JPS59159734A - Method for treating large-sized fish such as tuna on board after fishing, and cooling water tank used therefor - Google Patents

Abstract

PURPOSE:To remove the blood line of a large-sized fish such as tuna, and to prevent the discoloration of the meat, by rapidly and perfectly killing the fish by breaking its brain, etc., lowering the body temperature of the fish as rapidly as possible, and freezing or refrigerating the body for storage. CONSTITUTION:Fished large-sized fish such as tuna is killed rapidly and perfectly e.g. by breaking its brain, and the body of the fish is cooled as rapidly as possible in a cooling water tank 1, and the fish is freezed or refrigerated for storage. A compressed air feed pipe 3 is placed near the cooling pipe 2 extended in the water tank 1 containing sea-water, and the pipe 3 is furnished with a number of air blowing holes 4 directed toward the cooling pipe 2. The sea-water in the water tank 1 is maintained at about 0 deg.C by the cooling pipe, and a fish body subjected to the blood-removing treatment is left in the sea-water for several hours - ten hours to effect the above freezing or refrigeration treatment. The generation of the blood line in the fish meat can be suppressed remarkably, and the obtained meat is resistant to discoloration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for processing large fish such as tuna on a ship after being caught, and a cooling water tank used to carry out the method.

With the recent development of refrigeration technology, tuna fishing boats are now equipped with ultra-low temperature freezing and refrigerating chambers, so the freshness of the caught fish seems to have improved at first glance, but after thawing, the fish meat remains There are many cases where the discoloration rate is very fast, and this tendency is particularly noticeable in those caught in the oceans of mid to low latitudes. In addition, after thawing, many surface lines are observed in the body, especially on the abdomen, and this is one of the reasons for the extremely low commercial value of tuna fish meat.

1- Based on the foresight that the problem described above may be caused by rapid freezing at ultra-low temperatures immediately after capture, we developed a new processing method to confirm this and eliminate this problem. In order to do so, we conducted the following experiment.

[Experiment details]

■, 40 tuna (20 out of an average weight of 50Kl) were pulled onto the deck of the tuna fishing boat to be tested. 2
,000. f! 1. ), a cooling pipe 2 is provided, a compressed air supply pipe 3 is provided adjacent to the cooling pipe 2, and a large number of air jet holes 4 are provided in the supply pipe 3 facing in the direction of the cooling pipe 2. A refrigerant supply pump 5 is connected to the cooling pipe 2, and a near compressor 6 is connected to the compressed air supply pipe 3.

” - Fill the water tank 1 with seawater at a water temperature of 22°C, supply refrigerant to the cooling pipe 2 to cool the seawater, and inject compressed air around the cooling pipe 2 to cool the cooling pipe 2. Prevents the surrounding area from freezing. After 10 hours of cooling, the water temperature decreased to -1,
The temperature dropped to 5 degrees Celsius, and many ice crystals formed like sherbet near the water surface.

In addition, a tuna (weight 40 KLj, body temperature 28°C) after treatment (removal of sea bream, removal of internal organs) was placed in this aquarium, and after being left for 10 hours, the core body temperature was +6°C. (3) Experiment details ■ Treatment Method A (conventional method) After hitting the heads of the five bigeye tuna used in the experiment (hereinafter referred to as hitting treatment), the conventional treatment (removal of the catfish and removal of internal organs) was performed. The cells were placed in a -45°C freezing chamber for 24 hours. No blood removal process.

■Processing method B For each of the 5 bigeye tuna to be tested, a brain and central nervous system destruction tool (for example, Utility Model Publication No. 53-22557, product name ``Toll'') was used to destroy the head and interior of each tuna (hereinafter referred to as , brain destruction treatment), followed by conventional treatment at -45°C.
It was placed in a freezing chamber for 24 hours. No blood removal process.

■Treatment method C: After brain destruction treatment was applied to the five bigeye tuna used in the experiment,
The animals are treated in a conventional manner and left for 10 hours in a bloodless state in the water tank of the experimental apparatus (but without spraying compressed air), which often results in some animals not being completely dead.

Therefore, if the fish is placed in cooling water after being beaten, rigor mortis will rapidly occur in the fish that are not dead, and in large fish, so-called "scorch" (alteration of proteins due to high body temperature) will occur near the center of the fish body, resulting in discoloration. However, when rapidly frozen after beating (processing method A),
Fish that are not completely dead undergo changes similar to this, resulting in a decrease in quality.

On the other hand, brain destruction treatment is a killing process that completely and immediately kills the fish body, so discoloration as described above is unlikely to occur, but if the brain destruction treatment is followed by quick freezing (processing method 13) or When placed in a cooling water tank that does not supply compressed air (processing method C), sufficient effects are unlikely to appear.

■About the cooling water tank When compressed air is not sent to the cooling water tank (processing method C)
, freezing occurs in the cooling pipes in the tank. Therefore, the seawater temperature did not easily drop, and after the tuna subject to the experiment was left for 10 hours, the core temperature of the fish body was +18°C, and the water temperature was +10°C.

When compressed air is sent (processing method D), the compressed air searches for and stirs water near the cooling pipes, so that no freezing occurs in the pipes. Therefore, the water temperature after being left for 10 hours was +2°C, and the core body temperature of the fish was +5°C.

When cooling in a cooling water tank before freezing, as in treatment method C, even if the cooling water is cooled in a cooling water tank without sending compressed air, discoloration cannot be sufficiently prevented. It has been found that discoloration can be suppressed by cooling with compressed air supplied.

(6) Summary Judging from the experimental results in I-L, it is important to promptly and completely kill captured large fish such as tuna by brain-destroying treatment, etc., and to reduce the body temperature of the fish as much as possible after killing. It can be seen that performing a cooling treatment to lower the temperature, that is, a pre-cooling treatment, is important for removing blood veins and preventing discoloration.

It is generally accepted that the product should be quickly frozen after the pre-cooling process described above, but this is necessary for long-term storage, so depending on the storage conditions, it may be necessary to store the product at around 0°C after the pre-cooling process. There is also.

As described above, according to the processing method of the present invention, the occurrence of blood veins in fish meat is extremely reduced, and the fish meat is less likely to discolor. Further, the cooling water tank according to the present invention can prevent the formation of ice around the cooling pipe and can sufficiently exhibit a cooling effect.

[Brief explanation of drawings]

The figure is a sectional view showing an example of a cooling water tank. 1... Cooling water tank, 2... Cooling pipe, 3... Compressed air supply pipe, 4. ...Air nrt outlet. Patent applicant Yoshimura Sangyo Co., Ltd.

Claims (2)

[Claims] (1) Large fish such as tuna that have been caught are quickly and completely killed by brain destruction treatment, etc., then subjected to cooling treatment to lower the body temperature of the fish as much as possible, and then frozen or cooled for storage. A method for processing large-sized fish such as tuna on a ship after catching the fish, which is characterized by: (2) Cooling the fish body temperature in a cooling tank filled with seawater, maintaining the seawater in the tank at around 0°C;
Leave the blood in the tank for several to 10 hours (3) Install a compressed air supply pipe near the cooling pipe drawn into the water tank, and attach an air jet hole in the compressed air supply pipe facing the direction of the cooling pipe. A cooling water tank characterized by having a large number of them.