TWI898299B - Method of preparing grilled fish with improved texture - Google Patents

Abstract

The present disclosure relates to a method of preparing grilled fish, the method including the step of pretreating the fish with an alkaline agent, and grilled fish with improved texture, which is prepared by the method.

Description

Method for preparing grilled fish with improved taste

The present invention relates to a method for preparing grilled fish and grilled fish with improved taste prepared by the method. The method comprises the step of pre-treating the fish with an alkaline agent and is suitable for refrigerated logistics distribution due to mass production.

Processed seafood products are produced by appropriately heat-treating various seafood ingredients for cooking and safety. To ensure freshness, more intensive heat treatment is required, but this can significantly degrade the seafood's unique qualities, such as color and physical properties. Grilled fish, in particular, is highly consumed and preferred among processed seafood products, and many different varieties have recently been commercialized. However, due to the aforementioned issues, there are not many products that offer excellent appearance and taste while ensuring a shelf life suitable for the refrigerated distribution required by mass production. Therefore, there is a need to technologically overcome these issues and provide consumers with higher-value products.

Generally, grilled fish is prepared by removing inedible parts (head, tail, intestines, scales, etc.), cleaning, heat-treating, and packaging. During preparation, grilled fish loses moisture and water-soluble components, resulting in a low yield and poor quality. When grilled fish is prepared from frozen fish, it undergoes a thawing process. During this thawing process, excessive moisture escapes from the fish, reducing yield and often resulting in a rough and tough texture. Furthermore, intensive heat treatment is required to maintain freshness, but this can significantly degrade the quality of grilled fish, resulting in a dry taste and an off-flavor.

Previously, Korean Patent KR 10-2320848 B1 disclosed a "Method for Preparing Convenient Grilled Fish, and Convenient Grilled Fish Prepared by the Preparation Method." Mackerel and Spanish mackerel fillets are marinated in a sauce, heat-treated using a superheated steam grill, and then frozen using an electromagnetic freezer. However, there remains a pressing need for a method for preparing grilled fish that is high-quality, convenient, and suitable for refrigerated distribution due to mass production.

The present invention provides a method for preparing grilled fish and grilled fish with an improved taste. [Technical Solution]

The present invention provides a method for preparing grilled fish, comprising the steps of pre-treating the fish with an alkaline agent containing sodium carbonate; heat-treating the pre-treated fish; and cooling the heat-treated fish.

Another object of the present invention is to provide a composition for pre-treating frozen fish, comprising an alkaline agent containing sodium carbonate.

Yet another object of the present invention is to provide grilled fish with improved taste prepared by the above method. [ Beneficial Effects ]

The quality of grilled fish can vary significantly depending on the processing method. The present invention improves water retention capacity by pre-treating the raw materials. Among various grilling heat treatment methods, a superheated steam heat treatment process and rapid cooling, which are excellent for ensuring appearance, taste quality, and microbial stability, are applied to produce grilled fish products with significantly improved yield and taste, while also ensuring a shelf life suitable for storage methods (particularly refrigerated logistics and distribution). This can increase the company's financial value by improving product yield and promote the development of the processed seafood industry and public health by providing consumers with high-quality grilled fish products.

The present invention is described in detail below. Furthermore, each description and embodiment disclosed herein is also applicable to other descriptions and embodiments. In other words, all combinations of the various elements disclosed herein fall within the scope of the present invention. Furthermore, the scope of the present invention is not limited by the specific descriptions below.

In addition, this specification also cites numerous papers and patent documents. The disclosures of these cited papers and patent documents are hereby incorporated by reference in their entirety to further clarify the level and scope of the subject matter of this invention.

One aspect of the present invention provides a method for preparing grilled fish, comprising the step of pretreating the fish with an alkaline agent containing sodium bicarbonate.

The method for preparing grilled fish of the present invention may include the following steps: pre-treating the fish using an alkaline agent containing sodium carbonate; heat-treating the pre-treated fish; and cooling the heat-treated fish.

As used herein, the term "alkaline agent" refers to a water-soluble alkaline substance. In the present invention, the alkaline agent may be, but is not limited to, sodium carbonate, sodium bicarbonate, or a combination thereof. Any alkaline agent that is suitable for use in food products may be included without limitation.

