Fresh-keeping method of fish roe sauce

Abstract

The invention relates to the technical field of food processing, and particularly discloses a fresh-keeping method of fish roe sauce. The fresh-keeping method of the fish roe sauce comprises the following steps: mixing fresh fish roes with salt particles, and stirring to obtain salt-milled fish roes; the method comprises the following steps: washing salt-milled fish roes with ozone water, soaking the washed fish roes in a soybean protein solution at 0-4 DEG C, and filtering out the soybean protein solution after 5-15 minutes to obtain spare fish roes; the soybean protein solution comprises 5-10% of soybean protein, 1-3% of glycerol and the balance of water. Pickling the fish roes for later use, putting the pickled fish roes into a container, extruding the fish roes in the container, discharging saline water and air, and extruding until no dirty saline water flows out, so as to obtain fish roe sauce; and filling the fish roe sauce into an inner packaging bag, vacuumizing, sealing the inner packaging bag, putting the inner packaging bag into a packaging box, filling nitrogen into the packaging box, and sealing the packaging box to finish fresh-keeping packaging. The method is helpful for keeping the original flavor and texture of the fish roe sauce, and the quality reduction of the fish roe sauce is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a method for preserving caviar. Background Art

[0002] In today's era of pursuing delicious food, caviar, as a precious ingredient, has won the favor of consumers around the world for its unique taste and rich nutrition. However, the shelf life and quality maintenance of caviar have always been important challenges in its production and sales. In order to solve this problem, people are constantly exploring new technologies and methods to extend the shelf life of caviar while maintaining its original high quality.

[0003] In recent years, with the continuous progress of food technology, some innovative technologies and methods have been gradually applied to the production and preservation of caviar. A processing technology for caviar is disclosed in the related art, which includes the following steps: scrubbing, weighing, pickling and canning and packaging. Scrubbing includes rubbing eggs and rinsing. Rubbing eggs is to place the ovaries on a sieve, select the number of rubbing eggs and the rubbing strength according to the egg development and rubbing speed, and rub the eggs down; rinsing is to pour ice water into the eggs, gently stir, and rinse repeatedly. The weighing pickling method comprises the following steps: pouring the drained eggs into a container and weighing them, adding salt at 2%-13% of the weight of the eggs, evenly sprinkling the salt on the egg surface, evenly stirring with a smooth spoon, stirring again after the salt is dissolved until bubbles are generated when the egg surface is lightly pressed with a spoon and disappear very slowly, and then paving and controlling the water; the canning and packaging comprises canning, packaging, refrigeration and inspection. During canning, a special box for containing eggs is sterilized, the box is packed according to a certain weight specification, the eggs are packed with a smooth soft shovel, the box is covered after weighing, a grade label is affixed, the box for containing eggs is placed on an operating table and pressed with a heavy object to squeeze out the salt water inside until the cover does not rebound, and then the box is sent to a cold storage room, pressed with an object for 2-5 days under a -5-5°C environment, taken out, covered with a leather cover and put back into the original warehouse.

[0004] Although the above processing method discharges the air and salt water in the caviar by squeezing, which can reduce the oxidation and deterioration of the caviar, if there is air remaining in the packaging box during packaging, or if air enters the packaging box during storage in the packaging box, the quality of the caviar will deteriorate. It is necessary to develop a caviar preservation method with better preservation effect. Summary of the invention

[0005] In order to improve the preservation effect of caviar, the present application provides a method for preserving caviar.

[0006] The present application provides a method for preserving caviar, which adopts the following technical solution:

[0007] A method for preserving caviar, characterized in that it comprises the following steps:

[0008] Salt-grinding: Mix fresh fish roe with salt grains and stir to obtain salt-grinded fish roe;

[0009] Cleaning and soaking: using ozone water to clean the salt-ground fish roe, soaking the cleaned fish roe in a soybean protein solution at 0-4°C, filtering out the soybean protein solution after 5-15 minutes to obtain the spare fish roe; the soybean protein solution comprises: 5-10% soybean protein, 1-3% glycerol, and the balance is water.

[0010] Post-processing: after the standby fish roe is pickled, the fish roe is placed in a container, the fish roe in the container is squeezed, the salt water and air are discharged, and the fish roe is squeezed until no turbid salt water flows out, so as to obtain fish roe sauce;

[0011] Fresh-keeping packaging: put the caviar into an inner packaging bag, seal the inner packaging bag after vacuuming, put the inner packaging bag into a packaging box, fill the packaging box with nitrogen, and seal the packaging box to complete the fresh-keeping packaging.

