PROCESS FOR THE FILLETING, TREATING, PACKAGING, FREEZING, AND THAWING OF VARYING TYPES OF TUNA AND OTHER PELAGIC SPECIES

Abstract

A method of treating fish to maintain freshness after freezing and thawing. A whole fish is chilled and cut into four loins, each with two flat sides forming a corner. The loins are chilled and either sliced cross sectionally to form steaks or sliced parallel to one of the flat sides to form sashimi slabs. If sashimi slabs are formed, the slabs are then preferably dipped in a warm flavor enhancing solution. The steaks or slabs are then sealed in non-permeable bags, preferably in a “puzzle pack” configuration that maximizes density and minimizes interstices. The bag with the steaks or sashimi slabs is then submerged in a brine solution. A treatment gas is then injected into the bag. After a treatment time, the gas is removed and the bag is vacuum packed. The bags are then frozen for shipping and storage. When needed, the bags can be thawed in a brine solution.

Description

TECHNICAL FIELD

[0001] This invention relates to a process for the filleting into steaks and sashimi slabs, treating, packaging, freezing, and thawing of varying types of tuna and other pelagic species including swordfish and marlin.

[0002] For hundreds of years varying types of fresh tuna-yellowfin, bigeye, bluefin, skipjack, and albacore—served as raw sashimi have become a staple of the Japanese diet. Over generations, as the population of Japan has grown, the market for raw tuna has grown in both fresh and frozen form with a premium going to the characteristics of a bright red color for appearance and high oil content for flavor. This Japanese sashimi market draws the highest quality and highest value tuna in the world and affects the parameters of international tuna exporters and the U.S. domestic market.

[0003] Tuna is an important commodity in the international market, far dwarfing the volume and value of any other species. According to the U.S. National Marine Fisheries Service the total world tuna catch grew from 2.1 million metric tons in 1985 to three million metric tons in 1991 with two-thirds of it being traded in the international market at a value of $4.3 billion for fresh, frozen, and canned tuna. During this 1985 to 1991 period, Japan's tuna production has been flat at 700,000 metric tons and their share of the growing global catch has been steadily declining.

[0004] In contrast, Japanese imports of fresh and frozen tuna have increased three times in volume and five times in value from 1984 to 1993. In 1991, Japan imported $422 million of fresh tuna and $702 million of frozen tuna compared to U.S. imports of $88 million of fresh tuna and $181 million of frozen tuna. Similarly U.S. imports have been growing as the volume of the domestic Gulf of Mexico catch has been falling. Fifteen years ago the U.S. only imported and produced canned tuna. In 1991 the combined total of $269 million for fresh and frozen tuna imports approached the U.S. world high total of $380 million of canned tuna imports. Since the Japanese market is the largest and highest value market for premium product, all top sashimi grade fresh and frozen tuna finds its way to Japan.

[0005] In order to satisfy the demand of this key market for tuna, the technology of harvesting varying resources, packaging it, and delivering it to Japan has become more and more sophisticated over time. The waters surrounding Japan have been the first to be depleted and have given way to two primary types of fleets now fishing for sashimi grade tuna around the world.

[0006] The first type of fleets are comprised of small boats fishing for high value fresh tuna. These fresh fleets have expanded in the past five to ten years from a few hundred boats to several thousand boats in the Pacific alone primarily managed by Taiwanese, mainland Chinese, and Korean fishing companies. New technology such as gel-ice refrigerant and insulated packing materials, and expanding jet freight capacity from all over the Pacific and other parts of the globe make it possible to deliver fresh high value sashimi grade tuna to Japan. However, because of the high cost of air freight and fluctuating market conditions in Japan, only 30% to 80% of any given catch can profitably go to the Japanese fresh sashimi market. This leaves an ever increasing resource of byproduct (“by-catch”) of 20% to 70% of the catch that can be used as raw material for the process of the invention described herein for distribution to the tuna steaking and sashimi slab markets in the United States.

[0007] The second type of fleets are large super freezer boats that go out for up to three months at a time and freeze the fish whole after catching them. This dramatically expands the geographic fishing area these fleets may cover. Although the value for frozen sashimi grade tuna is less than fresh, the costs of transporting by surface rather than air are also less. Those whole frozen fish that are graded as acceptable for the sashimi market go to Japan, and those of lower grades are processed while frozen for the U.S. and other steaking markets. However, such processing has often resulted in unsightly brown freezer burn making the resultant frozen tuna steaks less marketable and marginally profitable as a product distributed to the U.S. market.

[0008] Since the primary fresh tuna market is in Japan, the U.S. fresh tuna market suffers from having a lower quality, lower value product facing the same high costs of international air freight as the higher value imports to the Japanese market. This results in lower profit margins and lower volumes for fresh tuna in the U.S. market. Importers of other species of seafood have solved this problem by shipping frozen product to the U.S. by much less expensive surface transportation. U.S. retailers thaw such products as needed and market them as “previously frozen.” Such products that have profitably penetrated the U.S. market are orange roughi, scallops, and shrimp. On seafood shelves, these products appear to be fresh, but are labeled as previously frozen and command a price slightly less, but close to the price of fresh seafood. The advantages to the retailer are lower costs and the ability to have continuous stocking by thawing whatever is necessary out of inventory.

