Pickling solution for seafood and method for pickling seafood

Abstract

To provide a technology that curbs a color change such as browning or color fading of a marine product having a red color in fish meat or body surface thereof while the marine product is stored or distributed.SOLUTION: A method of immersing a marine product in an immersing liquid including plum vinegar curbs a color change of the marine product. It is preferable that the immersing liquid has a citric acid concentration of 0.1-20.0 wt.%, a malic acid concentration of 0.02-4.0 wt.%, a sodium chloride concentration of 0.4-5.0 wt.%, and pH of 7.0-10.0.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for inhibiting discoloration of marine products. [Background technology]

[0002] Most seafood is distributed frozen or refrigerated to maintain freshness. Raw seafood is an appealing food due to its freshness and unique texture, which is fibrous and elastic. However, frozen seafood suffers from quality degradation due to discoloration that progresses during frozen storage and dripping that occurs upon thawing, while refrigerated seafood suffers from discoloration that progresses during refrigerated storage. Discoloration of seafood significantly reduces its commercial value, and dripping reduces the seafood's original texture and flavor. This also reduces yield. To address these issues, techniques have long been devised to prevent quality degradation in seafood by soaking seafood in a soaking solution containing salt and alkali. For example, it has been found that increasing the amount of a component that increases the ionic strength of the pickling solution minimizes the impact on taste and texture and maintains yield (Patent Document 1). It is also known that a pickling solution containing plum vinegar and an alkali metal salt improves the texture and taste of seafood and other foods (Patent Document 2).

[0003] However, in the case of fishery products whose flesh or body surface is red in color, browning and discoloration can occur during storage by freezing or refrigeration or during distribution, and conventional pickling solutions have not been able to fully maintain the commercial value of the products. One of the causes of discoloration in fish meat and other foods is changes in myoglobin and carotenoid pigments. It has been reported that trisodium citrate delays the methemoglobin formation of tuna myoglobin (Non-Patent Document 1), and that citric acid and sodium ascorbate prevent the oxidation of carotenoids (Non-Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6641518 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-240294 [Non-patent literature]

[0005] [Non-Patent Document 1] Yasuyuki Tsuka, "Quality Changes and Color Retention of Cultured Bluefin Tuna Meat During Refrigeration," 21st Century COE Program 2003-2004 (Heisei 15-16) Interim Report (2005) 163-166. [Non-patent document 2] Masaaki Sugimoto, "Color Changes in Seafood During Freezing and Refrigeration," Journal of the Japan Cold Chain Research Association, "Food and Low Temperatures," Vol. 12, No. 4, 137-142, (1986) Summary of the Invention [Problem to be solved by the invention]

[0006] However, the effects of these conventional techniques in inhibiting discoloration of marine products have not always been satisfactory. In addition, consumers tend to avoid artificial additives, and there is a demand for seasonings derived from natural ingredients. In view of the above circumstances, an object of the present invention is to provide a technology for suppressing discoloration such as browning and fading in marine products over time and / or temperature. [Means for solving the problem]

[0007] As a result of extensive research to solve the above problems, the present inventors have discovered a pickling solution containing plum vinegar. The present inventors have found that discoloration of marine products can be suppressed by soaking them in soy sauce, and have completed the present invention.

[0008] That is, the present invention is as follows. [1] A pickling solution containing plum vinegar for inhibiting discoloration of seafood, The pickling solution has a citric acid concentration of 0.1 to 20.0% by weight. [2] The pickling solution according to [1], wherein the concentration of malic acid in the pickling solution is 0.02 to 4.0% by weight. [3] The pickling solution according to [1] or [2], wherein the concentration of sodium chloride in the pickling solution is 0.4 to 5.0% by weight. [4] The pickling solution according to any one of [1] to [3], which has a pH of 7.0 to 10.0. [5] The pickling solution according to any one of [1] to [4], which has an ionic strength of 0.5 to 3.0 mol / kg. [6] The pickling solution according to any one of [1] to [5], wherein the total concentration of free asparagine and free aspartic acid in the pickling solution is 0.002 to 0.3% by weight. [7] A method for inhibiting discoloration of marine products, comprising the step of immersing marine products in the immersion liquid according to any one of [1] to [6]. [8] The method according to [7], wherein the immersion time is from 1 second to 48 hours. [9] The method according to [7] or [8], wherein the soaking is carried out at 0 to 20°C.

