KR102088561B1 - The method of thawing and maturing for frozen tuna - Google Patents

Abstract

The present invention relates to a method for thawing and aging frozen tuna, and more specifically, storing a frozen tuna block stored at -60 ° C to -50 ° C in a freezer for 20 to 30 hours so that the surface temperature of the tuna block is -25 ° C. The tuna block that has completed the above temperature change before thawing to maintain the temperature until ~ -20 ℃ and keep it again in the refrigerator for 3 to 4 hours to maintain the temperature of the surface of the tuna block from -12 ℃ to -8 ℃. After cutting 2-3 pieces, measure the total weight of the tuna block, prepare water equivalent to 2 to 3 times the measured tuna block, maintain the temperature of the water at 10 ℃ ~ 20 ℃, and after the salt water is completely dissolved, the tuna Preparation of thawing by adding grapefruit extract to a saline solution having a salinity of 3.5% to 4.5% depending on the amount of fat, freshness, season, etc. of the block, and dipping it in the prepared saline for 1-3 minutes depending on the amount, size, and distortion of the tuna block Deliver After removing the bones and skins, remove the water and foreign substances on the surface of the tuna block by wiping it with thaw paper, and wrap the tuna block with the water off the surface with a new thaw paper, wrap it or vacuum-pack it to make contact with oxygen. Step 2 of blocking defrosting, storing the prepared tuna block in the refrigerator for 2-3 hours to thaw the temperature formed on the surface and inner layers of the tuna block gradually, then changing the temperature and the tuna block undergoing the temperature change again. Wrapped in defrosted paper and wrapped or vacuum-packed, the inside of the storage space is directly cooled to be placed in a aging container at -1 ° C to 0 ° C that can maintain the moisture of the frozen tuna block, depending on the fat content and freshness of the tuna block. And aging for 20 hours.
According to the present invention, the temperature of the frozen tuna block before and after thawing is controlled, and according to the condition of the tuna block, other salinity is controlled and the saline temperature is set low and the immersion time to put the tuna block into the saline is minimized. It improves the freshness by preventing discoloration, slowing down the oxidation rate, and using fresh sea salt and grapefruit extract to improve product taste by defrosting process (lower yield), taste and freshness of tuna sashimi, and overall preference such as texture and odor. There is this.

Description

The method of thawing and maturing for frozen tuna}

The present invention relates to a method of thawing and aging frozen tuna, and more specifically, it does not defrost frozen tuna blocks at -60 ° C to -50 ° C through rapid temperature changes, but gradually raises or lowers the temperature to a target temperature that has already been set. By thawing while giving, and adjusting the salinity and immersion time of the saline solution formed by the sun salt and aging by using the direct cooling method

It prevents tuna's natural texture loss and product loss (decreased yield) due to the thawing process, while at the same time eases the difficulty of the thawing process due to different fat mass, freshness, thickness, and distortion, and maintains the unique texture of tuna, resulting in rich flavor, It is a method of thawing and ripening frozen tuna that gives elasticity of fish meat and improves texture and flavor.

Compared to the past, the current situation of the tuna distribution market is in a situation where it is difficult to continuously supply quality tuna due to global warming, elino phenomenon, and soaring demand.

Accordingly, it is proposed to maintain a certain taste through thawing and aging methods that divide tuna frozen in different states at the time of fishing into fat, freshness, and the like.

The species of tuna are largely divided into red tuna and white or whiteish tuna. It is divided into, whitefish, sailfish, and blackfish.

It is divided into sashimi and stewed or grilled, steak, and canned food depending on the purpose of reuse, and for the sashimi, northern bluefin tuna, southern bluefin tuna, bigeye tuna, yellowfin tuna, and swordfish are used, and the rest are divided into stewed and grilled according to freshness. In addition, products that are inconsistent in shape or inferior in utilization value are processed into canned food.

In addition, according to the distribution method of tuna, it is largely divided into raw tuna and frozen tuna, and in general, raw tuna is caught near fishing grounds (South Pacific, Atlantic-Hawaii, Spain, Italy, Ecuador, Philippines, Indonesia, etc.) Most of them are in circulation.

When raw tuna is distributed in other areas, it is stored in ice or dry ice like salmon for air transportation. At this time, it is caught and stored in fresh condition + storage period in local airport baggage + travel time in aircraft + domestic airport Luggage storage period + customs clearance period + time to reach a consumer by catching one tuna, including the period of moving to a domestic tuna distributor and storage period, and also the size of one is 20kg ~ 100kg In the case of tuna that is diverse and large in size, a serious problem arises in freshness through a long-term distribution process.

Because of this, most of the raw tuna that is distributed in Korea distributes only small-sized tuna, so it is not enough to feel the unique taste of the fish species, so the frozen tuna market is superior to raw tuna.

Only when you use frozen tuna of a certain size (eg, bluefin tuna: over 200 kg / eye tuna: over 50 kg), you can feel good meat and natural taste.

The bluefin tuna farming in Jeju, Korea, has good meat quality and keeps it fresh, but its small size makes it difficult to feel the rich fat of the tuna that was mentioned above.

For this reason, it is difficult to supply delicious tuna raw fish in Korea smoothly, so the texture, color, taste, and odor are different depending on the thawing and aging method using cryogenic frozen tuna in a state that has a better taste and flavor. Therefore, the present invention was started while defrosting frozen tuna and researching to approximate the state of raw tuna.

Finally, after catching, it is divided into agitation (frozen in the hull) and land dong (frozen in the land) according to the method of freezing.

At this time, tuna frozen to -60 ℃ through agitation has a certain salinity inside the tuna depending on the climate and environment.

In the present invention, when thawing frozen tuna in this way, it will be in an optimal state if it is thawed with the correct salinity of seawater at the time of fishing, but it minimizes the time to immerse the tuna block in saline with a constant salinity due to the unmeasurable relationship. This is to suppress the extreme osmotic action due to the difference in salinity of the.

