Salt-reduced tuna mince restructured fish fillet and method for preparing the same

Abstract

The application discloses a kind of salt-reduced tuna minced meat restructured fish fillet and preparation method thereof, the fish fillet is composed of tuna minced meat, tuna surimi, salt, TG enzyme and soybean protein isolate, the addition amount of tuna surimi accounts for 40%~50% of the total mass of tuna minced meat and tuna surimi, the addition amount of salt accounts for 2% of the total mass of tuna minced meat and tuna surimi, the addition amount of TG enzyme accounts for 0.3%~0.5% of the total mass of tuna minced meat and tuna surimi, and the addition amount of soybean protein isolate accounts for 6% of the total mass of tuna minced meat and tuna surimi.The application synergistically enhances TG enzyme and soybean protein isolate, effectively compensates for the decrease in gel performance and texture quality caused by low-salt environment when the salt addition amount is reduced from 3% to 2% (decreased by 33.3%), and the obtained fish fillet has good hardness, elasticity, chewiness, gel strength and low cooking loss rate, meeting the processing and consumption needs of low-salt healthy food.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a reconstituted fish fillet made from reduced-salt tuna minced meat and its preparation method. Background Technology

[0002] Tuna is a high-quality, high-protein, low-fat food, prized for its delicious flavor and high nutritional value. It is one of the world's three most nutritious fish recommended by the International Nutrition Society. Reconstituted tuna products, due to their convenience and stable taste, have become an important product type in the seafood processing industry. Traditionally, reconstituted tuna products require the addition of about 3% salt to achieve good gelation and texture. While high-salt formulations can improve protein dissolution and gel strength, they do not align with modern healthy eating trends. Excessive salt intake is a significant contributing factor to chronic diseases such as hypertension and cardiovascular disease. Directly reducing the amount of added salt leads to insufficient protein dissolution, a loose gel network structure, and consequently, decreased hardness, elasticity, chewiness, reduced gel strength, and increased cooking losses, failing to meet production and consumer demands.

[0003] Currently, research on low-salt processing technologies for reconstituted tuna products remains limited, lacking effective solutions to simultaneously maintain and improve product texture and gelation properties while significantly reducing salt content. Furthermore, tuna processing generates a high proportion of byproducts such as meat scraps. Developing low-salt reconstituted products using these byproducts would not only achieve high-value utilization of these byproducts but also align with the development trend of low-salt healthy foods. Therefore, developing a processing technology that can significantly reduce salt usage while ensuring the texture, gelation properties, and cooking stability of reconstituted fish fillets is of significant practical importance. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a low-salt tuna mince reconstituted fish fillet and its preparation method, addressing the shortcomings of existing technologies. This invention utilizes the synergistic effect of TG enzyme (transglutaminase) and soy protein isolate to effectively compensate for the decline in gel performance and textural quality caused by a low-salt environment, even when the salt content is reduced from 3% to 2% (a reduction of 33.3%). The resulting tuna mince reconstituted fish fillet exhibits good hardness, elasticity, chewiness, gel strength, and a low cooking loss rate, meeting the processing and consumption needs of low-salt healthy foods.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a reconstituted fish fillet with reduced-salt tuna minced meat, composed of tuna minced meat, tuna paste, salt, TG enzyme and soy protein isolate, wherein the amount of tuna paste added accounts for 40% to 50% of the total mass of tuna minced meat and tuna paste, the amount of salt added accounts for 2% of the total mass of tuna minced meat and tuna paste, the amount of TG enzyme added accounts for 0.3% to 0.5% of the total mass of tuna minced meat and tuna paste, and the amount of soy protein isolate added accounts for 6% of the total mass of tuna minced meat and tuna paste.

[0006] The salt content of the fish fillets in this invention is reduced by 33.3% compared to the conventional 3%. The resulting fish fillets have significantly higher hardness, elasticity, chewiness, and gel strength than traditional 3% salt products. The cooking loss rate is lower than that of traditional 3% salt products, and the microstructure is dense and uniform.