[0012] By adopting the above technical scheme, by the salt grinding step and the cleaning and soaking step, the unnecessary impurities such as the egg membrane in the roe are removed, and, owing to being immersed in the soy protein solution containing the above-mentioned raw material proportioning, the soy protein forms a layer of protective film on the surface of the flying fish roe, glycerol can be inserted between the soy protein molecular chain, reduces the intermolecular interaction force, thereby increases the ductility of the protective film, prevents the protective film from rupturing, and the protective film helps to improve the fresh-keeping effect of the flying fish roe, and simultaneously, keeps the mouthfeel and the nutritional value of the roe. In the post-processing step, by extruding, the salt solution and the air in the roe sauce are discharged, the oxygen content and the moisture content in the roe sauce are reduced, the oxidation of the roe can be reduced in the preservation process, and moisture-proof can be again. In the fresh-keeping packaging step, after the roe sauce is loaded into the inner packaging bag, vacuumization is carried out, the oxygen in the inner packaging bag is discharged, and a protective layer is formed outside the roe sauce, which isolates the contact of oxygen with the roe sauce. Vacuuming has also reduced the humidity in the inner packaging bag, further enhancing the moisture-proof effect. The encapsulation box is sealed under a nitrogen environment so that the encapsulation box is filled with nitrogen. Nitrogen is an inert gas and is not easy to react with food ingredients, which further reduces the possibility that oxygen enters the inner packaging bag. The encapsulation box can reduce the impact of ambient temperature fluctuations on the caviar. Therefore, the present application helps to keep the original flavor and texture of the caviar, and reduces the quality degradation of the caviar.

[0013] In a specific possible implementation scheme, the inner packaging bag is a packaging bag made of an oxygen-barrier cling film material, and the oxygen-barrier cling film material includes a polyethylene layer, an ethylene-vinyl alcohol copolymer layer and an antibacterial inner layer stacked in sequence, and the antibacterial inner layer includes the following raw materials in parts by weight: 80-90 parts of polyethylene, 5-15 parts of triethyl citrate, 1-3 parts of nano-silver antibacterial agent and 0.5-2 parts of vitamin E.

[0014] By adopting the above technical scheme, the polyethylene layer has gas barrier properties, and the ethylene-vinyl alcohol copolymer layer has excellent oxygen barrier properties, which can effectively block external oxygen from entering the packaging bag, thereby greatly reducing the oxidation rate of caviar. The nano-silver antibacterial agent in the antibacterial inner layer can destroy the cell wall of bacteria, causing bacterial death, thereby effectively inhibiting the growth and reproduction of microorganisms in the packaging bag, and helping to prevent corruption and deterioration caused by microorganisms. Vitamin E can remove free radicals, slow down the oxidation process of fat and other ingredients, and further extend the shelf life of caviar. Polyethylene and triethyl citrate help to improve the flexibility and processing properties of the antibacterial inner layer, making the inner packaging bag easier to operate during vacuuming and packaging, and reducing the risk of damage caused by the brittleness of the material.

[0015] In a specific embodiment, the method for preparing the oxygen barrier cling film material comprises the following steps:

[0016] The polyethylene, triethyl citrate, nano silver antibacterial agent and vitamin E are uniformly mixed, melted, extruded and granulated to obtain an antibacterial inner layer masterbatch;

[0017] A multi-layer co-extrusion film blowing machine is used to heat and melt polyethylene, ethylene-vinyl alcohol copolymer and antibacterial inner layer masterbatch respectively, and extrude them through a co-extrusion die to form a three-layer composite film, which is then cooled to obtain an oxygen-barrier cling film material.

[0018] By adopting the above technical solution, the polyethylene layer, the ethylene-vinyl alcohol copolymer layer and the antibacterial inner layer can be effectively integrated together through multi-layer co-extrusion technology, thereby forming an oxygen-barrier cling film material with low oxygen permeability in the outer layer and antibacterial and fresh-keeping in the inner layer. It is helpful to prevent oxygen from contacting the caviar during the storage of the caviar and better maintain the freshness and taste of the caviar.

[0019] In a specific embodiment, the thickness ratio of the polyethylene layer, the ethylene-vinyl alcohol copolymer layer and the antibacterial inner layer is (3-5):2:(3-5).

[0020] By adopting the above technical solution, the thickness ratio of the polyethylene layer, the ethylene-vinyl alcohol copolymer layer and the antibacterial inner layer is set to the above ratio, and the relatively thick polyethylene layer provides good mechanical strength. Although the ethylene-vinyl alcohol copolymer layer is relatively thin, the antibacterial inner layer ensures that gas is difficult to penetrate. The thicker antibacterial inner layer enables the antibacterial agent to continuously and effectively exert antibacterial effects, thereby extending the shelf life of caviar. Therefore, adopting the above thickness ratio not only ensures good oxygen barrier and antibacterial effects, but also makes the overall structure of the oxygen barrier cling film material more stable.

