JP3017229B2 - Thawing method of frozen red fish meat - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for thawing lean fish meat containing muscle pigment myoglobin.

"Prior art and its problems" Many large fresh fish, including sushi, are removed from gills and gills immediately after being caught at the catching area, blood is removed, and rapidly frozen at an extremely low temperature of around -60 ° C. . These frozen fish are sold in the form of sashimi of about several hundred g or sliced sashimi when they are lined up in the store after some thawing process.

Thawed fish meat quality is generally assessed by color and freshness. Among them, the redness of red fish meat such as tuna and bonito is mainly due to muscle pigment myoglobin (Mb) and hemoglobin hemoglobin (Hb).
Most of the dye is Mb. Mb is originally dark purple red (reduced), but it has been found that when it combines with oxygen in the air to form oxymyoglobin (MbO ₂ ), a beautiful bright red color is obtained. However, further oxidation of Mb and MbO ₂ produces metmyoglobin (metMb), which takes on a brown or dark brown color. Tuna discoloration means that Mb or MbO ₂ has changed to meMb. Such autoxidation reactions have been studied well since they have a direct effect on flesh color, and furthermore, when the temperature increases, the autoxidation rate increases, and when the oxygen partial pressure in the meat decreases, It is known that the autoxidation rate is increased.

Therefore, in order to thaw frozen tuna and obtain a bright red tuna, the oxidation of Mb may be suppressed to MbO ₂ so as not to generate metMb, but this is difficult with the conventional thawing method. In addition, during the thawing process, a large temperature difference was generated between the surface and the central portion, which made it difficult to obtain a fresh red fish meat as a whole. For example, when thawing a block of several kilograms in running water or still water, the temperature of the surface meat increases until the thawing of the central part of the fish meat is completed, and metMb
Is promoted and the color becomes brown. In addition, refrigerator (0-4
C) slowly exposes to a temperature zone where metMb is most likely to be generated (near -3C to -8C), resulting in brown color. Furthermore,
As described above, the autoxidation reaction is promoted as the oxygen partial pressure in the meat is lower. However, when the meat is thawed in a block shape, sufficient oxygen is supplied to the surface portion of the meat, whereas in the central portion, it is supplied. In this case, the supply of oxygen becomes extremely insufficient. As a result, even if a bright red color is obtained in the display, the central portion turns brown. Therefore, there has been a demand for a thawing method in which metMb quickly passes through a temperature body at which it is most likely to be generated, and furthermore sufficiently combines with oxygen in the air to exhibit a bright red color.

In addition, adenosine triphosphate (AT
P) shows adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosinate (IM
It is known that P), inosine (HxR) and hypoxanthine (Hx) are sequentially decomposed and changed. That is, a large amount of inosine (HxR) and hypoxanthine (Hx) means that the freshness has been reduced. Decomposition changes due to these enzymes can be suppressed by keeping the temperature as low as possible, but with conventional thawing methods, for example, natural thawing, a large temperature difference occurs between the surface and the center of fish meat,
For this reason, it was difficult to maintain freshness.

"Object of the Invention" The present invention is based on the theoretical recognition of color and freshness, and in the thawing process, minimizes the occurrence of a temperature difference between the surface and the central portion, and defrost conditions where metMb is unlikely to occur. It is another object of the present invention to provide a method for thawing frozen red fish meat, which is sufficiently bonded with oxygen.

[Summary of the Invention] The present invention is based on the idea of minimizing the occurrence of a temperature difference between the surface and the central part during the thawing process, and the temperature range (maximum color) where metMb is most likely to occur in red fish meat containing muscle pigment myoglobin. It has been completed as a result of research in order to satisfy both the ideas of passing through the inflection zone quickly. According to previous studies, metMb was -3 to-
It has been found that this is most likely to occur at 4 ° C and at -6 to -8 ° C in the center.

The present invention provides a method for thawing frozen red fish meat stored at −35 ° C. or lower, preferably about −50 ° C., where metMb is less likely to occur in red fish meat containing Mb. Suddenly raise the temperature until just before the inflection,
Thereafter, it was made based on the idea of rapidly passing the maximum color change zone and actively contacting the air.

