WO2012009234A2

WO2012009234A2 - Methods of removing heavy metals from food products

Info

Publication number: WO2012009234A2
Application number: PCT/US2011/043426
Authority: WO
Inventors: Billy M. Groves; Ethan J. Whitbeck; F. M. Henderson
Original assignee: Grovac Systems International L.C.
Priority date: 2010-07-16
Filing date: 2011-07-08
Publication date: 2012-01-19
Also published as: WO2012009234A3

Abstract

A method of processing a food, comprising receiving a food that contains a heavy metal; exposing the food to an aqueous solution comprising an organic acid and a heavy-metal binding ligand which forms a heavy-metal chelate with the heavy metal in the food; cycling the food between the solution and a vacuum environment; and, rinsing the food, is described.

Description

METHODS OF REMOVING HEAVY METALS FROM FOOD PRODUCTS Cross-Reference to Related Applications

This application claims priority to US Provisional Application No. 61/364,876 filed July 16, 2010, which is herein incorporated in its entirety by reference.

Background of the Invention

[0001] This invention relates to the removal of heavy metals from food products using a heavy metal-binding ligand.

[0002] Heavy metals, such as mercury and lead, are not metabolized by the body and if accumulated in the body, cause toxic effects by interfering with physiological functions. Heavy metals are found everywhere in the environment; they are naturally part of the earth's crust. Additionally, metallic elements, such as cadmium, chromium, copper, lead, mercury, nickel, and zinc are used to manufacture products and are present in some industrial, municipal, and urban runoff as they are used in coatings, paints, lacquers for packaging, toys, furniture, etc. They do not break down or decompose and tend to build up in plants, animals, and people. They enter living organisms via food, drinking water, and air. Removal of heavy metals from organisms is a difficult process.

[0003] Of particular concern is the presence of heavy metals in fish. The retail market for fish in the United States alone is more than $65 billion dollars and is projected to continue growing at 4 to 5% annually, which is about 2% more than the average market sector. The popularity of fish in the United States is partly due to the repeated media messages to the American consumers about the health benefits of consuming fish that are high in omega 3 fatty acids. The American Heart Association, Center for Disease Control and the American Dietetic Association endorse twice-a- week consumption of fish as part of a balanced diet. Such a diet is said to help insure healthy babies, to promote healthy hearts and to reduce the risk of cancer. [0004] Unfortunately, fish and shell fish are the number one sources of mercury to Unites States consumers. Thus, a need exists for a method of removing mercury, such as methyl mercury, and all other heavy metals from fish and other seafood products.

Brief Summary of the Invention

[0005] The invention is directed to a method of processing a food, comprising receiving a food that contains a heavy metal, exposing the food to an aqueous solution comprising an organic acid and a heavy-metal binding ligand which forms a heavy- metal chelate with the heavy metal in the food and; and cycling the food between the solution and a vacuum environment; and rinsing the food. In one embodiment, the rinsing separates the heavy metal- chelate from the food. In another embodiment, the rinsing does not separate the heavy metal-chelate from the food and, when the food containing the heavy metal-chelate is consumed, the heavy metal-chelate passes through the body of a consumer without being absorbed. In one embodiment, the heavy metal is selected from the group consisting of mercury, lead, uranium, cadmium and mixtures thereof. In one embodiment, the food product is an animal protein. In another embodiment, the food product is a plant. In a preferred embodiment the food product is a fish, a shell fish or soybeans. In one embodiment, the ligand is selected from the group consisting of polygalatcuronic acid, HCI, citric acid, ascorbic acid, alpha lipoic acid (ALA), phytic acid, N-acetyl-L-cysteine, oxalic acid, sodium thiosulfate and methylsulfonyl methane (MSM). In a preferred embodiment, the cycling between the solution and the vacuum environment is repeated.

Brief Description of the Drawings

[0006] Figure 1 is a schematic of a vacuum tumbler machine and process.

[0007] Figure 2 is a schematic of a vacuum dip machine and process.

[0008] Figure 3 is a schematic of an exemplary control panel.

[0009] Figure 4 is a flow diagram in a vacuum dip process. [0010] Figure 5 is a schematic of an exemplary continuous vacuum process. Detailed Description of the Invention

[0011] The term "heavy metal" refers to a member of the dense, higher atomic weight elements that have metallic properties at room temperature. "Heavy metals" include at least cadmium, chromium, copper, lead, manganese, mercury, nickel, zinc, barium, selenium, and silver, which tend to be toxic in low concentrations and tend to accumulate in the food chain. Heavy metals may also include iron, aluminum, tin, cobalt, gallium, lithium, arsenic, beryllium, vanadium, and even other metals and metalloids. In a preferred embodiment, the heavy metal is methyl mercury.

[0012] The "Iigand" is a molecule or group of molecules that binds to another chemical entity to form a complex. In the present invention, the resulting complex is referred to as a "chelate." The Iigand is a "chelating agent" or "chelating compound." Chelating agents include Alpha lipoic acid (ALA), Aminophenoxyethane-tetraacetic acid (BAPTA), Deferasirox, Deferiprone, Deferoxamine, Diethylene triamine pentaacetic acid (DTPA), Dimercaprol (BAL), Dimercapto-propane sulfonate (DMPS), Dimercaptosuccinic acid (DMSA), Ethylenediamine tetraacetic acid (EGTA) and D-penicillamine.

