Method for producing bivalve mollusks or crustaceans for cooking

Abstract

To provide a technique for simply producing bivalves or crustaceans for heating, which have an excellent yield and a soft texture after heating even when brought into contact with a sodium chloride-containing liquid before heating. The present invention provides a method for producing bivalve mollusks or crustaceans for cooking, comprising the steps of: This production method involves contacting unheated bivalve mollusks or crustaceans with an aqueous solution containing an alkali metal alginate and sodium chloride and having a viscosity of less than 200 dPa·s. It is preferable that no prior treatment with a divalent or higher metal cation is performed. It is preferable that the bivalve mollusks or crustaceans are oysters. It is also preferable that the viscosity of the aqueous solution is less than 20 dPa·s at 10°C. It is also preferable that the concentration of sodium chloride in the aqueous solution is 2 to 5% by mass.

Description

[Technical Field]

[0001] The present invention relates to a method for producing bivalve mollusks or crustaceans for cooking. [Background technology]

[0002] Bivalves such as oysters and crustaceans such as shrimp are known to have a high water content within their bodies. When heated, the water easily leaks out of the body, causing them to shrink and reduce yield. Furthermore, as the water leaks out during heating, they shrink and their appearance deteriorates. Furthermore, heating also makes them hard in texture.

[0003] Meanwhile, technologies for coating food surfaces with gelling agents are known. Conventionally, when using sodium alginate for coating, it is common to preliminarily add divalent or higher metal cations, such as calcium ions, to the target object. In this regard, Patent Document 1 describes a method for producing a surface-coated food, which involves treating the food surface with a water-soluble thickener, stabilizer, paste, or gelling agent that thickens or gels upon reaction with cations, without pre-treating the food to be coated with cations. The method involves reacting the food surface with the thickener, stabilizer, paste, or gelling agent to thicken or gel the food surface, thereby coating the food surface. The document also describes that the immersion or spray liquid is used at a temperature of 10°C or below and with a viscosity of 20,000 cps (200 dPa·s) (paragraph

[0009] ). Furthermore, the examples in the document use only pectin as a gelling agent. The document also describes that the method described in the document does not result in a loss of freshness, and the coating components do not affect the taste with simple operations. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-121181 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, bivalve mollusks or crustaceans are prone to a decrease in yield when heated, and there is a strong demand for improving this situation due to the recent decline in seafood resources, etc. In particular, when bivalve mollusks or crustaceans are immersed in a sodium chloride-containing solution before heating in consideration of taste, the heating yield and texture tend to decrease, and a technology that can improve the decrease in yield when heated and the texture is also useful. However, in the above cases, a technique for easily producing bivalve or crustacean shellfish for heating that has an excellent yield and texture when heated has not been fully investigated. Furthermore, the present inventors have found that when uncooked bivalve mollusks or crustaceans are coated with a gelling agent made of pectin as described in Patent Document 1, it is difficult to obtain an effect of improving yield, and the texture is inferior.

[0006] Therefore, an object of the present invention is to provide a technology for easily producing bivalve or crustacean shellfish for heating that has an excellent yield after heating and a good texture even when contacted with a sodium chloride-containing liquid before heating. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have surprisingly found that the above-mentioned problems can be solved by contacting bivalve mollusks or crustaceans with a specific aqueous solution containing an alkali metal alginate.

[0008] The present invention is based on the above findings, and is a method for producing bivalve mollusks or crustaceans for heating, comprising: The method comprises contacting uncooked bivalve mollusks or crustaceans with an aqueous solution containing an alkali metal alginate and sodium chloride and having a viscosity of less than 200 dPa·s.

[0009] The present invention also provides a method for producing cooked bivalve or crustacean, which comprises heating the bivalve or crustacean for heating obtained by the above-mentioned production method. [Effects of the Invention]

[0010] According to the present invention, bivalve mollusks or crustaceans for heating can be provided by a simple method, which have excellent yield and texture after heating, even when the bivalve mollusks or crustaceans are contacted with a sodium chloride-containing liquid before heating. Furthermore, according to the present invention, heated bivalve mollusks or crustaceans having excellent yield and texture can be obtained by a simple method. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below based on preferred embodiments thereof. The present invention relates to a method for producing bivalve mollusks or crustaceans for cooking, comprising the steps of: This relates to a manufacturing method in which uncooked bivalve mollusks or crustaceans are brought into contact with an aqueous solution containing an alkali metal alginate and sodium chloride and having a viscosity of less than 200 dPa·s (hereinafter also referred to as the "specific aqueous solution").