Alkaline agents may include, for example, sodium metaphosphate, potassium metaphosphate, DL-malic acid, DL-sodium malate, acidic sodium aluminum phosphate, acidic sodium pyrophosphate, acidic calcium pyrophosphate, sodium sesquicarbonate, ammonium chloride, tribasic sodium phosphate, tribasic calcium phosphate, dibasic sodium phosphate, dibasic magnesium phosphate, dibasic ammonium phosphate, dibasic potassium phosphate, dibasic calcium phosphate, and dibasic calcium phosphate. phosphate), monobasic sodium phosphate, monobasic ammonium phosphate, monobasic potassium phosphate, monobasic calcium phosphate, potassium DL-bitartrate, potassium L-bitartrate, sodium carbonate, magnesium carbonate, sodium hydrogen carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, ammonium carbonate, potassium carbonate, calcium carbonate, sodium polyphosphate, potassium polyphosphate, sodium pyrophosphate pyrophosphate), potassium pyrophosphate, etc.

The alkaline agent may further include sodium bicarbonate.

More specifically, the alkaline agent may be a combination of sodium carbonate and sodium bicarbonate, wherein the ratio of sodium carbonate to sodium bicarbonate may be 0.5:9.5, 1:9, 1.5:8.5, 2:8, 2.5:7.5, 3:7, 3.5:6.5, 4:6, 4.5:5.5, 5:5, 5.5:4.5, 6:4, 6.5:3.5, 7:3, 2.5:7.5, 8:2, 8.5:1.5, 9:1, or 9.5:0.5, but is not limited thereto.

Here, the alkaline agent may be used after being dissolved in a solvent, wherein the solvent may be water, and may be in the form of an alkaline aqueous solution, but the solvent is not limited as long as it is a solvent that can be used for general foods.

The pH of the alkaline aqueous solution may be 7.0 or higher, and may be 8 to 12, specifically 8.5 to 11.5.

Furthermore, when the alkaline agent is used in an aqueous solution, its concentration can be 1.5 to 2.5 times the weight of the raw material in a 2% to 4% aqueous solution.

Furthermore, the step of pre-treating the fish may refer to pre-treating frozen fish or non-frozen fish. More specifically, the fish may be frozen fish.

Furthermore, regardless of whether the alkaline agent is used before or after thawing the frozen fish, it is preferred to use the alkaline agent during the thawing process, but the present invention is not limited thereto.

Fish may include, but are not limited to, mackerel, Spanish mackerel, plaice, cutlassfish, Atka mackerel, saury, redfish, flatfish, tuna, cod, pollack, brown croaker, pomfret, dark-banded rockfish, tongue fish, salmon, rockfish, eel, horse mackerel, croaker, herring, and the like.

In addition, the step of pre-treating the fish includes methods used in a pre-treatment process including a common thawing process, such as immersing the fish in a solution containing an alkaline agent, spraying, coating, injecting, tumbling, etc., but is not limited thereto.

In a specific embodiment of the present invention, the method includes soaking and thawing the frozen fish in an aqueous solution containing an alkaline agent for about 30 minutes, but is not limited thereto.

In an exemplary embodiment of the present invention, the pretreatment step using an alkaline agent was demonstrated to achieve low hardness, high moisture content, improved process yield, and excellent overall taste, thereby producing a soft mouthfeel and excellent taste.

The method for preparing grilled fish of the present invention may further include a cleaning step after pre-treatment.

In this regard, the washing step can be carried out using cold water at 1°C to 10°C for 10 to 20 minutes.

The method for preparing grilled fish of the present invention may further include a marinating and/or seasoning process after the pretreatment step.

The heat treatment step is a step of heating the fish after the pretreatment step. The heat treatment can be performed using superheated steam, dry heat, moist heat, infrared radiation, etc., and specifically superheated steam heat treatment can be used.

The temperature of the superheated steam heat treatment step may be 300°C to 400°C, 305°C to 395°C, 310°C to 390°C, 315°C to 385°C, 320°C to 380°C, 325°C to 375°C, 330°C to 370°C, 335°C to 365°C, 320°C to 360°C, 325°C to 355°C, or 320°C to 350°C, but is not limited thereto.