[10] A processed seafood product produced by immersing a seafood product in the immersion liquid according to any one of [1] to [6]. [Effects of the Invention]

[0009] According to one aspect of the present invention, discoloration during freezing can be suppressed in marine products, particularly marine products with red flesh or body surface. Also, in one aspect of the present invention, discoloration during refrigeration can be suppressed. Also, in one aspect of the present invention, discoloration during thawing can be suppressed. Discoloration here includes browning and fading over temperature and / or time. Furthermore, marine products treated according to the present invention also have excellent yield and / or water retention. Therefore, quality deterioration during storage or distribution can be suppressed. Furthermore, because the present invention utilizes natural ingredients, it also meets the demand for products free of artificial additives. [Brief explanation of the drawings]

[0010] [Figure 1] Graph showing the centrifugal drip rate of horse mackerel after soaking treatment. [Figure 2] A graph showing the red color (a* / b* value) of horse mackerel after it has been pickled, frozen, and then thawed. [Figure 3] Graph showing centrifugal drip rate of bonito after pickling treatment. [Figure 4] A graph showing the red color (a* / b* value) of bonito after it has been pickled, frozen, and then thawed. [Figure 5] A graph showing the red color (a* value) of salmon that has been marinated, frozen, and then thawed. [Figure 6] A graph showing the red color (a* value) of salmon that was marinated, frozen, thawed, and then grilled. [Figure 7] A graph showing the change over time in the red color (a* value) of salmon that has been thawed after being frozen after marinating (difference from day 0, ΔE*ab). DETAILED DESCRIPTION OF THE INVENTION

[0011] The pickling liquid of the present invention contains plum vinegar. Plum vinegar is an extract obtained by salting plums. The plum vinegar in the present invention may be either white plum vinegar or red plum vinegar to which shiso leaves have been added, with white plum vinegar being more preferred. It may be either desalted or not, with non-desalted being more preferred. It may also be powdered plum vinegar. Ume vinegar typically contains organic acids such as citric acid, malic acid, and fumaric acid; polyphenols (such as ume lignans); sodium chloride; and free amino acids, the amount of which varies depending on the raw ume and the method of production. When preparing the pickling liquid of the present invention, the plum vinegar is usually diluted with water to adjust the components described below.

[0012] The concentration of citric acid in the pickling liquid of the present invention is 0.1 to 20.0% by weight, preferably 0.14 to 10.0% by weight, and more preferably 0.4 to 3.0% by weight. The concentration of malic acid in the pickling liquid of the present invention is preferably 0.02 to 4.0% by weight, more preferably 0.02 to 2.0% by weight, and even more preferably 0.05 to 0.5% by weight. The organic acids contained in these pickling solutions are preferably derived from plum vinegar, and are usually adjusted to the above concentrations by adding plum vinegar when preparing the pickling solution. The ratio of organic acids derived from plum vinegar to the organic acids contained in the pickling liquid is 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0013] The sodium chloride concentration in the pickling liquid of the present invention is preferably up to 5.0% by weight, more preferably 0.1 to 5.0% by weight, and even more preferably 0.4 to 3.5% by weight. The concentration of sodium chloride in the pickling liquid can be adjusted depending on the level of saltiness desired for the marine product after pickling. The sodium chloride contained in the pickling liquid is preferably derived from plum vinegar, and is usually adjusted to the above concentration by adding plum vinegar when preparing the pickling liquid. The ratio of sodium chloride derived from plum vinegar to the sodium chloride contained in the pickling liquid is 10% by weight or more, more preferably 30% by weight or more, and even more preferably 50% by weight or more.

[0014] The pickling solution of the present invention may contain alkali metal salts or alkaline earth metal salts other than sodium chloride. By adding such salts, the pH of the pickling solution can be increased, thereby improving the yield of the pickled seafood product and / or further enhancing the effect of inhibiting discoloration. Such salts are preferably edible, and specific examples include sodium salts, potassium salts, calcium salts, magnesium salts, etc.

[0015] The pH of the pickling solution of the present invention is preferably 7.0 to 10.0, more preferably 7.0 to 9.7, and even more preferably 7.0 to 9.4. Because plum vinegar generally has a low pH, it is advisable to adjust the pH to within the above range using an aqueous sodium hydroxide solution or the like. Making the pickling solution more alkaline can improve the yield of the pickled seafood and / or further enhance the effect of inhibiting discoloration. Here, the pH is the value at the temperature during pickling.

