JP7368652B1 - Shrimp with shell and its manufacturing method - Google Patents

Abstract

[Problem] To provide shrimp in the shell, which effectively suppresses the hardness of the shell and the feeling of the shell remaining in the mouth when chewed with the molar teeth when eating the whole shell while suppressing the deterioration of the texture of the shrimp. [Solution] The present invention provides a shrimp with a shell that has an abdominal body and a shell that covers the abdominal body and can be eaten with the shell attached, and the shell thickness of the cephalothorax is 0.09 mm or more. Shrimp with shells are prepared by soaking shrimp having a size of 0.21 mm or less in an aqueous solution of at least one kind of alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid with a pH of 10.0 or less. [Selection diagram] Figure 1

Description

The present invention relates to shelled shrimp that can be eaten with the shell and a method for producing the same.

Generally, shrimp are eaten with the shells removed, and are loved for their plump texture. On the other hand, shrimp shells are rich in calcium, and if you can eat shrimp with the shell on, you can reduce the cost of removing the shell, and it is economically advantageous because it gives a sense of volume. It is also possible to add value as a health food. Therefore, there is a strong demand for technology that allows shrimp in the shell to be eaten deliciously at low cost.

Conventionally, when eating shrimp with their shells, there is a problem that the shrimp shells are hard and difficult to eat.To solve this problem, shell softening treatments include soaking in hydrochloric acid (Patent Document 1), heating under reduced pressure, and heating. A process of applying pressure heating (Patent Document 2), treatment with an organic acid and a chitin-degrading enzyme (Patent Document 3), etc. have been proposed.
Furthermore, Patent Document 4 discloses that living shrimp are added to a liquid composition containing a chitooligosaccharide metal compound, sodium carbonate, potassium citrate, sodium hydrogen phosphate, and water, and then the shrimp glands are removed and an organic acid is added. It is described that it is immersed in a solution.

Furthermore, although the purpose is not to eat shrimp with their shells, Patent Document 5 describes the purpose of improving the color of shrimp shells as a document containing 38% sodium acetate (buffering agent) and calcium oxide (alkaline agent).
It is described that an immersion liquid with a pH of 11 was prepared by dissolving a solid content of 30% and 32% glucose (osmotic agent) in water, and sakura shrimp was immersed in the immersion liquid.

Japanese Patent Application Publication No. 5-268916 Japanese Patent Application Publication No. 2006-20527 JP2008-245624A Chinese Published Patent No. 107647326 Japanese Patent Application Publication No. 2002-017308

However, both the method using a strong acid such as hydrochloric acid in Patent Document 1 and the method using reduced pressure heating and pressurized heating in Patent Document 2 have the problem that the texture and taste of the shrimp are greatly deteriorated. Furthermore, in the treatment with an organic acid and a chitin-degrading enzyme in Patent Document 3, since the optimum temperature of the chitin-degrading enzyme is around 35°C, it is necessary to boil the shrimp before treating it with the chitin-degrading enzyme for food safety. This has the disadvantage that it requires
Furthermore, Patent Documents 4 and 5 describe the use of organic acid salts in combination with alkaline agents under strongly alkaline conditions such as pH 11, but such agents may cause problems such as excessive softening of the texture of the shrimp. There is a problem.

An object of the present invention is to provide a shelled shrimp that suppresses deterioration of the texture of the shrimp, such as the texture of the shrimp when eaten, and improves the hard texture of the shell, and a method for producing the same.

The inventor of the present invention conducted a thorough study on the texture of the shells of conventional shrimp with shells, and found that the hardness of the shells when chewed with the back teeth and the feeling of the shells remaining in the mouth after swallowing the shrimp were particularly important when eating shrimp with shells. We found that it has a large effect on the difficulty of the process. Surprisingly, by treating shrimp shells of a specific thickness with a specific salt, it is possible to effectively reduce the hardness of the shells when chewed with the back teeth, and the shells are kept in the mouth after the shrimp are swallowed. It was discovered that the sensation that remains in the mouth (the feeling of the shell remaining in the mouth) can also be suppressed.

