JP6234529B2 - How to maintain freshness of fresh seafood - Google Patents

Description

  The present invention relates to a method for maintaining freshness of fresh seafood.

  In order to maintain the freshness of fresh seafood, it has been conventionally practiced to cool fresh seafood with ice. For example, when a fishing boat goes fishing, a large amount of ice is loaded on the fishing boat, and the captured fish is transported in a container filled with water ice (ice + seawater). However, in the case of ice made from fresh water, when the ice melts, the salinity of seawater used to maintain freshness decreases. As a result, there is a problem that due to the osmotic pressure, water enters the body of the fish immersed in water ice, and the freshness and taste of the fish deteriorate.

  Therefore, in Patent Document 1, salt-containing ice obtained by freezing salt-containing water having a salt concentration of about 0.5 to 2.5% is formed into a slurry to be used for maintaining freshness of fresh food. In the salt-containing water ice making method, raw water such as seawater that has been sterilized by filtration is adjusted to have a salt content of about 1.0 to 1.5%. A method for producing slurry-like salt-containing ice having a freezing point temperature of −5 to −1 ° C. corresponding to the salinity concentration is disclosed.

  Moreover, in patent document 2, bittern is added to 0.2-5.0% (w / v) salt solution, and a fresh fish is immersed in the immersion liquid hold | maintained at the water temperature of -3-10 degreeC for a fixed time. A method is disclosed.

JP 2002-115945 A JP 2006-158301 A

Water in fresh seafood crystallizes when frozen, but in the case of the conventional method, ice crystals in the fresh seafood become large, so there is a problem that the cell structure of the fresh seafood is destroyed and the freshness and taste cannot be maintained.
In addition, in the case of the conventional methods described in Patent Documents 1 and 2, since the freezing point temperature of the slurry-like salt-containing ice and the water temperature of the immersion liquid are not so low, the freshness of the fresh seafood can be maintained only for a short period of time. There is a problem that it cannot be transported.

  The present invention has been made in view of such circumstances, and provides a method for maintaining the freshness of fresh seafood that can be transported to a remote place for a long time without losing freshness and taste even when the fresh seafood is frozen. With the goal.

In order to achieve the above object, the method for maintaining freshness of fresh seafood according to the present invention comprises the following steps.
(1) A step of producing an ice slurry by mixing ice frozen salt water having a salt concentration of 13.6 to 23.1% and salt water having a salt concentration of 13.6 to 23.1%. 2) A step of immersing fresh seafood in the ice slurry and instantly freezing the fresh seafood

Moisture in fresh seafood crystallizes when frozen, but when fresh seafood is slowly frozen, ice crystals become larger, resulting in destruction of the cellular structure of the fresh seafood and deterioration of the freshness and taste of the fresh seafood.
On the other hand, in the present invention, since the fresh seafood is instantly frozen, the ice crystals generated in the fresh seafood tissue are reduced, the fresh seafood tissue is less damaged, and the freshness and taste of the fresh seafood are maintained.

In the present invention, in order to instantly freeze fresh seafood, the salinity of salt water, which is a raw material for ice slurry, is significantly higher than that in the past. The theoretical saturation freezing point of salt water having a salinity concentration of 13.6% is −9.8 ° C., and the theoretical saturation freezing point of salt water having a salinity concentration of 23.1% is −21.2 ° C.
When the salinity of salt water is less than 13.6%, the freezing rate of fresh seafood by the produced ice slurry becomes slow. On the other hand, when the salt concentration of the salt water is more than 23.1%, the salt is precipitated as crystals, so that the saturation freezing point of the salt water is increased.

  Even if the salt concentration is high, the surface of fresh seafood freezes and freezes, so that salt does not enter the fresh seafood.

  In the method for maintaining freshness of fresh seafood according to the present invention, it is preferable that the ice and the salt water to be mixed have the same salinity.

  When the salinity concentration of ice is higher than the salinity concentration of salt water, the ice temperature is lower than the saturation freezing point of the salt water, so that the water freezes immediately after the salt water having a low salinity concentration is mixed. On the other hand, when the salinity of ice is lower than the salinity of brine, the ice melts because the saturation freezing point of salt water is lower than the saturation freezing point of ice, and the temperature of the ice slurry decreases. Therefore, in order not to fluctuate the state of the ice slurry, it is preferable that the salinity concentrations of the ice to be mixed and the salt water are approximately the same.

  In the method for maintaining freshness of fresh seafood according to the present invention, it is preferable that the mass ratio of the ice to be mixed with the salt water is ice: salt water = 75: 25 to 20:80.

  When the mass ratio of ice exceeds 75% by mass, the ratio of the solid content increases, so that a gap is generated between the fresh seafood and the ice slurry, and the ice slurry does not adhere to the fresh seafood. On the other hand, when the mass ratio of ice is less than 20% by mass, it is difficult to instantly freeze fresh seafood by the produced ice slurry.