[0009] Thus, the large potential U.S. market for “previously frozen” tuna steaks has not yet been profitably developed because of (1) a lack of sufficient raw material until now; and (2) a lack of technology that efficiently fillets, treats packages, freezes, and thaws the product while maintaining the bright red color and the appearance of freshness after thawing without unsightly browning. No one until now has developed a process that controls the primary aspects that allows previously frozen tuna to appear fresh-color, texture, and the ability to maintain its freshness for a period of time after thawing. The process described herein provides the technology necessary to profitably penetrate the U.S. frozen tuna steaking market just as similar previously frozen seafood products have done.

[0010] In addition, a secondary market of frozen sashimi slabs for Japanese restaurants and sushi bars can now be exploited in the U.S. by adding a flavor enhancing soaking step to the process described herein for tuna steaks. This allows tuna below sashimi grade for the Japanese market to be enhanced through treatment and provided as previously frozen sashimi to restaurants and sushi bars in the U.S.

[0011] It is therefore an object of the present invention to provide a process to efficiently fillet, treat, package, freeze, and thaw varying types of tuna and other pelagic species.

[0012] It is a further object of this invention to provide a filleting component of a process that most efficiently fillets each tuna into four loins—left back, right back, left belly, and right belly—and then fillets each loin into tuna steaks or sashimi slabs.

[0013] It is a still further object of this invention to fillet each loin into tuna steaks of a shape that can be packed to a maximum density in a rectangular configuration.

[0014] It is a still further object of this invention to fillet each loin into sashimi slabs of an alternative shape that can be packed to a maximum density in a rectangular configuration.

[0015] It is a still further object of this invention to treat each sashimi slab in a solution to stabilize color, enhance flavor, and firm texture.

[0016] It is a still further object of this invention to treat each tuna steak or sashimi slab with a gas flush to maintain or improve color and freshness.

[0017] It is a still further object of this invention to package each layer of tuna steaks so they may be handled individually or packaged together with other layers without damaging the product.

[0018] It is a still further object of this invention to absorb excess moisture after thawing and to reduce or eliminate air contacting the meat while frozen resulting in unsightly browning.

BACKGROUND ART

[0019] Various aspects of the individual steps of the multiple step process of this invention are known in the art, and various aspects appear to be new, useful, and unobvious. However no reference can be located that describes the combination of process steps disclosed herein.

[0020] U.S. Pat. No. 1,977,373 to Birdseye discloses a process where individual fillets are wrapped and boxed before being frozen. This process utilizes a rigid cardboard container rather than a flexible non-permeable plastic barrier bag utilized in the invention described herein.

[0021] U.S. Pat. No. 2,555,584 to Fairbank discloses a process of packing and orienting meat and poultry foodstuff in a rigid tray with five sides which is then inserted into an envelope. The tray covered on five sides prevents meat and poultry oils from contacting the packing envelope and causing failure in the heat sealing of the envelope. Fish oils do not contaminate a flexible non-permeable plastic barrier bag utilized in the invention described herein, and a four sided spatula shovel is used to pack the bag rather than being part of the package.

[0022] U.S. Pat. No. 3,593,370 to Lapeyre discloses a method for butchering tuna while frozen, teaching the cutting of the tuna into cross sections and removing the skin and entrails while the cross sectional pieces remain substantially frozen. The invention described herein prefers unfrozen tuna for both the butchering and packing steps. In addition, the invention described herein teaches a butchering process whereby the whole tuna is first subdivided into sections parallel with the longitudinal axis, whereas Lapeyre teaches to first subdivide into cross sections transverse to the longitudinal axis.

[0023] U.S. Pat. No. 3,594,191 to Lapeyre discloses an improved method for commercial processing of tuna for a canned pack where the tuna is subdivided into parts while in a substantially frozen condition. Process steps relating to canning are not relevant to the invention described herein. U.S. Pat. No. 2,920,968 to Grandy discloses the packing of individual frozen seafood articles such as shrimp by sealing each in a plastic strip. The elongated strip is then boxed. The invention described herein first packs then freezes the product.

[0024] U.S. Pat. No. 2,020,109 to De Meric De Bellefon et al discloses the storage of fresh whole unprocessed fish in hermetically sealed boxes with an optional freezing step of submersing the sealed boxes into a brine.

[0025] U.S. Pat. No. 3,959,505 to Valiant discloses a process for packing tuna into cylinders for canneries.

[0026] U.S. Pat. No. 4,812,320 to Ruzek discloses a process for forming and vacuum packing fresh meat products onto a tray.

[0027] U.S. Pat. No. 5,356,649 to LaMotta et al discusses placing a raw food product on a tray, wrapping the tray, cooking the product, and then freezing the product. The invention described herein does not utilize cooking and the tuna is not packed in tray compartments.

[0028] U.S. Pat. No. 3,637,405 to Mendelson et al discusses the step of placing poultry on a plastic tray, enclosing the tray in plastic, and aging at specific temperatures for specific times to improve shelf life and tenderness. The aging characteristics of this process refer to mammals and not to fish.

[0029] U.S. Pat. No. 3,036,923 to Mahon et al teaches inhibiting the loss of moisture by dipping seafood into sodium and potassium salts of dehydrated phosphoric acids. The invention described herein does not utilize phosphoric acids.

[0030] U.S. Pat. No. 4,978,546 to Haram discusses placing fresh fish in a cooling liquid containing alcohol which is not used in the invention described herein.

[0031] U.S. Pat. No. 4,657,768 to Nagoshi discusses a freezing method for perishable foods including preserving fish products in a brine. The invention described herein does not utilize this method.

[0032] U.S. Pat. No. 4,601,909 to Nagoshi discusses freezing seafood in a brine solution containing a percentage of rapeseed oil to reduce freezing time which is not used in the invention described herein.