This process should be avoided if the frozen tuna is defrosted in saline for a long time using the existing thawing method because the fat or nutrients inside the tuna are deprived by the osmotic action between the frozen tuna block and the saline.

In general, the thawing method of frozen tuna is largely divided into flowing water thawing, saline thawing, natural thawing, ultrasonic thawing, ICE thawing, and pressure thawing. In addition, there are high frequency thawing and heating thawing.

Among them, in the thawing method using water such as flowing water, saline defrosting, and ICE defrosting, discoloration occurs when the frozen tuna block stays in high temperature water (including saline).

The production rate of MET Mb (meta myoglobin = discoloration probability: -8 ℃ ~ -3 ℃) of the superficial meat is higher in the case of 0 ℃ and 30 ℃ than in the case of 10 ℃ ~ 20 ℃ under the influence of the thaw water temperature.

The high production rate of MET Mb at 30 ° C thawing was because the temperature of the superficial meat was increased until the end of thawing at the center, and the production of MET Mb was accelerated. The high production of MET Mb at 0 ° C thawing was the production of MET Mb. The most prone temperature. That is, the surface meat was thawed over a relatively long period of time at -3 ° C to -4 ° C, and -6 ° C to -8 ° C inside.

In other words, when thawing, the water temperature is appropriately 10 ° C to 20 ° C, and the probability of discoloration inside the tuna block is low.

Most commonly, the saline defrosting method is used, which is 2 to 3 times the amount of tuna blocks to defrost frozen tuna blocks at -60 ° C to -50 ° C, and a saline solution with a salinity of 3% (salt water salt) at a temperature of 28 ° C. After soaking for about 18 minutes, take it out, remove bones and skins, wipe off the water, wrap it in defrosting paper or a clean towel, put it in a refrigerator (Maturity High School), mature it, and eat it after 1 hour.

At this time, by freezing the frozen tuna block from -60 ℃ to -50 ℃ in a saline solution at a high temperature of 28 ℃, the temperature suddenly decreases again and the MET Mb (meta myoglobin = probability of discoloration: -8 ℃ to -3 ℃) Discoloration begins inside the tuna block after staying in the section for a long time, several times.

This discoloration can be solved by gradually lowering or raising the temperature, but similar to rapidly increasing the temperature of the tuna block, it rapidly decreases, removes water and puts into the maturation chamber, and eats after 1 hour, and the internal discoloration promotes oxidation and accelerates maturation. Through this, the inside water is not completely removed, which may lead to fishy smell. At this time, the tuna that contains the moisture will not have the unique taste.

In addition, it is explained as a serious error in the thawing method because the surface of the tuna block is crushed and the texture and yield (the amount that can be used after thawing) is lowered while immersed in high temperature (saline at 28 ° C) for more than 10 minutes.

Frozen tuna blocks caught in different environments do not know the exact salinity inside, so if they are soaked in normal salt water for a long time (more than 10 minutes), pickling and osmotic phenomena are severe and excessive salinity penetrates into the tuna fish meat. As it is rapidly discharged, elements such as the fat layer (protein, fat, amino acid, nucleic acid, etc.) are also discharged, and the texture of the sashimi deteriorates and there is a problem of losing the flavor of tuna.

That is, long-term saline defrosting has a large loss in the defrosting process, such as the loss of salinity or absorption, the thinning of the surface, the decomposition of the fat layer, the shrinking shrinkage of the surface as it distorts, and the marked deterioration of texture.

No matter the size of the tuna block, the difference in fat, the difference in distortion, etc., saline thaw at a high temperature for a certain period of time, and by not considering each difference, color development (natural color rises rapidly) and discoloration (oxidation changes color) , The color changes and the fishy) progresses differently, and you notice a remarkable difference in texture, flavor, and freshness.

In other words, the size of frozen tuna blocks is different, the degree of distortion (jijim phenomenon) is different, the fat is high and low, and the freshness is good and bad. .

In this regard, Korean Registered Patent No. 10-1234291 provides an appropriate thawing temperature according to the amount and size of frozen tuna, however, it is possible to adjust the salinity and low saline according to the temperature change of the frozen tuna block before thawing and the condition of the frozen tuna block. The effects of minimizing the temperature and time of immersion in saline have no effect on the properties, functionality, and overall taste of tuna.

The present inventor has been studying to improve the taste, texture, and odor of tuna sashimi, but not the rapid temperature change, but the temperature change over time and the other salinity control method according to the tuna block condition and the time to lower the saline temperature and immerse it in saline solution. The present invention was completed by confirming that it can be as close as possible to the tuna's original taste by minimizing.

Domestic registered patent No. 10-1234291

Accordingly, an object of the present invention is to provide a method for thawing and aging frozen tuna to provide tuna sashimi in excellent condition by improving the color, taste and freshness, texture and flavor of tuna sashimi.

In order to achieve the above object,

(a) The temperature change before thawing to keep the tuna block frozen at -60 ℃ ~ -50 ℃ in the freezer for 20 ~ 30 hours to maintain the temperature until the surface temperature of the tuna block becomes -25 ℃ ~ -20 ℃ Stage 1; (b) The tuna block maintained at the temperature of -25 ° C to -20 ° C was put in a refrigerator of 3 ° C to 5 ° C for 3 to 4 hours to maintain the surface temperature of the block at a temperature of -12 ° C to -8 ° C. Preliminary thawing temperature change 2 steps; (c) After cutting 2-3 pieces of tuna block after step (b), measure the total weight of the tuna block, prepare water corresponding to 2 to 3 times the metered tuna block, and prepare the water temperature of 10 ℃ A thawing preparation step of maintaining at ~ 20 ° C and maintaining salt water having a salinity of 3.5% to 4.5% depending on the amount of fat or freshness or season of the tuna block; (d) Soaked in salt water after step (c) for 1 to 3 minutes depending on the amount of fat or the size or distortion of the tuna block, and then dried to remove bones and shells, and then wiped with a thaw to remove water and foreign substances from the surface of the tuna block. Stage 1; (e) a second step of thawing to wrap the tuna block from which the surface has been removed with a new thawing paper, and then wrap it in a wrap or vacuum packaging to block contact with oxygen; (f) The tuna block that has been subjected to step (e) above is stored in a refrigerator at 3 ° C to 5 ° C for 2 to 3 hours, and the thaw is gradually lowered so that the temperature formed on the surface and inside of the tuna block is maintained at -1 ° C to 2 ° C. After temperature change step; (g) After the tuna block that has been subjected to step (f) is completely wrapped with a new thaw, wrap it in a wrap or vacuum packaging and place it in a aging pan at -1 ℃ to 0 ℃, depending on the fat amount or freshness of the tuna block, 5 to 20 Method of thawing and aging frozen tuna, characterized by the step of aging for a period of time.