In addition, the time condition may be 1 minute to 10 minutes, 1 minute 30 seconds to 9 minutes 30 seconds, 2 minutes to 9 minutes, 2 minutes 30 seconds to 8 minutes 30 seconds, 3 minutes to 8 minutes, 3 minutes 10 seconds to 7 minutes 50 seconds, 3 minutes 20 seconds to 7 minutes 40 seconds, 3 minutes 30 seconds to 7 minutes 30 seconds, 3 minutes 30 seconds to 7 minutes, 3 minutes 30 seconds to 6 minutes 30 seconds, 3 minutes 30 seconds to 6 minutes, 3 minutes 30 seconds to 5 minutes 30 seconds, 3 minutes 40 seconds to 5 minutes 20 seconds, 3 minutes 50 seconds to 5 minutes 10 seconds, 3 minutes 50 seconds to 5 minutes, or 4 minutes to 5 minutes.

At this time, the core temperature of the grilled fish may be about 70°C to about 110°C, about 75°C to about 105°C, about 80°C to about 100°C, about 81°C to about 99°C, about 82°C to about 98°C, about 83°C to about 97°C, about 84°C to about 96°C, or about 85°C to about 95°C, but is not limited thereto.

The cooling step may be a step of cooling the grilled fish by natural cooling, gentle cooling (1°C to 10°C), or rapid cooling after the heat treatment step, and the cooling step may specifically refer to a rapid cooling step, but is not limited thereto.

The temperature conditions of the rapid cooling step may be -1°C to -40°C, -5°C to -35°C, -10°C to -30°C, -13°C to -27°C, -15°C to -25°C, -15°C to -23°C, or -15°C to -20°C, but are not limited thereto.

Furthermore, the time condition may be 1 minute to 20 minutes, 2 minutes to 18 minutes, 3 minutes to 17 minutes, 4 minutes to 16 minutes, 5 minutes to 15 minutes, 6 minutes to 14 minutes, 7 minutes to 13 minutes, 8 minutes to 12 minutes, or 9 minutes to 11 minutes, but is not limited thereto.

At this time, the core temperature of the grilled fish may be about 0°C to about 20°C, about 1°C to about 19°C, about 2°C to about 18°C, about 3°C to about 17°C, about 4°C to about 16°C, about 5°C to about 15°C, about 6°C to about 14°C, about 7°C to about 13°C, or about 8°C to about 12°C, but is not limited thereto.

Furthermore, after the heat treatment and cooling steps, the method for preparing grilled fish may further include a sealing and nitrogen-filled packaging step, a sterilization step, etc., but is not limited thereto.

The sealing and nitrogen-filling packaging steps are sufficient to package the fish using a packaging film by filling with nitrogen. Any method is sufficient as long as it is generally used in the food field, and there is no particular limitation on the method.

Moreover, the sterilization step can be carried out after the packaging step, and any method as long as it is the common method in this area is sufficient to be competent, and there is no special restriction. The grilled fish that is convenient to eat packaged in this way can be stored for a long time under refrigeration.

In an exemplary embodiment of the present invention, it was confirmed that when the superheated steam heat treatment step was performed, the hardness was low and the moisture content was high, resulting in a soft mouthfeel and excellent preference.

The results also confirmed that the rapid cooling step showed significant microbial control efficacy compared to mild cooling at 4°C.

Another aspect of the present invention provides a composition for pre-treating frozen fish, comprising an alkaline agent containing sodium carbonate.

Alkaline agents and pretreatments were as described above.

The alkaline agent may further include sodium bicarbonate.

In addition, in the alkaline agent, the ratio of sodium carbonate:sodium bicarbonate may be 2:8 to 8:2.

Another aspect of the present invention provides grilled fish with improved taste prepared by the above method.

The hardness of grilled fish can be 900 (g-force) to 1200 (g-force), 910 (g-force) to 1190 (g-force), 920 (g-force) to 1180 (g-force), 930 (g-force) to 1170 (g-force), 940 (g-force) to 1160 (g-force), 950 (g-force) to 1150 (g-force), 960 (g-force) to 1140 (g-force), 960 (g-force) to 1130 (g-force), 960 (g-force) to 1120 (g-force), 960 (g-force) to 1110 (g-force), 960 (g-force) to 1100 (g-force), 960 (g-force) to 1090 (g-force), 960 (g-force) to 1080 (g-force), 960 (g-force) to 1070 (g-force), 960 (g-force) to 1060 (g-force), or 960 (g-force) to 1050 (g-force), but not limited thereto.

