Manufacturing method for packaged fish products

Abstract

To provide packaged seafood products that achieve both high yield and suppression of drip during heat sterilization after vacuum packaging. [Solution] A soaking step in which fish and shellfish are soaked in a soaking solution containing an alkaline agent, The first heating step involves heating the seafood after the immersion process to a product temperature of 65°C or lower, A packaging step in which the seafood after the heating step is vacuum-packed, A method for producing packaged seafood food, comprising a second heating step of heating the package obtained in the packaging step. Preferably, the method further comprises a freezing step of freezing the package after the second heating step. Preferably, a water-retaining powder is dispersed in the immersion liquid. Preferably, the water-retaining powder is starch powder.

Description

Technical Field

[0001] The present invention relates to a method for producing packaged seafood food products.

Background Art

[0002] In recent years, demand for vacuum-packaged seafood food products has been growing as they are easy to preserve for a long time and have excellent distribution properties. For example, it has been proposed to produce vacuum-packaged frozen foods for grilled fish and the like (for example, Patent Document 1). On the other hand, Patent Document 2 describes a method for producing a meat patty, in which meat is heated at a product temperature of less than 70°C, then vacuum-packaged, and the resulting package is heated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0004] In recent years, due to the decline in the catch of seafood, it is required to improve the yield in order to increase the unit price per individual. Seafood has soft flesh and is prone to generating drip during heating. The inventors have confirmed that, when simply heated, vacuum-packaged and frozen as in Patent Document 1, the weight loss is large during baking before packaging. On the other hand, if unheated seafood is directly vacuum-packaged and then subjected to heat sterilization, a large amount of drip is generated during heat sterilization after packaging, which reduces the yield and also deteriorates the appearance of the packaged product due to the drip. In particular, when an immersion treatment is performed before packaging to increase the yield, the amount of drip generated becomes large. As described above, sufficient measures were not taken to achieve both drip suppression and good yield in packaged pre-cooked seafood products. On the other hand, Patent Document 2 does not address how to achieve both drip prevention and yield in seafood that has undergone prior immersion treatment.

[0005] The objective of this invention is to provide a technology that can prevent dripping during sterilization and achieve a high yield for vacuum-packed seafood. [Means for solving the problem]

[0006] The present invention was discovered to solve the above problems, and comprises an immersion step of immersing fish and shellfish in an immersion solution containing an alkaline agent, The first heating step involves heating the seafood after the immersion process to a product temperature of 65°C or lower, A packaging step in which the seafood after the heating step is vacuum-packed, The present invention provides a method for manufacturing packaged seafood products, comprising a second heating step of heating the package obtained in the packaging step. [Effects of the Invention]

[0007] The present invention makes it possible to provide packaged seafood products with good yield by suppressing drip in vacuum-packed seafood. [Modes for carrying out the invention]

[0008] The present invention will be described below based on its preferred embodiments. The present invention relates to a soaking step in which fish and shellfish are soaked in a soaking solution containing an alkaline agent, The first heating step involves heating the seafood after the immersion process to a product temperature of 65°C or lower, A packaging step in which the seafood after the heating step is vacuum-packed, This is a method for producing packaged seafood food, comprising a second heating step of heating the package obtained in the packaging step. As is clear from the comparison of Example 1 and Comparative Examples 1-3 described later, in the present invention, by setting the temperature of the first heating step to 65°C or lower and combining it with a prior immersion treatment, it is possible to improve yield while suppressing drip during the second heating step (sterilization) after packaging. The reason for this is not clear, but as can be seen from the comparison between Comparative Example 3 (corresponding to Patent Document 2) and Example 1 described later, if the heating temperature of the first heating step after the immersion treatment is 65°C or lower, the weight loss due to heating in the first heating step after water absorption by the immersion treatment can be reduced. Also, since the water retention performance of the water absorbed during immersion is high in the seafood after vacuum packaging, it is thought that drip is less likely to occur even when heated in the second heating step while vacuum packaged. Furthermore, even with low-temperature heating, by going through the first heating step, the second heating step can be completed in a short time, so drip is less likely to occur, and as a result it is thought that it is easier to maintain both yield and drip suppression. In contrast, as shown in the comparison between Comparative Example 2 (corresponding to Patent Document 1) and each example, when low-temperature firing is performed without immersion treatment, the yield improvement effect is significantly inferior compared to when immersion treatment is performed.