[0013] Other chelating agents include phytic acid (inositol hexakisphosphate), glutathione, polygalatcuronic acid, triethylenetetramine (TETA), NAC, TIRON, FRO, TRIEN, bacterial metalloregulatory protein (MerR), a fibrous protein, such as keratin, and sulfur/and sulfate derivatives and salt forms of the above. Other chelating agents are HCI, NaCI, N-acetyl-L-cysteine, oxalic acid, sodium thiosulfate and methylsulfonyl methane (MSM). In a preferred embodiment, the chelating agent is polygalatcuronic or pectic acid, or esters and salts thereof. Polygalatcuronic acid may be derived from a natural source such as citrus or a grain or soybean. The preferred polygalatcuronic acid is a short chain polygalatcuronic acid. In one embodiment, a combination of chelating agents is used. [0014] Chelating agents are discussed in the following publications: "Hemochromatosis: Monitoring and Treatment," National Center on Birth Defects and Developmental Disabilities (NCBDDD). 2007-1 1-01 ; "Questions and Answers: The NIH Trial of EDTA Chelation Therapy for Cornary Artery Disease", National Center for Complementary and Alternative Medicine (NCCAM)(November 1 1 , 2002); Natural Standard Professional Monograph, (www.naturalstandard.com); Bridges, S. (2006). "The promise of chelation," Mothering, 54-61 ; Ernst E (2000). "Chelation therapy for coronary heart disease: An overview of all clinical investigations". Am. Heart J. 140 (1 ): 139-41. Weber W, Newmark S (2007). "Complementary and alternative medical therapies for attention- deficit/hyperactivity disorder and autism". Pediatr Clin North Am 54 (6): 983-1006; Atwood KC, Woeckner E, Baratz RS, Sampson Wl (2008), "Why the NIH Trial to Assess Chelation Therapy (TACT) should be abandoned," Medscape J Med 10 (5): 1 15; "American Heart Association: Chelation Therapy" (www.americanheart.org); "Government probes chelation-heart disease study," Washington Post (AP) (September 25, 2008); Seely DM, Wu P, Mills EJ (2005) "EDTA chelation therapy for cardiovascular disease: a systematic review," BMC Cardiovasc. Disord. 5: 32; Bernard S, Enayati A, Roger H, Binstock T, Redwood L (2002)"The role of mercury in the pathogenesis of autism" Mot. Psychiatry 7 (Suppl 2): S42-3; Stokstad E (2008). "Stalled trial for autism highlights dilemma of alternative treatments". Science 321 (5887): 326; Immunization Safety Review Committee, Board on Health Promotion and Disease Prevention, Institute of Medicine (2004) Immunization Safety Review: vaccines and Autism, Washington, DC, The National Academies Press; Doja A, Roberts W (2006). "Immunizations and autism: a review of the literature". Can J Neurol Sci 33 (4): 341-6; Thompson WW, Price C, Goodson B et al. (2007). "Early thimerosal exposure and neuropsychological outcomes at 7 to 10 years" N. Engl. J. Med 357 (13): 1281-92; Rutter, M. (2005) "Incidence of autism spectrum disorders: changes over time and their meaning". Acta Paediatr 94 (1 ): 2-15; Blakeslee, Sandra (2004-05-19); Knudtson ML, Wyse DG, Galbraith PD, et al. (2002). "Chelation therapy for ischemic heart disease: a randomized controlled trial". JAMA 287 (4): 481-6; and Baxter AJ, Krenzelok EP (2008). "Pediatric fatality secondary to EDTA chelation," Clin Toxicol (Phi la) 46: 1083. [0015] The solution may comprise the chelating agent in water. The chelating agent may or may not be encapsulated in oil prior to dispersing into water. The solution may further comprise a sodium content such that the food product processed is submerged into a hypotonic solution allowing for improved intracellular transfer of the ligand by osmosis. Additionally, the solution may contain a variety of organic acids, such as citric acid or ascorbic acid, to improve the functionality of the chelating agent as well as incorporate the benefits of the vacuum/solution process synergistically.

[0016] Exemplary methods by which the food product is cycled between a vacuum and the solution containing the food product are described in the following patents and applications, each of which is hereby incorporated by reference in its entirety: US Patent No. 5,543, 163, US Patent No. 6,896,921 , US Patent No. 7,007,594 and Patent Cooperation Treaty Application No. US 2007/78427 and US Patent Application Nos. 1 1 /737,848, 12/440,751 and U.S. Provisional applications 61/446,371 and and 61 /477,957. The methods described in the above patents and applications, wherein food products are exposed to repeated alternating vacuum and solution environments, permit the ligand to bind with the heavy metals in the tissue of the food product as the alternating vacuum and solution enhance the penetration of the ligand. Thus, the processing has both a mechanical and chemical aspect.

[0017] For instance, in one embodiment, the vacuum tumbler process is that which is described in US Patent No. 5,543,163, which is best understood by referring to Figure 1 , like numerals being used for like and corresponding parts of the various drawings. In this embodiment, the present invention contemplates a method for processing animal and plant food products and a system for carrying out the method. The method has both a mechanical and chemical aspect. For instance, with regard to the processing of fish, the vacuum tumbling enhances cleaning and exposes greater cellular membrane area to the extraction process. During vacuum tumbling, the fish retains a desired percentage of the processing solution to improve overall appearance and taste. Vacuum tumbling also contributes to bacterial lysis which improves the shelf life of the fish. Another mechanical aspect of the present invention is tissue perforation, especially of the membrane covering areas, which assures uniform and more extensive exposure of the catfish to vacuum processing. Several chemical aspects of this embodiment of the present invention enhance the quality and flavor of the fish, and improve its shelf life. A hypotonic saline solution enhances osmosis into the cellular structure which contributes significantly to the dilution and extraction of contaminants such as heavy metals. An organic acid additive, such as 1 -glutamic, citric or ascorbic acid, is also used.

