JP3070743B1 - Method and apparatus for maintaining freshness of fish and shellfish - Google Patents

Abstract

[PROBLEMS] To establish a method for maintaining the time limit of current fresh fish preservation methods for a longer time, and to provide a method and apparatus for facilitating the survival of large fish. SOLUTION: A method for keeping fish and shellfish alive,
After temporarily lowering the environmental temperature where seafood is grown in advance to make the seafood immovable or in a suspended state, a method for maintaining the freshness of the seafood to survive, and an aquarium set to the environmental temperature at which the seafood grows A seafood freshness maintaining device comprising a water tank and a slaughter device set at a temperature lower by 4 ° C. to 20 ° C. than the ambient temperature for growing, and through which the fish and shellfish are killed step by step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for killing fish and shellfish which are subjected to a low-temperature shock in advance, and a more effective, safe and economical method for maintaining freshness of fish and shellfish using the method and apparatus. And equipment.

[0002]

2. Description of the Related Art Fish and shellfish as food are produced by capture or cultivation. However, in Japan, there is a culture of eating raw fish, and keeping freshness of fish and shellfish has been an important issue since ancient times.
For this reason, there are many studies on freshness, taste, color, etc. of slaughtered fish (Japanese Society of Fisheries Science 36: 977-992 (1970),
Tokai Water Research Report 84: 51-113 (1976), "Extract Components of Fish and Shellfish" (edited by Morihiko Sakaguchi) Koseiseya Koseikaku pp104
-115 (1988)). When the distance between the producer and the consumer of the seafood is short, there is not much problem with maintaining freshness.However, the fact that there is a distance between the two and the sluggish inshore fisheries has relatively increased the operation of pelagic fisheries In addition, the imports of seafood are expanding due to the sluggishness of the Japanese fishery itself, which is why the transportation of seafood takes time.

[0003] At present, most of the seafood is currently frozen and stored and transported. In recent years, flash freezing methods that do not produce ice crystals in fish cells and lower freezing storage temperatures (-
(70 ° C.). However, once the frozen fish is thawed, it cannot be re-frozen and the texture and taste are impaired. On the other hand, the "live-tightening" method by sacrifice of the medulla oblongata has been widely used as a processing method of freshness because the freshness of fish is maintained extremely well. The storage condition, taste and texture of fish meat change depending on the state of slaughter of the fish. It is a kind of writhing death that is called “field tightening” and is empirically known to seriously impair the freshness of fish meat (Japanese Fisheries Science Society 56: 1673-1678). (1990)).