[0021] In a specific possible implementation scheme, the packaging box includes a box body, a box cover and an elastic pressure pad, the elastic pressure pad is located inside the box body, the box cover abuts against the elastic pressure pad, and the inner packaging bag is located inside the box body. When the box cover closes the box body, the inner box cover applies pressure to the inner packaging bag through the elastic pressure pad.

[0022] By adopting the above-mentioned technical scheme, the close contact of box lid and elastic pressure pad guarantees the excellent sealing property of packaging box.When box lid is closed, box lid applies pressure to elastic pressure pad, makes pressure pad closely fit inner packaging bag, thereby effectively isolates external air and moisture, and nitrogen is sealed in box body, greatly reduces the possibility that oxygen and moisture infiltrate through gap, helps to keep the freshness and mouthfeel of caviar.Elastic pressure pad not only provides good sealing effect, but also can absorb impact force in transportation or storage process, reduces the risk that caviar leaks because of shaking.Therefore, the application has slowed down oxidation and the corruption process of caviar by optimizing the sealing property and isolation property of packaging box.

[0023] In a specific feasible implementation scheme, the box body, the box cover and the elastic pressure pad are all made of oxygen-barrier and moisture-proof material, and the oxygen-barrier and moisture-proof material includes a shell layer, an aluminum foil layer and an artificial stone inner layer stacked in sequence from the outside to the inside, and the artificial stone inner layer comprises the following raw materials in parts by weight: 40-50 parts of TPE resin, 10-15 parts of polyvinylidene chloride, 10-15 parts of medical stone powder, 3-5 parts of nano-grade zinc oxide, and 2-5 parts of edible grade wax.

[0024] By adopting the above technical solution, the aluminum foil layer can effectively prevent external oxygen and moisture from entering the interior of the oxygen barrier and moisture-proof material. The TPE resin and polyvinylidene chloride in the inner layer of artificial stone enhance the durability of the entire oxygen barrier and moisture-proof material, ensuring that the oxygen barrier and moisture-proof material is not easily damaged during transportation and storage. Medical stone powder increases antibacterial properties while absorbing and removing odors and harmful substances in the package. Nano-grade zinc oxide and edible-grade wax further enhance the antioxidant properties of the oxygen barrier and moisture-proof material. Moreover, edible-grade wax can improve the surface smoothness of the inner layer of artificial stone, making the sealing of the joints between the box body, the lid and the elastic pressure pad better.

[0025] In a specific embodiment, the artificial stone inner layer further includes hollow glass microspheres.

[0026] By adopting the above technical solution, since the hollow glass microspheres have a unique nanoporous structure, these nanoporous structures are filled with gas, and the thermal conductivity of the gas is relatively low, the hollow glass microspheres are added to the inner layer of the artificial stone to form tiny thermal blocking layers in the inner layer of the artificial stone. These thermal blocking layers effectively slow down the speed of heat transfer. When the external temperature changes, the speed at which heat passes through the inner layer of the artificial stone can be slowed down, thereby providing a more stable temperature environment for caviar.

[0027] In a specific embodiment, the method for preparing the oxygen barrier and moisture proof material comprises the following steps:

[0028] The nano zinc oxide and the edible wax are mixed evenly to obtain a hydrophobic filler;

[0029] The TPE resin, polyvinylidene chloride, medical stone powder, hydrophobic filler and hollow glass microspheres are mixed evenly, added into a twin-screw extruder, and extruded into granules to obtain composite material granules;

[0030] compression molding the composite material particles into an artificial stone layer;

[0031] The artificial stone layer and the aluminum foil layer are composited by hot pressing, and then the polyester shell layer is covered on the aluminum foil layer, and they are bonded together by hot pressing to obtain an oxygen-barrier and moisture-proof material.

[0032] By adopting the above technical solution, a twin-screw extruder is used to mix multiple materials evenly and then extrude and granulate them to form uniform composite material particles. The composite material particles can form an artificial stone layer with stable structure and uniform performance in the subsequent compression molding process, thereby improving the overall stability and durability of the material. The artificial stone layer is tightly combined with the aluminum foil layer through hot pressing composite technology, and then covered with a polyester shell layer to form a multi-layer structure of oxygen-barrier and moisture-proof material.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. The present invention removes unnecessary impurities such as the egg membrane in the fish roe through a salt grinding step and a cleaning and soaking step, then soaks the fish roe in a soy protein solution to form a protective film on the surface of the fish roe, discharges the salt water and air in the fish roe sauce by squeezing in a post-processing step, adopts an inner packaging bag to package the caviar, and is contained in a packaging box filled with nitrogen, so as to improve the effects of moisture-proof, oxygen-barrier and heat-insulating, help maintain the original flavor and texture of the fish roe sauce, and reduce the quality decline of the fish roe sauce.