[0009] (Soaking process) Seafood includes fish, shellfish, crustaceans, and cephalopods. Fish, in particular, include greenling, red grouper, red snapper, horse mackerel, conger eel, sweetfish, anglerfish, grunt, threadfin bream, sardine, char, eel, ray, lizardfish, scorpionfish, trevally, rockfish, sculpin, marlin, skipjack tuna, cuttlefish, barracuda, flounder, filefish, amberjack, sillago, rockfish, sprawn, croaker, flathead, bighead carp, salmon (including Atlantic salmon, trout salmon, and coho salmon), mackerel, shark, saury, and Japanese dace. Examples of fish include: ra, saury, grass carp, silver carp, pangasius, flounder, loach, sea bass, cod, sea bream, hairtail, flying fish, loach, Nile tilapia, catfish, herring, rainbow trout, goby, grouper, conger eel, flounder, yellowtail, pufferfish, crucian carp, amberjack (including growth names and seasonal names such as yellowtail, young yellowtail, and adult yellowtail), Atka mackerel, hoki, sea bass, tuna, common carp, milkfish, rockfish, mamakari, Japanese carp, and rofu. Examples of shellfish include: oysters, clams, Manila clams, scallops, and ark clams. Examples of crustaceans include: shrimp, crabs, and mantis shrimp. Examples of cephalopods include: squid and octopus.

[0010] In particular, fish are preferred in this invention because they are more likely to produce drip during secondary heating, thus enhancing the effectiveness of the invention. Among these, mackerel, horse mackerel, sardines, bonito, flounder, salmon, trout, sole, sea bream, hairtail, herring, sole, yellowtail, tuna, amberjack, cod, Atka mackerel, and red snapper are more preferred, mackerel, horse mackerel, bonito, salmon, trout, sea bream, amberjack, yellowtail, tuna, cod, Atka mackerel, and red snapper are especially preferred, mackerel, horse mackerel, and red snapper are even more preferred, and mackerel or horse mackerel are particularly preferred. The immersion process is typically applied to uncooked seafood.

[0011] In the present invention, it is preferable that the seafood is in a shape that is easy to eat before vacuum packaging. Examples of such shapes include slices, dice, bite-sized pieces, and other cuts. The size of each piece is not particularly limited, but for example, 10 to 100 g is preferable in terms of ease of consumption and the effects of the present invention, and 20 to 40 g is particularly preferable.

[0012] The immersion solution contains an alkaline agent to improve water retention and yield. From these viewpoints, the pH of the immersion solution at 10°C is preferably 6.0 or higher, more preferably 6.1 or higher, and particularly preferably 6.2 or higher. Furthermore, the pH of the immersion solution at 10°C is preferably 9.0 or lower in terms of preventing off-flavors and improving yield, more preferably 8.5 or lower, and particularly preferably 8.2 or lower.

[0013] Examples of alkaline agents include sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, disodium phosphate, trisodium phosphate, sodium pyrophosphate, sodium polyphosphate, ammonium carbonate, calcium carbonate, magnesium carbonate, magnesium hydroxide, and calcined seashell calcium. At least one selected from sodium bicarbonate is preferred because it easily imparts an appropriate pH.

[0014] The amount of alkaline agent in the immersion solution is preferably, for example, 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, from the viewpoint of flavor, the amount of alkaline agent in the immersion solution is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and even more preferably 3.0% by mass or less.

[0015] Furthermore, it is preferable for the immersion liquid to contain salt for better taste. From this viewpoint, the amount of salt in the immersion liquid is preferably 0.5% by mass or more, and more preferably 3.0% by mass or more. Also, from the viewpoint of improving yield, the amount of salt in the immersion liquid is preferably 3.5% by mass or less, and more preferably 3.0% by mass or less. Here, the salt content in the immersion liquid includes the salt content in seasoning liquids other than salt, such as soy sauce.

[0016] The impregnation liquid preferably has a water-retentive powder dispersed therein. It is considered that the water-retentive powder dispersed in the impregnation liquid is taken into fishery products during impregnation, and is likely to be retained inside by heating the proteins of the fishery products to a temperature not higher than a certain level in the first heating step. Then, the water-retentive powder exerts a water retention function during heating in the second heating step, whereby an excellent drip suppression function is exhibited, and the texture such as softness is thereby effectively improved.