[0016] The ionic strength of the pickling solution of the present invention is preferably 0.5 to 3.0 mol / kg, more preferably 0.55 to 3.0 mol / kg, and even more preferably 0.60 to 3.0 mol / kg. A higher ionic strength of the pickling solution can improve the yield of the pickled seafood product and / or further enhance the effect of inhibiting discoloration. The ionic strength here refers to the "aqueous solution ionic strength," which is calculated by adding up the molar concentration of each ion and the square of its charge for all ionic species in the solution and dividing that sum by half, as shown in the formula below.

[0017]

number

[0018] However, when marine products are immersed in the immersion liquid of the present invention, the "total ionic strength" is preferably 0.2 to 1.5 mol / kg, more preferably 0.3 to 1.5 mol / kg, and even more preferably 0.4 to 1.5 mol / kg. This is because even if the aqueous solution ionic strength of the pickling solution is determined, the effect will change if the amount of pickling solution for the seafood changes. The "total ionic strength" is defined as "aqueous solution ionic strength x aqueous solution volume) / (aqueous solution volume + seafood weight)" by regarding the weight of the seafood as the amount of water. will be done.

[0019] The aqueous solution ionic strength and total ionic strength can be adjusted using edible organic acid salts and / or inorganic acid salts, specifically, any one or combination of sodium salts, potassium salts, calcium salts, magnesium salts, or any one or combination of citrates, carbonates, bicarbonates, ascorbic acid, erythorbate, lactates, succinates, acetates, malates, fumarates, gluconates, polymerized phosphates, and hydrochlorides. More specifically, preferred examples include sodium chloride, trisodium citrate, potassium chloride, tripotassium citrate, calcium citrate, sodium lactate, sodium succinate, sodium acetate, sodium malate, sodium fumarate, sodium gluconate, potassium gluconate, calcium gluconate, calcium lactate, magnesium chloride, calcium chloride, sodium erythorbate, and polymerized phosphates.

[0020] The total concentration of free asparagine and free aspartic acid in the pickling liquid of the present invention is preferably 0.002 to 0.3% by weight, more preferably 0.0025 to 0.2% by weight, and even more preferably 0.005 to 0.1% by weight. The organic amino acids contained in these pickling solutions are preferably derived from plum vinegar, and the above concentrations are usually adjusted by adding plum vinegar when preparing the pickling solution. The ratio of organic amino acids derived from plum vinegar to the organic amino acids contained in the pickling liquid is 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0021] The polyphenol concentration in the pickling solution of the present invention is preferably 0.003 to 0.4% by weight, more preferably 0.005 to 0.2% by weight, and even more preferably 0.01 to 0.1% by weight. Examples of polyphenols include, but are not limited to, plum lignans (syringaresinol, pinoresinol, epoxyleoniresinol, leoniresinol, etc.). The polyphenols contained in these pickling solutions are preferably derived from plum vinegar, and the above concentrations are usually adjusted by adding plum vinegar when preparing the pickling solution. The proportion of polyphenols derived from plum vinegar in the polyphenols contained in the pickling liquid is 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0022] By soaking seafood in the pickling solution of the present invention, discoloration of the seafood can be suppressed. That is, the pickling solution of the present invention can be suitably used to suppress discoloration of marine products. The present invention also provides a method for suppressing discoloration of marine products. Furthermore, processed marine products produced by pickling marine products in the pickling solution of the present invention are ones in which discoloration is suppressed.