[0004] For this reason, instantaneous slaughter by vigilance aims at avoiding the above-mentioned agony death of fish and at the same time maintaining the state of the fish at the time of slaughter. For this reason, the amount or timing of shipment of cultured fish can be controlled, so that freshness can be maintained for a certain period of time. However, it is difficult to maintain freshness for a long time at present because there is not enough room to transport fresh fish from scattered cultivation areas and catching and collecting areas to all places in Japan.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to establish a method and an apparatus for maintaining the time limit of current fresh fish preservation methods for a longer period of time, and to facilitate the survival of large fish. Methods and apparatus.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has given a low-temperature shock immediately before alive shutting, so that compared to a conventional case where the live was kept at the rearing temperature, They succeeded in maintaining the freshness for about twice as long, and found that the conditions of the low-temperature shock differed depending on the fish species, and completed the present invention. That is, the present invention provides the following method. (1) A method for keeping fish and shellfish alive, characterized in that the temperature of the environment where the shellfish grows is temporarily lowered in advance, and the fish and shellfish are immobilized or suspended, and then alive. A method for maintaining the freshness of seafood. (2) A method for keeping fish and shellfish alive, in which the environmental temperature at which the fish and shellfish grows is shifted in advance to an environmental temperature lower by 4 ° C. to 20 ° C. than the environmental temperature at which the shellfish grows normally, and the fish and shellfish are immobilized. Alternatively, a method for maintaining the freshness of fish and shellfish, wherein the fish and shellfish are kept alive after being put into a suspended state. (3) The method for keeping fish and shellfish alive, wherein the method according to the above (2) is characterized in that the environmental temperature at which the fish and shellfish grow is lowered for 1 minute to 10 minutes. (4) The range of the above (1) to (1), wherein the range of the environmental temperature to be temporarily lowered is within the temperature range in which the target fish can grow.
The method for maintaining freshness of fish and shellfish according to (3). (5) The method for maintaining freshness of fish and shellfish according to any one of (1) to (4) above, wherein the freshness of the seafood is refrigerated at a temperature of 0 ° C to 10 ° C after alive. (6) An aquarium set at an environmental temperature at which fish and shellfish grow, an aquarium set at 4 ° C to 20 ° C lower than the environmental temperature at which the shellfish grows, and a slaughter device. A device for maintaining the freshness of fish and shellfish, characterized by performing livelihood.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Fresh fish and shellfish means that fish meat is preserved at the time of slaughter. Fish meat changes gradually after the fish dies and eventually rots. After death, stiffness appears after death, softens after continuing for a certain period of time, and rot occurs after autolysis. Food is used up to self-digestion, while sashimi is generally used during periods of stiffness after death. Postmortem stiffness is a phenomenon that occurs immediately after a fish dies, and is the stage at which fish meat hardens. The cause is not yet well understood, but during stiffness after death, muscle glycogen is glycosylated and turned into lactic acid. Adenosine triphosphate (ATP) dissociates from muscle myosin and is degraded. These change the fish meat from neutral to acidic, with a pH of 5.5 to 6.5.
It drops to about 5.

[0008] It is said that the speed up to stiffness becomes faster as the agony dies, and that the quality of fish meat is better as the stiffness speed is lower. When writhing to death, the fish consume more energy and the decomposition of ATP also progresses, resulting in faster stiffness and faster quality deterioration. It is stiff meat that is chewy with sashimi, and this condition is often preferred by Japanese. Then, the rigidity is released after a certain time. The process of softening fish meat, but the cause is still unknown. The pH gradually returns to neutral.

When the stiffness is released, self-digestion begins.
It is also called aging, and it is the stage where enzymes contained in meat work to break down their own proteins. As a result, amino acids are separated, and umami components are released. Livestock meat has a market value at this stage, but fish meat has no commercial value after this stage because it begins to rot in a short time.
Therefore, the fact that the fish and shellfish are fresh generally refers to a state of stiffness after death, and survival is a technique for maintaining a stiff state after death long.

[0010] Temperature shock is a self-defense mechanism that appears widely from bacteria to higher animals as a phenomenon. High temperature shock (heat shock) has been studied as a more general phenomenon and is well understood, but research on low temperature shock has not progressed much.
Both are defense mechanisms for responding to changes in body temperature caused by sudden environmental changes, but it is believed that there is no common mechanism between the two. The control method for cold shock used in the present invention produces immobility or asphyxia of the fish by forcibly lowering the body temperature of the fish or shellfish, which is a thermothermic animal. When the temperature decreases, a temporary immobility or asphyxia occurs due to a temperature shock.

At this time, it is possible that an opioid peptide which is a hormone in the brain is involved. This is apparent from the fact that immobility is released when naloxone, an antagonist of opioid peptides, is administered.
It is unknown at present which of the opioid peptides is involved, but administration of methionine enkephalin and morphiseptin at room temperature induces the same effect, so that δ (delta) and μ (mu) Opiate receptors may be involved.

When the fish and shellfish are kept alive, the environmental temperature at which the fish and shellfish are grown is temporarily lowered to immobilize the fish and shellfish, and then the fish and shellfish are killed. This low-temperature environment is performed by shifting to an environment temperature lower by 4 ° C. to 20 ° C. than the environment temperature at which normal growth occurs. Since the environmental temperature for normal growth varies depending on the type of fish and shellfish, it is necessary to know in advance the range of the growth environment of the fish and shellfish for processing. The temperature is kept at an environment temperature lowered by 4 ° C. to 20 ° C. from the temperature and the fish and shellfish are immobilized or put into a suspended state.). Once the type of fish and shellfish is determined, the optimum temperature for the low-temperature treatment can always be used.