The present invention is based on the above-mentioned findings, and provides a shelled shrimp that has an abdominal body and a shell that covers the abdominal body and can be eaten with the shell on,
Shrimp whose shell thickness in the cephalothorax is 0.09 mm or more and 0.21 mm or less, with or without removing the cephalothorax, and selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid. To provide shrimp with shells, which are soaked in an aqueous solution of at least one kind of alkali metal salt having a pH of 10.0 or less.

Furthermore, the present invention processes shrimp whose abdominal meat and cephalothorax shell have a thickness of 0.09 mm or more and 0.21 mm or less, by removing the cephalothorax or without removing the cephalothorax. To provide a method for producing shrimp with shells, which is prepared by immersing shrimp in an aqueous solution with a pH of 10.0 or less of at least one kind of alkali metal salt selected from ascorbic acid and phosphoric acid.

According to the present invention, while suppressing the deterioration of the texture of the meat, the hardness of the shell when eaten with the shell and chewing with the molar teeth is effectively reduced, and the feeling of the shell remaining in the mouth is suppressed. Served with shrimp.

FIG. 1 is a schematic side view of an example of shelled shrimp to be subjected to the immersion treatment of the present invention. In order to explain the position of L1 in FIG. 1, it is an enlarged schematic side view of an example of a shrimp with a shell.

Hereinafter, the present invention will be explained based on its preferred embodiments. The present invention provides a shelled shrimp that has an abdominal body and a shell that covers the abdominal body and can be eaten with the shell attached,
Shrimp whose cephalothorax shell thickness is 0.09 mm or more and 0.21 mm or less are immersed in an aqueous solution of at least one alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid with a pH of 10.0 or less. The shrimp is served in its shell.

FIG. 1 shows an embodiment of shelled shrimp 100 to be subjected to the dipping treatment of the present invention. The shelled shrimp 100 has an abdominal body 50 and a shell 10 covering the abdominal body 50. The shell 10 may cover only a part of the abdominal body 50, or may cover the entire abdominal body 50. As shown in FIG. 1, the abdominal body 50 has six abdominal segments from the first abdominal segment 1 to the sixth abdominal segment 6. The shell 10 has a ventral segment side shell 11 to a ventral segment side shell 16 as shell portions that cover each of them. In the example shown in FIG. 1, the cephalothorax of the shelled shrimp 100 is not removed, but after measuring the thickness of the shell of the cephalothorax, the cephalothorax may be removed and subjected to soaking treatment. In the present invention, it is preferable that the shrimp with shells have a cephalothorax, since it is possible to obtain voluminous shrimp having a good texture of the shell as well as the texture of the abdominal meat at a low cost.

The thickness of the shrimp cephalothorax shell used in the present invention is 0.09 mm or more and 0.21 mm or less.
Surprisingly, the present inventors have found that when the shell thickness of the cephalothorax falls within a certain range, organic acid salts and phosphorus, which were conventionally only known as buffering agents, have been used as treatment agents for shrimp with shells. Treatment with a neutral to weakly alkaline aqueous solution of acid salts can effectively reduce the hardness of the shell when chewed with the back teeth, and the sensation of the shell remaining in the mouth after swallowing the shrimp (the feeling of the shell remaining in the mouth) It was also found that the residual feeling) can also be reduced.
That is, the use of neutral or weakly alkaline aqueous solutions of organic acid salts and phosphates, such as sodium acetate, for softening shells has hardly been considered in the past. However, the present inventors have found that shrimp shells can be softened even by using a neutral or weakly alkaline aqueous solution of these salts, as long as the shrimp shell thickness is below a predetermined value. Although not limited to this, an example of the softening mechanism is thought to be that calcium in the shell is eluted and combined with chitin, etc. in the shell to denature the structure that made up the hard shell. . When treated with an aqueous solution of such a specific phosphate or organic acid salt, the deterioration of the texture of the meat is more effectively suppressed than when treated with an acid such as an organic acid instead of these salts. can do.
Note that the thickness of the shell in the cephalothorax of a shrimp is usually thicker than the thickness of the shell that covers the body of the shrimp's abdomen. There is also a correlation between the thickness of the shell in the cephalothorax and the thickness of the shell that covers the shrimp's abdomen; the thicker the shell that covers the abdomen of the shrimp, the thicker the shell in the cephalothorax. Tend. For these reasons, in the present invention, the thickness of the shell of the cephalothorax is used as an index of the thickness of the shrimp shell. However, as described above, in the present invention, the shelled shrimp may or may not have a cephalothorax.
Furthermore, the present invention has technical significance when applied to shrimp, which conventionally have been difficult to eat without shells. From this point of view, in the present invention, the lower limit of the thickness of the shrimp cephalothorax shell is defined as 0.09 mm or more.