[0017] Examples of the water-retentive powder include curdlan, alginic acid, and starch.

[0018] Examples of the starch include corn starch, waxy corn starch, tapioca starch, potato starch, wheat starch, rice starch, and processed starches thereof. Examples of the processed starch include those subjected to treatments such as etherification (hydroxypropylation and the like), esterification (acetylation and the like), crosslinking (phosphate crosslinking, adipate crosslinking and the like), oxidation, and oil-and-fat processing.

[0019] Among them, it is preferable to use starch as the water-retentive powder from the viewpoints of good taste, favorable water retention function and excellent drip suppression function, processed starch is more preferable, starch subjected to one or more processing treatments selected from acetylation, hydroxypropylation and crosslinking is still more preferable, and starch subjected to acetylation is even more preferable from the viewpoint of excellent water retention performance and drip prevention performance. When the water-retentive powder is acetylated starch, it may be starch that has been subjected to other treatments such as crosslinking and oil-and-fat processing in addition to acetylation. Particularly preferred starches include, for example, acetylated starch, acetylated phosphate crosslinked starch, and acetylated adipate crosslinked starch, particularly preferred are acetylated starch and acetylated adipate crosslinked starch, and most preferred is acetylated starch. Further, as the starch, tapioca-derived starch is preferable from the viewpoints of good flavor and less likelihood of impairing the texture of fishery products.

[0020] The content of the water-retentive powder in the immersion liquid is preferably 0.5 mass% or more, as the drip prevention effect and yield improvement effect are favorable, more preferably 1 mass% or more, and even more preferably 1.5 mass% or more. In addition, the content of the water-retentive powder is preferably 5.0 mass% or less from the viewpoints of taste, texture, and prevention of sticky appearance, more preferably 4.0 mass% or less, particularly preferably 3.0 mass% or less, and even more preferably 2.0 mass% or less.

[0021] In order to improve the dispersibility of the water-retentive powder and increase the yield upon thawing, the immersion liquid preferably has a viscosity equal to or higher than a certain level. The immersion liquid preferably has a viscosity at 20°C of 3 mPa·s or more, more preferably 8 mPa·s or more, still more preferably 15 mPa·s or more, particularly preferably 20 mPa·s or more, and especially preferably 35 mPa·s or more. In addition, the viscosity of the immersion liquid is preferably equal to or lower than a certain level from the viewpoint that the water-retentive powder is easily incorporated into fish and shellfish. From this perspective, the viscosity of the immersion liquid is preferably 300 mPa·s or less, more preferably 250 mPa·s or less, still more preferably 200 mPa·s or less, even more preferably 150 mPa·s or less, particularly preferably 120 mPa·s or less, especially preferably 100 mPa·s or less, and even more preferably 85 mPa·s or less. The viscosity of the immersion liquid can be measured by the method described in the following Examples. For the viscosity measurement, 100 g of the immersion liquid sample was adjusted to 20°C, and the viscosity of the aqueous solution was measured using a B-type viscometer. The viscosity measurement with the B-type viscometer was performed using a TVB10 / 15 type viscometer (Toki Sangyo Co., Ltd.), with an M20 rotor, under the condition of 60 rpm.

[0022] To adjust the viscosity of the immersion solution to the aforementioned range, thickening polysaccharides can be used as appropriate. Preferably, the thickening polysaccharides are sodium alginate; gums such as xanthan gum, guar gum, locust bean gum, gum arabic, and tamarind seed gum; and at least one selected from pectin, pullulan, alginate ester, glucomannan, carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, etc. At least one selected from gums is even more preferable because it easily imparts viscosity to the immersion solution without affecting the flavor and can impart viscosity without heating, and xanthan gum is particularly preferred.

[0023] The content of thickening polysaccharides in the immersion solution is preferably 0.01% by mass or more, which provides a good drip prevention effect; more preferably 0.02% by mass or more; even more preferably 0.03% by mass or more; and particularly preferably 0.07% by mass or more. Furthermore, the content of water-retaining powder is preferably 2% by mass or less, which is preferable from the viewpoint of taste and texture; more preferably 1.2% by mass or less; even more preferably 0.8% by mass or less; and particularly preferably 0.4% by mass or less.