[0012] Examples of the alkali metal alginate include sodium alginate and potassium alginate, with sodium alginate being preferred in terms of availability and taste.

[0013] Examples of bivalve mollusks used in the present invention include bivalve mollusks from the families Pectinidae, Portulidae, Mytilidae, Pectinidae, Bucconidae, Bucconidae, Veneridae, Acanthidae, Malariaidae, Corbiculatus, Schistidae, and Bucconidae. Examples of Pectinidae include Pectinidae, Scallops, Scallops, Akazara mussels, and Azuma mussels. Examples of Pectinidae include Pen oysters. Examples of Mytilidae include Purple mussels. Examples of Pectinidae include Crassostrea genus shells such as Crassostrea and Iwagaki, as well as Crassostrea genus shells such as Crassostrea spp. and Crassostrea spp., and Crassostrea genus shells such as Crassostrea spp. Shellfish of the family Botryllidae include giant tortoiseshell oysters, giant tortoiseshell oysters, giant tridacna, red oysters, and flat oysters. Shellfish of the family Botryllidae include the giant clam and giant oyster. Shellfish of the family Veneridae include the littleneck clam and the hard clam. Shellfish of the family Acanthidae include the cobweb. Shellfish of the family Malidae include the giant clam and cockle. Shellfish of the family Corbiculatidae include the clam and the like. Shellfish of the family Brachydae include the ark shell and the like. Shellfish of the family Bivalidae include the pearl oyster, the Japanese bush clam, and the like.

[0014] Crustaceans used in the present invention include shrimp, crabs, and mantis shrimp. Examples of shrimp include shrimp from the Penaeidae family, Caridea, Stenopodidae, Scyllariidae, Solenoceridae, and Pandalidae families, with shrimp from the Penaeidae family being preferred. Examples of the Penaeidae family include white-spotted shrimp (Litopenaeus vannamei), black tiger shrimp (Penaeus monodon), kuruma shrimp (Marsupenaeus japonicus), mud shrimp (Metapenaeus joyneri), poo-valang shrimp (Metapenaeus dobsoni), endeavor shrimp (Metapanaeus endeavouri), Bangladesh brown shrimp (Metapenaeus onoceros), Asian king shrimp (Fenneropenaeus chinensis), and banana shrimp (Fenneropenaeus merguiensis).

[0015] The bivalve or crustacean used in the present invention is usually a marine product. The uncooked bivalve or crustacean used in the present invention may be frozen or may be used as is after being caught or harvested. If the bivalve or crustacean is frozen, it is preferable to bring it into contact with the specific aqueous solution after thawing.

[0016] Furthermore, uncooked bivalves or crustaceans tend to contain a large amount of water within their bodies, resulting in a tendency for the water to be lost and weight to be reduced when heated. However, in the present invention, contacting a specific aqueous solution with uncooked bivalves or crustaceans can prevent water loss during heating. The inventors believe that this is because the method allows bivalves or crustaceans to be coated with a coating of the alginic acid component contained in the specific aqueous solution, and this coating may be suitable for preventing water loss during heating. While the reason for the formation of this coating is unclear, it is thought that the bivalves or crustaceans themselves may contain divalent or higher metal cations (e.g., calcium ions, magnesium ions, iron ions, zinc ions, copper ions, manganese ions, etc.), which may cause the alginic acid (alkali metal alginate) to react effectively with these ions to form a gel. The reason why the use of bivalves or crustaceans in the present invention has an excellent effect on improving yield is not clear, but it is thought that this may be due to the fact that they contain a large amount of divalent metal ions, which may react with alkali metal alginate to form a gel. Furthermore, as shown in the results of the contact treatment yield B / A in each example described below, in the present invention, by contacting a specific aqueous solution with unheated bivalves or crustaceans, it is possible to increase the weight of the bivalves or crustaceans, which also contributes to improving the yield.

[0017] When bivalves are used in the present invention, it is preferable to remove the shells of the bivalves before contacting them with the specific aqueous solution, as this is effective in improving yield. Furthermore, when crustaceans are used, it is preferable to remove at least a portion of the shells of the crustaceans before contacting them with the specific aqueous solution, as this is effective in improving yield. For example, in the case of shrimp or mantis shrimp, it is preferable to remove the abdominal shells, as this is effective in improving yield, and it is particularly preferable to remove the head and / or tail as well.