The present invention is characterized in that the temperature of the frozen tuna block is moderately changed before and after defrosting, the amount of fat or freshness of the tuna block is adjusted according to the other salinity, and the salt water temperature is set relatively low and the immersion time for placing the tuna block in the salt water is minimized. It prevents discoloration inside the tuna block and slows the oxidation rate. In addition, by providing a method for improving freshness by using fresh sea salt and grapefruit extract, the product loss (decreased yield) due to the thawing process, a method for improving the taste and freshness of tuna sashimi and the overall preference for texture and flavor, according to the present invention The method of thawing and aging frozen tuna can be useful throughout the manufacture and distribution of tuna.

Hereinafter, terms used herein are defined.

The term 'tuna' used in the present invention is limited to tuna that can be used as tuna, and does not include other tuna for roasting and canning.

The main species used for tuna are bluefin tuna, blue eye tuna, yellow fin tuna, southern blue tuna, southern blue fin tuna, and swordfish (SWORD MARLINE / 10 ~ 300KG) ) 5 fish species and other fish species are relatively small. However, even if the catch is small, the value of use is not low, and it is used for purposes other than tuna sashimi (grilled, stewed, steak, etc.) and is limited to the above mentioned five fish species.

The 'tuna block' used in the present invention includes pear / neck / back / whisper and tail of the 5 fish species mentioned above after agitation in the ship at -60 ℃ after catching (船 凍: quenching at the cryogenic temperature of the ship after catching). Therefore, it is commonly referred to as a cut lump for each part of 'tuna' that has been cut to an appropriate size for circuit use and frozen at -60 ℃ to -50 ℃ at cryogenic temperature. The shape of this mass is similar to the shape of a small brick block, so it is called a 'block'.

The term 'thawing' as used in the present invention means complete thawing in the absence of ice crystals inside the tuna, and 'mature' is gradually softened as it undergoes post-stiffness after being caught and stored at a constant temperature after being caught. The flavor is also improved and a certain period during which these changes can proceed is called the aging period, and leaving it left during this period is called aging.

The 'salt' used in the present invention, for example, 4% salinity refers to 40 g of salt of 99% purity in 1 L of water.

The 'thaw paper' used in the present invention is mainly used for aging fish and meat, and if there is no thaw, it is possible to use a clean cloth or a kitchen towel, etc. In addition, dry cloth, paper towel, oil paper, and aged sheet paper are used together.

By the method according to the invention

First of all, the items to be controlled before starting the description of the present invention must be frozen and stored at an extremely low temperature of -60 ° C to -50 ° C for at least 5 to 10 days depending on the size of processed frozen tuna.

This is related to the discoloration of the surface layer of the frozen tuna block. When cutting a large frozen tuna, the meat color of the cut surface (the part that did not come into contact with air) has a purple color, which is the reduction of meat globin (Mb). Therefore, it gradually returns to its original color as time passes. After this process, the defrosting process begins.

Hereinafter, a method of thawing and ripening frozen tuna according to the present invention will be described in more detail.

In the method according to the present invention, step (a) is when the tuna block frozen at -60 ° C to -50 ° C is stored in the freezer for 20 to 30 hours when the surface temperature of the tuna block is -25 ° C to -20 ° C. It is the stage of temperature change before thawing that keeps the temperature until.

In the method according to the present invention, step (b) is a tuna block maintained at a temperature of -25 ° C to -20 ° C in a refrigerator at 3 ° C to 5 ° C for 3 to 4 hours, and the surface temperature of the tuna block is -12. It is the stage of temperature change before thawing to keep the temperature from ℃ to -8 ℃.

In the present invention, the temperature of the tuna block that was frozen and stored at -60 ° C to -50 ° C before thawing in step (a) (b) described above was passed from -25 ° C to -20 ° C to -12 ° C to -8 ° C. Slowly raising or lowering step by step is a gentle temperature change step before thawing which acts as the most important factor in the present invention, and is closely related to the discoloration of the inner layer of the tuna block.

Frozen tuna is discolored, but frozen tuna is cut at -60 ° C to -50 ° C to use a saw with a high turnover during processing. Due to the high temperature generated at this time, MET Mb (meth myoglobin = probability of discoloration: -8 ℃ ~ -3 ℃) It stays in the section and discolors for a while, but after 5-10 days, it is reduced to its original color, and in the process of thawing, frozen tuna blocks of -60 ℃ ~ -50 ℃ are thawed rapidly at high water temperature or thawed. Afterwards, the inside of the tuna block discolors and stays for a long time by storing at an inappropriate temperature.

If the second process continues, the internal discoloration may not be reduced, so the temperature of the frozen tuna block itself should be raised or lowered step-by-step to easily escape the MET Mb section and prevent discoloration.

Discoloration of tuna meat (肉) occurs in the surface layer part after the tuna block stays in the MET Mb section for a long time through thawing process and appears first in the inner layer part and oxidizes with time. The discoloration described here is only for tuna, and it is a process in which the red color inherent to tuna is dark brown inside the tuna block when defrosted or oxidized over time to gradually turn gray or brown from the outside.