[0023] Marine products can be pickled at a temperature that does not affect the quality of the marine products, usually 0 to 20° C. If the marine products after pickling are to be eaten raw, such as sashimi, it is preferable to pickle them at a temperature of 0 to 10° C. from the viewpoint of the allowable bacterial count. The soaking time for the seafood may be from 1 second to 48 hours, more preferably from 1 second to 24 hours, and even more preferably from 1 second to 18 hours, depending on the size, shape, and allowable bacterial count of the seafood, or the storage period after thawing. If the seafood after soaking is intended to be eaten raw, such as sashimi, it may be soaked for from 1 second to 10 minutes, preferably from 1 second to 5 minutes, and even more preferably from 1 second to 1 minute. If the seafood after soaking is intended to be cooked, it may be soaked for from 1 second to 48 hours, preferably from 10 minutes to 24 hours, and even more preferably from 1 hour to 18 hours. If the seafood is intended to be cooked, it will be displayed in supermarkets and the like for several days after thawing, and therefore discoloration must be suppressed for a long period of time. Therefore, it is preferable to soak the seafood for a longer time than if it is intended to be eaten raw. The pickling method may be either a method of immersing the seafood in the pickling liquid or a method of spraying the pickling liquid onto the surface of the seafood. The pickling liquid may be in the form of a seasoning liquid for pickling fish (miso-pickled, sake lees-pickled, Saikyo-pickled, etc.). There is no particular upper limit to the soaking time, but it is not necessary to soak it for an unnecessarily long time so as not to affect the quality of the seafood, and an appropriate time should be set taking into account other work involved.

[0024] The amount of the pickling liquid to be used to soak the marine product is preferably adjusted to 10 to 200% by weight relative to the weight of the marine product.

[0025] The marine products in the present invention are usually those whose flesh or body surface is red due to the presence of chromoproteins or carotenoid pigments. Fish that are red in color due to chromoproteins are generally called red fish, and contain 10 mg or more of chromoproteins per 100 g. Examples of red meat fish include the genus Scomber (chub mackerel, yellow mackerel, etc.) belonging to the family Scombridae in the order Perciformes, the genus Tuna (southern bluefin tuna, Atlantic bluefin tuna, dogtooth tuna, bigeye tuna, etc.), the genus Bonito (skipjack tuna), the genus Pongo (golden tuna), the genus Piscalifrons (Japanese Spanish mackerel, barracuda), the genus Dorado (striped dolphinfish, striped dolphinfish, etc.) belonging to the family Scombridae in the order Perciformes, and the jack mackerel belonging to the family Carangidae in the order Perciformes. These include the genus Juglans (horse mackerel, yellowtail, round jack, etc.), the genus Seriola (yellowtail, yellowtail, amberjack, amberjack), the genus Saury (Pacific pacific saury) belonging to the family Sauridae, the genus Sardina, the genus Piscivorus, the genus Engraulis, the genus Tenualosa (fish), the genus Clupeidae (Atlantic herring, etc.), and the genus Omola (sunfish, etc.) belonging to the family Omola, order Pectinifera. The discoloration of red fish is related to the oxidation-reduction of the pigment protein myoglobin. Deoxymyoglobin is dark red, oxymyoglobin is bright red, and metmyoglobin is brown. In vivo, metmyoglobin is reduced to deoxymyoglobin, but after death, the reduction stops in the flesh of the fish, causing metmyoglobin to accumulate. Over time after death, the flesh turns brown and loses its commercial value.

[0026] Fish that are red in color due to carotenoid pigments include fish belonging to the Salmonidae family (salmon, trout), the Sparidae family (Porgonioidea), and the Alfinidae family (Alfonsino), etc. Crustacean shrimp also exhibit a red color due to carotenoid pigments, and specifically include pistol shrimp, kuruma prawn, black tiger shrimp, vannamei, shiba shrimp, monkey shrimp, fan shrimp, Japanese tiger shrimp, octopus shrimp, otohime shrimp, spiny lobster, slipper lobster, lobster, cherry shrimp, glass shrimp, northern red shrimp (Amur shrimp), nephrops prawn, isostoma shrimp, Pandalus nigricans, koshima garishi shrimp, rachis shrimp, crayfish, striped shrimp, Examples include freshwater shrimp, crayfish, and American crayfish. Approximately 200 types of carotenoid pigments exist in nature, and approximately 30 types are known to exist in seafood. The most common of these is the red pigment astaxanthin, accounting for nearly 50%. Carotenoid pigments have many double bonds and a structure with conjugated carbon chains, making them prone to oxidation and unstable. They gradually oxidize and fade even when stored at low temperatures. Fading is also accelerated by sunlight and light.