DISCLOSURE OF INVENTION

[0033] The process of this invention is to efficiently fillet, treat, package, freeze, and thaw varying types of tuna and other pelagic species. Each whole tuna is first ice brine chilled and then filleted into four loins—left back, right back, left belly, and right belly. A majority of the loins go to the steaking fillet process, while a minority of the loins go to the sashimi slab fillet process.

[0034] Each loin in the steaking fillet process is then ice brine chilled and filleted manually using a jig, or mechanically using a meat slicing machine, into cross sectional tuna steaks in a preferred range of ¾″ to 1″ thick. Some tuna steaks are larger and some smaller, and all share the common characteristic of two sides being at 90 degrees.

[0035] The tuna steaks are next packed on a four sided spatula shovel area of {fraction (91/2)}″ by {fraction (121/2)}″ with the 90 degree cut sides of four steaks aligned with the four corners of the rectangular area, and the interior area of the rectangle “puzzle packed” with tuna steaks of varying size and orientation until a maximum density is achieved.

[0036] The tuna steak puzzle pack configuration is covered with an absorbent paper towel and placed in a non-permeable barrier bag with the spatula shovel. The shovel is flipped over, tilted up, and removed. The tuna steak puzzle packs are next low pressure vacuum packed, sealed, and placed in an ice brine.

[0037] Each loin in the sashimi slab process is first cut into loin sections 13″ in length. Each loin section is filleted longitudinally, slicing slabs in a preferred range of ⅞″ to 1″ thick, and parallel to one of the 90 degree cut sides of each loin section, either manually in a jig, or mechanically with a meat slicing machine.

[0038] Each sashimi slab is dipped in a warm flavor enhancing solution for three minutes, dried, and packed in the spatula shovel to a maximum density in the sashimi slab puzzle pack configuration. The length and thickness of the sashimi slabs are consistent, and the width and angle of the uncut edge vary. These characteristics allow for a configuring process of rotating and flipping the slabs to minimize the open space in a {fraction (91/2)}″ by {fraction (121/2)}″ rectangular area on the spatula shovel.

[0039] The sashimi slab puzzle pack configuration is covered with an absorbent paper towel and placed in a non-permeable barrier bag with the spatula shovel. The shovel is flipped over, tilted up, and removed. The sashimi slab puzzle packs are next low pressure vacuum packed, sealed, and placed in an ice brine.

[0040] Each puzzle pack is removed from the brine and dried off. A preferred {fraction (1/16)}″ to ⅛″ diameter hole is cut into each pack and a gas nozzle is inserted to add a pillow like amount of a varying blend of gases to the bag. Each gas blend varies with the species, the color, and the market to which the product is going. After the gas is added, each puzzle pack bag is closed with a clamp, placed on rolling treatment racks, and transferred to cold storage for a preferred treatment period of 4 to 12 hours.

[0041] After sufficient treatment exposure the racks are removed from cold storage and returned to the treatment area. Each clamp is removed from each puzzle pack bag, a vacuum nozzle is inserted and the gas is evacuated into the atmosphere outside the treatment room.

[0042] Each puzzle pack is next taken to the vacuum packing area and cut open. The paper towel is removed, a permeable plastic membrane backed with absorbent diaper material is added, and the unit is vacuum packed, resealed, and placed in an ice brine.

[0043] Each puzzle pack is next removed from the brine, dried off, and placed on freezer racks to be taken for high air circulation blast freezing at a preferred range of less than minus 40 degrees Fahrenheit.

[0044] Four to five frozen puzzle pack layers are next packed in master shipping cartons which are waxed or treated with a water resistant coating to prevent deterioration. Within each carton foam plastic layers act as cushions between puzzle pack layers. 25 shipping cartons are placed on pallets and shrink wrapped for shipping in frozen containers at less than 10 degrees Fahrenheit.

[0045] The seafood product retailer, restaurant, or sushi bar thaws only the number of puzzle packs needed in a cold water and salt solution for approximately forty minutes. Each package is dried, cut open, and the tuna steaks or sashimi slabs are displayed for sale in a store or served in a restaurant.

[0046] Other objects, features and advantages of the present invention will become more full, apparent from the following detailed description of the preferred embodiments for carrying out the invention and the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0047] FIG. 1 is a flow chart of the complete process showing the distinct physical areas necessary and the steps performed in each area.

[0048] FIG. 2 is a full fish description of loin locations.

[0049] FIG. 3 is a view of the V-shaped jig for manually cutting tuna steaks from tuna loins.

[0050] FIG. 4 is the tuna steak cutting plan for each tuna loin resulting in varying size tuna steaks.

[0051] FIG. 5 is a view of the spatula shovel used for configuring the tuna steaks or the sashimi slabs and inserting them into barrier bags.

[0052] FIG. 6 is an example of a tuna steak puzzle pack configuration.

[0053] FIG. 7 is a view of the sashimi slab jig with guide bars and cutting board.

[0054] FIG. 8 is the sashimi slab cutting plan for each tuna loin resulting in varying size sashimi slabs.

[0055] FIG. 9 is an example of a sashimi slab puzzle pack configuration.

[0056] FIG. 10 is a view of the gas treating step with a gas nozzle in a puzzle pack barrier bag.

[0057] FIG. 11 is a view of the gas treatment rolling rack for transport to the cold storage treatment room.

[0058] FIG. 12 is a view of a tuna steak puzzle pack with permeable plastic membrane vacuum packed.

[0059] FIG. 13 is a view of the master shipping carton.