With the exception of raw materials for products that are heat-processed, such as CAN (canned food), tuna for sashimi such as tuna sashimi or sushi cannot be peculiar to color and become fishy, causing product value to drop significantly.

The red color of tuna is mainly due to the muscle pigment myoglobin (Mb) and the hemoglobin hemoglobin (Hb), but most of the pigments are myoglobin (Mb), except for rapid bleeding after catching like tuna.

When cutting large frozen tuna fish, the meat color of the cut surface (the part that did not touch the air) often has a purple color. This is because myoglobin is present in reducing properties.

In other words, it means that the color that has changed from purple to dark brown over time (5 to 10 days) in the frozen storage state is reduced to the original color.

When this is thawed, meat oxygen is gradually reduced to its original color because oxygen in the air is combined with myoglobin (Mb) in tuna meat to produce oxy myoglobin (Mb O2).

However, as time passes, oxy myoglobin (Mb O2) once generated is oxidized to meth myoglobin (MET Mb), so the flesh color changes to brown or blackish brown again. This phenomenon is higher in fat-rich tuna meat.

The present invention significantly reduces the difference between the frozen tuna block before thawing, the saline temperature, and the storage temperature after thawing through a process of gradually raising and lowering the temperature, and quickly exits a section in which meth myoglobin (MET Mb) is generated. It is characterized by improving the texture, texture, elasticity and cohesiveness by reducing the discoloration rate inside the tuna block and maintaining freshness for a long time.

In the method according to the present invention, in step (c), after dividing 2 to 3 pieces of tuna blocks through the steps (a) and (b), the total weight of the tuna blocks is weighed, and 2 to 3 times the measured tuna blocks. Prepare the corresponding water, and maintain the temperature of the water at 10 ℃ ~ 20 ℃ and add grapefruit extract to the saline solution with the salinity of 3.5% ~ 4.5% depending on the amount of fat, freshness, and season of the tuna block after the salt water is completely dissolved. It is a step.

In the step (c), the tuna block is cut into 2-3 pieces to increase the number of cross sections in contact with saline or air to quickly remove the cold air remaining in the inner layer of the tuna block.

The present invention is to measure the total weight of the tuna block in the above-described step (c) and prepare water corresponding to 2 to 3 times the measured tuna block is the amount of water in the frozen tuna block stored at -60 ℃ ~ -50 ℃ When immersed in saline at 1 to 1.5 times and water temperature of 28 ℃, the saline temperature drops rapidly and stays in the MET Mb section (-8 ℃ to -3 ℃) for a long time, causing discoloration of the inner layer of the tuna block.

Therefore, it is possible to prevent discoloration by preparing a water of 2 to 3 times through gentle temperature drop.

In the step (c), maintaining the water temperature of the saline at 10 ℃ ~ 20 ℃

In the existing thawing method, frozen tuna blocks of -60 ℃ to -50 ℃ are immersed in a saline temperature of 28 ℃ and defrosted through rapid temperature changes, so that the above-mentioned production of metioglobin is actively performed -8 ℃ to -3 ℃ It is easy to discolor by staying at the temperature for a long time.

The present invention has already raised the temperature of the frozen tuna block in step (a) (b) step by step from -25 ° C to -20 ° C to -12 ° C to -8 ° C in order to prevent discoloration inside the tuna block. It is a method to quickly pass the corresponding temperature because it is immersed for a short time for 1-3 minutes in a suitable saline solution of ℃ ~ 20 ℃.

The salt water used in the step (c) is irrespective of the use of ordinary salt, but is characterized by good color development (quickly sharpened with the original color) and improved freshness by using the sea salt without guard.

Although a lot of salt is used, the salt itself has a lot of salt, so if it is immersed in a saline solution with a high salinity for a long time, there is a pickling phenomenon inside the tuna, so it takes a long time to remove the salty taste.

When you use the sun salt that is lacking in salt water, it has less salt and feels sweet, so it increases the salinity by about 0.5% compared to Hangeumgeum. In the case of sun salt, the coloration (the original color returns) is fast because the salinity is high, and the oxidization time is gradually progressed for 10 to 20 hours compared to the Hangeumgeum when aged.

Prior to setting the salinity of the saline during the thawing process, the salinity used in the present invention refers to the salinity after the salt particles have disappeared and stir until all the salts are dissolved because the particles of the sun salt are thick.

The salinity of the saline solution is maintained at 3.5% to 4.5%, which is similar to or higher than that of seawater (3.5%).

At this time, the saline solution of different salinity is maintained according to the fat amount, freshness, season, etc. of the tuna block.

The condition to be thawed with high salinity is that the frozen tuna block is cut and the color is not formed after a short time (reduction of myoglobin), if the freshness of the frozen tuna block itself is poor, if there is little fat, aged (30 If you use it after a certain period of aging (within 6 hours) without going through it, and you can improve the appearance (color, sign, etc.) by setting the salinity to 4.5% for fast color development in summer when the room temperature is high. However, thawing of high salinity is difficult to maintain freshness for a long time.

Generally used salinity is 3.5% high in fat, good freshness, and used in winter when the room temperature is low.

When a saline solution with a strong salinity (5.5% or more) is used, the salinity of the saline solution is significantly stronger than the salinity in the frozen tuna block due to severe osmotic pressure, resulting in warping from the surface of the tuna. After thawing, the color of the exterior quickly changes to brown and starts to oxidize rapidly. It does not significantly affect the texture, but it affects the appearance and freshness, and the color of the surface layer quickly progresses during tasting after aging, so the value of the product drops significantly due to fishy peculiar fishy.

In step (c), the tuna block to be thawed is kept fresh (continued for 24 to 36 hours) by adding grapefruit extract, which acts as a natural preservative, to saline water to improve freshness after making a saline solution of constant temperature and salinity. It can be stored.