[0018] In the present invention, it is preferable to use bivalve mollusks, particularly bivalve mollusks, among bivalve mollusks or crustaceans, because of their excellent yield improvement effect according to the present invention. The reason for this is that bivalve mollusks are prone to moisture loss, particularly when heated, and the present invention can effectively prevent this moisture loss, thereby improving yield. The inventors also believe that bivalve mollusks are suitable as the subject of the present invention because they have a high content of divalent metal cations and therefore have excellent reactivity with sodium alginate. Among bivalve mollusks, shellfish from the families Ostrichidae or Crassidae are particularly preferred, with shellfish from the genus Crassidae being most preferred. Shellfish from the families Ostrichidae or Crassidae are generally referred to simply as "oysters."

[0019] Furthermore, "unheated" refers to a product that has not been subjected to heat treatment at 60°C or higher, and particularly preferably to a product that has not been subjected to heat treatment at 50°C or higher.

[0020] In the present invention, there is no need to perform a prior treatment of adding divalent or higher metal cations before contacting uncooked bivalve mollusks or crustaceans with the specific aqueous solution. Without this treatment, the present production method becomes simpler, and the resulting bivalve mollusks or crustaceans for cooking tend to have a good taste when eaten. "Without prior treatment of adding divalent or higher metal cations" means that the prior active treatment of adding divalent or higher metal cations before contact with the aqueous solution, which has traditionally been performed when forming a gel coating on the surface of foods using an aqueous solution of alkali metal alginate, is not performed.

[0021] Examples of "prior treatment with divalent or higher valent metal cations" include artificially preparing a solution containing divalent iron ions, trivalent iron ions, calcium ions, magnesium ions, strontium ions, barium ions, radium ions, divalent silver ions, trivalent silver ions, copper ions, zinc ions, selenium ions, manganese ions, chromium ions, cobalt ions, etc., and administering this to the surface of uncooked bivalve mollusks or crustaceans before contact with an aqueous solution of an alkali metal alginate. These ions can be obtained by mixing salts or compounds such as chlorides and other halides, sulfates, carbonates, hydroxides, and oxides with water. The content of these ions in the solution may be 1% by mass or more, 0.1% by mass or more, 0.01% by mass or more, or 0.001% by mass or more, based on the metal cations. The content of these ions in the aqueous solution may be 5% by mass or less, 10% by mass or less, or 20% by mass or less. For example, seawater contains trace amounts of iron (Fe 2+ ), magnesium (Mg 2+ ), calcium (Ca 2+ ) containing divalent or higher metal cations. In this regard, contacting bivalve mollusks or crustaceans with seawater before contacting the unheated bivalve mollusks or crustaceans with the specified aqueous solution does not fall under the "prior treatment of adding divalent or higher metal cations" referred to here. Furthermore, bivalve mollusks such as oysters contain a lot of iron, and it goes without saying that applying iron or other fertilizer to oyster farms does not fall under the "prior treatment of adding divalent or higher metal cations" referred to here.

[0022] In the present invention, the bivalve or crustacean may or may not be washed with fresh water or saline water before contacting it with the particular aqueous solution.

[0023] Furthermore, the specific aqueous solution may or may not contain divalent or higher metal cations, but a lower content of divalent or higher metal cations in the specific aqueous solution is preferable in terms of the flavor of the resulting bivalve or crustacean. When the specific aqueous solution contains divalent or higher metal cations, the content may be 0.03% by mass or less, 0.02% by mass or less, 0.01% by mass or less, 0.005% by mass or less, 0.003% by mass or less, or 0.001% by mass or less, based on the metal cations.

[0024] The specific aqueous solution used in the present invention contains sodium chloride. The inclusion of sodium chloride in unheated bivalve mollusks or crustaceans improves the flavor after heating. Furthermore, when bivalve mollusks or crustaceans containing sodium chloride are heated, the degree of moisture loss during heating tends to increase. However, in the present invention, weight loss during heating is mitigated by contacting the bivalve mollusks or crustaceans with sodium alginate before heating. This results in an excellent yield improvement effect when the specific aqueous solution is contacted with bivalve mollusks or crustaceans. Furthermore, it is believed that the inclusion of sodium chloride in the specific aqueous solution increases the viscosity of the specific aqueous solution, facilitating the formation of a coating around the oysters. For these reasons, the use of an aqueous solution containing sodium chloride and sodium alginate improves the flavor of the heated bivalve mollusks or crustaceans and improves the yield. The amount of sodium chloride in the specific aqueous solution is preferably 2 to 5% by mass, more preferably 2.5 to 4.5% by mass, and particularly preferably 3 to 4% by mass.