[0018] In this embodiment, Figure 1 illustrates the process steps and components of processor 10. The operation of processor 10 will be described with reference to catfish, but it should be understood that processor 10 may be used successfully with any other appropriate food products. The process steps performed in processor 10 are shown in a particular order but may be performed in a different sequence without departing from the scope of the present invention. In addition, process steps may be performed at a single location or multiple locations. Fish, such as catfish 12 of varying sizes are caught and sorted based on size, appearance, or other appropriate characteristic to select sorted catfish 14 appropriate for processing by processor 10. Sorted catfish 14 are then de-headed, eviscerated, and de-boned by an automatic skinner-fillet machine 16. Skin, fins, and other similar material may be diverted for sale to the animal food preparation industry. The resulting fillet 18 from automatic skinner-fillet machine 16 is then ready for the various processing steps performed by processor 10. The following steps performed in processor 10 will be described with reference to a de-headed, de-boned, and eviscerated fillet, but it should be understood that the present invention contemplates processing animal products that include bones, internal organs, and other portions not intended for consumption.

[0019] The membranes of fillet 18 are optionally perforated by perforator 20 to allow better tissue access during processing. Perforator 20 may be a single roller with perforating protrusions or a pair of rollers as shown in Figure 1. Those of skill in the art would understand that other types of perforators may be used in accordance with this embodiment of the invention. Perforated fillet 22 may then be weighed at scale 24 and analyzed for various variables, such as fat, lipid or heavy metal content by analyzer 26. Both scale 24 and analyzer 26 may transmit data regarding these variables of perforated fillet 22 to computer 28 over data collection lines 30. One of skill in the art would understand that analyzer 26 may also be adapted to measure any other monitored component of fillet 22.

[0020] Perforated or non-perforated fillets 22 are loaded into vacuum tumbler 32 for processing. Vacuum tumbler 32 comprises a cylindrical drum 34 mounted to rotate about a central axis. Affixed to the internal wall of cylindrical drum 34 are ribs 36 extending substantially parallel to the axis of rotation of cylindrical drum 34. Door 38 provides access to the inside of cylindrical drum 34, and drain 39 allows filling and draining of cylindrical drum 34 with processing solution 48, described below. Motor 40 rotates cylindrical drum 34 either directly or through an appropriate transmission 42 using gears, pulleys, belts, or other appropriate members. It should be understood that the present invention contemplates any motor or engine 40 optionally coupled with an appropriate transmission 42 that can impart a rotational velocity to cylindrical drum 34. Vacuum source 44 is also connected to cylindrical drum 34 through vacuum source access port 46. Vacuum source 44 may be removable from vacuum source access port 46 to allow for free rotation of cylindrical drum 34. Vacuum source 44 operates to reduce the internal pressure of cylindrical drum 34. In one embodiment, vacuum source 44 reduces the internal pressure of cylindrical drum 34 by at least twenty five inches of mercury (Hg). The specific vacuum level may be adjusted based on the age and condition of the fish, as well as other factors. Both motor 40 and vacuum source 44 are connected to computer 28 through control lines 47.

[0021] Partialy filling the inside of cylindrical drum 34 is processing solution 48. In one embodiment, processing solution 48 comprises: (i) water (H₂0) in an amount approximately equal by weight to fillets 22, and (ii) sodium chloride in an amount no more than 0.9 percent of the weight of fillets 22. To increase the osmotic absorption of processing solution into the membranes of fillets 22, a hypotonic saline solution of approximately 0.45 percent sodium chloride (NaCI) may be used. Although the amount of processing solution 48 should be approximately equal to the weight of fillets 22, the amount may vary without departing from the scope of the present invention. One of skill in the art would understand that the classification of a solution as "hypotonic" depends on the tonicity of the food product being processed. For instance, a hypotonic processing solution for land based fresh water animals may include a sodium chloride content of no more than 0.9 percent of the weight of the water, whereas for salt water animals, the sodium chloride content is typically no more than 3.8 percent of the weight of the water. Other suitable processing solutions may be utilized within the scope of the invention. And, for processing plants, such as soybeans, no hypotonic solution may be included. The amount of the processing solution within the drum should be no more than the weight of the food product being processed but this would vary depending upon the food product.

[0022] An organic acid may also be added in an amount sufficient to adjust the pH of processing solution 48 to a value preferably from 4.5 to 5.5, but in any event less than 8.0. In another embodiment, the pH of the processing solution is approximately 1.8 to approximately 7.0 and preferably between 1.8 and 3.8. The vacuum tumbler may include pH monitors and sensors. The organic acid may be 1 -glutamic acid, ascorbic acid, or any other appropriate acid. At least one chelating agents is also added. Other ingredients, such as flavor enhancers also may be added. After loading perforated fillets 22 and processing solution 48, and after creating a partial vacuum within cylindrical drum 34 by vacuum source 44, cylindrical drum 34 is rotated by motor 40 at a predetermined rate and for a predetermined time. In one embodiment, cylindrical drum 34 is rotated at eight revolutions per minute for eight to twelve minutes. After the predetermined time for tumbling, the partial vacuum is released and fillets 22 may be drained, rinsed, and re-drained. The draining and rinsing steps (not shown) may be performed before or after removing fillets 22 from vacuum tumbler 32.

[0023] After tumbling for a suitable period of time, the partial vacuum is released and fillets may be drained, rinsed and re-drained. The draining and rinsing steps may be performed before or after removing fillets from the cylindrical drum. Processed filets may then be weighted by scale and analyzed for various variables, such as heavy metal content. Processed filets are then sorted and packaged, according to methods known in the art.

[0024] The entire above described process may be monitored by computer, as describe in US Patent No. 6,896,921 , which is incorporated herein by reference.

[0025] In another embodiment, the alternate exposure of the food product being processed to a vacuum and a solution may be accomplished through a dipping, rather than rotation process. That embodiment is described in WO 2008/034020, the entire contents of which are herein incorporated by reference. The dip-vacuum process of Figure 2 illustrates the process steps and components of a process 10 for processing biological products in accordance with one embodiment of the present invention. Process 10 is described herein with reference to red meat; however, the process 10 may be used successfully with other suitable food and biological products, which includes but are not limited to fish, poultry, fruits, shrimp, shell fish, vegetables, nuts, soybeans, coffee beans, and cut flowers. The process steps performed in the process 10 are shown in a particular order but may be performed in a different sequence without departing from the scope and spirit of the present invention. In addition, process steps may be performed at a single location at multiple locations.