It is known that naringine contained in grapefruit extract acts as a natural preservative and contains more ingredients in grapefruit (0.17%) than ordinary citrus fruits (0.06%), so the grapefruit extract is used in the present invention.

The amount of grapefruit extract used is 5 to 10 parts by weight based on 100 parts by weight. If this is exceeded, the peculiar flavor of grapefruit can be a factor that hinders the natural taste of tuna.

In the present invention, texture, color, texture, elasticity, hardness, or cohesiveness are improved by improving the freshness of tuna by thawing the frozen tuna block in step (c) by adding salt water and sea salt and grapefruit extract of optimum salt and temperature. We can see that it improves together.

In the method according to the present invention, in step (d), after dipping in saline in step (c) for 1 to 3 minutes depending on the condition of the tuna block, remove and remove bones and skins, then wipe with thaw paper to bite the surface of the tuna block. And it is a step to remove foreign substances.

In step (d), soak in saline for 1 to 3 minutes depending on the size, fat amount, and distortion of the tuna block. In the existing thawing method, frozen tuna blocks of -60 ℃ to -50 ℃ were immersed in a saline solution of 28 ℃ for about 18 minutes, the surface of the tuna block was crushed, and the texture and yield (the actual usable amount after thawing) deteriorated. It is explained as a serious error in the method.

Frozen tuna blocks caught in different environments do not know the exact salinity inside, so if they are soaked in normal salt water for a long time (more than 10 minutes), pickling and osmotic phenomena are severe and excessive salinity penetrates into the tuna fish meat. As it is rapidly discharged, elements such as the fat layer (protein, fat, amino acid, nucleic acid, etc.) are also discharged, and the texture of the sashimi deteriorates and there is a problem of losing the flavor of tuna.

That is, long-term saline defrosting has a large loss in the defrosting process, such as the loss of salinity or absorption, the thinning of the surface, the decomposition of the fat layer, the shrinking shrinkage of the surface as it distorts, and the marked deterioration of texture.

No matter the size, fat amount, or distortion of the tuna block, saline is thawed for a certain period of time at a high temperature, and each color is not taken into consideration (color of the original color rises rapidly) and discoloration (oxidation changes color, color The speed of this changeable and fishy) is different and you will notice a significant difference in texture, flavor and freshness.

At this time, the size is large and small, there is a lot of distortion, and it depends on the amount of fat and the amount is small. The size is small, the amount of distortion and the amount of fat is 1 minute.

In the process of immersing in saline in the step (d), the process of turning over the surface of the frozen tuna block so that the top and bottom are evenly immersed is repeatedly wiped by hand.

When removing bones, skins, and blood pressure meat in step (d), the bones are not discarded with broth, sashimi, sushi, and the skin is burned or boiled at high temperature to remove scales. Although it appears to be a lump of blood, it actually consists of mostly iron, so it is suitable for women to eat, so it is used as sashimi, steak, tempura, etc. through the process of drawing blood.

The defrosting paper used in step (d) is generally used as a defrosting paper used in Japanese food, but it is also irrelevant to use a clean boiled cloth or kitchen towel. However, it is not suitable when eating fast food or thawing frozen tuna that has moisture due to its low water absorption.

In the method according to the present invention, in step (e), a new thawing paper is used to wrap it tightly to block discoloration by blocking oxygen with wrap or vacuum packaging and gradually remove the remaining moisture while slowing the oxidation rate.

The present invention is a step before aging in which the physical properties such as texture, texture, and freshness are improved by blocking oxygen and gradually removing cold and moisture remaining in the center of the tuna block at the optimum temperature.

In the method according to the present invention, in step (f), the tuna block subjected to step (e) is stored in a refrigerator at 3 ° C. to 5 ° C. for 2 to 3 hours, so that the temperature formed in the surface layer portion and the inner layer portion of the tuna block is −1. It is a temperature change step after thawing, which is gradually lowered to maintain ℃ ~ 2 ℃.

In the step (f), storage in the refrigerator at 3 ° C to 5 ° C is the same as raising the temperature gradually during the initial thawing process, and immersed in saline at 10 ° C to 20 ° C for 1 to 3 minutes to raise the surface layer and inner layer. The color of the inner layer portion is prevented from being discolored as described above by gradually lowering the negative temperature to remain at -1 ° C to 2 ° C.

It is easy to discolor the inside of the tuna block due to the rapid temperature change by moving to the aging chamber at -1 ℃ ~ 0 ℃ immediately after the saline thawing using the existing thawing method to remove the cold air in the inner layer.

In the method according to the present invention, in step (g), the tuna block that has undergone step (f) is completely wrapped again with a new thaw, wrapped with a wrap or vacuum packaging to maintain the moisture of the tuna block at -1 ° C to 0 ° C. It is a step of aging for 5 to 20 hours depending on the amount of fat and freshness of the tuna block by storing it in a aging high-grade aging can.

In the step (g) of the present invention, it is irrelevant to use for sashimi or sushi in a state in which cold and moisture are properly removed, but good decay through post-stiffness, that is, better texture, texture, flavor, cohesiveness, etc. through aging process To improve.

The aging time in step (g) is determined by the amount of fat and freshness of the tuna block. This is suitable for areas with a lot of fat and poor freshness for 5 to 10 hours, and for areas with little fat and good freshness, suitable for 15 to 20 hours, and if it exceeds significantly at that time, the scent becomes deeper but discoloration and texture due to rapid oxidation It is appropriate to use it within the corresponding time for reasons such as deterioration.

The aging used in the existing defrosting method mentions that it is possible to eat after 1 hour after removing water, but the old or present or after 1 hour of eating refers to eating after the defrosting process excluding aging.

In recent years, most frozen tuna that is distributed in Korea is mostly frozen in a state in which moisture is contained in tuna meat. When thawing frozen tuna block with moisture in the conventional way, the moisture inside the tuna block is not completely removed after 20 hours after saline defrosting. After 1 hour, eating tuna sashimi and drinking a sip of water I think it is the same.