[0007] This invention uses minced tuna and tuna paste as the main ingredients, which together constitute the main body of the reconstituted tuna fillet. The tuna paste acts as a natural binder, binding the minced tuna together to create a fillet with the texture of natural fish fibers. During the chopping and mixing process with the tuna paste, salt promotes the dissolution of myofibril proteins in the fish meat, improving the adhesiveness of the fish proteins and forming an elastic three-dimensional gel network, thereby increasing gel strength. This invention reduces the amount of salt added to 2% of the total mass of the minced tuna and tuna paste, a 33.3% reduction compared to the traditional 3%, achieving the salt reduction goal. TG enzyme catalyzes the transacylation reaction between glutamine and lysine residues in the protein molecules, causing covalent cross-linking of the protein molecules. Soy protein isolate cross-links with the fish protein through covalent bonds; the two work synergistically to compensate for the loss of gel performance under low salt levels, promoting the formation of the reconstituted fish fillet gel network structure and improving the product's taste, texture, and nutritional value under low salt conditions.

[0008] Preferably, the amount of tuna surimi added accounts for 40% of the total mass of tuna mince and tuna surimi, and the amount of TG enzyme added accounts for 0.4% of the total mass of tuna mince and tuna surimi. Under this preferred formula, the resulting fish fillet achieves an optimal balance of hardness, elasticity, chewiness, and gel strength, while fully utilizing the tuna mince and realizing high-value utilization of by-products.

[0009] The preparation method of the above-mentioned low-salt tuna minced meat reconstituted fish fillet includes the following steps: tuna paste and salt are chopped and mixed, then tuna minced meat, soy protein isolate and TG enzyme are added and mixed evenly, the fish fillet is shaped and then gelled, and then cooked to obtain the low-salt tuna minced meat reconstituted fish fillet.

[0010] The preparation method of this invention can ensure that the texture properties, gel strength and cooking loss rate of the recombinant fish fillets are superior to those of traditional 3% salt products. Moreover, the preparation method is simple to operate and suitable for industrial production.

[0011] The preparation method of this invention makes full use of the scrap meat by-products generated during tuna processing, improves the comprehensive utilization rate of tuna resources, enhances the overall economic value of tuna, and the resulting low-salt tuna scrap reconstituted fish fillet conforms to the modern dietary concept of convenience and health.

[0012] Preferably, the tuna paste and salt are chopped for 3 minutes to promote the dissolution of salt-soluble proteins and enhance the gel network structure and water retention of the fish fillets under low-salt conditions.

[0013] Preferably, the TG enzyme is dissolved in ultrapure water before use. The tuna paste with added salt is then chopped with the TG enzyme for 3 minutes to ensure that the components are fully and evenly distributed, while avoiding over-stirring which would damage the fish meat fiber structure and ensure the texture and taste of the fish fillet.

[0014] Preferably, the soy protein isolate is fully swollen with water at a mass ratio of 1:4 before use, so that the soy protein isolate is uniformly hydrated, which facilitates subsequent cross-linking with fish protein and, together with TG enzyme, compensates for the loss of gel performance caused by salt reduction.

[0015] As a preferred method, the mixing time after adding tuna mince and soy protein isolate is 5 minutes, which allows the components to be fully and evenly distributed, while avoiding over-stirring and damaging the fish fiber structure, thus ensuring the texture and taste of the fish fillet.

[0016] Preferably, the fish fillet is shaped using a mold to form a uniform and fixed shape, so as to ensure that the product has a regular and consistent shape.

[0017] Preferably, the gelation temperature is 40℃~45℃ and the time is 20~40 minutes. More preferably, the gelation temperature is 40℃ and the time is 30 minutes. Under these gelation conditions, the TG enzyme activity is moderate, which can fully catalyze the protein cross-linking reaction to form a dense and stable gel network structure, while avoiding gel deterioration caused by excessively high temperatures.

[0018] Preferably, the cooking method is steam cooking with boiling water at a temperature of 100°C for 3-8 minutes, more preferably 5 minutes. Under these cooking conditions, the center temperature of the fish fillet reaches the safe cooking requirement while maintaining its elasticity and texture, avoiding overheating that could lead to moisture loss and a loose texture. The preferred cooling method after cooking is running water cooling, under which the prepared tuna fillet has the best texture.

[0019] Compared with the prior art, the present invention has the following advantages: 1) This invention focuses on salt reduction and health, using tuna mince and tuna surimi as the main raw materials. The amount of salt added is reduced from 3% to 2%, a reduction of 33.3%. Through the synergistic effect of TG enzyme-catalyzed cross-linking and soy protein isolate, the cross-linking of fish protein molecules is promoted, and a dense and stable gel network is constructed, which successfully solves the technical problem of the deterioration of the quality of reconstituted fish products under salt reduction conditions.