From the viewpoint of making the above effects even more effective, the thickness of the shrimp cephalothorax shell is preferably 0.18 mm or less, more preferably 0.16 mm or less. As mentioned above, the thickness of the shell of the cephalothorax of shrimp is 0.09 mm or more, preferably 0.10 mm or more, and furthermore, 0.11 mm or more, which improves the availability of shrimp and the technical aspects of the present invention. It is preferable from the point of view of significance, and particularly preferably 0.12 mm or more.

Specifically, the shell thickness of the shrimp cephalothorax is determined as follows.
As shown in Figure 1, when a shrimp is viewed from the side, there is a flat part on the dorsal side of the cephalothorax. Specifically, as shown in FIG. 2, along the midline, a straight line L1 connecting the tip T2 of the forehead horn located at the rearmost position and the rear end T1 of the cephalothorax on the dorsal side runs along the flat part. ing. As shown in FIG. 1, a line L2 perpendicular to the straight line L1 is drawn from a point that bisects the straight line L1. L2 is a straight line segment starting from the center point of L1 and ending at the ventral edge of the shell 31 covering the cephalothorax 21 when the shrimp is viewed from the side. The thickness of the shell located at the point C1 that bisects L2 when the shrimp is viewed from the side is measured on both the left and right sides of the shrimp, and the average value is taken as the thickness of the cephalothorax of the shrimp.

As mentioned above, in the present invention, the regulation of the shell thickness of the cephalothorax allows that the resulting shelled shrimp does not have a cephalothorax. This is because the thickness of the shell only needs to be determined before the immersion treatment using an aqueous solution of a specific alkali metal salt (organic acid salt or phosphate) as an immersion liquid. Note that the thickness of the shell includes the thickness of the thin film located inside the shell. The thickness of the shell can be measured, for example, by cutting the shrimp shell at a designated area into approximately 5-7 mm squares, and then using a thickness meter (Mitutoyo Digimatic Thickness JAN: 4946368124261).

Further, the shrimp used in the present invention preferably has a shell thickness of 0.05 mm or more and 0.12 mm or less in the second abdominal segment. Specifically, the thickness of the shell of the second abdominal segment 2 is specified as follows.
As shown in FIG. 1, when the shrimp is viewed from the side (when viewed from the side), at the dorsal edge line along the midline of the ventral segment side shell 12 covering the second abdominal segment 2, The caudal end of the upper 11 and the caudal end of the ventral segmental upper 12 are identified and connected by a straight line segment L3. In a side view of the shrimp, a line L4 is drawn from the center point of the line segment L3 to be orthogonal to the straight line L3. In a side view of the shrimp, L4 is a straight line segment starting from the center point of L3 and ending at the ventral edge of the ventral carapace 12, and the shell at point C2 that bisects L4. The thickness is measured on both the left and right sides, and the average value is determined.

In the present invention, the thickness of the shell of the second abdominal segment 2 is preferably 0.05 mm or more and 0.16 mm or less. The second abdominal segment 2 is usually the part where the teeth come into direct contact with the shell when eating shrimp with the shell on. This treatment can more effectively reduce the hardness of the shell when chewing with the back teeth and the sensation of the shell remaining in the mouth after swallowing the shrimp. From this viewpoint, the thickness of the shell of the second abdominal segment 2 is more preferably 0.16 mm or less, more preferably 0.12 mm or less. The thickness of the shell of the second abdominal segment 2 is preferably 0.06 mm or more in terms of the availability of shrimp and the technical significance of the present invention, and more preferably 0.07 mm or more.