In general, after the aging time of 15-20 hours for bigeye and bigfin tuna (YellowFin) with relatively little fat, after 5 ~ 10 hours of aging for bluefin tuna (BlueFin), post-stiffness is achieved after the aging time. You can feel good texture, texture and scent through.

In the step (g), storage methods include a simple cooling method (air method, through the wind) and a direct cooling method (direct cooling). In the case of the intercooled type, the air cooled by the motor is lowered or raised in the temperature inside the storage space through air, which causes the surface, including fish and meat, to dry, causing the surface layer to shimmer or easily tear, resulting in the outer wall of the storage space Direct cooling to directly lower the temperature or use a cooling method (direct cooling) to prevent the shape of the surface layer from drying.

Hereinafter, the test examples were described using the table to more clearly understand the above-mentioned contents.

[Test Example 1]

Difference between rapid temperature change (existing defrosting method) and gentle temperature change defrosting method (invention)

<Table 1> is a frozen tuna block of -60 ℃ ~ -50 ℃ through (1) -25 ℃ ~ -20 ℃ to prevent discoloration inside the tuna block, which is the most important element in the present invention (2)- After gradually raising the temperature step by step from 12 ℃ to -8 ℃, go through the refrigerating chamber at 3 ℃ to 5 ℃, immerse it in saline solution at 10 ℃ to 20 ℃ for about 1 to 3 minutes, and then go through the refrigerating chamber at 3 ℃ to 5 ℃- After thawing the frozen tuna block of -60 ° C to -50 ° C in high saline at 28 ° C for about 18 minutes in the thawing method and the existing thawing method of the present invention stored in an aged high temperature of 1 ° C to 0 ° C -1 ° C to It shows the difference when stored in an aged high temperature 0 ° C.

In the existing defrosting method, in the pretreatment of thawing, soak the frozen tuna block stored at -60 ℃ ~ -50 ℃ in a saline solution of 28 ℃ for 18 minutes, and if it holds both ends of the block, take it out to a degree that it is slightly bent and wipe it evenly with thawing paper and wrap it with thawing paper for aging After storing for 1 hour in the go, eat.

At this time, by immersing a large amount of frozen tuna blocks at a high saline temperature, the water temperature of 28 ℃ quickly goes down to -10 ℃ to -5 ℃ and the surface of the tuna shrinks and the MET Mb (meth myoglobin = discoloration) Probability: -8 ℃ ~ -3 ℃) There is a high probability that the inner layer will discolor for a long time and several times in the interval.

In addition, the salt is deprived or absorbed by saline for a long time, and the surface is thinned or the fat layer is decomposed, and the surface is distorted.

The present invention compensates for shortcomings such as rapid temperature changes of frozen tuna blocks, defrosting other tuna blocks with the same salinity, high saline temperature, and soaking in saline for a long time in the existing thawing method. Raises and lowers the MET Mb section quickly, uses different salinity depending on freshness, fat mass, distortion, size, etc., lowers the saline temperature during thawing, and immerses it in saline for a short time, so that the salinity of the frozen tuna block and the salinity of the saline The loss due to osmotic pressure that occurs when they are not identical is minimized.

[Test Example 2] Discoloration of frozen tuna block according to temperature

This test describes the discoloration of frozen tuna blocks according to temperature, and is closely related to the saline temperature, storage temperature after thawing and aging temperature.

The temperature of the surface layer of the tuna block taken out from the saline of 10 ℃ ~ 20 ℃ is increased to 5 ℃ ~ 10 ℃ depending on the immersion time, but the inner layer stays at 0 ℃ ~ 5 ℃. At this time, the temperature may be increased by storing at room temperature (around 24 ° C), but the texture of the surface layer is impaired due to the rapid temperature change.

Accordingly, in the present invention, after thawing, in order to gradually increase the temperature difference between the surface layer and the inner layer, when stored in a refrigerator at 3 ° C to 5 ° C for 2 to 3 hours, the surface layer and the inner layer stay at -1 ° C to 2 ° C and -1 ° C to 0 ° C. It will be moved to and stored in the aging high school.

In general, the storage temperature of aging high is -1 ℃ ~ 0 ℃, and the higher the temperature, the faster oxidation occurs and when it is below -2.5 ℃, it starts to freeze.

<Table 2> compared the production rate of MET MB by temperature (meth myoglobin = probability of discoloration: -8 ° C to -3 ° C), and the higher the temperature, the faster the production rate of MET MB can be confirmed.

Discoloration starts from 20% to 30% of the production rate of MET Mb. Therefore, it is desirable that the storage temperature does not exceed 2 ° C to 5 ° C, and it is better not to be exposed to room temperature (around 24 ° C).

As shown in <Table 2> above, the rate of MET Mb is greater in the surface layer (the part from 2 to 10 mm from the surface) than the inside of the tuna meat (part of 5 to 10 mm from the surface). It's a natural result when you think about touching it.

In the present invention, the higher the temperature, the faster the oxidation rate, the faster the decay rate, and the faster the oxidation of the surface layer than the inner layer, so the temperature and saline temperature of the frozen tuna block and the temperature difference in the storage area are reduced to reduce the physical properties and functionality of tuna sashimi. It is improved so that you can feel the best texture and taste.

[Test Example 3] Discoloration of frozen tuna according to storage temperature: Storage temperature during aging

The term 'aging' means that the muscles of the fish are gradually softened and the flavor is improved through post-stiffening through storage at a constant temperature after being caught, and the period during which these changes can proceed is called the aging period, and is left unattended during this period. This is called aging.

However, 'aging' in the present invention means a state through post-stiffening for several hours by storing frozen tuna after catching at a constant temperature in a complete thaw in which ice crystals or moisture are removed.