The low-temperature treatment can be achieved by charging ice or the like and transferring the fish and shellfish to a water tank kept at a low temperature in advance. The time for the low-temperature treatment may be about 1 minute to 10 minutes. The movement of the fish and shellfish slows down due to the low temperature and almost stops, but in this state, the animals survive. The range of the environmental temperature to be temporarily lowered needs to be within a temperature range in which the target fish can grow. That is, the present invention does not mean shock death due to low temperature. The method and apparatus for maintaining freshness of fish and shellfish of the present invention do not prevent the use of other methods and apparatuses for maintaining freshness or freshness preserving agents, and include all methods that can be used in combination with the present invention.

[0014]

EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Other examples or modifications within the scope of the technical concept are all included in the present invention.
As the first test object of the present invention, firstly, cutthroat trout (scientific name: Oncorhynchus
clarki), a body weight of about 200 g and a body length of about 25 cm were used. In this example, a water tank having two temperature ranges of 13 ° C. and 2 ° C. was prepared, and a low-temperature shock was applied by moving a cut throat trout between the two water tanks. As a second test object, an adult sea fish, flatfish (scientific name: Paralichthys olivaceus), weighing about 1.2
kg and a body length of about 38 cm were used.

In this example, a water tank having two temperature ranges of 18 ° C. and 9 ° C. was prepared, and a low-temperature shock was given by moving flounder between the two water tanks. 2
The reason for preparing the water tanks having the two different temperature ranges is to make the temperature change more quickly, and to eliminate the bias of the temperature in the water tank and reduce the experimental error.
In the present example, the two temperature ranges of 13 ° C. and 2 ° C. or 18 ° C. and 9 ° C. are that the breeding temperature of cut throat trout or flounder is 13 ° C., respectively.
C or 18 ° C., and both fish inhabit cold regions, and their immobility occurred at 2 ° C. and 9 ° C., respectively. Other fish have different growth temperatures and thus different treatment temperatures.

In the present embodiment, the immobile or suspended state refers to a state in which the fish is in a fixed position without moving the fins while being in the normal position or overturning at the bottom of the aquarium. In the range of the environmental temperature to be temporarily lowered, the respiration in the temperature range in which the target fish can grow is greatly reduced in a normal case, but does not stop. The movement of the lid per unit time is reduced from 1/4 to 1/10. Also, in this state, you become insensitive to external stimuli,
Even if people touch it, it does not go wild. That is, no stress is caused.

[0017] Survival was performed by cutting the medulla oblongata of the fish with a knife. The medulla oblongata is the rear soft part following the skull of the fish, and the medulla oblongata of the fish was cut off from right above with a blade in a right angle direction. Immediately after the amputation, apply a knife at right angles to the base of the tail fin of the fish (mostly the right side, and the white back of the flounder) and the artery located at the bottom of the spine. Blood was squeezed out of the blood. Assay of fish meat was performed by observing the state of stiffness after death as described later and observing the state of drip of the cut. This is due to the fact that a form based on the fact that fresh fish are bought and sold in a rigid state after death is considered.
The stiffness after death was observed by leaving the blood-deprived fish as it was, and the drip was cut and observed.

Further, in order to examine whether or not the effect of the temperature shock of the present invention is due to the opioid peptide of neurons released or produced from the white fish to be tested, an antagonist of the opiate receptor was used. One naloxone was injected intraperitoneally prior to a temperature shock followed by a medullary sting. In addition, each representative opioid peptide was also injected alone, treated similarly, and compared.