BEST MODE FOR CARRYING OUT INVENTION

[0060] The best mode contemplated for carrying out the present invention is the preferred embodiments of the steps of the process illustrated by way of example in FIGS. 1 through 13.

[0061] Referring specifically to FIG. 1, each tuna is brought fresh to the processing facility joining room where the air temperature is kept within an operability range of 32 to 45 degrees Fahrenheit, a preferred range of 36 to 40 degrees and an optimal temperature of 38 degrees Fahrenheit. Each tuna comes in on crushed ice or in a tote of a brine solution and is placed in a salt brine chilling tank with water, ice, and sufficient salt to keep the solution temperature at an operability range of 28 to 36 degrees Fahrenheit, a preferred range of 30 to 32 degrees Fahrenheit and an optimal temperature of 31 degrees Fahrenheit.

[0062] Referring to FIG. 2, after chilling, each tuna is cut into four loins—left back, right back, left belly, right belly—with skin removed and partial red bloodline remaining at the apex of each loin as a visual clue for freshness. Since the tuna without head and gills has the form of a cylinder tapered at each end, a cross section taken at any point along its length will show each of the four loins as a 90 degree pie shaped sector with the cross sections and the corresponding four pie shaped sectors smaller at the ends and largest in the middle.

[0063] The loins are next placed in a colder brine solution of water, ice, and sufficient salt to keep the solution temperature at an operability range of 20 to 27 degrees Fahrenheit, a preferred range of 22 to 25 degrees Fahrenheit and an optimal temperature of 24 degrees Fahrenheit. The loins are chilled until the temperature of each loin is in an operability range of 27 to 35 degrees Fahrenheit, a preferred range of 28 to 32 degrees and an optimal temperature of 30 degrees Fahrenheit. The loins are carried in brine totes to the filleting room which is kept within the same operability range, preferred range, and optimal temperature as the loining room.

[0064] The loins are trimmed if necessary, inspected, and dried with sterile absorbent paper towels. The majority of the loins are to be filleted for the much larger tuna steaking market. Referring to FIG. 3, each loin is placed with the 90 degree cut sides down into a food-grade plastic V-shaped jig with slots for slicing with a long thin bread knife or a Japanese tuna knife, or alternatively in a meat slicing machine. Each loin is sliced cross sectionally into an operability range of ⅝″ to {fraction (11/8)}″ thick pie shaped tuna steaks and a preferred range of ¾″ to 1″. Referring to FIG. 4, some tuna steaks are larger and some smaller, and all share the common characteristic of two sides being at 90 degrees.

[0065] Referring to FIG. 5, a food-grade plastic four-sided spatula shovel with handle is used for configuring and packing the tuna steaks into tuna steak “puzzle pack” configuration. The inside dimensions of the spatula shovel are {fraction (91/2)}″ wide by 14″ long for the bottom side by {fraction (11/2)}″ high for the back wall and two side walls with a line marked across the interior width at {fraction (121/2)}″ forward from the back wall. The back wall, two side walls, and the {fraction (121/2)}″ line form the rectangular area of {fraction (91/2)}″ by {fraction (121/2)}″ into which are placed the tuna steaks in puzzle pack configuration.

[0066] Referring to FIG. 6, four of the larger tuna steaks are selected and the 90 degree sides of each are aligned with the corners of the rectangular area in the spatula shovel. Other tuna steaks are then placed in the interior of this outer rectangle with the flexibility of the raw steaks allowing for some distortion of the 90 degree sides and the arc side to maximize the density and minimize the interstices within the rectangle. The result is the puzzle pack configuration with a weight within an operability range of 3.3 to 6.0 lbs with a preferred range of 4.0 to 5.33 lbs. The average ideal weight of a puzzle pack configuration varies with the thickness preferred by the customer with ¾″ thick steaks averaging 4.0 lbs, ⅞″ thick steaks averaging 4.66 lbs, and 1″ thick steaks averaging 5.33 lbs.

[0067] The tuna steak puzzle pack configuration in the spatula shovel next has a sterile absorbent paper towel 10″ by 13″ placed on top and tucked in along the sides and back wall. Then the spatula shovel with the tuna steaks is slid into a non-permeable barrier bag. The spatula shovel and bag are flipped over with the absorbent towel now on the bottom of the tuna steaks. The spatula shovel is tilted up with the front edge down and it is pulled out of the bag leaving the tuna steaks in the puzzle pack configuration.

[0068] The tuna steak puzzle packs are next low pressure vacuum packed, sealed and placed in a brine solution of water, ice, and sufficient salt to keep the solution temperature at an operability range of 23 to 30 degrees Fahrenheit, a preferred range of 25 to 27 degrees Fahrenheit and an optimal temperature of 26 degrees Fahrenheit. The tuna steak puzzle packs are carried in brine totes to the gas treatment room.

[0069] A minority of the loins are to be filleted for the smaller sashimi tuna slab market. Each loin is first cut into a multiple of 13″ long loin sections with a remainder section less than 13″ in length. This remainder section may be sliced into less than optimal length sashimi slabs, or alternatively into tuna steaks. Referring to FIG. 7, each 13″ loin section is placed in a food-grade plastic jig with two guide bars 24″ long by 1″ wide by varying thickness bolted in a counter sunk manner onto a 24″ long by 15″ wide food-grade plastic cutting board with 1″ by 2″ by 2″ supporting feet at the corners, or alternatively in a meat slicing machine. One of the guide bars is stationary and the other guide bar is movable with slots for the holding bolts retained by wing nuts under the cutting board.