Mainly, in the case of tuna, it is performed while suppressing the growth of bacteria at a temperature of -1 ° C to 0 ° C. Since the freezing point of aging high reaches -2.5 ℃, -1 ℃ of the degree that the surface does not freeze is appropriate, and the higher the temperature, the higher the temperature is automatically oxidized and the discoloration to dark brown begins and a bad odor appears.

This test is carried out as a method to improve the freshness, texture, texture, and odor after thawing. At this time, it is a process to find the optimum temperature of the ripening high while reducing the discoloration of the color of the surface layer.

<Table 3> prepares several samples to examine the color change from the surface layer to the inner layer step by step, and analyzes discoloration of frozen tuna according to MET Mb (meth myoglobin production rate) at each stage to find the freezing temperature of the surface. The temperature before freezing is set to the optimum temperature.

In other words, as it is stored at a high temperature, as in the case where the oxidation rate is fast, the production rate of MET Mb is significantly increased from the point where the temperature of the storage space reaches the frozen state of tuna meat, thereby increasing the discoloration rate.

When the temperature of the storage space is -1.3 ℃ ~ 2 ℃, freezing starts slowly from the surface layer, so storing at 0 ℃ ~ -1 ℃ is the optimal temperature for improving color preservation and freshness.

As shown in <Table 3>, the tuna block stored at a temperature of -2.5 ° C gradually increases the MET Mb production rate from the 5 mm portion to the inner layer portion of the surface corresponding to the surface layer portion, so that discoloration begins. When the temperature reaches -5 ° C, the discoloration becomes worse as it goes to the inner layer than the surface layer, resulting in a dark brown color.

Hereinafter, the present invention will be described in more detail through specific examples.

[Test Example 4] The difference between the frozen tuna thawing method and the different method according to the present invention

Example 1: Method of thawing frozen tuna according to the present invention

First, frozen freshness of -60 ° C to -50 ° C was good and 5 kg of fatty tuna block bigeye was prepared. After moving the frozen tuna block to the freezer for 20 to 30 hours, the internal temperature of the tuna block reaches -25 ℃ to -20 ℃, and then it moves to the refrigerating chamber at 3 ℃ to 5 ℃, and the thawing is carried out after 3-4 hours. Conduct.

After completing the temperature change, cut the tuna block into 3 pieces, measure the total weight of the tuna block, prepare water corresponding to twice the measured tuna block, maintain the temperature of the water at 15 ° C. After that, grapefruit extract is added to a saline solution having a salinity of 3.5%.

After immersion in the prepared saline solution for about 2 minutes, the bones and skins are removed, and then wiped with thawing paper to remove water and foreign substances from the surface of the tuna block. After the tuna block on the surface of which has been removed is wrapped with new thaw paper, wrap it tightly with a wrap and store it in the refrigerator for 2-3 hours to gradually lower the temperature formed in the surface and inner layers of the tuna block. After wrapping it completely with new thawing paper, wrap it in a wrap and cool it inside the storage space to store it for 5 hours in the aged aging from -1 ℃ to 0 ℃, which can maintain the moisture of the frozen tuna block.

Comparative Example 1 : Existing thawing method

Prepare 5kg of frozen tuna block BigEye from -60 ℃ to -50 ℃.

At this time, the temperature of the frozen tuna block is not gradually lowered, the total weight of the tuna block is measured, and water corresponding to twice the measured tuna block is prepared, and then immersed in a saline solution of 3% saline with a water temperature of 28 ℃ for 18 minutes. Take it out, rinse again with clean brine and wipe off with defrost paper.

After completing the above process, the tuna block is transferred to a ripening pit of -1 ° C to 0 ° C and stored for 5 hours.

Comparative Example 2 : Pretreatment of thawing using different salinity

The same procedure as in Example 1 was performed, but a saline solution having a salinity of 1.5% was prepared.

Comparative Example 3 : Thawing pretreatment using different salinity

The same procedure as in Example 1 was performed, but a saline solution having a salinity of 5.5% was prepared.

Comparative Example 4 : Defrosting pretreatment with different salts

The same procedure as in Example 1 was carried out, and a saline solution having the same salinity of 3.5% was prepared with flower salt.

Comparative Example 5 : Thawing pretreatment using different saline

Prepared in the same manner as in Example 1, a saline solution in which the grapefruit extract was not diluted was prepared.

In <Table 4>, physical properties and sensory evaluation were conducted through Examples and Comparative Examples, and 20 food departments and 20 global cooking departments were selected as panels, and the texture and texture, color, flavor, freshness, and overall preference were selected. 10-point scoring method (10: very good, 1: very bad)

As confirmed in Table 4 above

Example 1 was evaluated according to the present invention, the color of the surface layer, the color of the center, and freshness were evenly evaluated. On the other hand, it can be seen that the texture, texture, and scent are slightly inferior to those of the aging stage.

In Comparative Example 1, by immersing a large amount of frozen tuna blocks at a high saline temperature, the water temperature of 28 ° C quickly decreased from -10 ° C to -5 ° C, and the surface of the tuna contracted once due to the high temperature and MET Mb (meth myoglobin) = Probability of discoloration: -8 ℃ ~ -3 ℃) There is a high probability that the inner layer will discolor for a long time and several times in the interval.

In addition, the salt is deprived or absorbed by saline for a long time, and the surface is thinned or the fat layer is decomposed, and the surface is distorted.

Comparative Example 2 uses a lower salinity than the reference salinity, so the color development of the surface is remarkably low, and accordingly, the color of the center is also inferior. Due to the osmotic pressure, salinity is taken out from the outside, and over time, the surface becomes like a sponge, tearing, tearing off, and the salinity is also taken away, and fat and nutrients are also taken away.

Comparative Example 3 uses a high salinity compared to the reference salinity to temporarily improve the color of the surface layer and feel the texture temporarily, but absorbs the salinity inside due to the osmotic pressure, so the taste is salty and the texture and freshness deteriorate over time. Discoloration proceeds rapidly to brown or dark brown.