  In the method for maintaining freshness of fresh seafood according to the present invention, it is preferable to take out the fresh seafood that has been instantly frozen from the ice slurry and store the fresh seafood in a frozen state at or below the temperature at the time of instant freezing. Thereby, even if it transports to a remote place for a long time, fresh seafood freshness and taste do not fall.

  In the method for maintaining the freshness of fresh seafood according to the present invention, the fresh slurry is brought into contact with the fresh seafood by bringing the ice slurry whose temperature is greatly lowered by significantly increasing the salinity of salt water, which is the raw material of the ice slurry, from the conventional level. You can instantly freeze seafood. As a result, the tissue damage of the fresh seafood is reduced, and the freshness and taste of the fresh seafood are maintained. In addition, the fresh seafood that has been instantly frozen is transported in a state of being frozen and stored below the temperature at the time of instantaneous freezing, so that the freshness and taste of the fresh seafood will not deteriorate even if transported to a remote location for a long time.

It is a fragmentary sectional perspective view of the ice making machine used for the freshness maintenance method of the fresh seafood concerning one embodiment of the present invention. It is a schematic diagram of the ice making system containing the ice making machine.

  Subsequently, an embodiment embodying the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

[Icemaker and ice making system]
FIG. 1 shows a partial cross-sectional perspective view of an ice making machine 10 used in the method for maintaining freshness of fresh seafood according to an embodiment of the present invention, and FIG. 2 shows an ice making system including the ice making machine 10.
The ice making machine 10 includes a vertical drum 11 whose inner peripheral surface is cooled by a refrigerant, and a rotating shaft 12 that is rotated by a geared motor 20 is disposed on the central axis of the vertical drum 11. The rotary shaft 12 rotates together with the rotary shaft 12 and has a plurality of pipes 13 having injection holes 13 a at the tip thereof for injecting salt water toward the inner peripheral surface of the vertical drum 11, and the radial direction of the vertical drum 11. An arm 14 that extends and rotates together with the rotating shaft 12 is attached. A blade 15 that scrapes off the ice generated on the inner peripheral surface of the saddle drum 11 is attached to the tip of the arm 14.

The saddle type drum 11 has an inner cylinder 22 in which ice is generated on the inner peripheral surface, and an outer cylinder 23 surrounding the inner cylinder 22. The inner cylinder 22 and the outer cylinder 23 are made of steel, and a clearance is provided between the inner cylinder 22 and the outer cylinder 23. Refrigerant is supplied to the clearance from a refrigerator (not shown) via the pipe 35.
The outer peripheral surface of the saddle drum 11 is covered with a cylindrical protective cover 19.

  The upper surface of the saddle drum 11 is sealed with an upper bearing member 17 having a shape in which the pot is inverted. A bush 28 that supports the rotating shaft 12 is fitted in the center of the upper bearing member 17. The rotating shaft 12 is supported only by the upper bearing member 17, and the lower end portion of the rotating shaft 12 is not pivotally supported. Therefore, there is no obstacle under the saddle drum 11 when the ice scraped off by the blade 15 falls, and the lower surface of the saddle drum 11 is a discharge port 16 for discharging ice. The ice that has fallen from the discharge port 16 is stored in an ice storage tank 34 disposed immediately below the ice making machine 10 (see FIG. 2).

The rotating shaft 12 is rotated around the material axis by a geared motor 20 installed above the upper bearing member 17. In the upper part of the rotating shaft 12, a hole 12a extending in the material axis direction and communicating with each pipe 13 is formed (see FIG. 2). A rotary joint 21 is attached to the top of the rotating shaft 12.
The salt water used as the raw material for ice is fed from the salt water storage tank 30 to the rotary joint 21 via the pipe 32 (see FIG. 2). The salt water fed to the rotary joint 21 is fed from the rotary joint 21 to the pothole 12a formed in the rotating shaft 12, and is fed to each pipe 13 from the pothole 12a.

The pipes 13 extend radially from the rotary shaft 12 in the radial direction of the saddle drum 11. The installation height of each pipe 13 is an upper position of the height of the inner cylinder 22 of the saddle drum 11, and salt water is injected toward the upper part of the inner peripheral surface of the inner cylinder 22 (see FIG. 1). The water pressure when injecting salt water from the injection holes 13a is about 0.01 MPa.
A spray nozzle or the like may be used instead of the pipe 13. In this case, the injection pressure is 0.2 to 0.5 MPa.

The arm 14 is mounted so as to be symmetric with respect to the rotating shaft 12. In the present embodiment, the number of arms 14 is two.
The blade 15 attached to the tip of each arm 14 is made of a stainless steel plate having a length substantially equal to the total length (total height) of the inner cylinder 22, and a plurality of saw teeth 15 a are provided on the end surface facing the inner cylinder 22. Is formed.