[0025] The specific aqueous solution contains an alkali metal alginate. By bringing the specific aqueous solution into contact with uncooked bivalve mollusks or crustaceans, the yield of the bivalve mollusks or crustaceans during heating is improved.

[0026] Although not limited thereto, it is preferable to use an alkali metal alginate whose viscosity as a 1% by mass aqueous solution at 20°C is 250 to 450 mPa·s, more preferably 300 to 400 mPa·s, and particularly preferably 320 to 380 mPa·s.

[0027] To further enhance the above-mentioned effects, the content of the alkali metal alginate in the specific aqueous solution is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. Furthermore, it is preferable that the content of the alkali metal alginate in the specific aqueous solution is below a certain level, because the yield improvement effect by heating is high. From this viewpoint, it is preferably 1.0% by mass or less, more preferably 0.7% by mass or less.

[0028] The viscosity of the specific aqueous solution is less than 200 dPa·s, preferably less than 20 dPa·s, more preferably 10 dPa·s or less, and particularly preferably 5 dPa·s or less. Patent Document 1 uses a pectin solution with a high viscosity of 20,000 cps (200 dPa·s) for the purposes of preventing oxidation and drying. In contrast, in the present invention, it is preferable that the viscosity of the specific aqueous solution be a certain level or less in order to improve the yield during heating. The reason for this is thought to be that a solution with a viscosity of a certain level or less is suitable for forming an even, thin film on soft objects with complex shapes, thereby improving the heating yield. If the viscosity of the specific aqueous solution is at a certain level or higher, the yield of the bivalve or crustacean to be heated is likely to be improved. From this viewpoint, the viscosity of the specific aqueous solution is preferably 0.008 dPa·s or higher, and more preferably 0.01 dPa·s or higher. The viscosity of the specific aqueous solution can be measured by the method described in the Examples below. For example, the viscosity of the specific aqueous solution is preferably 0.3 dPa·s or higher. ·s For viscosity values below this, another B-type viscometer can be used, for example, the TVB10 / 15 viscometer (Toki Sangyo).

[0029] The viscosity of the specific aqueous solution is measured at 10° C. and can be measured by the method described in the Examples below.

[0030] The specific aqueous solution to be brought into contact with unheated bivalve mollusks or crustaceans preferably has a pH of 6 to 8. The pH of the specific aqueous solution referred to here is the pH at 10°C.

[0031] The treatment of bringing bivalve mollusks or crustaceans into contact with the specific aqueous solution may be any treatment that brings the surface of the bivalve mollusks or crustaceans into contact with the specific aqueous solution, and may be an immersion treatment, a spray treatment, or an injection treatment. Immersion treatment is particularly preferred because it allows the entire surface of the bivalve mollusks or crustaceans to be uniformly contacted with the specific aqueous solution.

[0032] The amount of the specific aqueous solution to be contacted is preferably 80 to 150 parts by mass per 100 parts by mass of unheated bivalve or crustacean, as this brings the entire surface of the bivalve or crustacean into contact with the specific aqueous solution, thereby increasing the effectiveness of the present invention and making it more economical; 90 to 120 parts by mass is more preferable, and 100 to 110 parts by mass is particularly preferable.

[0033] The contact time between the bivalve or crustacean and the specific aqueous solution may be short, for example, 5 minutes or more, or 7 minutes or more. In addition, since it is difficult to improve the yield even if the contact time between the bivalve or crustacean and the specific aqueous solution is longer than that, from the viewpoint of production costs, the contact time is preferably 20 minutes or less, and more preferably 15 minutes or less. In the present invention, even if the treatment is carried out for a short time, the yield can be improved.

[0034] The temperature of the specific aqueous solution used in the present invention is preferably 5 to 15°C, particularly preferably 7 to 10°C, from the viewpoint of hygiene and treatment efficiency to improve yield.