[Test Using Cut Throat Trout] (Example 1) The cut throat bred at about 13 ° C. is immersed in ice water at about 1 ° C. until the movement stops or becomes dull (about 5 minutes). Cold treatment was performed, and the medulla was immediately stabbed and sacrificed. Comparative Example 1 Similarly, a cut throat bred at about 13 ° C. was sacrificed by puncturing the medulla oblongata without performing the low-temperature treatment of Example 1. This is the usual method of living confinement performed conventionally. Comparative Example 2 Similarly, 0.375 μg / g of naloxone, an antagonist of opiate receptors, was injected intraperitoneally into cut throats raised at about 13 ° C. (10 minutes before slaughter). At the same rearing temperature, low-temperature treatment was performed under the same conditions as in the present invention. Immediately thereafter, the medulla was stabbed and sacrificed. Comparative Example 3 Similarly, DADLE, an opioid peptide liquid, was added to cut throats bred at about 13 ° C.
(Δ opioid peptide) 1.5 μg / g body weight of the fish was injected intraperitoneally, kept at the same breeding temperature for 30 minutes and sacrificed by medulla oblongata. (Comparative Example 4) Morphiceptin (M opioid peptide), which is an opioid peptide liquid, was applied to cut throats similarly raised at about 13 ° C.
5 μg / g fish body weight was injected intraperitoneally and kept at the same rearing temperature for 30 minutes.
After separation, the medulla was stabbed and sacrificed. (Comparative Example 5) Similarly, dynorphin A (Dynorphin A: kappa opioid peptide), which is an opioid peptide liquid, was fed to cut throat bred at about 13 ° C.
5 μg / g fish body weight was injected intraperitoneally and kept at the same rearing temperature for 30 minutes.
After separation, the medulla was stabbed and sacrificed.

After the treatment of Example 1 and Comparative Examples 1 to 5, the ratio was shown by using the hanging degree and hardness of the fish placed horizontally as an index. In general, fish bodies are flexible, so if you put them on a flat table for rigidity index measurement, the obi will hang down, but if you get stiff, the obi will start to rise,
Eventually it becomes level and inflexible, leading to complete rigidity. In this way, the state of complete rigidity was defined as 100%, and the degree of rigidity was evaluated in each of the steps leading to the state, and the degree was expressed in%. Although this rigidity evaluation method has not yet been established, it is a general evaluation method.

FIG. 1 shows the results. In this case, in order to observe the stiffness of each fish quickly (in an accelerated test), the temperature after alive was kept at 19 ° C.
In Comparative Example 1 according to the conventional living closing method, the graph 2 in FIG.
As shown in FIG. 1, the rigid state is completely entered in about 4 hours. In contrast, in Example 1 in which the low-temperature treatment of the present invention is performed, as shown in the graph 1 of FIG. 10
It took time. As described above, although the time required to reach rigidity is delayed by the low-temperature treatment of the present invention, it means that freshness can be maintained accordingly. The naloxone competitive inhibitor of the opiate receptor regard to Comparative Example 2 was injected intraperitoneally, as shown in the graph 3 in FIG. 1, in the same manner as in Comparative Example 1
It took about 4 hours to reach a completely rigid state. It is presumed that this is due to the opioid peptide of neurons released or produced from the fish white by the low-temperature treatment (temperature shock) of the present invention. I understand.

Among the DADLE (δ opioid peptide) of Comparative Example 3, the morphiceptin (μ opioid peptide) of Comparative Example 4 and the dynorphin A (κ opioid peptide) of Comparative Example 5, the stiffness after mortality was delayed. Significant influences are shown in graphs 4, 5, and 6 in FIG.
As shown in the figure, the morphiceptin (μ opioid peptide) of Comparative Example 4 was almost equivalent to Example 1 of the present invention. In other words, it was confirmed that the low-temperature treatment of the present invention had the same effect as that of morphiseptin (μ opioid peptide) injected intraperitoneally.