Next, operations of the ice making machine 10 and the ice making system having the above-described configuration will be described.
The refrigerant is supplied to the vertical drum 11 by operating the refrigerator, and the temperature of the inner peripheral surface of the vertical drum 11 is set to −20 to −25 ° C.
Next, the geared motor 20 is operated to rotate the rotating shaft 12 around the material axis, and salt water is supplied into the rotating shaft 12 through the rotary joint 21. The rotational speed of the rotating shaft 12 is 2 to 4 rpm. When a spray nozzle is used instead of the pipe 13, the rotational speed of the rotary shaft 12 is 10 to 15 rpm.

  The salt water sprayed from the pipe 13 that rotates together with the rotating shaft 12 toward the inner peripheral surface of the saddle drum 11 freezes instantly when it contacts the inner peripheral surface of the saddle drum 11. The ice generated on the inner peripheral surface of the saddle drum 11 is scraped off by the blade 15 that rotates together with the arm 14. The scraped ice falls from the discharge port 16. The ice dropped from the discharge port 16 is stored in an ice storage tank 34 disposed immediately below the ice making machine 10 and used for maintaining the freshness of fresh seafood.

  On the other hand, the salt water that does not become ice but flows down the inner peripheral surface of the saddle drum 11 is stored in the salt water storage tank 30 and is fed again to the rotary joint 21 via the pipe 32 by operating the pump 31 ( (See FIG. 2). In addition, when the salt water in the salt water storage tank 30 decreases, the salt water stored in the salt water tank 33 is supplied to the salt water storage tank 30.

[How to keep fresh seafood]
The procedure of the method for maintaining freshness of fresh seafood according to one embodiment of the present invention will be described below.
(1) An ice slurry prepared by mixing ice produced by the ice making machine 10 using salt water having a salt concentration of 13.6 to 23.1% and salt water having a salt concentration of 13.6 to 23.1%. (Sorbet-shaped ice) is manufactured. The temperature of the produced ice slurry is −9.8 to −21.2 ° C., but the lower the temperature, the smaller the ice crystals generated in the fresh seafood.
The temperature of the salt water mixed with the produced ice is normal temperature or lower. In addition, ice-making efficiency becomes high, so that the temperature of salt water is low.
Moreover, it is preferable that the salt concentration of the ice to be mixed and the salt concentration of the salt water are approximately the same (concentration difference within several percent), and the mass ratio of the ice to the salt water to be mixed is ice: salt water = 75: 25-20: 80. Preferably, ice: salt water = 60: 40 to 50:50.

(2) The fresh seafood is immersed in the produced ice slurry, and the fresh seafood is snap frozen. Although immersion time changes with kinds of fresh seafood, it is about 1 minute-1 hour, for example. The surface of fresh seafood immersed in ice slurry freezes instantly.
(3) Remove the freshly frozen fresh seafood from the ice slurry. And the taken-out fresh seafood is frozen-stored below the temperature (-9.8--21.2 degreeC) at the time of instant freezing, and is transported in the state preserve | saved frozen.

[Methods for thawing fresh frozen seafood]
When thawing the freshly frozen fresh seafood by natural thawing, the thawing time varies depending on the type of fresh seafood, but is about 1 to 2 hours, for example. Thereby, almost the same taste and texture as fresh seafood can be obtained.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, in the above embodiment, a drum type ice making machine is used as the ice making machine, but the invention is not limited to this, and other types of ice making machines may be used.

10: ice making machine, 11: vertical drum, 12: rotating shaft, 12a: coffin hole, 13: pipe, 13a: injection hole, 14: arm, 15: blade, 15a: saw blade, 16: discharge port, 17: upper bearing Member: 19: Protective cover, 20: Geared motor, 21: Rotary joint, 22: Inner cylinder, 23: Outer cylinder, 28: Bush, 30: Salt water storage tank, 31: Pump, 32, 35: Piping, 33: Salt water Tank 34: Ice storage tank

Claims (4)

A step of producing ice slurry by mixing ice frozen salt water having a salt concentration of 13.6 to 23.1% and salt water having a salt concentration of 13.6 to 23.1%;
A step of immersing the fresh seafood in the ice slurry and instantly freezing the fresh seafood.   2. The method for maintaining freshness of fresh seafood according to claim 1, wherein the ice and the salt water to be mixed have approximately the same salinity.   3. The method for maintaining freshness of fresh seafood according to claim 1 or 2, wherein the mass ratio of the ice to be mixed with the saltwater is ice: saltwater = 75: 25 to 20:80. .   The fresh seafood freshness maintaining method according to any one of claims 1 to 3, wherein the freshly frozen seafood is taken out of the ice slurry, and the fresh seafood is frozen and stored at a temperature equal to or lower than the temperature at the time of instant freezing. A method for maintaining freshness of fresh seafood.

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