[0024] When using oils and fats in the immersion solution, it is preferable that the solution contains an emulsifier to ensure even distribution of the oils and fats to the fish and shellfish. The immersion solution preferably contains an emulsifier. Examples of emulsifiers include glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, and lecithin. Here, glycerin fatty acid esters include glycerin and fatty acid esters, as well as glycerin acetate, glycerin acetate fatty acid esters, glycerin lactate fatty acid esters, glycerin tricethic acid fatty acid esters, glycerin succinate fatty acid esters, glycerin diacetyl tartaric acid fatty acid esters, polyglycerin fatty acid esters, and polyglycerin condensed ricinoleic acid esters. Lecithin includes fractionated lecithin, enzymatically hydrolyzed lecithin, and enzymatically treated lecithin. From a taste perspective, glycerin fatty acid esters are preferred.

[0025] If the immersion liquid used in the present invention contains an emulsifier, the amount of emulsifier is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and particularly preferably 0.04% by mass or more, in order to enhance the above-mentioned effects of using an emulsifier. Furthermore, in terms of flavor, it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and particularly preferably 0.2% by mass or less.

[0026] The immersion liquid preferably contains liquid oils and fats, as this further improves yield and prevents dripping during secondary heating. Liquid oils and fats are oils and fats that are liquid at 25°C. Specific examples of liquid oils and fats used in this invention include corn oil, cottonseed oil, soybean oil, rapeseed oil, rice oil, sunflower oil, safflower oil, linseed oil, fractionated low-melting-point portion of palm oil, olive oil, and sesame oil. As liquid oils and fats, soybean oil, rapeseed oil, cottonseed oil, or corn oil are preferred in terms of flavor and taste. The rising melting point of the liquid oils and fats is preferably 20°C or lower, and more preferably 10°C or lower. The rising melting point can be determined by, for example, the measurement method for rising melting point, as described in Section 2.2.4.2-1996 of the Standard Methods for Analysis of Fats and Oils (I), 1996 edition, established by the Japan Oil Chemists' Society.

[0027] The amount of liquid oil in the immersion solution is preferably 2% by mass or more, and more preferably 4% by mass or more, in order to improve texture. On the other hand, from an economic standpoint, since further increasing the amount of liquid oil does not improve texture, the amount of liquid oil in the immersion solution is preferably 15% by mass or less, and more preferably 12% by mass or less.

[0028] The immersion solution is preferably made to contain sugars in order to further enhance its water retention capacity. Examples of sugars include sugars and sugar alcohols. Examples of sugars include monosaccharides such as glucose, xylose, ribose, and arabinose; disaccharides such as maltose, sucrose, trehalose, and palatinose; oligosaccharides; mixtures of sugars such as dextrin and isomerized sugar; and liquid sugars such as honey, corn syrup, and maple syrup. Examples of sugar alcohols include reduced maltose, reduced corn syrup, xylitol, erythritol, sorbitol, mannitol, lactitol, and xylobiitol. Sugar alcohols are particularly preferred in terms of water retention and texture, and reduced corn syrup is especially preferred.

[0029] If the immersion solution contains sugars, it is preferable that the amount is 5.0% by mass or more in the immersion solution from the viewpoint of improving the immersion effect, and 20.0% by mass or less from the viewpoint of taste. From this viewpoint, it is more preferable that the amount of sugars in the immersion solution is 8.0% by mass or more and 16.0% by mass or less.

[0030] Water is preferred as the liquid medium for the immersion solution. If the immersion solution contains water, the water content is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. Furthermore, in order to ensure the amounts of other components, the water content is preferably 95% by mass or less, more preferably 90% by mass or less, and particularly preferably 85% by mass or less.

[0031] Methods for preparing the immersion solution include preparing an aqueous phase and mixing and stirring it with an emulsifier and an oil phase as needed. In this case, it is preferable to include the water-retaining powder in the aqueous phase before adding it to the oil phase. Furthermore, it is preferable to include thickening polysaccharides, alkaline agents, salt, emulsifiers, and sugars, which are used as needed, in the aqueous phase before adding them to the oil phase. Methods for stirring the aqueous phase, emulsifier, and oil phase include mixing and emulsifying the aqueous phase and oil phase, and examples include stick mixers, stand mixers, colloid mills, homomixers, ultrasonic emulsifiers, high-pressure homogenizers, etc.