[0035] 2. In the present application, the packaging bag made of oxygen-barrier preservative film material and the packaging box made of oxygen-barrier moisture-proof material are preferably used to help prevent oxygen from contacting the caviar during the storage of the caviar and better maintain the freshness and taste of the caviar. DETAILED DESCRIPTION

[0036] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are purchased from the market, wherein the flying fish roe is produced in Peru. The model of the nano silver antibacterial agent is Mingkai KF107. The TPE resin is DuPont 7246. Medical stone powder is a powder with a particle size of 200-325 mesh. Nano zinc oxide is a powder with a particle size of 80-100 mesh. The model of edible grade wax is T1-FP. Hollow glass microspheres are particles with a particle size of 15-135 microns.

[0037] The present application is further described in detail below in conjunction with embodiments and comparative examples.

[0038] Example

[0039] Example 1

[0040] The present embodiment provides a method for preserving caviar, characterized in that it comprises the following steps:

[0041] In an environment of 0-4°C, fresh fish roe and salt particles are mixed in a ratio of 97:3, stirred for 3 minutes, and then the stirring is stopped to obtain salt-ground fish roe.

[0042] In an environment of 0-4°C, the salt-ground fish roe is cleaned with ozone water for 30 minutes, the cleaning is stopped, and then centrifugal dehydration is performed to remove the damaged fish roe, and the remaining cleaned fish roe is immersed in a soybean protein solution for 10 minutes, and the soybean protein solution is filtered out to obtain spare fish roe. The soybean protein solution comprises: 7% soybean protein, 2% glycerol, and the balance is water.

[0043] The method comprises the following steps: pickling the spare fish roe in an environment of 0-4 DEG C, draining off excess salt water on the surface, sterilizing the fish roe, putting the fish roe into a container, controlling the initial pressure at 0.1MPa, slowly squeezing the fish roe in the container to gradually discharge the salt water and air, and squeezing for 2 minutes, gradually increasing the pressure to 0.3MPa, and continuing to squeeze. When no turbid salt water flows out and the fish roe is in a compact and uniform state, squeezing is stopped to obtain fish roe sauce.

[0044] In an environment of 0-4°C, the caviar is put into an inner packaging bag, the inner packaging bag is vacuumed, and when the vacuum degree is -0.08MPa to -0.1MPa, the inner packaging bag is sealed, and then the inner packaging bag is sealed with a sealing box. The inner packaging bag is a packaging bag made of a PE preservative film with a thickness of 0.02mm. The sealing box includes a metal box and a metal cover. The sealed inner packaging bag is put into the metal box, nitrogen is filled into the metal box, and the metal box is sealed with a metal cover to complete the fresh-keeping packaging.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that the soy protein solution comprises: 5% soy protein, 3% glycerol, and the balance is water.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 1 is that the soy protein solution comprises: 10% soy protein, 1% glycerol, and the balance is water.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that the inner packaging bag is a packaging bag made of an oxygen-barrier cling film material with a thickness of 0.02 mm. The oxygen-barrier cling film material includes a polyethylene layer, an ethylene-vinyl alcohol copolymer layer and an antibacterial inner layer stacked in sequence, and the antibacterial inner layer includes the following raw materials: 90 g polyethylene, 8.5 g triethyl citrate, 1 g nano silver antibacterial agent and 0.5 g vitamin E.

[0051] The preparation method of the oxygen barrier cling film material comprises the following steps:

[0052] According to the proportion, polyethylene, triethyl citrate, nano silver antibacterial agent and vitamin E are mixed evenly, and then added into a twin-screw extruder for melting, extrusion and granulation to obtain the antibacterial inner layer masterbatch.

[0053] Then, a multi-layer co-extrusion film blowing machine is used to heat and melt polyethylene, ethylene-vinyl alcohol copolymer and antibacterial inner layer masterbatch, wherein the melting temperature of polyethylene is 160-180°C, the melting temperature of ethylene-vinyl alcohol copolymer is 180°C-200°C, and the melting temperature of antibacterial inner layer masterbatch is 160°C-180°C, and a three-layer composite film with a thickness of 0.02 mm is formed through a co-extrusion die head, and an oxygen-barrier cling film material with a thickness of 0.02 mm is obtained after cooling. The die head temperature is 180°C-200°C, and the thickness ratio of the three layers in the oxygen-barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 2:1:2.