The present invention relates to a method for thawing frozen red fish meat containing muscle pigment myoglobin, wherein several hundred g to several kg of block-shaped frozen red fish meat are stored in a closed container, and the center temperature is about -12 ° C to -12 ° C.
A block thawing step of setting the temperature to 6 ° C .; and removing the frozen red fish block having a central temperature of about −12 ° C. to −6 ° C. from the closed container, contacting with air, and removing the block from the block. The method is characterized in that a plurality of small flutes having a large surface area as a whole are taken out, and a filing step of proceeding with thawing by leaving them in a state where they do not come into contact with each other is performed without an interval.

The fried crispy can be eaten as sashimi after being thawed as it is, but it is also kept until the central temperature reaches about -3 to -1C, and then kept at -1 to 4C. It can be stored and aged and then eaten.

The method of the present invention is applied to the thawing of red fish meat containing Mb, such as tuna and bonito, and has an excellent effect of solving the above-mentioned problem of eating.

"Embodiments of the Invention" The present invention will be described in more detail with reference to FIG. This example is directed to tuna as frozen red meat containing Mb.

a. "Dismantling Step" This step is a step of cutting out a tuna block 12 weighing several hundred g to several kg from a frozen tuna 11 frozen at about -50C. Since the kitchen knife does not enter, it is cut with a saw-like electric cutter, for example. The block 12 is generally cut out in a rectangular parallelepiped shape, but its shape does not matter.

b. "Block dismantling step" This step is a step of putting the tuna block 12 in a closed container 13 made of, for example, a stainless steel material and thawing it in a sealed state. Since the surface of the tuna block 12 cut out in the dismantling step is dirty, it is preferable to wash away dust and scum adhering to the surface with running water and put the same in the closed container 13. What is important in this process is the tuna block 12
Cools the air in the closed container 13, the closed container 13 becomes a refrigerator using the tuna block 12 as a cold heat source. As a result, the temperature of the surface and the center of the tuna block 12 of the closed container 13 is almost It is a point that rises uniformly. That is, only the surface of the tuna block 12 is not excessively thawed,
The rise in the surface temperature is absorbed by exchanging heat with the inside, and as a result, thawing proceeds in a state in which the temperature difference between the surface and the center is extremely small. In order to make the block thawing process proceed quickly, the outside of the closed container 13 can be blown with a fan or running water.

In the conventional thawing method, since the outside of the tuna block 12 is always in contact with the outside air, the thawing of the surface portion proceeds excessively faster than the inside. As a result, as the thawing progresses, the temperature difference between the surface portion and the central portion increases.

The center temperature of this tuna block 12 is about -12 to-
When the temperature reaches 6 ° C., it is taken out of the closed container 13. Preferably, when the temperature reaches -10 to -8 ° C, it is good to take out. The temperature range where metMb is likely to occur is -3 to -4 ° C on the surface and -6 to -8 ° C at the center (maximum color change zone). Before reaching, the tuna block 12 is taken out of the closed container 13. When the temperature reaches -10 ° C, it can be cut with a kitchen knife.

Note that “sealing” of the container 13 does not mean a state in which air cannot enter or exit at all. Even if there is a slight ingress or egress of air, it is possible to obtain the above-described effects.

c. “Drilling process” From the tuna block 12 taken out of the sealed container 13, several hundred g (10-20mm x 40-55mm x 10-250mm of "drilled" 14 is cut out and brought into contact with air. As is well known, “saku” refers to a shape before being sliced as sashimi.