[0020] 2) The reduced-salt tuna scraps reconstituted fish fillets prepared by this invention exhibit superior hardness, elasticity, chewiness, and gel strength compared to traditional high-salt products, while reducing salt content by 33.3%. They also show lower cooking loss and a denser, finer microstructure. Furthermore, this invention fully utilizes byproducts generated during tuna processing, achieving high-value utilization of tuna resources. Using food-grade raw materials, this invention is safe and non-toxic, providing a theoretical basis and technical support for the low-salt, healthier, and industrialized production of tuna products. Attached Figure Description

[0021] Figure 1 To investigate the effects of adding only salt to traditional tuna mince reconstituted fish fillets in Examples 1-5 on the hardness, elasticity, chewiness, gel strength, and cooking loss rate. Figure 2 The effects of different mass ratios of minced tuna to surimi in Examples 1-5 on the hardness, elasticity, chewiness, gel strength, and cooking loss rate of reconstituted tuna fillets. Figure 3 The effects of different salt addition amounts on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna fillets in Examples 6-11; Figure 4 The effects of different amounts of TG enzyme added in Examples 12-17 on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna mince; Figure 5 The effects of different amounts of soy protein isolate added in Examples 18-23 on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna mince; Figure 6 A comparison of the hardness, elasticity, chewiness, gel strength, and cooking loss rate of traditional reconstituted fish fillets and optimized reconstituted fish fillets made from reduced-salt tuna mince. Figure 7 A comparison of sensory scores between traditional reconstituted fish fillets and optimized reconstituted fish fillets made with reduced-salt tuna mince; Figure 8 A comparison of the microstructures of traditional reconstituted fish fillets and optimized reconstituted fish fillets made from reduced-salt tuna mince. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings, embodiments, comparative examples, and experimental examples. The present invention does not have any special limitations on the source of the raw materials; commercially available products conventional in the art can be used.

[0023] Example 1: (1) The amount of tuna paste added accounts for 10% of the total mass of tuna mince and tuna paste. Weigh 45g of tuna mince and 5g of tuna meat accurately. Rinse them in 3 times the amount of ice water, stir slowly for 3 minutes, let stand for 3 minutes, and pour off the rinsing liquid. Repeat the above rinsing steps three times and drain until no water drips off the surface to obtain cleaned tuna mince and tuna meat. (2) Grind the tuna meat from step (1) into tuna paste using a food processor for 5 minutes; (3) Accurately weigh 2% of the total mass of the tuna minced meat in step (1) and the tuna paste in step (2) and chop them together with the tuna paste in step (2) for 3 minutes using a chopper. (4) Accurately weigh 0.4% of the total mass of the tuna minced meat in step (1) and the tuna paste in step (2), dissolve it in a small amount of ultrapure water, and then chop it with the tuna paste in step (3) for 3 minutes using a grinder. (5) Add soy protein isolate to water in a 1:4 ratio and mix until the soy protein isolate is fully swollen. Accurately weigh 6% of the total mass of the tuna mince from step (1) and the tuna surimi from step (2). (6) Mix the tuna minced meat from step (1), the tuna paste from step (3), and the soy protein isolate from step (5), and stir for 5 minutes. After molding the mixture with a mold, heat it in a water bath at 40°C for 30 minutes, steam it with boiling water for 5 minutes, and cool it with running water to obtain the finished product.

[0024] Example 2: The specific implementation method is the same as that of Example 1, except that in step (1), the amount of tuna paste added accounts for 20% of the total mass of tuna mince and tuna paste, and 40g of tuna mince and 10g of tuna meat are accurately weighed.

[0025] Example 3: The specific implementation method is the same as that of Example 1, except that in step (1), the amount of tuna paste added accounts for 30% of the total mass of tuna mince and tuna paste, and 35g of tuna mince and 15g of tuna meat are accurately weighed.

[0026] Example 4: The specific implementation method is the same as that of Example 1, except that in step (1), the amount of tuna paste added accounts for 40% of the total mass of tuna mince and tuna paste, and 30g of tuna mince and 20g of tuna meat are accurately weighed.

[0027] Example 5: The specific implementation method is the same as that of Example 1, except that in step (1), the amount of tuna paste added accounts for 50% of the total mass of tuna mince and tuna paste, and 25g of tuna mince and 25g of tuna meat are accurately weighed.

[0028] Example 6: The specific implementation method is the same as that of Example 4, except that salt is not added in step (3).