[0054] Example 5

[0055] The only difference between this embodiment and embodiment 4 is that the antibacterial inner layer includes the following raw materials: 80 g polyethylene, 15 g triethyl citrate, 3 g nano silver antibacterial agent and 2 g vitamin E.

[0056] Example 6

[0057] The only difference between this embodiment and embodiment 4 is that the antibacterial inner layer includes the following raw materials: 85g polyethylene, 10g triethyl citrate, 3g nano silver antibacterial agent and 2g vitamin E.

[0058] Example 7

[0059] The only difference between this embodiment and embodiment 4 is that the antibacterial inner layer includes the following raw materials: 90 g polyethylene, 5 g triethyl citrate, 3 g nano silver antibacterial agent and 2 g vitamin E.

[0060] Example 8

[0061] The only difference between this embodiment and embodiment 4 is that the thickness ratio of the three layers in the oxygen barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 1:1:1.

[0062] Example 9

[0063] The only difference between this embodiment and embodiment 4 is that the thickness ratio of the three layers in the oxygen barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 3:2:3.

[0064] Example 10

[0065] The only difference between this embodiment and embodiment 4 is that the thickness ratio of the three layers in the oxygen barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 5:2:5.

[0066] Embodiment 11

[0067] The only difference between this embodiment and embodiment 4 is that the thickness ratio of the three layers in the oxygen barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 3:1:3.

[0068] Example 12

[0069] The difference between this embodiment and embodiment 1 is that the packaging box of this embodiment includes a box body, a box cover and an elastic pressure pad, and the box body, the box cover and the elastic pressure pad are all made of oxygen-barrier and moisture-proof material. The oxygen-barrier and moisture-proof material includes a shell layer, an aluminum foil layer and an artificial stone inner layer stacked in sequence from the outside to the inside. The artificial stone inner layer has the following raw materials in parts by weight: 45g TPE resin, 13g polyvinylidene chloride, 13g medical stone powder, 4g nano-grade zinc oxide, and 3g edible grade wax.

[0070] The preparation method of the oxygen barrier and moisture proof material comprises the following steps:

[0071] Nano zinc oxide and edible wax are mixed according to a ratio, heated to 70° C., and stirred until uniform to obtain a hydrophobic filler.

[0072] Then, TPE resin, polyvinylidene chloride, medical stone powder and hydrophobic filler are added into a high-speed mixer, mixed evenly at 90° C., and then added into a twin-screw extruder for melting, extrusion and granulation to obtain composite material particles.

[0073] The composite material particles were added into a compression molding machine and compression molded into a 1 mm artificial stone layer at 180°C and 15 MPa.

[0074] The artificial stone layer and the 10 μm thick aluminum foil layer are stacked and hot-pressed at 160°C and 12 MPa, and then a 20 μm thick polyester shell layer is covered on the aluminum foil layer and bonded together by hot pressing at 150°C and 10 MPa to obtain an oxygen-barrier and moisture-proof material.

[0075] The cylindrical box body, the box cover and the round elastic pressure pad are made of oxygen-proof and moisture-proof materials. The diameter of the elastic pressure pad is equal to the inner diameter of the box body.

[0076] The sealed inner packaging bag is placed in the box body, the elastic pressure pad is placed in the box body, nitrogen is filled into the box body, and the box body is closed with a box cover to complete the fresh-keeping packaging.

[0077] Embodiment 13

[0078] The only difference between this embodiment and embodiment 12 is that the raw materials of the artificial stone inner layer are as follows in parts by weight: 40 g of TPE resin, 15 g of polyvinylidene chloride, 15 g of medical stone powder, 5 g of nano-grade zinc oxide, and 5 g of edible-grade wax.

[0079] Embodiment 14

[0080] The only difference between this embodiment and embodiment 12 is that the raw materials of the artificial stone inner layer are as follows in parts by weight: 50 g of TPE resin, 10 g of polyvinylidene chloride, 10 g of medical stone powder, 3 g of nano-grade zinc oxide, and 2 g of food-grade wax.

[0081] Embodiment 15

[0082] The difference between this embodiment and embodiment 12 is that the raw materials of the artificial stone inner layer are as follows by weight: TPE resin 45g, polyvinylidene chloride 13g, medical stone powder 13g, nano zinc oxide 4g, edible wax 3g, hollow glass microspheres 7g. In the preparation method of oxygen barrier and moisture-proof material: TPE resin, polyvinylidene chloride, medical stone powder, hydrophobic filler, hollow glass microspheres are added to a high-speed mixer, mixed evenly at 90°C, and then added to a twin-screw extruder for melting, extrusion, and granulation to obtain composite material particles.