In order to quickly pass the maximum color change zone and promote the conversion of Mb to MbO ₂ , in this process, cut out the tuna 14 from the tuna block 12, increase the surface area, and positively contact the tuna meat with air . When the tuna block 12 that has reached just before the maximum color change zone is cut out as a fence 14, the surface of the fence 14 is sufficiently in contact with the outside air, the temperature rises, and the tuna block 12 quickly passes through the maximum color change zone. At this time, it is desirable that the fence 14 cut out from the block is immersed in a salt water having a concentration of 3 to 3.5% to remove free water from the meat, taken out from the salt water, and then wipe the surface with a dry paper towel. . Due to the difference in osmotic pressure between the tuna having a salt concentration of usually about 1% and free water, the generation of drip can be suppressed by previously removing free water. The crust 14 is made of dry fukin or 3
It is preferable to arrange them on a tray 16 on which a fukin 15 moistened with saline having a concentration of .about.3.5% is laid so as not to contact with each other. When the claws 14 are brought into contact with each other, the contact portion becomes in an oxygen-deficient state, and generation of metMb is promoted to turn brown. When the fukin 15 is laid, the lower surface of the fence 14 can also be brought into contact with air. In addition, the size of fence 14 is 10-20 mm × 40
Since it is about 55 mm × 100 to 250 mm, thawing can be performed in a state where the temperature difference between the surface and the center is small and oxygen is sufficiently supplied also to the center.

The crust 14 thus thawed can be cut into sashimi and eaten as it is.

In addition, when further storing the crust 14 as it is, when the center temperature of the crust 14 reaches about -3 to -1 ° C, preferably about -2 to 1.3 ° C, put it in a cool box of about -1 to 4 ° C. . If the center temperature is lower than -3 ° C, the temperature is in the maximum color change zone, so that metMb is generated and the color is easily changed. If the temperature is higher than -1 ° C, the surface temperature rises rapidly, and the formation of metMb is promoted, resulting in inconvenience of discoloration. Also, -1.3 ° C. is said to be the temperature at which the tuna develops the brightest red color (the freezing point of the tuna).

Then, after putting it in the cool box for about 24 hours, the fence 14 comes into contact with the air further, and the conversion of Mb to MbO ₂ is promoted, and a bright red tuna is obtained. In addition, during this storage, ATP is sequentially decomposed into IMP, HxR, and Hx, and umami comes out. And -1
A storage temperature of about 4 ° C. suppresses the growth of mesophilic bacteria that cause food poisoning.

[Effect of the Invention] As described above, the present invention provides a muscle pigment myoglobin (Mb)
When thawing frozen red fish meat containing, firstly, it is cut into blocks and thawed in a closed container, so that a temperature difference between the surface and the central portion hardly occurs. Immediately before reaching the maximum color change zone, in order to reduce the size by removing it, the surface area is increased, so that not only the surface but also the center is sufficiently in contact with air,
The product temperature can be rapidly increased. Therefore, it is possible to quickly pass through the maximum color change zone, change the muscle pigment myoglobin (Mb) to oxymyoglobin (MbO ₂ ),
A beautiful bright red thawed red fish meat is obtained. After filing,
Furthermore, if it is left until the center temperature becomes about -3 to -1 ° C and then stored in a cold storage at -1 to 4 ° C, both color and freshness can be kept for a longer time.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a method of thawing frozen red fish meat according to the present invention. 11 ... Frozen tuna chunks (fish meat chunks), 12 ... Tuna blocks, 13 ... Closed containers, 14 ...

Continuation of front page (56) References JP-A-63-240766 (JP, A) JP-A-58-205453 (JP, A) JP-A-62-14739 (JP, A) JP-A-62-134040 (JP, A) , A) Tuna & Bonito Thawing Q & A (Japan Bonito Tuna Fishery Cooperative Association (August 1988)) January District Management Committee (Nagano Living Cooperative (January 1988)) (58) Fields surveyed (Int.Cl. ⁷ , DB name) A23B 4/06-4/09

Claims (3)

(57) [Claims] 1. A method for thawing frozen red fish meat containing muscle pigment myoglobin, wherein a block of frozen red fish meat of several hundred g to several kg is stored in a closed container, and the center temperature is about -12 ° C. to −12 ° C. A block thawing step in which the block is allowed to stand at 6 ° C .; and the frozen red fish block having a center temperature of about −12 ° C. to −6 ° C. is taken out of the closed container and brought into contact with air. A method of extracting a plurality of small fishes having a large surface area as a whole and leaving them in a state where they do not come into contact with each other to carry out thawing; 2. The thawing method according to claim 1, wherein the dried fried food is further left until the central temperature becomes about -3.degree. C. to -1.degree. To defrost frozen red fish meat stored in 3. The method for thawing frozen red fish meat according to claim 1 or 2, wherein the red fish meat is tuna or bonito.