[0032] The immersion process may involve rotation such as stirring or tumbling, or it may be carried out in a static state. However, carrying it out in a static state is preferable in terms of reducing manufacturing costs and improving the appearance of the product. Here, carrying it out in a static state includes cases where the seafood is added and stirred, and then left to stand.

[0033] The temperature of the immersion solution is preferably between 1°C and 10°C, and more preferably between 5°C and 10°C. In each example and comparative example, the materials were immersed in an immersion solution with a temperature of 5°C to 10°C. The immersion time is preferably between 15 minutes and 12 hours, and more preferably between 15 minutes and 6 hours.

[0034] (1st heating step) The seafood after the immersion process is heated to a temperature of 65°C or lower. This process makes it easier to trap the components of the immersion liquid along with the water-retaining powder within the seafood, preventing dripping during the second heating process and improving yield. In particular, when using an immersion liquid in which water-retaining powder is dispersed, heating to a temperature of 65°C makes it easier to trap the water-retaining powder within the seafood, further effectively suppressing dripping and improving texture. The heating process in the first heating process in which the water-retaining powder is dispersed can include baking (including both direct heating on a heating container such as a frying pan and indirect heating in an oven, etc.) and steam heating. However, a baking process is preferred because it makes it easier to trap the components of the immersion liquid containing the water-retaining powder within the seafood, thus improving yield and preventing dripping. Indirect heating in an oven, etc., is particularly preferred in terms of improving appearance, and is especially preferred when successfully producing baked seafood, particularly grilled fish. Baking should be carried out at a product temperature of 65°C or lower, which improves the yield after thawing. The product temperature during baking is preferably 65°C or lower, and more preferably 55°C or lower. Furthermore, a baked product temperature of 40°C or higher is preferable in terms of improving yield and texture, and 45°C or higher is more preferable.

[0035] The heating time for the first heating step is preferably 100 seconds or more, more preferably 180 seconds or more, even more preferably 190 seconds or more, and particularly preferably 200 seconds or more. It is also preferably 400 seconds or less, more preferably 300 seconds or less, even more preferably 260 seconds or less, and particularly preferably 240 seconds or less. Within the above range, the fillet size is particularly preferably 15 to 60 g, and particularly preferably 20 to 60 g.

[0036] In this specification, the product temperature is preferably the core temperature of the seafood. The core temperature is measured at the center position in the thickness, width, and length directions. The product temperature was measured using a waterproof digital food thermometer SK-250WPII-N manufactured by Sato Keiryoki Seisakusho Co., Ltd.

[0037] Furthermore, the process may include a step of spraying a sugar solution onto the surface of the seafood before the first heating step and after the immersion step. This makes it easier to create a charred surface and an appetizing appearance if the first heating step is a baking step. The sugars referred to here include those described in the immersion solution section. The sugar solution includes aqueous solutions of sugars. Additionally, a step of searing the surface may be added after the first heating step and before the packaging step, provided that the temperature of the product is kept below 65°C.

[0038] (packaging process) In this invention, seafood is vacuum-packed after the first step. The packaging material used in this embodiment is not particularly limited as long as it can package the flesh of seafood and has gas barrier properties that can be used for vacuum packaging. Plastic film is usually used, and examples of materials include synthetic resin films, such as VDC / MA (vinylidene chloride / methyl acrylate copolymer), HIPS (high-impact polystyrene), PVDC (polyvinylidene chloride), PVC (polyvinyl chloride), PA (polyamide), PE (polyethylene), PP (polypropylene), EVOH (ethylene vinyl alcohol copolymer), PET (polyethylene terephthalate resin), and composites of one or more of these. Polyvinylidene chloride, polyamide, polypropylene, or composites thereof are preferred in terms of tear resistance, heat resistance, and shelf life.

[0039] In this embodiment, the seafood is placed in packaging material and vacuum-packed. After the seafood is placed inside, the inside of the packaging material is suctioned and evacuated using a vacuum pump, and the packaging material is sealed by heat sealing or the like.

[0040] In the vacuum packaging described above, a vacuum level of 95-99% is preferable in terms of shelf life and oxidation prevention, given that absolute vacuum is 100% and atmospheric pressure is 0%.

[0041] Here, the product temperature at the start of vacuum packaging is preferably, for example, 20-50°C, as this further suppresses drip and improves yield, and more preferably 20-45°C.