[0029] Example 7: The specific implementation method is the same as that of Example 4, except that the amount of salt added in step (3) is 0.5% of the total mass of tuna mince and tuna paste.

[0030] Example 8: The specific implementation method is the same as that of Example 4, except that the amount of salt added in step (3) is 1% of the total mass of tuna mince and tuna paste.

[0031] Example 9: The specific implementation method is the same as that of Example 4, except that the amount of salt added in step (3) is 1.5% of the total mass of tuna mince and tuna paste.

[0032] Example 10: The specific implementation method is the same as that of Example 4, except that the amount of salt added in step (3) accounts for 2% of the total mass of tuna mince and tuna paste.

[0033] Example 11: The specific implementation method is the same as that of Example 4, except that the amount of salt added in step (3) is 2.5% of the total mass of tuna mince and tuna paste.

[0034] Example 12: The specific implementation method is the same as that of Example 4, except that TG enzyme is not added in step (4).

[0035] Example 13: The specific implementation method is the same as that of Example 4, except that the amount of TG enzyme added in step (4) is 0.1% of the total mass of tuna mince and tuna surimi.

[0036] Example 14: The specific implementation method is the same as that of Example 4, except that the amount of TG enzyme added in step (4) is 0.2% of the total mass of tuna mince and tuna surimi.

[0037] Example 15: The specific implementation method is the same as that of Example 4, except that the amount of TG enzyme added in step (4) is 0.3% of the total mass of tuna mince and tuna surimi.

[0038] Example 16: The specific implementation method is the same as that of Example 4, except that the amount of TG enzyme added in step (4) is 0.4% of the total mass of tuna mince and tuna surimi.

[0039] Example 17: The specific implementation method is the same as that of Example 4, except that the amount of TG enzyme added in step (4) is 0.5% of the total mass of tuna mince and tuna surimi.

[0040] Example 18: The specific implementation method is the same as that of Example 4, except that soy protein isolate is not added in step (5).

[0041] Example 19: The specific implementation method is the same as that of Example 4, except that the amount of soy protein isolate added in step (5) accounts for 2% of the total mass of tuna mince and tuna surimi.

[0042] Example 20: The specific implementation method is the same as that of Example 4, except that the amount of soy protein isolate added in step (5) accounts for 4% of the total mass of tuna mince and tuna surimi.

[0043] Example 21: The specific implementation method is the same as that of Example 4, except that the amount of soy protein isolate added in step (5) accounts for 6% of the total mass of tuna mince and tuna surimi.

[0044] Example 22: The specific implementation method is the same as that of Example 4, except that in step (5), the amount of soy protein isolate added accounts for 8% of the total mass of tuna mince and tuna surimi.

[0045] Example 23: The specific implementation method is the same as that of Example 4, except that in step (5), the amount of soy protein isolate added accounts for 10% of the total mass of tuna mince and tuna surimi.

[0046] Comparative Example 1: The amount of tuna paste added accounted for 40% of the total mass of tuna mince and tuna paste. 30g of tuna mince and 20g of tuna meat were accurately weighed. The tuna mince and tuna meat were placed in 3 times the amount of ice water and rinsed for 3 minutes. After standing, the rinsing liquid was poured off. The rinsing was repeated 3 times and drained until no water dripped from the surface. The drained tuna meat was then minced for 5 minutes using a food processor to obtain tuna paste. Salt, accounting for 0% of the total mass of tuna mince and tuna paste, was added to the tuna paste and chopped for 3 minutes. After chopping, the tuna mince was added and mixed for 5 minutes. The mixture was then poured into a mold and placed in a 40℃ water bath for 30 minutes. After gelation, it was steamed for 5 minutes and then cooled with running water.

[0047] Comparative Example 2: The specific implementation method is the same as that of Comparative Example 1, except that salt accounting for 1% of the total mass of tuna mince and tuna paste is added during chopping and mixing.

[0048] Comparative Example 3: The specific implementation method is the same as that of Comparative Example 1, except that salt accounting for 2% of the total mass of tuna mince and tuna paste is added during chopping and mixing.

[0049] Comparative Example 4: The specific implementation method is the same as that of Comparative Example 1, except that salt accounting for 3% of the total mass of tuna mince and tuna paste is added during chopping and mixing.

[0050] Comparative Example 5: The specific implementation method is the same as that of Comparative Example 1, except that salt accounting for 4% of the total mass of tuna mince and tuna paste is added during chopping and mixing.