Hardness (g) is the force required to achieve a predetermined deformation (the force value at the highest peak in the graph) and can be measured using a taste analyzer (TA-XT plus, Stable Micro Systems, UK) under the following physical conditions. -Probe type: Warner-Bratzler shear blade -Speed at which the probe descends onto the sample (pre-test speed): 1.00 mm/sec -Speed at which the probe penetrates the sample after reaching the sample surface (test speed): 2.00 mm/sec -Speed at which the probe returns to its original position after penetrating the sample (post-test speed): 10.00 mm/sec -Distance at which the probe recognizes the sample surface and penetrates the sample (distance): 20.00 mm -Conditions under which the probe recognizes the sample (trigger type): Automatic (forced) -Minimum force required for the probe to recognize the presence of a sample (trigger force): 5.0 g

In addition, the grilled fish may have a moisture content of 50% to 70%, 52% to 66%, or 54% to 64%, specifically, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, but not limited thereto.

In an exemplary embodiment of the present invention, it was demonstrated that the grilled fish prepared by the method for preparing grilled fish of the present invention had lower hardness than other commercially available refrigerated or frozen grilled fish, and was therefore softer, and had a high water content, exhibiting a moist taste and excellent overall preference. Therefore, the grilled fish was demonstrated to be a high-quality grilled fish product and suitable for refrigerated logistics distribution due to mass production.

Another aspect of the present invention provides use of a composition comprising an alkaline agent containing sodium carbonate in the pretreatment of frozen fish.

Alkaline agents and pretreatments were as described above.

The alkaline agent may further include sodium bicarbonate.

Furthermore, in the alkaline agent, the ratio of sodium carbonate:sodium bicarbonate may be 2:8 to 8:2.

Another aspect of the present invention provides the use of a pretreatment composition comprising an alkaline agent containing sodium carbonate in preparing grilled fish with improved taste. The alkaline agent and pretreatment are as described above.

The alkaline agent may further include sodium bicarbonate.

In addition, the ratio of sodium carbonate to sodium bicarbonate in the alkaline agent may be 2:8 to 8:2. [ Methods of Implementing the Invention ]

The present invention is described in more detail below using exemplary embodiments. However, these exemplary embodiments are intended only to illustrate preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Furthermore, technical matters not described in this specification will be readily understood and implemented by those skilled in the art or similar technical fields to which the present invention pertains.

Experimental Materials The fish used in the experiment were frozen Norwegian mackerel fillets, with the head, tail, intestines, and scales removed. They were purchased from a Chinese seafood processing company (Qingdao Yihexing Foods Co., Ltd.) and stored frozen at -25°C until the time of the experiment.

Preparation Example 1. Step of Pre-treating Fish with Alkaline Agents Sodium bicarbonate (NaHCO ₃ ) and sodium carbonate (Na ₂ CO ₃ ) were provided by SJD Co., Ltd. for testing the efficacy of alkaline pretreatment, and phosphate (Polymix CS) purchased from Seodo BNI Co., Ltd. was used.

To examine the efficacy of three alkaline pretreatment agents in improving the water-holding capacity of raw materials, a control group was immersed in room temperature water and thawed for 30 minutes. Test groups were immersed in 3% sodium carbonate, 3% sodium bicarbonate, and 3% phosphate solutions and thawed for 30 minutes. Furthermore, to examine the synergistic effect of combining two top-tier materials with improved water-holding capacity, the raw materials were thawed for 30 minutes by immersing in 3% solutions of sodium carbonate and sodium bicarbonate in ratios of 7:3, 5:5, or 3:7, two top-tier materials previously identified in experiments. The ratio of thawed raw materials to the alkaline pretreatment mixture was adjusted to 1:2.

Preparation Example 2. Superheated Steam Heat Treatment Step for Grilled Fish To compare the grilled fish product quality between heat treatment using a heat treatment source primarily used for grilled fish and heat treatment in a superheated steam oven, marinated ingredients were heated under the conditions shown in Table 1 in a superheated steam oven (QF-5100CB, Naomoto Co., Ltd., Japan), an infrared oven (UH-DORI JC-9282, JC Electric Co., Ltd., Korea), a wet heat oven (Air-O-Steam Combination Oven (268783), Electrolux AB, Sweden), and a dry heat oven (Impinger II Oven, Lincoln Corporation, USA) to a core temperature of 85°C or higher.