[0083] Example 16

[0084] The difference between this embodiment and embodiment 1 is that the inner packaging bag is a packaging bag made of an oxygen-barrier cling film material with a thickness of 0.02 mm. The oxygen-barrier cling film material includes a polyethylene layer, an ethylene-vinyl alcohol copolymer layer and an antibacterial inner layer stacked in sequence, and the antibacterial inner layer includes the following raw materials: 90 g polyethylene, 8.5 g triethyl citrate, 1 g nano silver antibacterial agent and 0.5 g vitamin E.

[0085] The preparation method of the oxygen barrier cling film material comprises the following steps:

[0086] According to the proportion, polyethylene, triethyl citrate, nano silver antibacterial agent and vitamin E are mixed evenly, and then added into a twin-screw extruder for melting, extrusion and granulation to obtain the antibacterial inner layer masterbatch.

[0087] Then, a multi-layer co-extrusion film blowing machine is used to heat and melt polyethylene, ethylene-vinyl alcohol copolymer and antibacterial inner layer masterbatch, wherein the melting temperature of polyethylene is 160-180°C, the melting temperature of ethylene-vinyl alcohol copolymer is 180°C-200°C, and the melting temperature of antibacterial inner layer masterbatch is 160°C-180°C, and a three-layer composite film with a thickness of 0.02 mm is formed through a co-extrusion die head, and an oxygen-barrier cling film material with a thickness of 0.02 mm is obtained after cooling. The die head temperature is 180°C-200°C, and the thickness ratio of the three layers in the oxygen-barrier cling film material is: polyethylene layer: ethylene-vinyl alcohol copolymer layer: antibacterial inner layer = 2:1:2.

[0088] The packaging box of this embodiment includes a box body, a box cover and an elastic pressure pad. The box body, the box cover and the elastic pressure pad are all made of oxygen-barrier and moisture-proof materials. The oxygen-barrier and moisture-proof materials include a shell layer, an aluminum foil layer and an artificial stone inner layer stacked in sequence from the outside to the inside. The artificial stone inner layer has the following raw materials in parts by weight: 45g TPE resin, 13g polyvinylidene chloride, 13g medical stone powder, 4g nano-grade zinc oxide, 3g edible-grade wax, and 7g hollow glass microspheres.

[0089] The preparation method of the oxygen barrier and moisture proof material comprises the following steps:

[0090] Nano zinc oxide and edible wax are mixed according to a ratio, heated to 70° C., and stirred until uniform to obtain a hydrophobic filler.

[0091] Then, TPE resin, polyvinylidene chloride, medical stone powder, hydrophobic filler and hollow glass microspheres were added into a high-speed mixer, mixed evenly at 90° C., and then added into a twin-screw extruder for melting, extrusion and granulation to obtain composite material particles.

[0092] The composite material particles were added into a compression molding machine and compression molded into a 1 mm artificial stone layer at 180°C and 15 MPa.

[0093] The artificial stone layer and the 10 μm thick aluminum foil layer are stacked and hot-pressed at 160°C and 12 MPa, and then a 20 μm thick polyester shell layer is covered on the aluminum foil layer and bonded together by hot pressing at 150°C and 10 MPa to obtain an oxygen-barrier and moisture-proof material.

[0094] The cylindrical box body, the box cover and the round elastic pressure pad are made of oxygen-proof and moisture-proof materials. The diameter of the elastic pressure pad is equal to the inner diameter of the box body.

[0095] The sealed inner packaging bag is placed in the box body, the elastic pressure pad is placed in the box body, nitrogen is filled into the box body, and the box body is closed with a box cover to complete the fresh-keeping packaging.

[0096] Comparative Example

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is that, in the method for preserving caviar:

[0099] The spare fish roe is pickled in an environment of 0-4°C, and then the excess salt water on the surface is drained, sterilized, and then placed in an inner packaging bag, and the inner packaging bag is vacuumed. When the vacuum degree is -0.08MPa to -0.1MPa, the inner packaging bag is sealed, and then the inner packaging bag is sealed with a packaging box. The inner packaging bag is a packaging bag made of a PE preservative film with a thickness of 0.02mm. The packaging box includes a metal box and a metal cover. The sealed inner packaging bag is placed in the metal box, nitrogen is filled into the metal box, and the metal box is sealed with a metal cover to complete the fresh-keeping packaging.

[0100] Comparative Example 2

[0101] The difference between this comparative example and Example 1 is that, under an environment of 0-4°C, the caviar is put into an inner packaging bag, the inner packaging bag is sealed, and then the inner packaging bag is sealed with a packaging box. The inner packaging bag is a packaging bag made of a PE preservative film with a thickness of 0.02 mm. The packaging box includes a metal box and a metal cover. The sealed inner packaging bag is put into the metal box, nitrogen is filled into the metal box, and the metal box is sealed with a metal cover to complete the fresh-keeping packaging.