[0027] The pickling solution of the present invention is thought to suppress discoloration of the red color over time and / or temperature due to the components derived from the plum vinegar contained therein. Specifically, it is thought that this is due to the reducing effect caused by the reaction of organic acids such as citric acid and malic acid with sodium chloride and / or alkali metal salts to produce organic acid salts in the pickling solution. It is also thought that the antioxidant effect of organic acids such as citric acid and malic acid and / or polyphenols may suppress oxidation of pigment proteins, carotenoid pigments, or phospholipids, thereby suppressing discoloration.

[0028] As used herein, "discoloration" refers to the browning or fading of the original red color of a marine product. Furthermore, "inhibition of discoloration" includes reducing the degree of browning or fading compared to untreated fish, slowing its progression, and / or maintaining the original red color. For blue fish, such as horse mackerel, this may also include inhibiting the fish from turning bluish-black or whitish.

[0029] By treating with the pickling solution of the present invention, discoloration can be inhibited even after freezing and thawing at -30°C to -5°C for 1 day to 12 months. Furthermore, when the pickled marine product is intended for raw consumption, the discoloration suppression effect can be obtained even after storage at 2°C to 15°C for 1 hour to 12 hours after thawing. Furthermore, when the pickled marine product is to be cooked, the discoloration suppression effect can be obtained even after storage at 2°C to 15°C for 1 to 5 days after thawing. After pickling, the seafood can be frozen at -30 to -5°C, preferably -30 to -10°C, and more preferably -30 to -20°C. Freezing can be slow or rapid, with rapid freezing being preferred. The seafood may be frozen after the pickling liquid is removed, or may be frozen with the pickling liquid still attached to the seafood. After freezing, the seafood can be stored for 1 day to 12 months at -30 to -5° C., preferably -30 to -10° C., and more preferably -30 to -20° C. Frozen storage can include storage in a freezer, transportation at frozen temperatures, and product display at frozen temperatures. The frozen seafood can be thawed at 0 to 40°C by thawing with air, thawing under running water, thawing in standing water, or natural thawing. By such treatment, marine products that have been pickled and then frozen, marine products that have been pickled and then frozen and stored, and marine products that have been pickled and then frozen or frozen and then thawed can be obtained. [Example]

[0030] The present invention will be described below based on examples, but the present invention is not limited to these examples. Unless otherwise specified, units are by weight.

[0031] <Test Example 1> Confirmation of effectiveness on horse mackerel (1) Sample preparation method The plum vinegar used in this example contains 3.5% by weight of salt, 18.1% by weight of citric acid, 3.1% by weight of malic acid, 0.4% by weight of polyphenols in total, and 0.441% by weight of free amino acids in total. The breakdown of the free amino acids is shown in Table 1. A pickling solution was prepared according to the formulation shown in Table 2. Fresh horse mackerel was used as the raw seafood material. The horse mackerel was filleted into three pieces and processed into fillets. Ten fillets were prepared for each example, and 100% by weight of the horse mackerel was soaked in water. The fish were soaked in the soy sauce for 1 minute at 10°C and then frozen at -20°C. After storing at -20°C for 7 days, they were thawed in running water (20°C) for 10 minutes. Immediately after thawing, they were arranged in a tray without overlapping, covered with plastic wrap, and stored in a refrigerator set to 10°C for 7 hours.

[0032] [Table 1]

[0033] [Table 2]

[0034] (2) Evaluation method (i) Atago The salt content (Atago (%)) of the pickling solution was measured using an electric salinity meter (ES-421, ATAGAO) by dropping the sample solution directly onto the sensor part of the instrument.

[0035] (ii) Brix The Brix (%) of the pickling solution was measured using a refractive index measuring Brix meter (APAL-1, AS ONE). Measurements were performed by dropping the sample solution directly onto the instrument's sensor. The Brix value indicates the soluble solids content (the total value of all substances that dissolve in water, such as sugars, proteins, and acids), and is an indicator of the concentration of the pickling solution.

[0036] (iii) Trisodium citrate concentration In the pickling solution containing plum vinegar, the trisodium citrate concentration was calculated assuming that all of the citric acid derived from the plum vinegar was converted to trisodium citrate in the pickling solution.

[0037] (iv) Ionic strength The "aqueous solution ionic strength" and "total ionic strength" were calculated according to the definitions given above.

[0038] (v) Yield The yield was calculated as the rate of increase in the weight of the seafood before pickling and after pickling and before freezing.