In Comparative Example 4, the color and freshness of the surface layer portion were relatively low and the storage period was shortened by using ordinary salt, unlike the sea salt salt used in Example 1.

In Comparative Example 5, the grapefruit extract used in Example 1 was not used, so that it was not immediately visible and improved, but over time, the freshness fell and the storage period was shortened.

[Test Example 5] Evaluation of physical properties and functionality after aging for a certain period of time

Through the questionnaire above, as a result of passing through the process of Example 1 in Test Example 4, it was confirmed that the overall preference or color change of the surface layer and the inner layer were significantly improved, especially in freshness, compared to Comparative Examples 1 to 5.

However, since the defrosting method without aging still retains moisture inside the tuna block, the texture, texture, and natural flavor of tuna are less felt.

Example 2 : Evaluation of physical properties and functionality by aging

After finishing Example 1, the tuna that has been relatively drained is wrapped in a new thawing paper and blocked again with oxygen to block the oxygen, thereby directly cooling the inside of the ripening chamber and lowering or raising the temperature to -1 ℃ in a mature cooling oven of direct cooling (direct cooling). Store at a temperature of ~ 0 ℃ for 20 hours.

Comparative Example 1 : Method by different storage method

When the storage method of the tuna block to be aged is matured in a storage place that uses a simple cooling method to raise or lower the temperature through the wind rather than directly cooling.

The <Table 5> was evaluated for physical properties and sensory properties through Example 1, Example 2 and Comparative Example. 4 tuna processing experts experienced over 10 years, 4 Japanese cooking experts experienced over 10 years, Master of Food and Nutrition The panel was selected as 2 or more, and 10 points were scored for texture, texture, color, flavor, freshness, and dryness of the surface layer (10: very good, 1: very bad)

Example 2 of <Table 5> is a step of aging, and it is irrelevant to use for sashimi or sushi in a state in which cold and moisture are properly removed, but good decay through post-stiffness, that is, texture than before aging in Example 1 through the aging process. The texture, flavor, and flavor were improved, but the color of the surface layer was relatively inferior as time passed.

In Comparative Example 1, as a storage method of the tuna block to be aged, there were a method of liver cooling (air method, through wind) and direct cooling (direct cooling). In the case of the intercooled type, the air cooled by the motor is lowered or raised in the temperature inside the storage space through air, which causes the surface including the fish and meat to dry, causing the surface layer to shimmer or easily tear.

Therefore, by using the direct cooling method (direct cooling) of the method of lowering or raising the temperature by directly freezing the outer wall of the aging high school, it is possible to prevent the surface layer from drying and reduce the oxidation rate.

As shown in <Table 5>, Example 2 evaluated the texture and texture, the color of the surface layer, the color of the inner layer, the scent, the freshness, the dryness of the surface layer, and the overall preference in comparison with Example 1 and Comparative Examples. In particular, compared to the comparative examples, the texture and color, the color of the inner layer, the odor, the freshness, and the dryness of the surface layer were improved.

Therefore, the tuna ash processed by the thawing and aging method of the frozen tuna block according to the present invention uses the same salinity control and high temperature saline, which does not distinguish the tuna block state by the conventional method, that is, the long time, It was confirmed that the cooling method of aging high, which did not use saline immersion, sea salt without salt water, or added a natural preservative grapefruit extract to saline, had better physical and sensory properties than tuna sashimi processed by indirect cooling.

Claims (4)

(a) The temperature change before thawing to keep the tuna block frozen at -60 ℃ ~ -50 ℃ in the freezer for 20 ~ 30 hours to maintain the temperature until the surface temperature of the tuna block becomes -25 ℃ ~ -20 ℃ Stage 1;
(b) The tuna block maintained at the temperature of -25 ° C to -20 ° C was put in a refrigerator of 3 ° C to 5 ° C for 3 to 4 hours to maintain the surface temperature of the block at a temperature of -12 ° C to -8 ° C. Preliminary thawing temperature change 2 steps;
(c) After cutting 2-3 pieces of tuna block after step (b), measure the total weight of the tuna block, prepare water corresponding to 2 to 3 times the measured tuna block, and the temperature of the water is 10. A defrosting preparation step of maintaining a temperature of 20 ° C. to 20 ° C. and maintaining salt water having a salinity of 3.5% to 4.5% depending on the amount of fat or freshness or season of the tuna block;
(d) Soaked in salt water after step (c) for 1 to 3 minutes depending on the amount or amount of fat or warp in the tuna block, removed and removed from bones and skins. Stage 1;
(e) a second step of defrosting, wrapping the tuna block from which the surface has been removed, with a new thawing paper and wrapping or wrapping with vacuum packaging to block contact with oxygen;
(f) The tuna block that has been subjected to step (e) above is stored in a refrigerator at 3 ° C to 5 ° C for 2 to 3 hours, and the thaw is gradually lowered so that the temperature formed on the surface and inside of the tuna block is maintained at -1 ° C to 2 ° C. After temperature change step;
(g) After completely wrapping the tuna block after step (f) with new thawing paper, wrap it in a wrap or vacuum packaging and place it in a aging jar at -1 ℃ to 0 ℃, depending on the fat amount or freshness of the tuna block, 5 to 20 Method of thawing and aging frozen tuna, characterized by the step of aging for a period of time. The method of claim 1
The salt used in the salt water of the step (c) is thawing and aging method of frozen tuna, characterized in that the salt water is a sun salt. The method of claim 2
In the step (c), a method of thawing and aging frozen tuna, comprising adding a grapefruit extract corresponding to 5 to 10 parts by weight based on 100 parts by weight of the brine. The method of claim 1
The aging step of step (g) is a method of thawing and aging frozen tuna characterized in that it is a direct cooling method capable of maintaining the moisture of frozen tuna by directly cooling the inside of the storage space.