Next, for the cut throats used in Example 1 and Comparative Examples 1 to 5, the state of dissolution from the start to the end of rigidity was examined. The result is shown in FIG. In this case, unlike the case of FIG. 1, all the fish were refrigerated at a low temperature after alive, that is, the temperature was maintained at 4 ° C. As shown in the graph 8 of FIG.
In contrast to the complete dissolution in time, as shown in the graph 7 of FIG. 2, it took one day to completely dissolve in the case where the low-temperature treatment of the example of the present invention was performed. 24 overall
There was an effect of prolonging stiffness after death. Comparative Example 2
When naloxone was injected intraperitoneally in advance (10 minutes before sacrifice), as shown in the graph 9 of FIG. In addition, DADL of Comparative Example 3 above
E (δ opioid peptide), morphifeptin (μ opioid peptide) of Comparative Example 4, and dynorphin A (κ opioid peptide) of Comparative Example 5 all showed rigid dissolution as shown in graphs 10 to 12 in FIG. There was an effect on the time delay (about 40 hours). However, those according to the present invention showed even better delays in rigid dissolution.

[Test Using Flounder] (Example 2) Flounder bred at 17.8 ° C. was treated with seawater at 9 ° C. for 5 minutes, immediately killed, and dismantled. I just kept alive. Lower the body to three pieces, and put the skin on the back and belly in a sterile petri dish for about 24 hours.
Stored at 18 ° C. for hours. A drip of the fillet was accumulated between the skin and the petri dish, and this was wiped off with a tissue and weighed. (Comparative Example 6) Japanese flounder bred at 17.8 ° C was not subjected to low-temperature treatment and was directly alive (conventional livelihood method).
As in Example 2, the body was lowered to three pieces, and the back and belly were placed on a sterile petri dish with the skin down for 18 hours for about 24 hours.
Stored at ° C. A drip of the fillet was accumulated between the skin and the petri dish, and this was wiped off with a tissue and weighed.

Table 1 shows the results of Example 2 and Comparative Example 6.
As shown in Table 1, the amount of drip per weight of Comparative Example 6 was:
The belly is 0.0126 and the back is 0.0111. Compared to this, the amount of drip per weight of the low-temperature-treated Example 2 of the present invention is 0.0087 for the belly and 0.0071 for the back. , Both are few. Taking the ratio of Example 2 and Comparative Example 6, the belly was 0.0087 / 0.0126 = 0.69, and the back was 0.0071 / 0.0111 = 0.64. That is, the drip amount of the Japanese flounder subjected to the low temperature treatment in Example 2 is about 70% of Comparative Example 6. The amount of drip was an indicator of the progress of putrefaction, and in the examples of the present invention, the amount was small and it was confirmed that there was a significant freshness retaining effect. In addition, as for the fillet, the low-temperature-treated Example 2 of the present invention did not have any gloss on both the belly and the back, and had a rough appearance, whereas the comparative example 6 had a smooth gloss. Further, after three days, all the cuts are glossy and the rot has already begun, so that the gloss of the cuts can also be used as an indicator of the decrease in freshness.

[0026]

[Table 1]

[0027]

According to the present invention, fish meat that has been subjected to livelihood processing at a low temperature can maintain freshness for a longer period of time as compared with fish meat prepared by conventional livelihood processing. Therefore, it is improved that the storage period of the conventional fish meat is short, which makes it difficult to deliver it to a remote place. From this, according to the present invention, the effect of keeping fresh fish,
Since it is about twice as large as the conventional method, it can be distributed almost nationwide. In addition, in the conventional distribution, the goal of maintaining freshness around the evening when fish reach the consumers,
There is a case where work is performed late at night by calculating the time of the livelihood processing back. However, according to the present invention, since the retention of the freshness is extended, the processing is more relaxed, the late night work is improved, and the cost is reduced. On the other hand, in the past, when alive, fish were deeply caught and caught in the water, and highly skilled craftsmen were engaged. The low temperature treatment of the present invention renders the fish immobile, which facilitates handling of the fish, simplifies livelihoods, and eliminates the need for specialized craftsmen. Therefore, production costs are reduced. In addition, it can be mechanized, and can process a large amount of fish. A conventional fish tank can also be used for the low-temperature processing apparatus, and the temperature can be controlled using ice, and there is an advantage that the cost required for this is low. Furthermore, the ability of the method and apparatus of the present invention to prolong the post-mortem stiffness of slaughtered fish means that bacterial growth is suppressed for a long period of time, and the occurrence of food poisoning can be reduced. Is enhanced.
In addition, there is no need to use an additive or the like for maintaining freshness, and similarly, there is an excellent effect that there is no effect on the human body.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a transition of a stiff state after death when the processes of Example 1 of the present invention and Comparative Examples 1 to 5 are performed.