[0039] (vi) Centrifugal drip rate The centrifugal drip rate was measured as follows: After soaking and freezing, the marine products were cut into pieces of approximately 5 mm cubes, and approximately 3 g of each sample was centrifuged in a centrifuge tube at 10°C, 300 G, for 10 minutes. The drip weight was calculated using the following formula 1 from the moisture content of the sample determined by the heat drying method (105°C, 3 hours). Calculation formula 1: Centrifugal drip rate (%) = drip weight (g) ÷ sample moisture content (g)

[0040] (vii) Confirmation of discoloration suppression effect The discoloration suppression effect was evaluated by measuring the color difference of the red color of seafood samples after soaking, freezing at -20°C for 7 days, thawing, and storing in a refrigerator at 10°C for 7 hours. The color difference was measured using a colorimeter (CR-400, Konica Minolta). In the case of horse mackerel, the blue color is strong, so the red color is evaluated. * Evaluate blue b * Divided by a * / b * The value was used as the evaluation index. To eliminate this effect, 10 fillets were prepared for each example, and one spot was measured on the surface of the center of the dark muscle for each fillet, for a total of 10 spots, and the average value was calculated.

[0041] (3) Results The evaluation results are shown in Table 3, Figures 1 and 2. A lower centrifugal drip rate indicates a higher water retention capacity of the seafood product. Example 1 had a lower centrifugal drip rate and improved water retention capacity compared to the untreated Comparative Example 1. Example 2, in which the pH was adjusted to alkaline by adding an alkali metal salt, had a particularly low centrifugal drip rate and significantly improved water retention capacity. Evaluating the redness of horse mackerel * / b * The values ​​of Examples 1 and 2 were higher than those of Comparative Examples 1 and 2. From this, it was confirmed that Examples 1 and 2 suppressed discoloration of horse mackerel.

[0042] [Table 3]

[0043] <Test Example 2> Confirmation of effect on bonito (1) Sample preparation method A pickling solution was prepared according to the formulation shown in Table 4. Fresh bonito was used as the raw seafood ingredient. Fresh bonito was filleted into three pieces, and the meat from the back of the bonito, called 'Obushi', was used. This meat was sliced ​​and processed into fillets, each weighing approximately 10 g. Ten fillets were prepared for each example, and after marinating at 10°C for 1 minute, they were frozen at -20°C. After storing at -20°C for 7 days, they were thawed in running water (20°C) for 10 minutes. Immediately after thawing, they were arranged in a tray without overlapping, covered with plastic wrap, and stored in a refrigerator set to 10°C for 7 hours.

[0044] [Table 4]

[0045] (2) Evaluation method Atago, Brix, trisodium citrate concentration, ionic strength, yield, centrifugal drip rate, and discoloration suppression effect were evaluated using the same methods as in Example 1.

[0046] (3) Results The evaluation results are shown in Table 5, Figures 3 and 4. A lower centrifugal drip rate indicates a higher water retention capacity of the seafood product. Example 3 had a lower centrifugal drip rate and improved water retention capacity compared to the untreated Comparative Example 3. Example 4, in which the pH was adjusted to alkaline by adding an alkali metal salt, had a particularly low centrifugal drip rate and significantly improved water retention capacity. Evaluating the redness of bonito * / b * The values ​​of Examples 3 and 4 were higher than those of Comparative Examples 3 and 4. From this, it was confirmed that Examples 3 and 4 inhibited discoloration of bonito.

[0047] [Table 5]

[0048] <Test Example 3> Confirmation of effectiveness in salmon (1) Sample preparation method A pickling solution was prepared according to the formulation shown in Table 6. Aki salmon was used as the seafood raw material. After thawing the dressed frozen Aki salmon, it was processed into loins and cut into fillets of 25±2 g each from the dorsal and ventral sides. The fillets were marinated in a marinade that was 100% by weight of the salmon weight at 5°C for 18 hours, then drained, frozen, and stored at -30°C for 3 days, shielded from light by aluminum foil. On the first day of refrigerated storage (day 0), the fillets were thawed by blowing air into a tray at room temperature, arranged so that they did not overlap, covered with plastic wrap, and stored in a refrigerator set at 10°C for 4 days, irradiated with light at 1400 Lux.

[0049] [Table 6]

[0050] (2) Evaluation method (i) Atago, Brix, trisodium citrate concentration, ionic strength, and yield Each evaluation was carried out in the same manner as in Example 1.