[0070] Each 13″ loin section is placed with one of the 90 degree cut sides down on the cutting board, the other 90 degree cut side adjacent to the stationary guide bar, and the uncut natural tapered side of the loin section adjacent to the movable guide bar. A sashimi slab the thickness of the guide bars is sliced longitudinally from the bottom of the loin section with the cutting edge of a long thin bread knife, or a Japanese tuna knife, traveling parallel to the top of the guide bars. Each sashimi slab is removed and the remaining loin section is replaced in the jig for the next sashimi slab cut. Referring to FIG. 8, the process is repeated until the remaining loin section is below the guide bars. Each sashimi slab has an operability range of ¾″ to {fraction (11/4)}″ thickness and a preferred range of ⅞″ to 1″.

[0071] Each sashimi slab is next placed in a dipping solution which stabilizes the color, enhances the flavor, and firms its texture. The dipping solution is mixed in quantity in the following proportions: 150 liters of boiled or purified water; 15 kilos of baking soda; 4-5 kilos of non-iodized salt; 2-4 drops of smoke oil; and 15-20 granules, or 1-2 drops, resulting in a 10 parts per million solution of chlorine. The dipping solutions maintained at an operability range of 80 to 92 degrees Fahrenheit, a preferred range of 83 to 89 degrees Fahrenheit, and an optimal temperature of 86 degrees Fahrenheit. The sashimi slabs are placed in trays and each tray dipped into a tub of solution for an operability range of 2:00 to 4:00 minutes, a preferred range of 2:30 to 3:30 minutes, and an optimal range of 2:45 to 3:15 minutes. After dipping the slabs are dried with sterile absorbent paper towels.

[0072] This added step of dipping is viable for sashimi slabs and not for tuna steaks, since the price for the sashimi slabs is higher justifying the additional cost of this step. In addition, the enhanced flavor is more noticeable when the sashimi slabs are thawed and eaten raw. The flavor enhancement of this step would not be noticeable for cooked tuna steaks.

[0073] Referring to FIG. 9, we use the spatula shovel previously described in FIG. 5 for configuring and packing the sashimi slabs into a sashimi slab “puzzle pack” configuration. The spatula shovel's back wall, two side walls, and the line parallel to, and {fraction (121/2)}″ from, the back wall form the rectangular area of {fraction (91/2)}″ by {fraction (121/2)}″ into which the sashimi slabs are placed in a sashimi slab puzzle pack configuration. Each sashimi slab has two consistent dimensions of 13″ in length by a preferred range of ⅞″ to 1″ in thickness with three side edges cut at 90 degrees to one another and at 90 degrees to the top and bottom. The only surface of each sashimi slab that is variable is the natural uncut side of the loin that curves inward and upward from bottom to top resulting in a variable sloping angle of less than 90 degrees. Further, each sashimi slab is wider at one end and narrower at the other due to the curvature of the body of the tuna. Thus, each sashimi slab varies in the slopina angle of the uncut edge and in the width dimension.

[0074] One of the larger sashimi slabs is selected and placed with its 90 degree sides aligned with the corners of the rectangular area in the spatula shovel. The slab is compressed slightly so that its 13″ natural length fits within the {fraction (121/2)}″ of the rectangle. The second piece reverses its orientation with its widest end opposite the widest end of the first slab. In addition, the second is flipped over so that the angles of the uncut edges are parallel. This slab is similarly compressed to the {fraction (121/2)}″ of the rectangle. The process continues with each slab selected, and rotated or flipped as necessary to maximize the utilization of the space and to reduce the contortion of the sashimi slab mating surfaces.

[0075] The result is the sashimi slab puzzle pack configuration with a weight within an operability range of 4.0 to 6.66 lbs with a preferred range of 4.66 to 5.33 lbs. The average ideal weight of a puzzle pack configuration varies with the thickness preferred by the customer with ⅞″ sashimi slabs averaging 4.66 lbs, and 1″ thick steaks averaging 5.33 lbs.

[0076] The sashimi slab puzzle pack configuration in the spatula shovel next has a sterile absorbent paper towel 10″ by 13″ placed on top and tucked in along the sides and back wall. Then the spatula shovel with the sashimi slabs is slid into a non-permeable barrier bag. The spatula shovel and bag are flipped over with the absorbent towel now on the bottom of the sashimi slabs. The spatula shovel is tilted up with the front edge down and it is pulled out of the bag leaving the sashimi slabs in the puzzle pack configuration.

[0077] The sashimi slab puzzle packs are next low pressure vacuum packed, sealed and placed in a brine solution of water, ice, and sufficient salt to keep the solution temperature at an operability range of 23 to 30 degrees Fahrenheit, a preferred range of 25 to 27 degrees Fahrenheit and an optimal temperature of 26 degrees Fahrenheit. The sashimi slab puzzle packs are carried in brine totes to the gas treatment room referred to in FIG. 1.

[0078] Referring to FIG. 10, each of the tuna steak puzzle packs and the sashimi slab puzzle packs is removed from the brine solution and dried with sterile absorbent paper towels. Each non-permeable plastic bag is punctured with a hole of a diameter in an operability range of {fraction (1/16)}″ to {fraction (3/16)}″ and a preferred range of {fraction (1/16)}″ to ⅛″, a gas nozzle is inserted, and a treatment gas is injected into the bag to a level equal to a soft pillow-like amount sufficient to cover all the edges of each puzzle pack configuration. Then the nozzle is removed and the bag is sealed with a 1″ wide metal clamp covered with rubber.