In addition, when shrimp with shells are shipped as multiple packages, even one of the packages may fall under the category of shrimp with shells of the present invention, but it must be soaked in a prescribed salt. It is also preferable that the average value of the thickness of the cephalothorax shell of a plurality of shrimp (for example, 5 or more shrimp) is within the range described above as the thickness of the cephalothorax shell. It is also preferable that the average value of the shell thickness of the second abdominal segment of a plurality of shrimp (5 or more shrimp) is within the range described above for the shell thickness of the second abdominal segment.

By using shrimp with the above shell thickness and soaking it in an aqueous solution of at least one kind of alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid (hereinafter also referred to as "soaking solution"), It can effectively reduce the hardness of the shell when chewing and the feeling that the shell remains in the mouth after swallowing the shrimp.
Conventionally, when salts of organic acids such as acetic acid and citric acid were used to soften the shell, they were used as an acidic buffering agent in combination with the organic acid, but in the present invention, these are used in a neutral or weakly alkaline state. Preferably, the alkali metal salt is, for example, a sodium salt or a potassium salt. Phosphates generally include orthophosphates, metaphosphates, polyphosphates, and pyrophosphates, but the phosphates used in the present invention are preferably orthophosphates and polyphosphates, particularly sodium polyphosphates and pyrophosphates. It is preferable to refer to at least one selected from dipotassium hydrogen phosphate. Examples of alkali metal salts of orthophosphoric acid include MH ₂ PO ₄ , M ₂ HPO ₄ and NM ₃ PO ₄ when M is an alkali metal. Examples of alkali metal salts of citric acid include trisodium citrate and tripotassium citrate.

Among these, in the present invention, from the viewpoint of achieving both the softening effect of the shell and the texture of the meat, it is preferable to use trisodium or tripotassium citric acid, an alkali metal salt of ascorbic acid, or an alkali metal salt of acetic acid. It is more preferable to use trisodium acid or tripotassium citrate or an alkali metal salt of acetic acid, and it is especially preferable to use sodium acetate. The use of sodium acetate is particularly effective in effectively reducing the hardness of the shell when chewed with the molars of the present invention and the sensation that the shell remains in the mouth after swallowing the shrimp, as well as its ease of availability and cost. It is also preferable. Also, by using sodium acetate, it is easy to impart a long-lasting effect.

Specifically, the pH of an aqueous solution of at least one alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid is 10.0 or less at 3 to 5°C, and the pH is neutral or weakly alkaline. A range of 6.5 to 9.0 is preferred, and a range of 6.5 to 8.9 is particularly preferred. More preferably, the pH of the aqueous solution at 10° C. is 6.7 to 8.5, and may further be 6.9 to 7.5. Surprisingly, even when immersed in such a neutral to weakly alkaline aqueous solution, shrimp shells of a specific thickness can be softened if a specific salt is used in combination. It is desirable that the pH of the dipping liquid used in the present invention is at least a predetermined value, since sourness and deterioration of the shrimp's flesh (shrinking of the shrimp's muscles, etc.) can be effectively prevented. In addition, if the pH of the dipping liquid used in the present invention is below a predetermined value, the meat may become denatured or become transparent if it is strongly alkaline, and the texture may become too soft. can be avoided.

In the dipping liquid used in the present invention, the amount of at least one kind of alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid is 2.0% by mass or more to easily obtain the shell softening effect of the present invention. The content is preferably 4.0% by mass or more, more preferably 4.0% by mass or more, and particularly preferably 5.0% by mass or more. The amount of at least one alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid in the soaking liquid is preferably 10.0% by mass or less in order to suppress the influence on the taste and discoloration of the shrimp. , more preferably 9.0% by mass or less, particularly preferably 8.0% by mass or less.

The immersion treatment in the immersion solution of the present invention is usually 1 hour or more, and from the viewpoint of obtaining the effect of softening the shell, it is preferably 2 hours or more, particularly 4 hours or more, and particularly The time period is more preferably 8 hours or more, and particularly preferably 16 hours or more. In addition, the immersion treatment with the immersion liquid is usually preferably carried out for 24 hours or less, more preferably 20 hours or less, and 18 hours or less, because the effect does not increase even after a longer period of time and for hygienic reasons. It is particularly preferable that there be.