[0042] (Second heating step) Next, the second heating process is carried out. The second heating step is preferably performed at a temperature of 90°C to 98°C in terms of improving yield and suppressing drip, and more preferably at a temperature of 92°C to 96°C. The duration of the second heating step is preferably 10 minutes to 20 minutes, and more preferably 12 minutes to 17 minutes. The temperature referred to here is the temperature of the steam that comes into contact with the packaging in the case of steam heating, and the water temperature in the case of boiling. The second heating step is typically a step in which the product temperature reaches 75°C or higher.

[0043] Freezing the packaged material after the second heating step is preferable in terms of preservation and in terms of demonstrating the yield and drip prevention effects of the present invention. The freezing temperature is preferably -15°C to -40°C in terms of inhibiting microbial growth. Furthermore, rapid freezing is preferable. As an example of rapid freezing, a freezing rate that reaches the target freezing temperature from room temperature in 60 minutes to 10 minutes is preferable in terms of inhibiting microbial growth, and more preferably in 40 minutes to 10 minutes. Therefore, a freezing rate of -0.25°C / min or higher is preferable, and -0.375°C / min to -4°C / min is more preferable.

[0044] In this invention, when the first heating step is a baking step, it is particularly preferable to produce, for example, grilled fish food, as this offers superior technical significance in terms of yield and drip prevention. [Examples]

[0045] 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 these examples. In Table 1, "%" means "mass%" unless otherwise specified.

[0046] <Examples 1-6> For the mackerel, we used uncooked, frozen fillets that had been thawed under running water. The weight was as shown in Table 2 (for 4 fillets). Tapioca-modified starch (type of processing: acetylated starch) was used as the starch. Glycerin fatty acid ester was used as emulsifier 1. Glycerin celic acid fatty acid ester was used as emulsifier 2. Salt, baking soda, xanthan gum, and starch were added to a container according to the proportions shown in Table 1 and mixed. Next, reduced starch syrup and water were added and stirred, and then emulsifier and soybean oil were added and stirred to obtain the immersion solution. 100 parts by mass of fish (mackerel fillets) were immersed in 70 parts by mass of immersion solution for 1 hour. After immersion, the mackerel was drained of the liquid, the fillets were arranged on a stainless steel mesh, and a 10% by mass xylose aqueous solution was sprayed onto them. The mackerel was then roasted in a gas oven for 3 minutes and 30 seconds. The temperature of the mackerel during the first roasting was 45°C. The surface of the mackerel, removed from the roasting machine, was seared with a torch for 3 seconds. During this time, the temperature of the product remained below 65°C. Nylon bags were used for vacuum packaging. Grilled mackerel was placed in these bags and vacuum-packed. Vacuum packaging was performed to achieve a vacuum of 95-99%. The temperature of the mackerel at the start of vacuum packaging was 40°C. The container containing the mackerel was heated with steam at 95°C for 15 minutes to raise the temperature to 85°C or higher. After sterilization, the mackerel was cooled and rapidly frozen in a freezer. After 3 days, it was thawed in a room at 25°C, and the amount of drip D that had formed in the bag was measured. The weight A of the raw material, the weight B after soaking and draining, and the weight C after grilling and roasting were measured, and the yield and other results obtained from these measurements are shown in Table 2.

[0047] <Example 7> Tapioca-modified starch (type of processing: acetylated adipic acid crosslinking) was used as the starch, and no emulsifier was used. The mass ratio of mackerel to soaking liquid was set at mackerel:soaking liquid = 100:70. In this example, 35 pieces of mackerel were used. Furthermore, the temperature of the product during the first firing was set to 40-45°C, and the firing time was set to 3 minutes and 20 seconds. Except for those points, the yield was evaluated in the same manner as in Examples 1-6. The results are shown in Table 2.

[0048] <Example 8> The procedure was the same as in Example 1, except that starch was not used. The weight A of the raw material, the weight B after soaking and draining, the weight C after firing and roasting, and the weight D of the drip were measured, and the yield and other results obtained from these are shown in Table 2.

[0049] <Comparative Example 1: No immersion treatment, high-temperature primary firing> Without immersion treatment, the mackerel was subjected to primary baking at a temperature of 80°C to 100°C for 6 minutes 30 seconds to 7 minutes. This mackerel was then vacuum-packed. Except for this point, the procedure was the same as in Example 1. This mackerel was vacuum-packed, and the amount of drip D was measured. The weight A of the raw material and the weight C after baking were measured, and the yield and other results obtained from these are shown in Table 2.