[0035] The surface temperature of the bivalve or crustacean to be brought into contact with the specific aqueous solution is preferably 0 to 15°C, more preferably 1 to 12°C.

[0036] In the specific aqueous solution used in the present invention, the amount of components other than water, sodium alginate, and sodium chloride is preferably 10.0% by mass or less, more preferably 8.0% by mass or less, even more preferably 5.0% by mass or less, particularly preferably 3.0% by mass or less, and most preferably 1.0% by mass or less. Furthermore, in the specific aqueous solution used in the present invention, the amount of components other than sodium alginate and sodium chloride is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 25 parts by mass or less, particularly preferably 10 parts by mass or less, and most preferably 5 parts by mass or less, per 100 parts by mass of the total amount of sodium alginate and sodium chloride.

[0037] The unheated bivalve or crustacean shellfish obtained by the above process can be eaten with the shell on and can be used for various cooking methods such as frying, boiling, steaming, and baking. By cooking in this way, cooked bivalve or crustacean shellfish can be obtained. Unheated bivalve mollusks or crustaceans and cooked bivalve mollusks or crustaceans are distributed frozen or chilled. The timing of distribution and chilling may be any time after contact with the specific aqueous solution.

[0038] For example, unheated bivalves or crustaceans for cooking can be stored frozen after contact with the specific aqueous solution. Furthermore, when unheated bivalves or crustaceans are heated to obtain cooked bivalves or crustaceans, they can be subjected to various cooking methods (frying, boiling, steaming, baking, etc.) in either a frozen or chilled state, or the bivalves or crustaceans can be stored frozen or chilled after cooking. A "frozen state" typically refers to storage at a temperature range below 10°C, and freezing is typically performed at temperatures lower than -3°C and higher than -45°C. For example, frozen bivalves or crustaceans for cooking of the present invention can be cooked as is or after thawing, resulting in improved yield and a favorable appearance. The bivalves or crustaceans for heating obtained by the present invention can be sold commercially as they are, or can be used as raw materials for producing various processed foods such as frozen foods, foods for microwave heating, diet foods, oil-based products such as fried foods, and chilled foods. [Example]

[0039] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0040] <Evaluation using oysters> Examples 1 and 2 Uncooked oysters were individually frozen after being shelled, thawed in hot water (approximately 58°C) for 30 seconds, and then drained before use. An aqueous solution was prepared by dissolving sodium chloride (NaCl) in water to a concentration of 3% by mass and dissolving sodium alginate (Kimica Co., Ltd. "Kimica Algin I-3") in the concentration shown in Table 1. Five oysters were placed in 100 g of this aqueous solution and immersed for the time shown in Table 1, then boiled for the time shown in Table 1, cooled under running water, and drained.

[0041] The viscosity of the aqueous solution was measured by the following method: The pH of the aqueous solution was measured using a tabletop pH meter F-71 (Horiba, Ltd.). <Method for measuring viscosity of aqueous solution> A 100 g sample of the aqueous solution was left to stand in a thermostatic bath at 10°C for 30 minutes, and then the viscosity of the aqueous solution was measured using a B-type viscometer. Viscosity measurements using the B-type viscometer were performed using a Viscometer VT-06 (Rion Co., Ltd.) with a No. 3 rotor.

[0042] (Comparative Example 1) In Example 1, the immersion treatment in the aqueous solution was not performed. Except for this, oysters to be heated were obtained in the same manner as in Example 1.

[0043] (evaluation) For the oysters to be heated and the heated oysters obtained in Examples 1 and 2 and Comparative Example 1, the weight A before soaking, the weight B at the time of draining after soaking, and the weight C after heating were measured, and various yields shown in Table 1 were calculated. The average values are shown in Table 1. In addition, the texture of the heated oysters obtained by the following method was evaluated by the following method. In addition, in Examples 1 and 2, a gloss was observed on the surface of the oysters before heating after immersion, which was not observed in Comparative Example 1, and it is believed that a gel-like coating was formed. In addition, the gloss of the surface before heating was also confirmed in other examples.

[0044] (Texture) 5: Fluffy and soft. 4: Slightly plump. 3: Normal. 2: Somewhat hard. 1: Hard and crumbly.

[0045] [Table 1]

[0046] As shown in Table 1, in each example in which oysters were soaked in a sodium alginate solution, the weight increased due to the soaking treatment, and the weight loss was small even after heat treatment, resulting in a high overall yield. In contrast, in Comparative Example 1, the yield decreased significantly due to heat treatment.