[Table 1] Heat treatment method Heat treatment time Heat treatment temperature (°C) 1 Superheated steam oven 4 minutes and 30 seconds Furnace temperature: 250 ˚C, superheated steam temperature: 350 ˚C 2 Dry heat oven 6 minutes and 30 seconds 250 ˚C 3 Wet heat oven 7 minutes and 30 seconds 250 ˚C, 100% steam 4 infrared oven 11 minutes - Preparation Example 3: Rapid Cooling Steps for Grilled Fish

Preparation Example 3. Rapid Cooling Step for Grilled Fish To examine the microbial control efficacy of rapid versus gentle cooling during the cooling process of grilled fish after heat treatment, based on a core temperature of 10°C or below, the control group (gentle cooling) was cooled at 4°C for 60 minutes, while the test group (rapid cooling) was cooled at -20°C for 11 minutes. The fish were then sealed with nitrogen and stored at 15°C.

Experimental Example 1. Verification of the Efficacy of Using an Alkaline Pretreatment Agent to Improve the Quality of Frozen Mackerel To examine the effectiveness of alkaline pretreatment and mixing concentration in improving water retention during grilled fish preparation, samples were prepared using the same method as in Example 1. Following the same salt soaking-heating-cooling process, the samples were converted into the final grilled product. The process yield, physical properties, and moisture content were tested, and sensory evaluation was conducted.

Experimental Example 1-1. Measuring the Pretreatment Process Yield To measure the process yield, the weight of the raw materials before thawing was measured. The measured weight of each baked product prepared using the method of Preparation Example 1 was then divided by the initial weight to calculate the process yield (%).

By measuring the process yield of grilled mackerel that had been pretreated with alkaline solution, the process yield of the raw material soaked in alkaline aqueous solution tended to increase compared to the untreated group that was thawed and soaked in water.

The process yield of grilled mackerel soaked in 3% sodium carbonate was 80.5%, an increase of 3.6 percentage points compared to the process yield of 76.9% in the untreated group, showing the largest increase in yield.

Furthermore, among the three treatment groups, sodium carbonate and sodium bicarbonate, which showed a high overall preference in sensory evaluation, were mixed in ratios of 7:3, 3:7, or 5:5, and the process yield was measured. The results showed that the process yield of grilled fish treated with alkaline pretreatment using this mixture was higher than that of grilled fish treated with either treatment alone. The highest process yield of 81.42% was achieved when the sodium carbonate to sodium bicarbonate ratio was 7:3.

[Table 2] Unprocessed Sodium carbonate Sodium bicarbonate phosphate Sodium carbonate: sodium bicarbonate 7:3 3:7 5:5 Process yield (%) 76.90 80.51 78.43 78.89 81.42 81.29 80.67

In other words, it was confirmed that the pretreatment with alkaline agent can improve the process yield of grilled fish.

Test Example 1-2. Physical Property (Hardness) Analysis (Fracture Test) The hardness of grilled mackerel prepared by alkaline pretreatment using the method of Preparation Example 1 was measured using the following method.

To analyze physical properties, samples were cut as evenly as possible into pieces 4 cm wide and 1 cm long. Hardness was then measured by fracture testing under refrigerated conditions using a taste analyzer (TA-XT plus, Stable Micro Systems, UK). Ten measurements were performed under identical conditions, and the average result was taken. The taste analyzer's probe descended vertically onto the sample at a controlled distance and speed. After descending a controlled distance, the probe was raised at an adjusted distance and speed. During this process, a force sensing device and sensor detected the force applied to the sample and transmitted the data (force value, operation time, and probe travel distance) to a computer. The definitions of terms related to the physical property measurements and the measurement conditions are as follows. (1) Hardness (g): Force required to achieve a predetermined deformation (force value of the highest peak in the graph) (2) Measurement conditions of physical properties: - Probe type: Warner-bratzler shear blade - Speed at which the probe descends onto the sample (pre-test speed): 1.00 mm/sec - Speed at which the probe penetrates the sample after reaching the sample surface (test speed): 2.00 mm/sec - Speed at which the probe returns to its original position after penetrating the sample (post-test speed): 10.00 mm/sec - Distance at which the probe recognizes the sample surface and penetrates the sample (distance): 20.00 mm - Conditions for the probe to recognize the sample (trigger type): automatic (forced) - Minimum force required for the probe to recognize the presence of the sample (trigger force): 5.0 g