FIG. 2 is a diagram illustrating an index of dissolution from the start to the end of a rigid state when the processing of Example 1 of the present invention and Comparative Examples 1 to 5 are performed.

[Explanation of symbols]

1 Transition of rigid state in Example 1 after low-temperature treatment 2 Transition of rigid state in Comparative Example 1 3 Transition of rigid state in Comparative Example 2 4 Transition of rigid state in Comparative Example 3 5 Transition of rigid state in Comparative Example 4 6 Transition of rigidity state in Comparative Example 5 7 Transition of melting immediately after hardening in Example 1 subjected to low-temperature treatment 8 Transition of melting immediately after hardening in Comparative Example 1 9 Transition of melting immediately after hardening in Comparative Example 2 10 Comparative Example 3 Transition of melting immediately after hardening in Comparative Example 4 11 Transition of melting immediately after hardening in Comparative Example 4 12 Transition of melting immediately after hardening in Comparative Example 5

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) A22B 3/08 A22B 3/00

Claims (6)

(57) [Claims] Claims: 1. A method for keeping fish and shellfish alive, wherein the temperature of the environment where the shellfish grows is temporarily lowered in advance, and the fish and shellfish are immobilized or suspended in a temperature range where they can grow .
A method for maintaining the freshness of fish and shellfish, wherein the fish and shellfish are viable at the temperature at which they can grow . 2. A method for keeping fish and shellfish alive, wherein the environmental temperature at which fish and shellfish grows is temporarily shifted to an environmental temperature temporarily lowered by 4 ° C. to 20 ° C. from the environmental temperature at which normal shellfish grows, A method for maintaining the freshness of fish and shellfish, wherein the fish and shellfish are immobilized or suspended in a temperature range where the fish and shellfish can grow , and then shut down at the growth temperature . 3. A method for keeping fish and shellfish alive, wherein the environmental temperature at which the shellfish grows is temporarily set to 1 minute to 10 minutes.
In the temperature range where fish and shellfish can be raised
A method for maintaining the freshness of fish and shellfish, wherein the fish and shellfish are kept alive at the temperature at which they can grow after being in a state . 4. A method for keeping fish and shellfish alive, wherein the temperature of the environment where the shellfish grows is temporarily reduced to an environment where the shellfish grows normally.
Ring reduced from temperature to 4 ° C to 20 ° C for 1 minute to 10 minutes
Temperature to the ambient temperature, and the fish and shellfish
Is a method for maintaining the freshness of fish and shellfish, wherein the fish and shellfish are kept alive at the temperature at which they can grow after being put into a suspended state . 5. After living tightened, 0 ° C~10 ° C according to claim 1, 2, 3 and 4, characterized in that the refrigerated at a temperature of
The method for preserving freshness of fish and shellfish according to any one of the preceding claims. 6. A water bath set at ambient temperature for fish to grow, the than growing environmental temperature was lowered 4 ° C. to 20 ° C., the low range of Do not environmental temperature target fish viable temperature
The fish and shellfish are immovable or
An apparatus for maintaining freshness of fish and shellfish, comprising a water tank and a slaughter device set so as to be capable of dying, wherein the fish and shellfish are alive and shut down in stages.