The temperature of the dipping liquid used in the present invention is preferably 1 to 10°C, and preferably 2 to 7°C, from the viewpoint of hygiene and the efficiency of softening the shell when immersed for a long time. The temperature is more preferably 3 to 5°C, particularly preferably.

It is preferable that the immersion liquid used in the present invention does not contain an organic acid in combination with an organic acid salt or a phosphate. This is because the use of organic acids causes disadvantages such as shrinking of the shrimp's muscles and turning the shrimp white, making it impossible to obtain the shrimp's original color. From this point of view, when an organic acid is used in the immersion liquid, the amount of organic acid is preferably 50% by mass or less, more preferably 30% by mass or less, based on the amount of organic acid salt or phosphate used. , more preferably 20% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less.
Examples of situations in which an organic acid is used in the present invention include a case where an immersion liquid is prepared by mixing an alkaline agent (sodium hydrogen carbonate or sodium carbonate) with an organic acid. The pH of the immersion liquid adjusted at that time is particularly preferably 6.5 or more and 10.0 or less, particularly preferably 7.0 or more and 8.5 or less at 3 to 5°C.
Note that the usage amount of the organic acid salt or phosphate mentioned above is, for example, when preparing an immersion liquid by mixing citric acid and sodium hydrogen carbonate, the amount of the organic acid salt or phosphate used is based on the component with a smaller reaction equivalent of citric acid and sodium hydrogen carbonate. The amount of trisodium citrate is the amount of trisodium citrate assuming that the entire amount of trisodium citrate is generated from the amount of citric acid used. amount assumed to have been used).

The amount of the alkaline agent in the immersion liquid used in the present invention is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, based on 100 parts by mass of the organic acid salt or phosphate used. The amount is most preferably 50 parts by mass or less, and may not be used. Here, the alkaline agents include sodium hydrogen carbonate, sodium carbonate, ammonium hydrogen carbonate, sodium hydroxide, calcium oxide, potassium hydroxide, calcium hydroxide, calcium carbonate, and the like. For example, an example of a situation in which an alkaline agent is used is when an immersion liquid is prepared by mixing an organic acid with an alkaline agent.
When preparing an immersion liquid by mixing an organic acid with an alkaline agent, as above, the amount of organic acid salt or phosphate used is the amount of the organic acid or phosphoric acid that is greater than the reaction equivalent of the alkaline agent and the organic acid or phosphoric acid. The amount of organic acid salt or phosphate is the amount of organic acid salt or phosphate when it is assumed that the entire amount of organic acid salt or phosphate is generated from a small amount of ingredients. The amount is calculated by subtracting the amount.

The dipping liquid used in the present invention may contain salt from the viewpoint of improving the quality of the shrimp, and in this case, the amount of salt is preferably 0.1 to 5.0% by mass, More preferably, it is 1.0 to 3.0% by mass.

In the immersion liquid used in the present invention, the amount of components other than at least one alkali metal salt selected from water, acetic acid, citric acid, ascorbic acid, and phosphoric acid and salt is preferably 10.0% by mass or less, and 8.0% by mass or less. It is more preferably at most 5.0% by mass, even more preferably at most 5.0% by mass, particularly preferably at most 3.0% by mass, and most preferably at most 1.0% by mass, including water, acetic acid, citric acid, ascorbic acid and phosphoric acid. It may not contain components other than at least one alkali metal salt selected from the following and salt.
In addition, in the immersion liquid used in the present invention, the amount of components other than water, at least one alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid and common salt is 100 parts by mass or less is preferable, 50 parts by mass or less is more preferable, even more preferably 25 parts by weight or less, and especially 10 parts by weight or less, based on 100 parts by mass of the total amount of at least one kind of alkali metal salt selected from the following and common salt. It is preferably 5 parts by weight or less, most preferably 1 part by weight or less, and even more preferably 1 part by weight or less.