[0102] Comparative Example 3

[0103] The difference between this comparative example and Example 1 is that, under an environment of 0-4°C, the caviar is placed in an inner packaging bag, the inner packaging bag is evacuated, and when the vacuum degree is -0.08MPa to -0.1MPa, the inner packaging bag is sealed, and then the inner packaging bag is sealed with a packaging box. The inner packaging bag is a packaging bag made of a PE preservative film with a thickness of 0.02mm. The packaging box includes a metal box and a metal cover. The sealed inner packaging bag is placed in the metal box, nitrogen is filled into the metal box, and the metal box is sealed with a metal cover to complete the fresh-keeping packaging.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 1 is that, in a 0-4°C environment, after the salt-ground fish roe is cleaned with ozone water for 30 min, the cleaning is stopped, and then centrifugal dehydration is carried out to remove the damaged fish roe to obtain standby fish roe.

[0106] Performance testing

[0107] The following performance tests were performed on the caviar that was packaged for freshness preservation in Examples 1-16 and Comparative Examples 1-3:

[0108] The caviar that has been packaged for freshness preservation in each embodiment and comparative example is placed in a refrigerated environment at 4°C and a humidity of 50%. After refrigeration for 7 days, 14 days, and 21 days, the moisture content of the caviar is tested according to GB / T5009.3-2016 "Determination of Moisture in Food". The total number of bacteria in the caviar is tested according to GB4789.2-2016 "General Rules for Food Safety National Standard for Microbiological Inspection of Food". The color, aroma, taste, and shape of the caviar are evaluated by professional tasters, and the evaluation grades of color, aroma, taste, and shape are divided into excellent, good, and poor from good to bad. The results are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112]

[0113] In conjunction with embodiment 1 and comparative examples 1-4 and in conjunction with table 1, it can be seen that, compared to embodiment 1, the moisture of caviar after the same refrigeration duration of comparative examples 1-4 is lower, and after refrigeration for 14 days and 21 days, the total bacteria count of caviar significantly increases, and, after refrigeration for 21 days, the evaluation grade of color, fragrance, taste, shape is poor. This explanation adopts the fresh-keeping method of embodiment 1, helps to prevent the water loss of caviar, and reduces the total bacteria count of caviar, thereby improves the quality of caviar.

[0114] In conjunction with embodiment 1-3 and in conjunction with Table 1, it can be seen that the moisture of the roe sauce of embodiment 1-3 after refrigeration for 21 days is still more than 70.0%, and the total bacteria count is below 1500cfu / g, and the evaluation grade of color, fragrance, taste, shape is good. This explanation, adopts the raw material proportioning of embodiment 1-3 all to help prevent the roe sauce from losing water, and reduces the total bacteria count of roe sauce.

[0115] In conjunction with Example 1, 4-7 and in conjunction with Table 1, it can be seen that, compared to Example 1, the moisture of the fish roe sauce in Example 4-7 is larger after the same refrigeration time, and the total bacteria count of the fish roe sauce is smaller after refrigeration for 14 days and 21 days, and the evaluation grade of color, fragrance, taste and shape is excellent after refrigeration for 21 days. This shows that, compared to the packaging bag made of PE preservative film, the oxygen barrier preservative film material of Example 4-7 is adopted, which helps to further prevent the water loss of the fish roe sauce and reduce the total bacteria count of the fish roe sauce.

[0116] In combination with Examples 4, 8-11 and Table 1, it can be seen that compared with Example 4, the moisture of the fish roe sauce in Examples 9-11 after refrigeration for 21 days is still above 74%, and the total bacteria count of the fish roe sauce is still less than 1000 cfu / g after refrigeration for 21 days, but the moisture of Example 11 is less than the moisture of Example 10. The moisture of the fish roe sauce in Example 8 after refrigeration for 21 days is less than 73%, and the total bacteria count of the fish roe sauce is greater than 1000 cfu / g after refrigeration for 21 days. This shows that the thickness ratio of the polyethylene layer, the ethylene-vinyl alcohol copolymer layer and the antibacterial inner layer is within the range of (3-5):2:(3-5), which helps to further prevent the loss of water from the fish roe sauce and reduce the total bacteria count of the fish roe sauce.

[0117] In combination with Examples 4, 12-15 and Table 1, it can be seen that compared with Example 4, the moisture change of the fish roe sauce in Examples 12-15 after refrigeration for 21 days is smaller, and the total bacteria count of the fish roe sauce is smaller after refrigeration for 21 days, and the moisture of the fish roe sauce in Example 15 is the largest, and the total bacteria count is the smallest. This shows that the packaging box using Examples 12-15 helps to further prevent the loss of water in the fish roe sauce and reduce the total bacteria count of the fish roe sauce.