[0079] A blend of gases is used depending on the desired treatment effect for the tuna steak and sashimi slab markets. To enhance the appearance of fresh after the freezing and thawing process, carbon dioxide, argon, and nitrogen inhibit bacteriological growth and decomposition. Oxygen maintains the natural color of the tuna, and blends including carbon monoxide can be used to improve color.

[0080] Referring to FIG. 11, the gas treated puzzle packs are placed on rolling racks with 48 shelves {fraction (131/4)}″ wide by 32″ long each holding two puzzle packs. The rack is rolled into the cold storage area referred to in FIG. 1 which is kept at an air temperature in an operability range of 25 to 31 degrees Fahrenheit, a preferred range of 27 to 29 degrees Fahrenheit and an optimal temperature of 28 degrees Fahrenheit. The bags are periodically agitated by slightly moving them or turning them over.

[0081] After sufficient treatment exposure time which varies with the blend of gases with an operability range of 2 to 24 hours and a preferred range of 4 to 12 hours, the racks are removed from the cold storage and taken back to the gas treatment area where each clamp is removed from each puzzle pack bag, a vacuum nozzle is inserted and the gas is evacuated into the atmosphere outside the treatment room.

[0082] Referring to FIG. 1, the puzzle pack bags are taken to the final vacuum packing area where each puzzle pack is placed with the paper towel side up and the tuna steaks or sashimi slabs facing down. Each puzzle pack bag is cut open, the paper towel is removed by hand, and a new pad with a permeable plastic membrane with an absorbent diaper material backing is placed over the top and around the edges of the puzzle pack configuration. This permeable plastic membrane facing the tuna steaks or sashimi slabs is {fraction (11)}″ wide by 14″ long by an operability range of ⅛″ to {fraction (5/16)}″ thick, and a preferred range of ⅛″ to ¼″ thick. It has the function of absorbing excess moisture after thawing and acts as extra padding around the corners and edges which are most susceptible to bumping and puncturing of the non-permeable barrier bag.

[0083] Next the unit is weighed and the weight and lot number are marked on the label and placed inside the bag. Then the bag is placed in a vacuum sealing machine which vacuums the bag, seals it, and trims off any excess plastic. The final vacuum packed puzzle packs are placed back into a brine solution of water, ice, and sufficient salt to keep the solution temperature at an operability range of 23 to 30 degrees Fahrenheit, a preferred range of 25 to 27 degrees Fahrenheit and an optimal temperature of 26 degrees Fahrenheit.

[0084] Referring to FIG. 12, the vacuum packed tuna steak puzzle packs with the permeable diaper membrane, and the vacuum packed sashimi slab puzzle packs with the permeable diaper membrane are removed from the brine solution, rinsed and dried with sterile absorbent paper towels. The puzzle packs are next loaded onto freezer racks and rolled into the freezer area where the product is blast frozen with a high circulation rate of cold air in an operability range of less than minus 10 degrees Fahrenheit and an optimal range of less than minus 40 degrees Fahrenheit.

[0085] Referring to FIG. 13, the master cartons have inside dimensions of 11″ wide by 14″ long by {fraction (51/2)}″ in height. Each box is waxed or treated with a water resistant coating to prevent deterioration during handling and exposure to air when water rapidly condenses on the outside after removal from frozen storage. Referring to FIG. 1, packing is done in the carton packing room with an air temperature in the operability range of 20 to 40 degrees Fahrenheit, and a preferred range of 25 to 30 degrees Fahrenheit. Either 4 or 5 units are placed in each carton for an operability range of 20 to 25 total lbs, and an optimal weight of 20 total lbs equal to 5 units averaging 4 lbs each or 4 units averaging 5 lbs each. Within each carton a foam plastic layer of 11″ wide by 14″ long by an operability range of 0.2″ to 0.4″ thick, and a preferred range of 0.25″ to 0.35″ thick, acts as a cushion between puzzle pack layers and fills any extra space in each carton.

[0086] Twenty-five cartons are placed on each pallet and stretch wrapped. The pallets are then returned to the freezer awaiting transport in frozen containers at an operability range of 10 degrees Fahrenheit or less, and an optimal range of minus 10 degrees Fahrenheit or less.

[0087] The thawing procedure is identical for tuna steak puzzle packs and for sashimi slab puzzle packs. The retailer, restaurant, or sushi bar thaws only enough for immediate sale by preparing a solution of cold water and one tablespoon of salt per gallon of cold water for each tuna steak or sashimi slab puzzle pack to be thawed. The salt prevents discoloring if the meat contacts the solution which is in an operability range of 40 to 50 degrees Fahrenheit, a preferred range of 42 to 48 degrees Fahrenheit, and an optimal temperature of 45 degrees Fahrenheit. Submerse each package for forty minutes or until partially thawed and easily separated. Remove from the solution and dry each package with a paper towel. Cut open the vacuum package, towel dry the tuna steaks or sashimi slab if necessary and display for sale in a refrigerated seafood section or prepare for sale in a restaurant or sushi bar.

INDUSTRIAL APPLICABILITY

[0088] This invention can be used to process varying types of tuna species and can similarly be used for other large bodied, pelagic species including marlin and swordfish.

Claims

1. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fish in a first ice brine solution containing water, ice and salt;

cutting the fish into four loins, each having a substantially V-shaped cross section;

chilling the loins in a second ice brine solution;

slicing the loins cross sectionally to form steaks;

sealing the steaks into non-permeable bags;

injecting a treatment gas into the bags;

evacuating the treatment gas from the bags after a sufficient treatment time;

vacuum packing the bags; and

freezing the steaks in the bags.