In the present invention, live shrimp may be added to the dipping liquid, but this is not necessary, and shrimp that have been frozen and thawed after being caught may also be used. Add uncooked shrimp to the soaking liquid. In the present invention, unlike Patent Document 3, the shells can be softened by soaking unheated shrimp in a soaking liquid, so compared to the conventional technology that requires heating in the shell softening process, overheating is possible. It is possible to prevent the deterioration of the texture of the meat caused by this. The unheated state refers to, for example, not being subjected to heat treatment at 60° C. or higher, and particularly preferably refers to not being subjected to heat treatment at 50° C. or higher.
Further, in the present invention, it is preferable to use shrimp of the genus Penaeidea, caridea, and stenopodidea, and it is more preferable to use shrimp of the family Penaeidae. The Penaeidae family includes Litopenaeus vannamei, Black Tiger (Penaeus monodon), Marsupenaeus japonicus, Metapenaeusjoyneri, Metapenaeus dobsoni, Endeavor shrimp (Metapanaeusendeavouri), and Bangladeshi brown (Metapenaeus onoceros). , Fenneropenaeus chinensis, banana shrimp (Fenneropenaeus merguiensis), etc. In particular, in the present invention, it is preferable to use vannamei shrimp because shrimp with a predetermined shell thickness can be easily obtained.

The amount of the soaking liquid is preferably 70 to 160 parts by mass, more preferably 80 to 150 parts by mass, and particularly preferably 90 to 130 parts by mass, per 100 parts by mass of unheated shrimp.

In the present invention, a cleaning treatment may be performed after immersion in the aqueous solution of the organic acid salt or phosphate. Examples of the cleaning process in this case include cleaning with running water and cleaning with stored water. From the viewpoint of shortening the production time, washing with water is preferably for example 10 minutes or less, more preferably 5 minutes or less, particularly preferably 1 minute or less.

In the present invention, after immersion in the organic acid salt or phosphate aqueous solution, it is preferable that no further immersion treatment in an organic acid aqueous solution is performed. This is because, as mentioned above, it is undesirable in terms of acidity and deterioration of the flesh (shrinking of the shrimp's muscles, etc.).

In the present invention, it is preferable not to use chitinolytic enzymes. This is because the optimal temperature of chitin degrading enzyme is 35° C. or higher, so using this makes boiling necessary and hygienic management becomes difficult.

In addition, in the present invention, the shrimp may be subjected to an immersion treatment with a water retention agent before the immersion treatment with the above-mentioned organic acid salt or phosphate.
Examples of the water retention agent include alkaline agents, such as sodium hydrogen carbonate and sodium carbonate. The water retention agent may be only one type of these or a combination of two or more types.

The total amount of the water retention agent in the immersion liquid consisting of an aqueous solution of the water retention agent is preferably 0.5% by mass or more and 10.0% by mass or less, and 1.0% by mass or more and 3.0% by mass in the immersion solution. % or less is more preferable.

Note that when an immersion liquid consisting of an aqueous solution of a water retention agent is used, it is preferable to immerse the shrimp at 5 to 15° C. for 1 to 3 hours, since the flavor of the shrimp can be retained. In addition, when using an immersion solution consisting of an aqueous solution of a water retention agent, it is recommended to drain the liquid at 5 to 20°C for 5 to 20 minutes and then perform immersion treatment with a specified organic acid salt or phosphate. Alternatively, it is preferred in terms of phosphate immersion efficiency.
However, in the present invention, by using a shell thickness below a predetermined value and using organic acid salts or phosphates, it is possible to obtain good texture of the flesh and texture of the shell even without prior water retention treatment. I can do it.

The unheated shelled shrimp obtained by the above process can be eaten with the shell, and can be used in various cooking methods such as cooking, boiling, steaming, and grilling. Furthermore, the heated shelled shrimp obtained by heating in this manner also corresponds to the shelled shrimp of the present invention.
The unheated shelled shrimp and the heated shelled shrimp may be frozen or chilled at any time after immersion in the aqueous solution of the organic acid salt or phosphate.