[0026] Referring to Figure 2, a selected feedstock 12, in this case an animal type giving red meat, is chosen from a variety of a feedstocks 1 1 that may be processed by the present invention. The selected feedstock 12 of varying shapes and sizes are gathered and sorted based on size, appearance, or other appropriate characteristics to select sorted feedstock 14 appropriate for processing by the process 10. A sorted feedstock 14 is then processed by any suitable raw processing process 16 to produce a plurality of raw products, such as fillet 18. For example, cattle would have to be slaughtered and butchered to produce the fillet 18. As given for the example, the fillet 18 is assumed to be de-boned, eviscerated, and having a generally rectangular shape. The fillet 18 may include bones, internal organs, and other portions not intended for human consumption, and may be any suitable shape or size. Fillet 18 is then ready for the various processing steps performed by the process 10.

[0027] The fillet 18 may then be mechanically or chemically treated in a pretreatment process 20 to allow better tissue access during processing. For example, fillet 18 may be mechanically perforated in pretreatment process 20 to create pretreated fillets 22. In reference to the foregoing example, red meat typically does not have to be perforated, but perforation may be beneficial for some other food or biological products. Other mechanical or chemical processes may occur at this step to transform fillets 18 into pretreated fillets 22 for further processing and will depend on the food or biological product to be processed. For example, the fillets 18 may be treated with potassium chloride, sodium phosphate, or potassium phosphate solutions or powders to prepare it for vacuum dip processing.

[0028] Pretreated fillets 22 are then loaded into a container 60 within the vacuum dip processor 40. In this embodiment, the vacuum dip processor 40 is comprised of a cylindrical-shaped drum 41 with a domed top 42 and domed bottom 43. The vacuum dip processor 40 is made of suitable materials, such as stainless steel 316 in this embodiment, that are able to withstand repeated cycling of internal pressures between a partial vacuum and atmospheric conditions as well as prolonged exposure to acidic liquid conditions. The vacuum dip processor's 40 interior is accessed via the domed top lid 46 by elevating the lid 46 on hinges 47 attached to the domed top 42. Other embodiments may permit different access to the vacuum dip processor's 40 interior for use and maintenance. Other embodiments allows access to the interior of the vacuum dip processor 40 by way of door mounted on the side of the drum 41 that can be attached either via hinges, allowing the door to open and swing outwardly from the drum 41 , or on sliding rails, permitting the door to be raised vertically. In the current example, when the lid 46 is closed and locked into place on the domed top 42 with locks 48, an air-tight compartment is formed within the vacuum dip processor 40. The vacuum dip processor 40 as a unit is raised off the ground and held aloft by several attached legs 44. [0029] A piston cylinder 50 is attached to the domed bottom 43. The piston cylinder 50 drives a rod 52 from below the drum 41 through a piston seal 53 at the bottom of the domed bottom 43 upwardly into the drum's 41 interior. Piston cylinder 50 may be driven by hydraulic, air, gas, or water power and is actuated by its respective components. The rod's 52 range of movement allows the container 60 to rise and fall within specified parameters inside the vacuum dip processor 40, preferably in a range from complete submersion of the contents of the container 60 in the processing solution 90 to complete exposure to the partial vacuum environment.

[0030] In this embodiment, the container 60 is made out of a non-corroding metal, such as stainless steel 316. Container 60 has perforations or is made from a mesh-like material, thereby allowing the processing solution 90 to fill the container 60 when submerged into the processing solution 90 and to drain from the container 60 when positioned outside the process solution 90. The container 60 is attached to the rod 52 by a quick connection/release mechanism 55. Although in this embodiment container 60 is described, other containers in which the pretreated fillets 22 are contained may be used, such as a perforated tray. The shape, organization, and method of containment of the container 60 will likely vary depending on the biological or food product being processed, such as using an enclosed basket shape for small, non-bundled foods such as coffee beans or nuts and a perforated tray shape for large items like whole shanks of meat.

[0031] Two valve ports are attached to the drum 41 to provide the ability to draw, monitor, and break the partial vacuum in the vacuum dip processor 40. A vacuum line port 70 is located above the surface of the processing solution 90, preferably as high up on the body of the drum 41 as possible, and provides attachment for a ball valve 71. A vacuum release port 72 is also located above the steady-state surface of the processing solution and provides for two attachments: a vacuum pressure gauge 73 and a ball valve 74. The two ball valves 71 and 74 and the vacuum pressure gauge 73 are made of suitable materials, such as stainless steel 316 in this embodiment, to withstand repeated exposure to the processing solution 90 as well as correspond with the materials of manufacture of the vacuum dip processor 40.

[0032] After loading the pretreated fillets 22 into container 60, the operator closes and seals the vacuum dip processor 40 by locking the lid 46 against the top dome 42 by tightening down the locks 48. There may be one or more locks 48 used to secure the lid 46 against the top dome 42. Figure 2 shows the container 60 in the position where the operator would load the pretreated fillets 22. This position also represents a "default" position for the container 60. Referring now to Figure 3 for a control panel 200, the operator then activates the process by turning on the vacuum dip processor 40 by manipulating an on/off switch 202 into the "ON" position, manipulating a process selection switch 204 to the desired process, and pressing a start button 206 on the control panel 200. The combination of the position of the process selection switch 204, depression of the start button 206, and the corresponding pH value of the water used for mixing the process solution 90, determines the combination of ingredients to use, the amount of each ingredient used to combine in vacuum dip processor 40 to create the processing solution 90, the strength of the partial vacuum to be created by a vacuum source 92, the length of overall processing time to treat the pretreated fillets 22 in the vacuum dip processor 40, and the respective lengths of intermediate time for exposing pretreated fillets 22 to the partial vacuum and the processing solution 90. The input variables are read by a PC-programmed microprocessor 150 (not shown). The microprocessor 150 in response to these inputs issues output commands through control lines 170 to initiate and control the process.