As shown in Table 3 below, the hardness of the grilled mackerel in the untreated group, sodium carbonate treated group, sodium bicarbonate treated group, and phosphate treated group was 1234.5 g-force, 1007.5 g-force, 1030.6 g-force, and 1043.9 g-force, respectively, confirming that the grilled mackerel treated with alkaline had a lower hardness than that of the untreated group.

Among them, the grilled mackerel pretreated with sodium carbonate showed a hardness of 1007.5, indicating the softest texture, confirming that the alkaline pretreatment process improves the taste of grilled fish.

[Table 3] Unprocessed Sodium carbonate Sodium bicarbonate phosphate Hardness (g-force) 1234.50 1007.47 1030.59 1043.88

Moisture content analysis For moisture content analysis, the samples were finely ground, 3 g of sample was taken, and the moisture content was measured by heating and drying method according to the American Association of Cereal Chemists (AACC) (44-16) method.

Measuring the moisture content of grilled mackerel prepared with alkaline pretreatment revealed that the alkaline pretreatment had a higher moisture content than the untreated group, indicating a moister texture. In particular, the moisture content of the sodium carbonate-treated group was 63.22%, which was 3.89% higher than the untreated group (59.33%).

[Table 4] Unprocessed Sodium carbonate Sodium bicarbonate phosphate Water content (%) 59.33 63.22 62.28 61.28

Sensory Evaluation In the sensory evaluation, five trained panelists tasted each refrigerated grilled fish product after it had been microwaved for one minute. After tasting each sample, they rinsed their mouths with water and were allowed to taste the next sample after one minute. They rated the intensity and preference of the mouthfeel, overall taste preference, and combined taste preference using a 5-point scale, as shown in Table 5.

[Table 5] 5-point system 1 2 3 4 5 Strength Very soft soft ordinary Hard Very hard Preference Very bad Difference ordinary good very good

As shown in the sensory evaluation results of grilled mackerel prepared according to the method of Experimental Example 1, the grilled mackerel treated with sodium carbonate exhibited the lowest mouthfeel intensity of 2.2, the grilled mackerel treated with sodium bicarbonate exhibited a mouthfeel intensity of 2.6, and the grilled mackerel treated with phosphate exhibited a mouthfeel intensity of 3.2. The mouthfeel intensity of the alkaline pretreatment group was confirmed to be softer than the mouthfeel intensity of the untreated grilled mackerel (3.4). In terms of mouthfeel preference, the sodium carbonate-treated group exhibited the highest preference of 4.4.

In addition, the alkaline pretreatment group's overall taste preference (sodium carbonate 4.4, sodium bicarbonate 4.0) and combined taste preference (sodium carbonate 4.4, sodium bicarbonate 4.0) were both superior to the untreated group's overall taste preference of 3.0 and combined taste preference of 3.2.

In other words, the above results confirm that pretreatment with alkaline agents improves the taste of grilled fish.

[Table 6] Unprocessed Sodium carbonate Sodium bicarbonate phosphate Taste intensity 3.4 2.2 2.6 3.2 Taste preference 3.2 4.4 3.6 2.8 Overall taste preference 3.0 4.4 4.0 3.4 Comprehensive taste preference 3.2 4.4 4.0 3.4

Experimental Example 2: Verifying the Efficacy of the Superheated Steam Oven Heat Treatment Process for Grilled Fish To test the effectiveness of the superheated steam oven heat source in the heat treatment process for grilled mackerel, samples prepared using the method of Preparation Example 2 were tested for moisture content, sensory quality, and physical properties. Three analytical parameters were measured using the same methods as in Experimental Example 1.

Experimental Example 2-1. Testing the Firmness of Grilled Fish by Heat Treatment Using the methods of Preparation Example 2 for each heat source, grilled fish pretreated in the same manner as Preparation Example 1 were subjected to superheated steam, wet heat, dry heat, and infrared heat treatments. The firmness was then analyzed in the same manner as in Experimental Example 1. The results showed that grilled mackerel treated with superheated steam had a firmness of 912 g-force, exhibiting the softest texture.

