to prevent any of liquid  25  from being projected, or splashed from a boundary layer on the surface of liquid  25  during processing. Conveyor system  30  has rollers  31  supporting conveyer belt  32  that is displaced by drives  33 . Drives  33  longitudinally and continuously move belt  32  and meat  100  through liquid  25  and past upper and lower arrays  40  and  50  of high power electro-mechanical transducers  45  and  55  that face and are located on opposite sides of belt  31  and immersed in liquid  25 . Rollers  31  and belt  32  are made and function in much the same manner that is well known in the food processing industry, and drives  33  are controlled motor-driven assemblies that have been used this way for years. Belt  32  may be an endless design that reaches across container  20  to pick up and deliver other slabs of meat  100  generally where drives  33  are located. At these locations more slabs of meat  100  can be placed for tenderizing and/or sterilizing or processed slabs can be removed for packaging, for example. 
     Conveyor belt  32  (and rollers  31 ) within container  20  may be made from rubber or equivalent natural or manmade compounds that have essentially the same density as the water or oil that is chosen as liquid  25 , the fluidic medium for transfer of shock waves from arrays  40  and  50 . This feature is of particular significance since it allows shock waves to be discussed below to pass through without substantial interaction or impedance with conveyor belt  32  (as well as rollers  31 ). This is done to increase the efficiency of tenderizer/ sterilizer  10  by allowing the timing of generated shock waves to be a straightforward process without the need to employ cumbersome higher mathematics, wave shapers and other complicated structures for wave compensation. 
     Upper array  40  and lower array  50  of high power electro-mechanical transducers  45  and  55  are spaced the same distance above and below conveyer belt  32 . High power electro-mechanical transducers  45  and  55  may each have a piston-shape and are respectively arranged in one or more adjacent rows  40   a  and  40   b , see also FIG. 3 (rows  50   a  and  50   b  of array  50  are not shown). Transducers  45  and  55  of arrays  40  and  50  are arranged to orient their flat, or planar projection surfaces  46  and  56  in substantially coplanar relationships. Coplanar projection surfaces  46  are virtually parallel with coplanar projection surfaces  56 . One typical design for each electro-mechanical transducer  45  and  55  could be the high power piezoelectric underwater transducer disclosed in U.S. Pat. No. 4,219,889, although many other different transducer designs might be selected to create converging shock waves in accordance with this invention. 
     Planar surfaces  46  and  56  of transducers  45  and  55  face conveyer belt  32  and meat  100  and are controlled to respectively each project energy away as first shock waves  47  and  57  that are projected separately in a planar form from each transducer and coaxial with the axis of each transducer. The energy of separate and planar first shock waves  47  from transducers  45  of array  40  is projected toward transducers  55  of array  50 , and the energy of the separate and planar first shock waves  57  from transducers  55  of array  50  is projected toward transducers  45  of the array  40 . Thus, arrays  40  and  50  project energy in the form of first shock waves  47  and  57  in an axially opposing relationship. Separate and planar first shock waves  47  and  57  each coalesce collectively a short distance from surfaces  46  and  56  to respectively form first composite shock waves  41  and  51  that are substantially coplanar. The directions of travel of first composite shock waves  41  and  51  are axially opposed and converge on meat  100  on conveyer belt  32 . 
     Proper convergence of axially opposed first shock waves  47  and  57  and their collectively coalesced first composite shock waves  41  and  51  tenderizes and/or sterilizes meat  100 . This processing is assured by appropriate actuation by proper timing signals from logic control and timing circuit  60  that are connected to power supply  70  and/or arrays  40  and  50 . These timing signals are fed to power supply  70  which couples properly timed driving potentials to actuate, or drive transducers  45  and  55  of arrays  40  and  50 , respectively. 
     The constituents of logic control and timing circuit  60  and power supply  70  for the control of high power electromechanical transducers are well known in the industry. For example, over the years, well-known arrangements of control logic, timing circuits, and power supplies with associated diodes and capacitor banks have been used to control the phase of projected energy in many different active arrays in sonar systems. Components  60  and  70 , therefore, can be readily fabricated by one skilled in the art to actuate transducers to create the desired planar shock waves. 
     Water, oil, or similar fluidic medium  25  fills container  20  a sufficient depth to cover and immerse central conveyer  30 , arrays  40  and  50 , and one or more batches of meat  100 . Successive batches of meat  100  to be tenderized/sterilized are sent down feeder conveyor  35  where they enter liquid  25  of tank  20  and travel to center conveyor  30 . Meat  100  is placed on conveyer belt  32  of central conveyer  30  by feeder conveyer  35 , and meat  100  is carried at a preset rate to and through liquid  25  in region  15  between arrays  40  and  50  of axially opposing high power electromechanical transducers  45  and  55 . Conveyer belt  32  continues to move meat  100  through region  15  while arrays  40  and  50  of axially opposing rows of high power electro-mechanical transducers  45  and  55  tenderize/sterilize meat  100  with projected converging shock waves of energy. After meat  100  has been suitably tenderized and/or sterilized, conveyer belt  32  moves meat  100  to a pick up conveyer  36  which takes it from liquid  25  to another processing area. This progression is continuous and, therefore, cost effective as compared to the higher cost stop-and-go procedures that are characteristic of current state of the art batch processing. 