[0050] <Comparative Example 2: No immersion treatment> The procedure was the same as in Example 1, except that mackerel that had not undergone immersion treatment was used for the primary firing. The weight A of the raw material, the weight C after firing and roasting, and the weight D of the drip were measured, and the yield and other results obtained from these are shown in Table 2.

[0051] <Comparative Example 3: With immersion treatment, high-temperature primary firing> The primary firing was performed by heating at a core temperature of 80°C to 100°C for 6 minutes 30 seconds to 7 minutes. The procedure was the same as in Example 1. The weight A of the raw material, the weight B after immersion and draining, the weight C after firing and roasting, and the weight D of the drip were measured, and the yield and other results obtained from these are shown in Table 2.

[0052] <Sensory evaluation>

[0053] Frozen mackerel was wrapped in plastic wrap and heated in a microwave (600W for 20 seconds per piece). The heated mackerel was evaluated according to the following criteria. The results are shown in Table 3. (1) Softness 5 stars. Very soft. 4 out of 5 stars. It's soft. 3 points - Slightly soft. 2 points - Slightly firm. One point is hard. (2) Moisture (not dry) 4 points - Very strong. 3 points - Strong. Two points weak. 1 point: Very weak.

[0054] [Table 1]

[0055] [Table 2]

[0056] Comparing Comparative Example 1 with Comparative Example 2, when the immersion treatment is not performed, lowering the temperature of the first heating step to 65°C or below improves the yield by 11.63% (=87.63%-76.00%). Comparing Comparative Example 1 with Comparative Example 3, the yield improves by 5.08% (81.08%-76.00%). In contrast, in Example 1, which uses the same immersion liquid conditions as Comparative Example 3 and the same temperature conditions as Comparative Example 2, if it were an additive effect, the yield should increase by 11.63% + 5.08%, resulting in 76.00% + 11.63% + 5.08% = 92.7%. However, a high yield of 93.7% is obtained, which is more than 1% higher than expected. In other words, in the present invention, by performing the immersion treatment and lowering the temperature of the first heating step to 65°C or below, a synergistic yield improvement effect is obtained. Furthermore, in Examples 1-7, which used an immersion solution containing dispersed water-retaining powder, superior drip suppression and texture improvement effects were obtained compared to Example 8. This is thought to be because the immersion solution containing a thickener with dispersed water-retaining powder facilitates the introduction of the water-retaining powder into the seafood.

[0057] (Example 9) For the raw material, we used uncooked horse mackerel that had been thawed in running water in a plastic bag. Aside from this, the procedure was the same as in Example 1. The results are shown in Table 3.

[0058] [Table 3]

Claims

1. A soaking process in which seafood is soaked in a soaking solution containing an alkaline agent, The first heating step involves heating the seafood after the immersion step to a product temperature of 65°C or lower. A packaging step of vacuum-packing the seafood after the first heating step, A method for producing packaged seafood food, comprising a second heating step of heating the package obtained in the packaging step.

2. A method for producing packaged seafood according to claim 1, wherein a water-retaining powder is dispersed in the immersion liquid.

3. A method for producing packaged seafood food according to claim 2, wherein the water-retaining powder is starch powder.

4. A method for producing packaged seafood according to any one of claims 1 to 3, wherein the content of the water-retaining agent powder is 1% by mass or more and 6% by mass or less in the immersion liquid.

5. A method for producing packaged seafood according to claim 1 or 2, wherein the immersion liquid contains a thickening agent.

6. A method for producing packaged seafood according to any one of claims 1 to 3, wherein the pH of the immersion liquid is 6.0 to 9.0 at 20°C.

7. A method for producing packaged seafood food according to any one of claims 1 to 3, wherein the seafood is mackerel or horse mackerel.

8. A method for producing packaged seafood food according to any one of claims 1 to 3, wherein the immersion liquid is an emulsified liquid.

9. A method for producing grilled fish, according to any one of claims 1 to 3, for producing packaged seafood food.

10. A method for producing packaged seafood according to any one of claims 1 to 3, wherein in the first heating step, the seafood is heated to a product temperature of 40°C or higher and 65°C or lower.

11. A method for producing packaged seafood according to claim 10, comprising a freezing step of freezing the package after the second heating step.

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