[Table 7] superheated steam Wet heat dry heat Infrared heating Hardness (g-force) 912 1,418 1,526 1,633

Experimental Example 2-2. Testing the Moisture Content of Grilled Fish by Heat Treatment Method Measurement of the moisture content of grilled fish by heat source revealed that grilled mackerel treated with infrared heat had the lowest moisture content of 46.3%, while fish treated in a superheated steam oven had the highest moisture content of 54.1%. The moisture contents of grilled fish treated in a wet heat oven and a dry heat oven were 53.7% and 53.6%, respectively.

The results of hardness and moisture content confirmed that fish heat-treated in a superheated steam oven had a softer texture due to lower hardness compared with fish heat-treated in a wet heat oven or a dry heat oven, although there was no significant difference in moisture content.

[Table 8] superheated steam Wet heat dry heat Infrared heating Water content (%) 54.1 53.7 53.6 46.3

Experimental Example 2-3 Sensory Evaluation of Grilled Fish Based on Heat Treatment A sensory evaluation of grilled mackerel prepared using the method described in Experimental Example 2 was conducted.

As shown in the results, the grilled mackerel heat-treated in the superheated steam oven had the lowest mouthfeel intensity of 2.6, while the grilled mackerel heat-treated in the dry heat oven had the highest mouthfeel intensity of 4.0.

Mackerel heat-treated in a superheated steam oven had the highest texture preference rating of 4.8. Furthermore, the overall taste preference rating of the superheated steam oven group was 4.6, which was superior to the overall taste preference ratings of the groups treated in wet, dry, and infrared ovens. The combined taste preference rating of the superheated steam oven group was 4.8, which was also superior to the combined taste preferences of the groups treated in wet, dry, and infrared ovens.

The above results confirmed that the grilled fish heat-treated with superheated steam was soft and moist due to its low taste intensity and had a higher taste preference due to its high water content.

[Table 9] superheated steam Wet heat dry heat Infrared heating Taste intensity 2.6 3.0 4.0 3.8 Taste preference 4.8 3.4 3.2 2.6 Overall taste preference 4.6 3.2 3.4 3.2 Comprehensive taste preference 4.8 3.4 3.2 3.2

Experimental Example 3. Verifying the Efficacy of Rapid Cooling for Microbial Control in Grilled Fish For microbial analysis of general bacteria and intestinal flora, 20 to 30 g of sample was collected, diluted 10-fold with saline, and 1 mL of the sample was applied to culture membranes for a four-log dilution (Aerobic Counter Plates (AC (for general bacteria))/Colour Counter Plates (CC (for intestinal flora)), 3M, USA).

Grilled mackerel prepared under the same conditions of pretreatment with an alkaline agent using the method of Preparation Example 1 and heat treatment using the method of Preparation Example 2 were gently cooled or rapidly cooled using the method of Preparation Example 3, and analyzed for general bacteria and intestinal flora.

As shown in the results, no common bacteria or intestinal flora were detected in the rapidly cooled grilled fish until the 20th day when stored at 15°C. In the mildly cooled grilled fish, no intestinal flora were detected until the 13th day when stored under refrigeration. However, ^5.0x10⁰ CFU/g of common bacteria were detected on the first day of refrigeration, and ^8.08x10⁴ on the 13th day of refrigeration. This indicates that the shelf life of mildly cooled grilled mackerel does not exceed two weeks.

[Table 10] Microbial counts in grilled fish after gentle cooling Mild cooling (Japanese) initial +1 +2 +3 +6 +13 Common bacteria (CFU/g) Not detected 5.0x10 ⁰ 5.0x10 ⁰ 3.47x10² 5.25x10² 8.08x10 ⁴ Intestinal flora (CFU/g) Not detected Not detected Not detected Not detected Not detected Not detected

[Table 11] Microbial counts in grilled fish after rapid cooling Rapid cooling (day) initial +3 +6 +8 +10 +14 Common bacteria (CFU/g) Not detected Not detected Not detected Not detected Not detected Not detected Intestinal flora (CFU/g) Not detected Not detected Not detected Not detected Not detected Not detected

Experimental Example 4: Quality Comparison with Commercially Available Refrigerated and Frozen Grilled Fish To compare the quality of refrigerated grilled fish prepared using the preparation example process series with commercially available refrigerated/frozen grilled fish, moisture content, sensory, and physical properties were examined. Three analytical parameters were measured using the same methods as in Experimental Example 1.