For example, unheated frozen shrimp with shells can be stored in a frozen state after being immersed in the organic acid salt or phosphate immersion solution. In addition, when heating unheated frozen shrimp with shells to obtain heated shrimp with shells, shrimp in either frozen or chilled state can be heated in various ways (oiled, boiled, steamed, grilled, etc.). ), or after cooking the shelled shrimp, it may be stored as is in a frozen or chilled state. Frozen state usually refers to storage at a temperature range of less than 10°C, and freezing is usually carried out at a temperature lower than -3°C and higher than -45°C. For example, when the frozen shelled shrimp of the present invention is thawed and eaten by microwave heating or natural thawing, it has the effect of reducing the hardness of the shell and reducing the feeling of remaining shell when chewed with the back teeth. That's what you get.
The shelled shrimp of the present invention can be used as various processed foods such as frozen foods, foods for microwave heating, diet foods, oil-based products such as fried foods, chilled foods, and raw materials for their production.

The present invention provides shelled shrimp produced by the above method. The present inventor has found that by treating shrimp with a specific shell thickness with a specific salt, it is possible to effectively reduce the hardness of the shell when chewing with the back teeth, and the shell remains in the mouth after the shrimp is swallowed. It was also found that the sensation (the feeling of the shell remaining in the mouth) can also be suppressed. However, shrimp are natural products, and the physical properties of shrimp shells and flesh after soaking vary from individual to individual, and establishing new analytical methods requires establishing new analytical methods, which requires a huge amount of time. Therefore, the applicant decided to define the present invention by subjecting shrimp having a shell thickness of a specific portion to a specific soaking treatment. As described above, in the present application, there were circumstances that made it impossible or impractical to define shrimp with shells as a product.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the scope of the invention is not limited to such examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

(Comparative Examples 1-1 to 1-3, Examples 1-1 to 1-4)
Based on the shell thickness of the second abdominal segment and the shell thickness of the cephalothorax, uncooked vannamei shrimp were prepared in a total of 7, Comparative Examples 1-1 to 1-3 and Examples 1-1 to 1-4. The fish were divided into groups (5 fish per group; the same applies to Examples 2-1 and subsequent examples). Table 1 shows the average values of the left and right thicknesses of the vannamei shrimp used in each of the Examples and Comparative Examples. The left and right average value of the shell thickness of the Vannamei shrimp in each Example and Comparative Example (average value for each Vannamei shrimp) had an error of less than 0.01 mm from the value listed in Table 1 for the shell thickness of the cephalothorax. (The same applies to Example 2-1 and subsequent examples). In addition, the vannamei shrimp had undergone freezing and thawing treatment after being caught (harvested) (the same applies to Examples 2-1 and subsequent examples).

After measuring the shell thickness, the shelled shrimp without the cephalothorax removed were soaked in an aqueous solution of 8% by mass of sodium acetate and 2% by mass of salt (3.8°C, 3.8°C before soaking) based on 100 parts by mass of shrimp. (pH 8.41) for the time shown in Table 1. After draining the liquid, it was immersed in the batter liquid and tempered with cooking oil at 180°C for 3 minutes. After adjusting the oil, 10 panelists ate them and evaluated them according to the following evaluation criteria. Table 1 shows the average evaluation scores of the 10 panelists. Note that in Comparative Example 1-3, water was used as the immersion liquid.

●Hardness of the shell when chewed with back teeth 10 Very strong 9 Very strong 8 Strong 7 Somewhat strong 6 Neutral 5 Somewhat weak 4 Weak 3 Very weak 2 Very weak 1 Very weak

- Shell taste 10 Very strong 9 Very strong 8 Strong 7 Somewhat strong 6 Neutral 5 Somewhat weak 4 Weak 3 Very weak 2 Very weak 1 Very weak

(Examples 2-1 to 2-2)
In place of the aqueous solution of 8% by mass of sodium acetate and 2% by mass of common salt, an aqueous solution of 8% by mass of sodium ascorbate and 2% by mass of common salt (pH 7.48 at 3.8°C before immersion) was used for immersion times of 4 and 8. The evaluation was carried out in the same manner as in Example 1-3, except that the time was changed to , 16, and 24 hours. The results are shown in Table 2.