[0033] Referring back to Figure 2, at initiation of the processing cycle, the microprocessor 150 sends commands via the control lines 170 to the saline solution source 93, the organic acid(s) source 94, and the additive(s) source 95, respectively, to dispense the proper volumes and combinations of concentrated materials ("concentrates") through process lines 100 into the vacuum dip processor 40 via the concentrates nozzle 105. In this embodiment of the invention, only one concentrates nozzle 105 is considered; however, each concentrate source may have its own respective concentrates nozzle 105 attached to the vacuum dip processor 40 or may share a concentrates nozzle 105 in combination with another concentrates source. The amount and combination of each process solution 90 component is predetermined based upon the biological or food product to be processed and the water's pH value. Water is dispensed from the water source 91 into the vacuum dip processor 40 through the water line 1 10 via the water nozzle 1 15 in a similar manner as the concentrates, but with sufficient force as to mix and solublize the other components. The mixture of water, saline solution, additives, and organic acid(s) creates the processing solution 90.

[0034] The microprocessor 150 also sends commands via the control line 170 to the vacuum source 92. Upon receiving a command from the microprocessor 150, the vacuum source 92 begins to pull a partial vacuum within the vacuum dip processor 40 through a vacuum line 120. Vacuum line 120 is attached to the vacuum dip processor via the ball valve 71 , which is attached to the vacuum line port 70.

[0035] After the processing solution 90 is created and the partial vacuum environment is established, the microprocessor 150 issues commands via the control line 170 to the piston cylinder 50 so that the rod 52 is manipulated in a manner so as to expose the pretreated fillets 22 to alternating periods of submersion in the processing solution 90 and exposure to the partial vacuum. This repeated and alternating cycle of exposure and submersion eventually transform the pretreated fillets 22 into vacuum treated fillets 26.

[0036] The overall length of processing time, the intermittent time of partial vacuum exposure, and the intermittent time of process solution 90 submersion are controlled and monitored by the microprocessor 150 based upon the operator's selection of the food or biological product to process. For example, if the operator selects "Ground beef using the process selection switch 204, the microprocessor 150, after both the process solution 90 and partial vacuum environments had been established, would actuate the piston cylinder 50 to position the rod 52 in a first position that exposes the container 60 and its contents to the partial vacuum for a total duration of five seconds. After five seconds, the microprocessor 150 would actuate the piston cylinder 50 again to position the rod 52 in a second position that submerges the container 60 and its contents in the processing solution 90 for a duration of three seconds. After three seconds, the microprocessor repeats actuation commands to the piston cylinder 50 that alternates the rod's 52 position between the first position for five seconds and the second position for three seconds. This series of timed commands from the microprocessor 150 to the piston cylinder 50 effects repeated "dunking" of the container 60 and its contents from the partial vacuum into the processing solution 90 and back into the partial vacuum environment. The series of alternating commands issued by the microprocessor 150 to the piston cylinder 50 continues until an overall processing time has elapsed.

[0037] The different preset timed exposures for the biological or food product to the partial vacuum and the processing solution 90 represents a novel and superior optimization of the process 10 not available in the prior art. The differentiation of exposure and submersion times gives treated biological or food products maximum benefits of vacuum dip processing-destruction of bacteria, removal of "off-flavor" chemicals, removal of chelating agents bound to heavy metals, removal and stabilization of fats, improvement of shelf life-while minimizing exposure of the biological or food product to the processing solution 90. Additionally, the preset exposures controlled by a microprocessor free the operator from monitoring and acting in the vacuum dip process itself, thereby improving reliability of product produced and freeing the operator from the burdens of the treatment process. As well, the repeated "dunking" motion is novel and superior to the prior art "tumbling" motion because it is gentler and easier to control, and permits materials that cannot easily be tumbled, such as cut flowers, nuts, coffee beans, soybeans, fruits and vegetables, to be processed using the process 10.

[0038] During the processing of pretreated fillets 22 into vacuum processed fillets 26, the microprocessor monitors the pH of the processing solution 90 by receiving pH data input via data collection line 160 from a pH sensor 140 attached to the vacuum dip processor 40. Upon the pH value exceeding a predetermined threshold value, the microprocessor 150 commands the organic acid(s) source 94 to dispense the proper volumes and combinations of organic acid(s) to the vacuum dip processor 40 via process lines 100. The organic acid(s) dispensed are incorporated into the process solution 90 to readjust the processing solution's 90 pH back into the desired operating range. The proper volumes and combinations of organic acid(s) dispensed may reflect the product being processed by the vacuum dip processor 40 via input received from the product selection switch 204. Microprocessor 150 may perform this adjustment step as many times as required to maintain the processing solution's 90 pH in a predetermined operating range. In one embodiment, the microprocessor 150 may control the process solution's 90 pH range within a range between and including pH values of 1 to 9. In an alternative embodiment, the volumes and combinations of organic acid(s) may be predetermined and are dispensed and incorporated into the processing solution 90 by way of a predetermined time schedule.

[0039] Upon the overall processing time lapsing, the microprocessor 150 commands the piston cylinder 50 to position the rod 52 so that the container 60 is out of the processing solution 90, or the "default" position, where it remains until the operator releases the partial vacuum on the vacuum dip processor 40. The operator can then access the vacuum-processed fillets 26 by closing the ball valve 71 , opening the ball valve 73 to break the vacuum seal, unlocking the locks 48, opening the lid 46, and removing the vacuum-processed fillets 26 from the container 60. The default position the container 60 is out of the process solution 90 to prevent chemical and osmotic damage and other undesired effects on the now vacuum-processed filets 26 as a result of unintended or prolonged exposure to the processing solution 90. The default position also minimizes operator contact with the processing solution 90. The operator then may further handle the vacuum-treated fillets 26 according to the ordinary practices of the processing industry, such as placing the product in a display packaging 28.