     In accordance with preestablished timing sequences of logic control and timing circuit  60  energy from the power supply  70  has already charged an internal bank of capacitors (not shown) that are linked to the rows of transducers  45  and  55  of arrays  40  and  50 . Logic control and timing circuit  60  then initiates rows of transducers  45  and  55  of arrays  40  and  50  so as to virtually simultaneously actuate the high power electromechanical transducers  45  and  55  in each array to project shock waves of energy. In addition, actuation of transducers  45  and  55  in the adjacent rows of array  40  and array  50  may also need to be slightly phased with respect to one another to more completely converge energy of the rows of transducers onto meat  100 . This actuation is initiated in sequences to produce simultaneous or phased sequences of first composite planar shock waves  47  and  57  to tenderized/sterilized meat  100  thoroughly as belt  32  carries it through region  15 . Successive ones of first planar shock waves  47  and  57  are transmitted to be separated by an interval of between 25 and 50 milliseconds for tenderizing and sterilizing meat  100  in water as liquid  25 . 
     Since each transducer  45  and  55  creates separate and planar first shock waves  47  or  57  within liquid  25 , these separate planar shock waves  47  or  57  simultaneously travel away from the rows of transducers  45  or  55  of array  40  or  50  that generated them. A very short distance from surfaces  46  and  56  of transducers  45  and  55 , these first shock waves  47  and  57  coalesce collectively to respectively form first composite shock waves  41  and  51  that may be substantially parallel to the upper and lower surfaces  100   a  and  100   b  of meat  100 , and as mentioned above, successive ones of composite shock waves  41  and  51  also are separated by an interval of between 25 and 50 milliseconds. Each of planar shock waves  47  and  57  and composite shock waves  41  and  51  has a positive phase component that is attributable to the positive pressure spike generated during the initial part of each shock wave and a negative phase component that is attributable to the negative transition to vacuum immediately after the positive pressure spike. 
     However, in addition to separate and planar first shock waves  47  and  57 , each transducer  45  and  55  of arrays  40  and  50  also produces an expanding bubble front. This bubble front expands behind each precursor shock wave (first planar shock wave  47  and  57 ), very close to the transducer that produced it, until the internal pressure forces of the bubbles and hydrostatic forces of fluid  25  reach equilibrium. When equilibrium is reached, each bubble front rapidly collapses and creates a separate and planar second shock wave  48  or  58  from each transducer  45  or  55 . Second shock waves  48  and  58  follow very closely behind first shock waves  47  and  57 , in the range of about 5 to 10 milliseconds behind the first shock waves. However, this timing is exemplary, and other timing schemes are possible. The timing of events is dependent on the energy density level deposited on the medium (water or oil); that is, a big shockwave takes longer to dissipate all its reverberation inside the chamber, affecting the ultimate trade-off among speed, distance, and power levels. 
     The multitude of second shock waves  48  and  58  coalesce collectively to respectively form large and substantially coplanar second composite shock waves  42  and  52 . Second composite shock waves  42  and  52  are respectively virtually parallel to the first composite shock waves  41  and  51  and follow very closely behind them, in the order of from about 5 to 10 milliseconds behind the first composite shock waves. 
     The set of first and second composite shock waves  41  and  42  and the set of first and second composite shock waves  51  and  52  from the axially opposing array  40  and  50  collide in meat  100 . This collision of the sets of composite shock waves produces Mach Stem effects that create two large spikes of pressure (or pressure spikes) closely separated in time. The first of the two large pressure spikes is caused by the colliding first composite shock waves  41  and  51  which each have a positive phase component and a negative phase component, and the second of the two large pressure spikes is caused by the colliding second composite shock waves  42  and  52 . 
     Each of the two pressure spikes exerts its pressure uniformly and each extends in a separate plane that is perpendicular to the opposite directions of travel of shock wave sets  41 ,  42 , and  51 ,  52  and substantially parallel to the planes of outer surfaces  100   a  and  100   b  of meat  100 . When proper timing of transducers  45  and  55  of arrays  40  and  50  brings these two pressure spikes, or two-phase shearing planes, within meat  100 , this effect cuts the sinuous fiber within meat  100  and thus tenderizes it along these planes. 
     Furthermore, having the two pressure spikes, or two-phase shearing planes separated by an interval of time in the range of 5 to 10 milliseconds provides for efficient sterilization by creating successive destructive absolute pressure spikes and absolute pressure differentials within and around each of bacteria and/or other undesirable organisms in meat  10 . The destructive pressure spikes and differentials are created by the traveling positive phase components and the subsequent negative phase components of the first composite waves  41  and  51  and the positive phase component of the second composite waves  42  and  52 . 