[0118] Combining Examples 1, 4, 12 and 16 and Table 1, it can be seen that the moisture content of the fish roe sauce in Example 16 is the largest after refrigeration for 21 days, and the total bacteria count of the fish roe sauce is still less than 1000 cfu / g after refrigeration for 21 days. This indicates that the combination of the inner packaging bag and the packaging box of Example 16 is helpful to improve the preservation effect of the fish roe sauce.

[0119] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preserving caviar, characterized in that: The steps include: Salt-grinding: Mix fresh fish roe with salt grains and stir to obtain salt-grinded fish roe; Cleaning and soaking: using ozone water to clean the salt-ground fish roe, soaking the cleaned fish roe in a soybean protein solution at 0-4° C., filtering out the soybean protein solution after 5-15 minutes, and obtaining spare fish roe; The soy protein solution comprises: 5-10% soy protein, 1-3% glycerol, and the balance is water. Post-processing: after the standby fish roe is pickled, the fish roe is placed in a container, the fish roe in the container is squeezed, the salt water and air are discharged, and the fish roe is squeezed until no turbid salt water flows out, so as to obtain fish roe sauce; Fresh-keeping packaging: put the caviar into an inner packaging bag, seal the inner packaging bag after vacuuming, put the inner packaging bag into a packaging box, fill the packaging box with nitrogen, and seal the packaging box to complete the fresh-keeping packaging.

2. A method for preserving caviar according to claim 1, characterized in that: The inner packaging bag is a packaging bag made of oxygen-barrier cling film material, which includes a polyethylene layer, an ethylene-vinyl alcohol copolymer layer and an antibacterial inner layer stacked in sequence, and the antibacterial inner layer includes the following raw materials in parts by weight: 80-90 parts of polyethylene, 5-15 parts of triethyl citrate, 1-3 parts of nano-silver antibacterial agent and 0.5-2 parts of vitamin E.

3. A method for preserving caviar according to claim 2, characterized in that: The preparation method of the oxygen barrier cling film material comprises the following steps: The polyethylene, triethyl citrate, nano silver antibacterial agent and vitamin E are uniformly mixed, melted, extruded and granulated to obtain an antibacterial inner layer masterbatch; A multi-layer co-extrusion film blowing machine is used to heat and melt polyethylene, ethylene-vinyl alcohol copolymer and antibacterial inner layer masterbatch respectively, and extrude them through a co-extrusion die to form a three-layer composite film, which is then cooled to obtain an oxygen-barrier cling film material.

4. A method for preserving caviar according to claim 2, characterized in that: The thickness ratio of the polyethylene layer, the ethylene-vinyl alcohol copolymer layer and the antibacterial inner layer is (3-5):2:(3-5).

5. A method for preserving caviar according to claim 1, characterized in that: The packaging box includes a box body, a box cover and an elastic pressure pad, wherein the elastic pressure pad is located inside the box body, the box cover abuts against the elastic pressure pad, and the inner packaging bag is located inside the box body. When the box cover closes the box body, the inner box cover applies pressure to the inner packaging bag through the elastic pressure pad.

6. A method for preserving caviar according to claim 5, characterized in that: The box body, the box cover and the elastic pressure pad are all made of oxygen-barrier and moisture-proof materials. The oxygen-barrier and moisture-proof materials include a shell layer, an aluminum foil layer and an artificial stone inner layer stacked in sequence from the outside to the inside. The artificial stone inner layer has the following raw materials in parts by weight: 40-50 parts of TPE resin, 10-15 parts of polyvinylidene chloride, 10-15 parts of medical stone powder, 3-5 parts of nano-grade zinc oxide, and 2-5 parts of edible wax.

7. A method for preserving caviar according to claim 6, characterized in that: The artificial stone inner layer also includes hollow glass microspheres.

8. The method for preserving caviar according to claim 1, characterized in that: The preparation method of the oxygen barrier and moisture proof material comprises the following steps: The nano zinc oxide and the edible wax are mixed evenly to obtain a hydrophobic filler; The TPE resin, polyvinylidene chloride, medical stone powder, hydrophobic filler and hollow glass microspheres are mixed evenly, added into a twin-screw extruder, and extruded into granules to obtain composite material granules; compression molding the composite material particles into an artificial stone layer; The artificial stone layer and the aluminum foil layer are composited by hot pressing, and then the polyester shell layer is covered on the aluminum foil layer, and they are bonded together by hot pressing to obtain an oxygen-barrier and moisture-proof material.

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