[0051] Experimental Example 1: The hardness, elasticity, chewiness, gel strength, and cooking loss rate of the reconstituted tuna fillets prepared according to different amounts of raw and auxiliary materials in Comparative Examples 1 to 5 and Examples 1 to 23 were tested respectively. Specific results are shown in […]. Figures 1-8 Meanwhile, the textural properties, gel strength, cooking loss rate, sensory scores, and microstructure of the reconstituted fish fillets before and after salt reduction were compared.

[0052] The determination methods for hardness, elasticity, chewiness, and gel strength were as follows: Reconstituted tuna fillets were subjected to TPA testing using a texture analyzer. The determination method for cooking loss rate was as follows: Fish fillets were cut into uniform 2cm×2cm×2cm cubes, dried, and accurately weighed (M1). The weighed fish fillets were placed in a cooking bag, sealed, and heated in a 90℃ water bath for 20 minutes. After cooling to room temperature, the surface liquid was dried, and the fish fillets were weighed again (M2). The cooking loss rate was calculated using the following formula: Cooking Loss Rate = (M1 - M2) / M1 × 100%. Microstructure was observed using a scanning electron microscope. For sensory evaluation, a sensory evaluation team of 10 personnel with professional sensory evaluation training was selected. The reconstituted fish fillets were evaluated based on five indicators: color, flavor, texture, elasticity, and organization. Specific evaluation criteria are shown in Table 1.

[0053] Table 1 Sensory Evaluation Criteria

[0054] Figure 1 To investigate the effects of adding only salt to traditional tuna mince reconstituted fish fillets in Examples 1-5 on the hardness, elasticity, chewiness, gel strength, and cooking loss rate. Figure 2 The effects of different mass ratios of minced tuna to surimi in Examples 1-5 on the hardness, elasticity, chewiness, gel strength, and cooking loss rate of reconstituted tuna fillets. Figure 3 The effects of different salt addition amounts on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna fillets in Examples 6-11; Figure 4 The effects of different amounts of TG enzyme added in Examples 12-17 on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna mince; Figure 5The effects of different amounts of soy protein isolate added in Examples 18-23 on the hardness, elasticity, chewiness, gel strength and cooking loss rate of reconstituted tuna mince; Figure 6 Comparison of hardness, elasticity, chewiness, gel strength and cooking loss rate between traditional reconstituted fish fillet (Comparative Example 4) and optimized reconstituted fish fillet with reduced salt tuna mince (Example 4); Figure 7 A comparison of sensory scores between traditional reconstituted fish fillets (Comparative Example 4) and optimized reconstituted fish fillets made from reduced-salt tuna mince (Example 4); Figure 8 A comparison of the microstructure of traditional reconstituted fish fillets (Comparative Example 4) and optimized reconstituted fish fillets made from reduced-salt tuna mince (Example 4).

[0055] Depend on Figure 1 It can be seen that with the increase of salt addition, the hardness, elasticity, chewiness, and gel strength of the reconstituted tuna fillets gradually increase, while the cooking loss rate gradually decreases. When the salt content accounts for 3% of the total mass of the tuna mince and tuna paste, the hardness, elasticity, chewiness, and gel strength of the reconstituted fillets reach their maximum values, while the cooking loss rate reaches its minimum value.

[0056] Depend on Figure 2 It can be seen that with the increase of tuna paste addition, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets made from reduced-salt tuna mince gradually increase, while the cooking loss rate gradually decreases. When the tuna paste addition accounts for 50% of the total mass of tuna mince and tuna paste, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets reach their maximum values, while the cooking loss rate is the lowest, and there is no significant difference compared with the 40% addition group. Considering the full utilization of tuna mince, the 40% addition amount was selected.

[0057] Depend on Figure 3 It can be seen that with the increase of salt addition, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets made from reduced-salt tuna mince gradually increase, while the cooking loss rate gradually decreases. When the salt addition accounts for 2% of the total mass of the tuna mince and tuna paste, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets reach their maximum values, while the cooking loss rate reaches its minimum value.

[0058] Depend on Figure 4 It can be seen that with the increase of TG enzyme addition, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets made from reduced-salt tuna mince gradually increased, while the cooking loss rate gradually decreased. When the TG enzyme addition accounted for 0.4% of the total mass of tuna mince and tuna paste, the gel strength of the reconstituted fish fillets reached its maximum value, and there was no significant difference compared with the 0.5% addition group.