[0040] The vacuum dip processor 40 has a number of safety and override features to permit operator intervention when necessary. A manual stop button 208 on the control panel 200 permits the operator to manually terminate the overall processing of the biological or food product. Upon the operator pushing the manual stop button 208, the microprocessor 150 commands the piston cylinder 50 to position the rod 52 so that the container 60 reaches the default position. The vacuum dip processor 40 also has a "kill" switch (not shown) that disengages the piston cylinder 50 from operating when the lid 46 of the vacuum dip processor 40 is ajar.

[0041] The processing solution 90 is removed from the vacuum dip processor 40 by way of a drain 80 attached to the bottom dome 43 with a ball valve 82 attached. Best practice is to have a crow's foot connection 84 in conjunction with the ball valve 82 so as to permit attachment of a hose with similar crow's foot connection (not shown) to controllably drain the processing solution 90 from the vacuum dip processor 40. Spray nozzles (not shown) on the underside of the lid 46 may be actuated to assist cleaning the vacuum dip processor 40 of processing residue.

[0042] Figure 4 is a flow diagram that illustrates the sequence of process steps performed by an exemplary vacuum dip process, including the information flow between the operator input buttons on control panel 200, microprocessor 150, pH sensor 140, piston 50, water source 91 , vacuum source 92, saline solution source 93, organic acid(s) source(s) 94, and additives source 95. It should be understood from the present invention that the process steps in the Figures maybe performed in various sequences without departing from the scope of the present invention.

[0043] According to Figure 4, processing begins with a selection of the food or biological product in a product selection block 500 to be later sorted in a product sorting block 502. The food or biological products are then processed in a raw product processing block 504, in the case of the prior red meat example the fillets 18, and then pretreated for processing in the pretreatment process block 506.

[0044] The following steps indicated by dashed block 508 indicate steps involving preparation of the vacuum dip processor 40 for processing. In a load fillets block 510 the pretreated fillets 22 are loaded into the vacuum dip processor 40 by inserting into the container 60 and closing and locking the vacuum dip processor 40. The operator then initiates the process by turning the vacuum dip processor 40 "on" in an on/off switch block 512, selects the proper process to perform in a process selection block 514, and presses the "start" button in a start process block 516. The information flow of an open loop system for determining the operational setting of the process selection switch 202 is received by the operator by the product selection block 500 via a feedforward information line 522 from the production selection block 500. Processing solution 90 then fills the vacuum dip processor 40 at fill with solution block 518 and a partial vacuum is created in the vacant space within the vacuum dip processor at partial vacuum block 520. The vacuum dip processor 40 is now ready for processing pretreated fillets 22.

[0045] In one embodiment of the invention, data generated at process selection block 514 is fed forward to determine the composition of the processing solution 90. The selection of the process in block 514 in combination with the depressing of the "start" button in block 516 relays instructions via the feed-forward information lines 522 to the microprocessor 150 (not shown). The microprocessor 150, in response to the inputs from blocks 514 and 516, sends commands via the feed-forward lines 522 to distribute a fixed quantity of saline solution 560, organic acid(s) 562, additive 564, and water 566 to the vacuum dip processor 40 to create the process solution 90 specific to the selected process. Additionally, the microprocessor 150 also feeds forward variable values based upon the process selection block 514 for the pH control range 570, the first predetermined time period 572, the second predetermined time period 574, and the overall processing time 576.

[0046] The following steps indicated by dashed block 524 indicate steps involving processing of the pretreated fillets 22 of Figure 2, into vacuum treated fillets 26. After beginning the vacuum dip processing at processing block 526, a comparison of the overall processing time 576 is made to the time elapsed in processing the pretreated fillets 22 in the overall processing time comparison block 528. If the decision block 528 determines that the overall processing time 576 has not elapsed, then vacuum dip processing continues. Upon continuation of processing, the pH level of the processing solution is obtained at pH monitoring block 530. The process pH value is compared to the pH control range 570 value at pH control range comparison block 532. If the process solution's 90 pH is not within the range set by the pH control range 570 value, a signal sent via feedback information line 536 to add additional organic acid(s) to the processing solution 90 at acid addition block 534. Upon addition of supplemental organic acid(s), the process is fed back via feedback information line 536 so that the processing solution 90 is evaluated again at the pH control range comparison block 532 for conformity to the pH control range 570 value. If the processing solution's 90 pH is within the range set by the pH control range 570 value, the process steps forward. Upon continuation of processing, the pretreated fillets 22 are exposed to the partial vacuum environment at exposure block 538. Upon exposing the pretreated fillets 22 to the partial vacuum, the first time period comparison block 540 compares the time of exposure of the pretreated fillets 22 to the partial vacuum to the first predetermined time period 572 value. If the exposure comparison block 540 determines that the pretreated fillets 22 have not been exposed long enough versus the value of the first predetermined time period 572 variable, the exposure is maintained at maintenance block 542 and the process feed back via feedback information line 536 for comparison again in the exposure comparison block 540. If the time of exposure is equal to or exceeds the first predetermined time period 572 value, the process steps forward. Upon continuation of processing, the pretreated fillets 22 are submerged into the processing solution 90 at submersion block 544. Upon submerging the pretreated fillets 22 to the processing solution 90, the second time period comparison block 546 compares the time of submersion of the pretreated fillets 22 to the second predetermined time period 574 value. If the submersion comparison block 546 determines that the pretreated fillets 22 have not been submerged long enough, the submersion is maintained at maintenance block 548 and the process feed back via feedback information line 536 for comparison again in the submersion comparison block 540. If the time of submersion is equal to or exceeds the second predetermined time period 572 value, the process steps forward and feeds back via feedback information line 536 to a point before the overall processing time comparison block 528. In this feedback loop, the vacuum dip processor 40 repeats the cycling of exposure and submersion that transforms p retreated fillets 22 into vacuum treated fillets 26 while controlling, depending on the product being processed, both the individual exposure times to the partial vacuum and process solution environments. This gives the improved and novel benefit of minimizes overall processing time while achieving maximum beneficial effects with minimal product damage. When overall processing time comparison block 528 determines that the overall processing time has elapsed based upon the overall processing time 576 variables, then the vacuum dip process proceeds through termination steps. The container 60 is positioned in the "default" position in "default" position block 550 and the vacuum dip processor 40 processing ends at end processing block 552.