Mackerel processed by the method of Preparation Example 1 were prepared by rapid cooling after heat treatment in a superheated steam oven, and the quality was compared (Preparation Example).

As shown in the results, the hardness of the grilled mackerel of the preparation example was 975.6 g-force, which showed the softest texture; the hardness of the frozen grilled mackerel of the 'O' company was 1465.8 g-force; and the hardness of the frozen grilled mackerel of the 'S' company was 1648.7.

[Table 12] Hardness comparison with commercially available grilled fish products Preparation Example 'O' Company (Frozen) 'S' Company (cold storage) Hardness (g-force) 975.6 1465.8 1648.7

As shown in the comparative analysis of moisture content using the method used in the experimental example, the moisture content of the grilled mackerel in the preparation example was 56.44%, indicating that its moisture content was higher than other commercially available grilled mackerel products. The moisture content of the frozen grilled mackerel from Company O was 49.44%, and the moisture content of the frozen grilled mackerel from Company S was 51.67%.

[Table 13] Preparation Example 'O' Company (Frozen) 'S' Company (cold storage) Water content (%) 56.44 49.44 51.67

As shown in the results of sensory evaluations conducted using the experimental example method, the grilled mackerel of Preparation Example had a mouthfeel intensity of 2.5, indicating the lowest mouthfeel intensity, compared to 2.7 for Company 'O' and 3.7 for Company 'S'. The grilled mackerel of Preparation Example had the highest mouthfeel preference. The grilled mackerel of Preparation Example had the highest overall taste preference of 4.5, compared to 3.8 for Company 'O' and 2.3 for Company 'S'. The grilled mackerel of Preparation Example had the highest overall taste preference of 4.7, compared to 3.8 for Company 'O' and 2.5 for Company 'S', demonstrating excellent sensory quality.

[Table 14] Preparation Example 'O' Company (Frozen) 'S' Company (cold storage) Taste intensity 2.5 2.7 3.7 Taste preference 4.5 3.8 2.8 Overall taste preference 4.5 3.8 2.3 Comprehensive taste preference 4.7 3.8 2.5

The above results demonstrate that the grilled fish prepared by the method of the present invention has excellent sensory quality and is suitable for refrigerated logistics distribution due to mass production.

Based on the foregoing description, those skilled in the art will appreciate that the present invention can be implemented in various specific forms without altering its technical spirit or essential characteristics. It should be understood that the foregoing embodiments are not limiting but rather illustrative in all aspects. The scope of the invention is defined by the appended claims, not by the description preceding them. Therefore, all changes and modifications that fall within the scope of the claims, or equivalents thereof, are intended to be covered by the claims.

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without.

Claims (9)

A method for preparing grilled fish, comprising the steps of: pre-treating the fish with an alkaline agent including sodium carbonate, wherein the pre-treating of the fish is performed by thawing the frozen fish by soaking, spraying, coating, injecting, or turning the fish with an alkaline solution; heat-treating the pre-treated fish, wherein the heat-treating is performed with superheated steam, and the superheated steam heat-treating step is performed at a core temperature of 80°C to 95°C at a temperature of 320°C to 365°C for 3 minutes 50 seconds to 5 minutes 50 seconds; and cooling the heat-treated fish. The method of claim 1, wherein the alkaline agent further comprises sodium bicarbonate. The method of claim 2, wherein the ratio of sodium carbonate to sodium bicarbonate in the alkaline agent is 2:8 to 8:2. The method of claim 1 further comprises the step of washing off the pretreatment agent after pre-treating the fish. The method of claim 1, wherein the cooling step is performed at a core temperature of 0°C to 15°C or at -10°C to -30°C for 5 minutes to 15 minutes. The method of claim 1, wherein the grilled fish is grilled fish that is delivered refrigerated. A composition for pre-treating frozen fish, comprising an alkaline agent including sodium carbonate. The composition as described in claim 7, wherein the alkaline agent further comprises sodium bicarbonate. The composition of claim 8, wherein the ratio of sodium carbonate to sodium bicarbonate in the alkaline agent is 2:8 to 8:2.