2. A method according to claim 1 further comprising:

placing the bags in salt water until the steaks are partially thawed; and

removing the steaks from the bags.

3. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fish having a backbone in a first ice brine solution containing water, ice and salt;

cutting the fish substantially horizontally and substantially vertically through an axis defined by the backbone to form four loins, each having a substantially shaped cross section;

chilling the loins in a second ice brine solution;

slicing the loins cross sectionally to form steaks;

sealing the steaks into non-permeable bags;

injecting a treatment gas into the bags;

evacuating the treatment gas from the bags;

vacuum packing the bags; and

freezing the steaks.

4. A method according to claim 3 further comprising:

placing the bags in salt water until the steaks are partially thawed; and

removing the steaks from the bags.

5. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fish in a first ice brine solution containing water, ice and salt;

cutting the fish into four V-shaped loins, each having two flat sides defining a corner and an arc shaped side;

chilling the loins in a second ice brine solution;

cutting the loins cross sectionally to form larger and other steaks;

placing four of the larger steaks in a substantially rectangular non-permeable bag having four corners so that the corners of each steak are in a corresponding corner of the bag;

placing other steaks between said four larger steaks in varying orientation to maximize density and minimize interstices within said rectangular bags;

sealing the bags;

injecting treatment gas into the bags;

evacuating the treatment gas from the bags;

vacuum packing the bags;

freezing the steaks.

6. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fish having a backbone in a first ice brine solution containing water, ice and salt;

cutting the fish vertically and horizontally through an axis defined by the backbone to form four V-shaped loins, each loin having two flat sides defining a corner and an arc shaped side;

chilling the loins in a second ice brine solution;

slicing each loin into sections parallel to one of said flat sides to form larger and other sashimi slabs;

placing a first larger sashimi slab in a rectangular non-permeable bag with four corners with said flat sides aligned with the corners of said bag;

placing a second larger sashimi slab in said rectangular bag in a reverse orientation and flipped over;

placing other sashimi slabs in said rectangular bag with said other slabs selected, rotated and flipped as necessary to maximize utilization of space and minimize contortion of the sashimi slabs;

sealing the sashimi slabs into the bag;

injecting treatment gas into the bags;

evacuating the treatment gas from the bags;

vacuum packing the bags;

freezing the sashimi slabs.

7. A method according to claim 6 further comprising:

placing the bags in salt water until the sashimi slabs are partially thawed; and

removing the sashimi slabs from the bags.

8. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fish in a first ice brine solution containing water, ice and salt;

cutting the fish into four V-shaped loins, each loin having two flat sides forming a corner and an arc shaped side;

cutting each loin substantially parallel to said flat sides to form sashimi slabs of predetermined thickness;

chilling the loins in a second ice brine solution;

placing the sashimi slabs into non-permeable bags

sealing the bags;

injecting treatment gas into the bags;

evacuating the treatment gas from the bags;

vacuum packing the bags;

freezing the sashimi slabs.

9. A method according to claim 8 further comprising:

placing the bags in salt water until the sashimi slabs are partially thawed; and

removing the sashimi slabs from the bags.

10. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a fish having a backbone in a first ice brine solution;

cutting the fish vertically and horizontally through an axis defined by the backbone of the fish to form four V-shaped loins, each loin having two flat sides defining a corner and an arc shaped side;

chilling the loins in a second ice brine solution colder than the first ice brine solution;

drying the loins;

cutting the loins substantially perpendicular to said flat sides to form steaks of larger and other sizes;

arranging four of the larger steaks on a rectangular substantially rigid supporting structure having four corners with a handle so that the flat sides of each steak are in a corner of the structure;

placing other steaks in the interior of the supporting structure between said four larger steaks in varying size and orientation to maximize density and minimize interstices within said rectangular bags;

sliding the structure with the steaks into a none-permeable plastic bag;

tilting the handle up and removing the structure but leaving the steaks in the plastic bag;

sealing and vacuum packing the bag;

submerging the bag in a third ice brine solution;

drying the bag;

injecting gas into the bag until all edges of the bag are covered;

clamping the opening in the bag where the gas was injected into the bag;

chilling the steaks and agitating them periodically;

evacuating the gas from the bag;

vacuum packing the bag;

submerging the steaks into a fourth ice brine solution;

removing the steaks from the fourth ice brine; and

freezing the steaks.

11. A method according to claim 10 wherein:

the first brine solution is at a temperature of between 28 and 36 degrees Fahrenheit;

the second brine solution is at a temperature of between 20 and 27 degrees Fahrenheit;

the third brine solution is at a temperature of between 23 and 30 degrees Fahrenheit; and the fourth brine solution is at a temperature of between and 30 degrees Fahrenheit.

12. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a substantially whole fresh fish in a first brine solution containing water, ice and enough salt to keep the solution temperature at between 28 to 36 degrees Fahrenheit;

cutting the fish on the vertical axis through the backbone of the fish;

cutting the fish on the horizontal axis through the backbone of the fish to form four V-shaped loins, each loin having two flat 90 degree sides and an arc shaped side;

skinning the loins;

chilling the loins in a second brine solution, colder than the first brine solution containing water, ice and salt at between 20 to 27 degrees Fahrenheit until each loin is between 27 to 35 degrees Fahrenheit;

drying the loins;

cutting the loins cross sectionally into slices of predetermined thickness to form larger steaks and other steaks;

arranging four of the larger steaks on a rectangular substantially rigid supporting structure having four corners with a handle so that the 90 degree sides of each larger steak are in a corner of the structure;

placing other steaks in the interior of the supporting structure between said four larger steaks in varying size and orientation to maximize density and minimize interstices in the interior of the supporting structure;

sealing and vacuum packing the bag;

placing the bag in a third ice brine solution at a temperature of between 23 to 30 degrees Fahrenheit;

inserting a gas nozzle into the bag;

injecting treatment gas into the bag;

clamping the opening in the bag where the gas nozzle was inserted

chilling the steaks at between 25 to 31 degrees Fahrenheit for 4 to 12 hours;

evacuating the treatment gas from the bags;

vacuum sealing the bags;

placing the steaks in the bags into a fourth ice brine solution at a temperature of between 23 to 30 degrees Fahrenheit;

removing the steaks in the bags from the fourth ice brine solution;

blast freezing the steaks in the bags with a high circulating rate of air at less than minus 10 degrees Fahrenheit;

stacking the bags in a container;

storing the steaks at less than 10 degrees Fahrenheit.

13. A method according to claim 12, further comprising:

submerging each bag in a solution of cold water and approximately one tablespoon of salt per gallon of water until the fish is partially thawed;

removing the bag from the water and drying the bag; and opening the bag and drying the fish.

14. A method of treating fish to maintain freshness even after it has been frozen and thawed comprising:

chilling a fish having a backbone in a first ice brine solution;

cutting the fish vertically and horizontally through an axis defined by the backbone of the fish to form four V-shaped loins, each loin having two flat sides defining a corner and an arc shaped side;

chilling the loins in a second ice brine solution colder than the first ice brine solution:

drying the loins with sterile absorbent paper towels;

cutting each loin into sections substantially parallel to said flat sides to form larger and other sashimi slabs;

dipping the sashimi slabs in a flavor enhancing solution;

arranging four of the larger sashimi slabs on a rectangular rigid supporting structure with a handle so that the flat sides of each sashimi slab are oriented in the corner of the structure;

placing other sashimi slabs in the interior of the supporting structure;

placing the supporting structure and sashimi slabs in a non-permeable bag;

removing the supporting structure from the bag;

sealing and vacuum packing the bag;

submerging the bag in a third ice brine solution;

drying the bag;

injecting treatment gas into the bag;

clamping the opening in the bag where the gas was injected into the bag;

chilling the sashimi slabs in the bag;

evacuating the gas from the bag;

vacuum packing the bag;

submerging the sashimi slab into a fourth ice brine solution;

removing the sashimi slab from the fourth ice brine; and

freezing the sashimi slabs.

15. A method of treating fish to maintain freshness even after it has been frozen and thawed which comprises:

chilling a substantially whole fresh fish having a backbone in a first brine solution containing water, ice and enough salt to keep the first brine solution at a temperature of between approximately 28 and approximately 36 degrees Fahrenheit;

cutting the fish vertically and horizontally through an axis defined by the backbone to form four V-shaped loins, each loin having two flat sides defining a corner and an arc shaped side;

skinning the loins;

chilling the loins in a second brine solution containing water, ice and salt at temperature of between approximately 20 and approximately 27 degrees Fahrenheit until each loin is at a temperature of between approximately 27 and approximately 35 degrees Fahrenheit;

drying the loins;

cutting each loin into sections substantially parallel to said flat sides to form larger and other sashimi slabs;

dipping the sashimi slabs in a flavor enhancing solution;

arranging two of the larger sashimi slabs on a rectangular rigid supporting structure with a handle so that the flat sides of each sashimi slab are oriented in a corner of the structure;

placing at least one other sashimi slab in the interior of the supporting structure between said larger sashimi slabs to maximize density and minimize interstices in the interior of the supporting structure;

placing the supporting structure inside a gas impermeable bag;

removing the supporting structure from the bag leaving sashimi slabs in the bag;

sealing and vacuum packing the bag;

placing the bag in a third ice brine solution at a temperature of between approximately 23 to approximately 30 degrees Fahrenheit;

inserting a gas nozzle into the bag;

injecting treatment gas into the bag;

chilling the sashimi slabs at between approximately 25 to approximately 31 degrees Fahrenheit for 4 to 12 hours;

evacuating the treatment gas from the bags;

vacuum sealing the bags;

placing the bags into a fourth ice brine solution at a temperature of between approximately 23 to approximately 30 degrees Fahrenheit;

removing the bags from the fourth ice brine solution;

rinsing and drying the bags with absorbent paper towels;

blast freezing the bags with the sashimi slabs with a high circulating rate of air at less than minus 10 degrees Fahrenheit;

treating containers with a water resistant coating;

stacking the bags in the container; and

storing the sashimi slabs in the bags at less than 10 degrees Fahrenheit.

16. A packing method for items of larger and smaller size where at least four of the larger items have sides forming a 90 degree angle, the method comprising:

placing four of the larger items in a bag so that the 90 degree sides of each item are in a corner of the bag; and

placing the smaller items in the interior of the bag in varying orientations to maximize density and minimize interstices within said rectangular bag.

17. A package comprising:

a rectangular bag;

a plurality of larger and other items, at least four of said larger items having two flat sides defining a corner, said corners being positioned in corresponding corners of said bag and the other items being positioned in the interior of said bag between said larger items in varying orientations to maximize density and minimize interstices within said rectangular bag.

18. A package according to claim 17, wherein said items are fish.