[0047] After the vacuum dip processor 40 has halted processing, the overall process continues at block 554 where the vacuum dip processed fillets 26 are sorted at block 554 and then packaged at block 556 to produce packaged fillets 28.

[0048] One of skill in the art would understand that although the above described processes are for beef or fish, the process of the present invention is applicable to any animal or plant product that contains heavy metal, whether domesticated/farm produced or wild. The metal-binding chelating agent is added to the aqueous solution and the process may include assessing the amount of heavy metal content in the food product before and after processing.

[0049] In one embodiment, the food product is fish or shellfish. Fish include, but are not limited to salmon, catfish, swordfish, shark, king mackerel, tilefish, Pollack and tuna. Shellfish include, but are not limited to, shrimp, lobsters, crayfish, crabs and are also intended to include bivalves, such as oysters, mussels and clams.

[0050] In another embodiment, however, the food product being treated is a plant. The plant may be a grain, such as maize, wheat or soybean. It is known that soybeans can absorb heavy metals in soil that has been exposed to sewage sludge (Reddy et al., "Heavy-Metal Absorption by Soybean on Sewage Sludge Treated Soil," J. Agric. Food Chem. 34: 750-753 (1986)) or in instances of crude oil contamination (Kisic, et al., "Heavy Metals Uptake by Aerial Biomass and Grain of Soybean," Soybean- Biochemistry and Physiology, InTech (Publ.) (201 1)). Thus, the present invention is needed to treat soybeans in situations where the source (i.e., the location of the soybean farm) is either not known or is of questionable quality.

[0051] One of skill in the art would understand that adjustments would be made to the solution concentrations, pH's and timing and length of cycles, depending upon the product and the size of the product being treated.

[0052] In one embodiment, the food is catfish and catfish tissue is sampled and the content of mercury in the sample is assessed using cold vapor atomic absorption spectrometry. One of skill in the art would understand that other methods and equipment are available for assessing the amount of heavy metal in a food sample. For instance, a Mercury Analyzer could be used. Catfish from a tested batch could then be gutted and then processed according to the invention.

[0053] In another embodiment, the catfish is de-headed, skinned, deboned, filleted and then processed in a dip vacuum processor, as described above, having a basket for holding the fish and containing an aqueous solution comprising less than 1 % (w/v) of ascorbic acid and a hypotonic sodium chloride (between 0.1 and 1 % (w/v)) and 0.125- 5% (w/v) polygalatcuronic acid, as a chelating agent. The vacuum internal pressure is maintained between fifteen (15) and twenty eight (28) inches of mercury (Hg). Preferably, the internal pressure is at twenty five (25) inches of mercury. The fish is cycled in and out of the aqueous solution every 3 to 8 to seconds, and preferably every 5 seconds, for a period of 6 to 25 minutes, and preferably for a period of 20 minutes. The pH is maintained at about 3.5. The temperature is maintained at ambient room temperature. The fish is then rinsed with water or mild water/base mixture content and assessed for mercury content using cold vapor atomic absorption spectrometry. In one embodiment, the rinsing removes the chelate-metal. In another embodiment, the chelate-metal is not removed but is not absorbed by the consumer and is passed through the digestive tract.

[0054] In another embodiment, the processed food is soybeans. The cracked soybeans are placed in a vacuum tumbler, as described above. In one embodiment, the cracked soybeans have been previously processed to mechanically remove the oil. The cracked soybeans are put into an aqueous solution comprising 0.5 to 2% (w/v) citric acid. No sodium chloride is added to the aqueous solution. Also included in the aqueous solution is a chelating agent, which is .1 M HCI. The pH of the aqueous solution is maintained at 2.1 -2.8. The temperature is maintained at ambient temperature. The soybeans are tumbled at 8 RPM for 6 to 20 minutes, preferably for 8 minutes. The vacuum internal pressure is maintained between fifteen (15) and twenty eight (28) inches of mercury (Hg). Preferably, the internal pressure is at twenty five (25) inches of mercury.

[0055] One of skill in the art would understand that the process of the invention could be performed on a commercial scale or at home, by a consumer. For instance, the home or small scale vacuum tumbler suitable for use in the invention could be those which are described in US Patent Nos. 7,007,594 and 7,838,054, the entire contents of which are hereby incorporated by reference. Although these patents are directed to methods of marinating food, the vacuum tumblers described therein are applicable for processing foods to remove heavy metals. Chelating agents could be added to the marinating liquids or to organic acid and/or salt solutions described above in connection with other vacuum tumblers.

[0056] Thus, in one embodiment, the invention is directed to a kit for purposes of removing heavy metals from food products, such as for example, meat and fish, at home. Such a kit would contain one or more a chelating agents and solutions suitable for use in a vacuum tumbler or vacuum dipper, such as a solution of citric or ascorbic acid and a salt and combinations thereof. Such kits could contain containers containing pre-mixed solutions or chemical compounds in powder form with instructions for mixing and using the same.