[0051] (ii) Confirmation of discoloration suppression effect After storing the sample at 10°C for 4 days, the sample was subjected to color difference measurement and sensory evaluation. After storing the sample for 4 days, the sample was baked in an oven at 250°C for 5 minutes, and then subjected to color difference measurement and sensory evaluation. The discoloration suppression effect was evaluated by measuring the color difference of the red color of the sample. The color difference measurement was performed using a color difference meter (CR-410, Konica Minolta) to evaluate the red color. * The value was used as an evaluation index for each of the back and belly meat, and measurements were taken at 5 spots per fillet in two sets, for a total of 10 spots, and the average value was calculated. * The value was set to 0, and the change in color over time (ΔE * ab) were compared. The sensory evaluation was carried out by four trained panelists with more than five years of experience in seafood research. The redness of the salmon meat before grilling was evaluated by comparing it with the standard. The redness of the salmon meat immediately after thawing and cutting into fillets was scored as 5 points, and after cutting, the salmon meat was stored in a refrigerator set at 10°C under 1400 lux light without marinating for one day with a score of 4 points, three days with a score of 3 points, four days with a score of 2 points, six days with a score of 1 point, and seven days with a score of 0 points. Regarding the redness of salmon meat after grilling, salmon meat that was thawed, cut into fillets, and grilled immediately was given a score of 5, salmon that was stored for one day in a refrigerator set at 10°C and exposed to light of 1400 Lux without being marinated and then grilled was given a score of 4, salmon that was stored for three days and then grilled was given a score of 3, salmon that was stored for four days and then grilled was given a score of 2, salmon that was stored for six days and then grilled was given a score of 1, and salmon that was stored for seven days and then grilled was given a score of 0, and the redness of the meat of each sample was then evaluated by comparing it with the standard.

[0052] (3) Results The results of evaluation of the pickling solution's Atago, Brix, trisodium citrate concentration, ionic strength, and yield, and * The color difference measurement results using the value as the evaluation index are shown in Table 7, Figures 5 and 6. , a at the start of refrigerated storage (day 0) *The value was set to 0, and the change in color over time (ΔE * ab) are shown in Table 8 and Figure 7. The yield was 134% by weight in Example 5 and 126% by weight in Example 6, both of which showed high values. Evaluating the redness of salmon * The values ​​for Examples 5 and 6 were higher than those for Comparative Examples 5 and 6, both before and after baking. In particular, the effect of inhibiting discoloration before baking was high. From this, it was confirmed that Examples 5 and 6 inhibited discoloration of the salmon. In the sensory evaluation, all four panelists gave the same score, and evaluated that Examples 5 and 6 inhibited discoloration of salmon.

[0053] [Table 7]

[0054] [Table 8]

Claims

1. A pickling solution for suppressing discoloration due to freezing and / or thawing of seafood, containing plum vinegar, The concentration of citric acid in the pickling solution is 0.4 to 3.0% by weight, The concentration of malic acid in the pickling solution is 0.05 to 0.5% by weight, The total concentration of free asparagine and free aspartic acid in the pickling solution is 0.005 to 0.1% by weight, The pH of the pickling solution is 7.0 to 10.0, The pickling solution is a fish in which the fish meat or body surface is red due to the inclusion of a pigment protein or a carotenoid pigment.

2. The pickling solution according to claim 1, wherein the sodium chloride concentration in the pickling solution is 0.4 to 5.0% by weight.

3. The pickling solution according to claim 1 or 2, having an ionic strength of 0.5 to 3.0 mol / kg.

4. A step of soaking a marine product in the pickling liquid according to any one of claims 1 to 3; and and freezing the pickled seafood product. The method for inhibiting discoloration of a marine product due to freezing and / or thawing, wherein the marine product is a fish whose flesh or body surface is red due to the inclusion of a pigment protein or a carotenoid pigment.

5. The method according to claim 4, wherein the soaking time is from 1 second to 48 hours.

6. The method according to claim 4 or 5, wherein the soaking is carried out at 0 to 20°C.

7. A step of soaking a marine product in the pickling liquid according to any one of claims 1 to 3; and and freezing the pickled seafood product. The method for producing processed seafood products, wherein the seafood is a fish whose flesh or body surface is red due to the inclusion of a pigment protein or a carotenoid pigment.

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