[0047] Example 3 As sodium alginate, a sodium alginate-containing preparation "Kombus Acid 421" (sodium alginate (85% by mass), calcium citrate (15% by mass)) was used instead of "Chimica Algin I-3". The boiling time was changed to 4 minutes. The number of oysters used per test plot was also changed from 5 to 3. Other than these points, the oysters for heating were obtained in the same manner as in Example 1.

[0048] (Comparative Example 2) In Example 3, the immersion treatment in the aqueous solution was not performed. Except for this, oysters to be heated were obtained in the same manner as in Example 3.

[0049] (evaluation) The oysters obtained in Comparative Example 2 and Example 3 were evaluated in the same manner as in the examples in Table 1. The results are shown in Table 2.

[0050] [Table 2]

[0051] As shown in Table 2, it can be seen that a similar excellent yield improvement effect can be obtained when using a different formulation containing sodium alginate as the main ingredient.

[0052] (Comparative Examples 3 to 5) In Example 1, LM pectin (Milky Ribbon, Unitec Foods) was used in place of sodium alginate at the concentration shown in Table 3. In addition, the number of oysters used in one test plot was four. Other than that, the same procedures as in Example 1 were followed to obtain oysters for heating.

[0053] (Comparative Example 6) In Comparative Example 3, the oysters to be heated were obtained in the same manner as in Comparative Example 3 except that the immersion treatment in the aqueous solution was not carried out.

[0054] (evaluation) The oysters obtained in Comparative Examples 3 to 5 and 6 were evaluated in the same manner as in the examples in Table 1. The results are shown in Table 3. As shown in Table 3, when LM pectin was used instead of sodium alginate, the yield rate of the heat treatment was low.

[0055] [Table 3]

[0056] <Evaluation using shrimp> Examples 4 and 5 Uncooked shrimp (variety Vannamei 41 / 50) were peeled, the tails and heads removed, and then individually frozen. They were thawed in hot water (approximately 60°C) for 30 seconds, then drained and used. Shrimp for heating was obtained by the same treatment as in Examples 1 and 2, except that the above shrimp was used instead of oysters. The number of shrimp used in each test was 10.

[0057] (Comparative Example 7) In Example 4, the immersion treatment in the aqueous solution was not carried out. Except for this, shrimp for heating was obtained in the same manner as in Example 4.

[0058] (evaluation) The shrimp obtained in Examples 4 and 5 and Comparative Example 7 were evaluated in the same manner as in the examples in Table 1. The results are shown in Table 4. As shown in Table 4, even in the case of shrimp, although the degree of improvement in yield was slightly lower than in oysters, it was found that immersion in an aqueous sodium alginate solution improved the yield rate of the immersion treatment and also improved the yield rate of the heat treatment, leading to an improvement in the total yield.

[0059] [Table 4] [Industrial Applicability]

[0060] According to the present invention, bivalves or crustaceans for heating are provided which have an excellent yield and a soft texture after heating by contacting them with a sodium chloride-containing liquid for a short period of time before heating.

Claims

1. A method for producing bivalve mollusks or crustaceans for cooking, comprising: A production method comprising contacting unheated bivalve or crustacean shellfish with an aqueous solution containing an alkali metal alginate and sodium chloride, the aqueous solution having a viscosity of 0.008 dPa·s or more and 5 dPa·s or less and a pH of 6 to 8.

2. The method according to claim 1 , wherein a prior treatment of adding a divalent or higher valent metal cation is not carried out.

3. The method of claim 2, wherein the bivalve or crustacean is an oyster.

4. The method according to claim 1 or 2, wherein the concentration of sodium chloride in the aqueous solution is 2 to 5% by mass.

5. The method according to claim 1 or 2, wherein the concentration of sodium alginate in the aqueous solution is 0.1 to 1.0% by mass.

6. The method according to claim 1 or 2, wherein the time for contacting the aqueous solution with the unheated bivalve or crustacean is 5 to 20 minutes.

7. The method according to claim 1 or 2, wherein the surface of uncooked bivalve or crustacean is coated with a gel derived from an alkali metal alginate.

8. A method for producing heated bivalves or crustaceans, which comprises heating bivalves or crustaceans obtained by the method according to claim 1 or 2.

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