[0057] In another embodiment, the vacuum tumbling process could be continuous, as described in US patent application Serial No. 61/477,957, the contents of which are hereby incorporated by reference. The essential feature of the invention is the "treatment" of the product by cycling of the product to be treated between a vacuum and an aqueous solution containing an organic acid and a chelating agent. This can be accomplished in a variety of ways, including but not limited to moving the product by tumbling, rotating, dipping, or movement of the product along a conveyor. Thus, when the term "vacuum tumbler" is used, it includes a dipping and a rotating vacuum machine. If the process is continuous, the product may be hung, as in the case of poultry, beef, pig or lamb carcasses, or the product may be moved in baskets or other containers, as in the case of fish, shell fish, vegetables or fruits. In another embodiment, the cycling between the vacuum and the solution occurs by way of increasing and then decreasing levels of solution to periodically expose the product to the vacuum. An example of a continuous flow vacuum process is shown in Figure 5. In Figure 5, the food (e.g., poultry) is attached to a line which is a shackle conveyor and which moves continuously in and out of the vacuum/solution. As such, the food is dipped in and out of the solution. The temperature and pH of the solution is monitored throughout the process. In one embodiment, the shackle conveyor also moves the food from one to the other subsequent vacuum tumbler machines and to the final stages for processing and packaging.

[0058] It should be understood by the skilled artisan, however, that the process according to the present invention can be a combination batch and conveyor process or just a conveyor process and can involve one or more vacuum tumbler machines. For instance, in one embodiment, the raw foods are rotated in a vacuum tumbler, as described in U.S. Patent No. 6,896,921 , and then removed by conveyor or other means to a second vacuum tumbler and so on. This is a combination conveyor and batch process. In an alternative conveyor only process, the raw foods are dipped in and out of the solution and vacuum continuously along a conveyor. According to the process of one embodiment of the invention, at least three vacuum tumbler machines are used in sequence to process the raw food product. The machines may be the same or different. In one embodiment, the vacuum tumbler machines have different lengths. For instance, the machines may range in length from 8 to 100 feet. Each machine machine contains an aqueous solution comprising at least one chelating agent, an organic acid and optionally sodium chloride. In one embodiment, no phosphates are used during the process.

[0059] Thus, a variety of vacuum-solution processes are available for use in removing heavy metals for foods, according to the invention. In all cases, after a sufficient amount of time has been allowed for the ligand to permeate the entire food product and bond to the heavy metal within the contaminated food product, e.g. from a few seconds to many minutes depending on the granularity of the food product, the contaminated food product is put through a rinse, such as water. The resulting water solution containing both the ligand solution and the chelate formed by the ligand and the heavy metal of the contaminated food product can then be subjected to a separation treatment, which removes the chelate, which can then be disposed. Upon rinsing, the contaminated food product is transformed into a clean food product, meaning that the heavy metal has been substantially reduced or removed. The clean food product can then be put through its conventional processing, which may include further treatments and rinses. In one embodiment, however, the chelate is not totally or partially removed from the food product in the rinse step. Rather the ligand bound to the heavy metal in the tissue of the food product remains but the heavy metal is not free to be absorbed by the consumer. Rather, the heavy metal is chemically bound to the chelating agent, and is therefore passed through the gastrointestinal tract like an insoluble fiber. An example of a chelating agent that functions as an insoluble fiber, in this regard, is polygalatcuronic acid.

The following Examples are for illustration purposes only and are not intended to limit the invention in any way. EXAMPLES

Example 1

[0060] Catfish tissue is sampled and the content of mercury in the sample is assessed using cold vapor atomic absorption spectrometry. Catfish from the tested batch is gutted and processed in a dip vacuum processor, as described above, having a basket for holding the fish and containing an aqueous solution comprising less than 1 % (w/v) of ascorbic acid and a hypotonic sodium chloride (less than 0.9% (w/v)) and 0.125-5% (w/v) polygalatcuronic acid as a chelating agent. The vacuum internal pressure is maintained between fifteen (15) and twenty eight (28) inches of mercury (Hg). The fish is cycled in and out of the aqueous solution every 5 seconds for a period of 20 minutes. The pH is maintained at 3.5. The temperature is maintained at ambient room temperature. The fish is then rinsed with water or mild water/base mixture content and assessed for mercury content using cold vapor atomic absorption spectrometry.

Example 2

[0061 ] Cracked soybeans in which oil has been mechanically extracted are placed in a vacuum tumbler, as described above, in an aqueous solution comprising less than 1 % (w/v) citric acid. No sodium chloride is added. Also included in the aqueous solution is a chelating agent, which is .1 M HCI. The pH of the aqueous solution is maintained at 2.1 -2.8. The temperature is maintained at ambient temperature. The soybeans are tumbled at 8 RPM for 8 minutes. The vacuum pressure is the same as described in Example 1 .

Claims

1 . A method of processing a food, comprising: receiving a food that contains a heavy metal; exposing the food to an aqueous solution comprising an organic acid and a heavy-metal binding ligand which forms a heavy-metal chelate with the heavy metal in the food and; cycling the food between the solution and a vacuum environment; and rinsing the food.

2. The method of claim 1 , wherein the rinsing separates the heavy metal- chelate from the food.

3. The method of claim 1 , wherein the rinsing does not separate the heavy metal- chelate from the food and, when the food containing the heavy metal-chelate is consumed, the heavy metal-chelate passes through the body of a consumer without being absorbed.

4. The method of claim 1 , wherein the heavy metal is selected from the group consisting of mercury, lead, uranium, cadmium and mixtures thereof.

5. The method of claim 1 , wherein the food product is an animal protein.

6. The method of claim 1 , wherein the food product is a plant.

7. The method of claim 1 , wherein the food is fish or shellfish.

8. The method of claim 6, wherein the plant is soybeans.

9. The method of claim 1 , wherein the ligand is selected from the group consisting of polygalatcuronic acid, HCI, citric acid, ascorbic acid, alpha lipoic acid (ALA), phytic acid, N-acetyl-L-cysteine, oxalic acid, sodium thiosulfate and methylsulfonyl methane (MSM).

10. The method of claim 1 , wherein the cycling between the solution and the vacuum environment is repeated.