     The timing or phasing of the actuation of rows of transducers  45  and  55  of each array  40  and  50  is varied over several successive cycles such that sets of composite shock waves  41  and  42  and sets of composite shock waves  51  and  52  collide sequentially along different planes at different depths within meat  100 . These sequential collisions of shock waves effectively tenderize it throughout the entire thickness of meat  100 . Between cycles of actuation a finite amount of time is allowed to lapse before the next actuation cycle to allow any secondary shock and pressure waves to reverberate and dissipate. An exemplary repetition rate having an interval of between 25 and 50 milliseconds between successive shock waves is given for a water medium  25 . Oil or other liquids for medium  25  would call for different repetition rates and different energy levels to achieve efficient sterilization and the two-phase shearing planes. Thus, it is seen that appropriate timing and phasing (firing of transducers) can be made to avoid any undesirable destructive or constructive shockwave interferences (attributable to time delay and/or mistiming between pulses and the speed of transition of meat  100  through tenderizer/sterilizer  10 ) that would degrade performance, repeatability, and uniformity of the delivered energy or power density levels of tenderizer/sterilized  10 . 
     Tenderizer/sterilizer  10  continuously tenderizes and simultaneously sterilizes meat  100  uniformly and reliably throughout its entire volume without the need of a protective plastic container. The colliding composite shock waves in meat  100  may be appropriately controlled in power, duration, and rate of repetition by circuit  60  and supply  70  to effect tenderization and sterilization simultaneously or separately in projections of shock waves from arrays  40  and  50 . These controlled colliding composite shock waves work like two hammers hammering simultaneously from axially opposed sides. 
     Tenderizer/sterilizer  10  makes efficient use of electrically induced mechanical shock waves for tenderizing and simultaneously sterilizing meat. High power electromechanical transducers  45  and  55  project axially opposing shock waves and can be used, or pulsed repeatedly at high rates over long periods of time without having to be replaced and without the producing contaminants. This feature further assures that tenderizer/sterilizer  10  is ideal for assembly line processing of batches of meat  100 . Tenderizer/sterilizer  10  does not use dangerous chemicals, explosives, or vaporizing electrodes and reduces the need to wrap meat that other processes need to avoid product contamination with byproducts of processing. Tenderizer/sterilizer  10  can be tuned (rate of fire, or pulsed actuation) and timed (firing time phasing) to project different levels of energy to tenderize/sterilize meat  100  so as to be effective on a variety of meat types, precut or whole carcasses. Tenderizer/sterilizer  10  allows control and variation of the degree of tenderization and sterilization, and its size can be scaled for use in both the heavy meat packing industry and for the home consumer. The processing of tenderizer/sterilizer  10  substantially reduces the time otherwise necessary for meat to be stored in refrigerated warehouses during aging. Since tenderizer/sterilizer  10  eliminates the need for aging, shelf life on grocers&#39; shelves can be increased, and taste of meat can be improved. Since large warehouses to store meat during chemical or environmental aging are no longer needed, the cost to deliver quality meat products is reduced, while using healthier low fat meat cuts. 
     Tenderizer/sterilizer  10  uses axially opposing high power electro-mechanical transducer arrays  40  and  50  to generate tenderizing and sterilizing shock waves. Shock waves produced by axially opposing high power electro-mechanical transducer arrays  40  and  50  create shock waves having longer pulse durations (positive pressure phases) than those attainable with explosive devices or electrode vaporization devices of the prior art. Shock waves produced by axially opposing high power electro-mechanical transducer arrays  40  and  50  create shock waves having sufficient peak pressure and impulse which are the time-pressure integrals that may be affected by length and frequency of pulses that actuate the transducers. This feature produces tenderizing and sterilizing of meat  100  more efficiently with respect to energy expended as compared to explosive devices or electrode vaporization devices. Explosive devices or electrode vaporization devices of the prior art produce sharp pressure pulse spikes, requiring over pressurization to effect work which could be done at lower pressures but with longer pulse durations by the invention. 
     The prior art has recognized the fact that work can be done by sharp pressure spikes more efficiently while under water or similar dense fluid, and this was the technical basis for development and fielding a family of underwater explosives of which PBXN-103 is probably the best known member. Thermodynamically speaking, no work and no energy can be exchanged in no time, and accordingly, substantial energy must be expended by large detonations to create pressure spikes significant enough to produce useful results. This substantial energy expenditure makes these detonations inefficient with respect to energy used by tenderizer/sterilizer  10  of this invention. 
     More powerful or less powerful axially opposing high power electro-mechanical transducers arrays  40  and  50  may be employed depending on the application. A limitation regarding size might be the level, or density of power fed to the axially opposing high power electromechanical transducer arrays  40  and  50 . The current moving capacity of modern conventional materials used in the high power electromechanical transducer industry might be exceeded so that alternative fluids might be used to perform this function. Tenderizer/sterilized  10  might be modified to clean things that are difficult to clean by other conventional methods, or it may be modified for use in lithotripsy. 
     Furthermore, having this disclosure in mind, one skilled in the art to which this invention pertains will select and assemble suitable components for fabrication of different tenderizers/sterilizers  10  from among a wide variety of materials and components available in the art to satisfactorily tenderize and/or sterilize meat  100  as disclosed herein. Therefore, the disclosed arrangement is not to be construed as limiting, but rather, is intended to be demonstrative of this inventive concept. 
     It should be readily understood that many modifications and variations of the present invention are possible within the purview of the claimed invention. It is to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.