[0059] Depend on Figure 5It can be seen that with the increase of the amount of soy protein isolate added, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets made from reduced-salt tuna mince gradually increase, while the cooking loss rate gradually decreases. When the amount of soy protein isolate added accounts for 6% of the total mass of tuna mince and tuna paste, the hardness, elasticity, chewiness, and gel strength of the reconstituted fish fillets reach their maximum values, while the cooking loss rate reaches its minimum value.

[0060] Depend on Figures 6-8 It can be seen that the recombinant fish fillets prepared by adding TG enzyme and soy protein isolate have a 33.3% lower salt content than the traditional 3%, improved texture and gel strength, reduced cooking loss, better sensory quality, more compact and orderly microstructure, more uniform pore size distribution, and fewer large-pore voids.

[0061] Experimental Example 2: The gel strength, hardness, cohesiveness, elasticity, adhesiveness and chewiness of the recombinant fish fillets of Example 4, Example 10, Example 16, Example 21 and Comparative Example 4 were tested respectively. The specific results are shown in Table 2.

[0062] Table 2 Comparison of properties of different reconstituted fish fillets

[0063] Table 2 shows that when the amount of tuna surimi added accounts for 40% of the total mass of tuna mince and tuna surimi, the amount of salt added accounts for 2% of the total mass of tuna mince and tuna surimi, the amount of TG enzyme added accounts for 0.4% of the total mass of tuna mince and tuna surimi, and the amount of soy protein isolate added accounts for 6% of the total mass of tuna mince and tuna surimi, the hardness, elasticity, chewiness, and gel strength of the resulting reconstituted fish fillet are significantly higher than those of the traditional group with 3% added salt. The loss rate during cooking is also lower, and the microstructure is more compact. At the same time, the amount of salt added is reduced by 33.3% compared to the traditional 3%, achieving the goal of salt reduction.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A reconstituted fish fillet made from reduced-salt tuna mince, characterized in that, It is composed of tuna mince, tuna paste, salt, TG enzyme, and soy protein isolate. The amount of tuna paste added accounts for 40% to 50% of the total mass of tuna mince and tuna paste, the amount of salt added accounts for 2% of the total mass of tuna mince and tuna paste, the amount of TG enzyme added accounts for 0.3% to 0.5% of the total mass of tuna mince and tuna paste, and the amount of soy protein isolate added accounts for 6% of the total mass of tuna mince and tuna paste.

2. The reconstituted fish fillet with reduced-salt tuna mince as described in claim 1, characterized in that, The amount of tuna surimi added accounts for 40% of the total mass of tuna mince and tuna surimi, and the amount of TG enzyme added accounts for 0.4% of the total mass of tuna mince and tuna surimi.

3. The method for preparing the reduced-salt tuna minced meat reconstituted fish fillet according to claim 1 or 2, characterized in that, The process includes the following steps: shredding and mixing tuna paste and salt, then adding minced tuna meat, soy protein isolate and TG enzyme and mixing evenly, followed by gelation treatment after shaping the fish fillet, and then cooking to obtain the reduced-salt tuna meat reconstituted fish fillet.

4. The method for preparing reconstituted fish fillets with reduced-salt tuna mince according to claim 3, characterized in that, The tuna paste and salt are chopped for 3 minutes.

5. The method for preparing reconstituted fish fillets with reduced-salt tuna mince according to claim 3, characterized in that, The TG enzyme is dissolved in ultrapure water before use. The tuna paste with added salt is then chopped and mixed with the TG enzyme for 3 minutes.

6. The method for preparing reconstituted tuna fillets with reduced salt content according to claim 3, characterized in that, Before use, the soy protein isolate is fully swollen at a mass ratio of soy protein isolate to water of 1:

4.

7. The method for preparing reconstituted fish fillets with reduced-salt tuna mince according to claim 3, characterized in that, The mixing time after adding the tuna mince and soy protein isolate is 5 minutes.

8. The method for preparing reconstituted tuna fillets with reduced salt content according to claim 3, characterized in that, The fish fillet is shaped using a mold to create a uniform and fixed shape.

9. The method for preparing reconstituted tuna fillets with reduced salt content according to claim 3, characterized in that, The gelation temperature is 40℃~45℃, and the time is 20~40 minutes.

10. The method for preparing the reconstituted fish fillet of reduced-salt tuna mince according to claim 3, characterized in that, The cooking method is boiling water steam cooking, the cooking temperature is 100℃, and the time is 3~8 minutes.

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