(Examples 3-1 to 3-2)
In place of the aqueous solution of 8% by mass of sodium acetate and 2% by mass of common salt, an aqueous solution of 8% by mass of sodium polyphosphate and 2% by mass of common salt (pH 8.25 at 3.8°C before immersion) was used for immersion times of 4 and 8. , 16, and 24 hours, the evaluation was performed in the same manner as in Example 1. The results are shown in Table 3.

(Examples 4-1 to 4-2)
Instead of an aqueous solution of 8% by mass of sodium acetate and 2% by mass of common salt, an aqueous solution of 8% by mass of dipotassium hydrogen phosphate and 2% by mass of common salt (pH 8.9 at 3.8°C before immersion) was used for 4 immersion times. , 8, 16, and 24 hours, but evaluation was performed in the same manner as in Example 1-3. The results are shown in Table 4.

(Examples 5-1 to 5-2)
Instead of the aqueous solution of 8% by mass of sodium acetate and 2% by mass of common salt, an aqueous solution of 8% by mass of trisodium citrate and 2% by mass of common salt (pH 8.3 at 3.8°C before immersion) was used for 4 immersion times. , 8, 16, and 24 hours, but the evaluation was carried out in the same manner as in Example 1-3. The results are shown in Table 5.

(Examples 6 to 9, Comparative Example 4)
Vannamei shrimp having the shell thicknesses listed in Tables 6 and 7 (cephalothorax shell thickness and second abdominal segment shell thickness) contain 2% by mass of salt and further contain an organic acid listed in Tables 6 and 7. The batter (wheat flour and starch (total of 30% by mass, the remainder being water), and the mixture was heated to 180°C for 2 minutes to prepare the oil. The texture of the shell and the texture of the body of the obtained shelled shrimp were evaluated using the following evaluation criteria, and the evaluation scores were calculated by averaging the evaluation scores of 10 people. The results are shown in Tables 6 and 7. Comparative Example 4 is an example in which water of the same temperature was used instead of the immersion liquid of each Example.

●Texture of shell 5 Feels soft.
3 Feels a little soft.
1 It feels hard.

●Texture of the body 5: It is plump.
3 Hard.
1 I'm a mess.

According to the present invention, while suppressing the deterioration of the texture of the meat, the hardness of the shell when eaten with the shell and chewing with the molar teeth is effectively reduced, and the feeling of the shell remaining in the mouth is suppressed. Served with shrimp.

Claims (7)

A method for producing shelled shrimp, which has an abdominal body and a shell that covers the abdominal body, and which can be cooked or heated and can be eaten with the shell attached,
Uncooked shrimp with a cephalothorax shell thickness of 0.09 mm or more and 0.21 mm or less, with or without removing the cephalothorax, prepared using acetic acid, citric acid , and ascorbic acid. A method for producing shelled shrimp, which comprises immersing shrimp in an aqueous solution having a pH of 10.0 or less and containing 2.0 to 10.0% by mass of at least one kind of alkali metal salt. The method for producing shelled shrimp according to claim 1, wherein the aqueous solution has a pH of 6.5 to 9.0. The method for producing shelled shrimp according to claim 1 or 2, wherein the temperature of the aqueous solution during shrimp soaking is 0.0 to 10.0°C, and the soaking time is 4 to 24 hours. The method for producing shelled shrimp according to claim 1 or 2, wherein the shrimp is obtained without further immersion treatment with an organic acid aqueous solution after being immersed in the aqueous solution. The method for producing shelled shrimp according to claim 1 or 2, wherein the shell thickness of the second abdominal segment of the shrimp immersed in the aqueous solution is 0.05 mm or more and 0.16 mm or less. The method for producing shelled shrimp according to claim 1 or 2, wherein the at least one alkali metal salt selected from acetic acid, citric acid , and ascorbic acid is sodium acetate. Shrimp with shells having an abdominal body and a shell covering the abdominal body and a shell thickness of 0.09 mm or more and 0.21 mm or less in the cephalothorax were softened by soaking and then cooked. A dipping liquid that can sometimes be eaten with the shell on ,
An immersion liquid that is an aqueous solution of at least one alkali metal salt selected from acetic acid, citric acid, ascorbic acid, and phosphoric acid with a pH of 10.0 or less.

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