Ultrahigh pressure-microcapsule synergistic tuna recombinant product nutrition stability improving method

Abstract

The invention discloses a method for improving the nutrition stability of a tuna recombinant product through ultrahigh pressure-microcapsule synergistic interaction. The method comprises the following steps: firstly, unfreezing a tuna raw material, peeling, removing bones and removing fascia, chopping, mixing and forming, and inducing myofibrillar protein denaturation and crosslinking through ultrahigh pressure treatment to form a gel matrix with a more compact three-dimensional network structure, thereby realizing construction of a tuna recombinant system with low fat loss; and then fish oil microcapsules are introduced in the minced fillet chopping and mixing stage, and the gel performance and the nutritional quality of the recombinant product are remarkably improved through the synergistic effect of ultrahigh pressure physical field regulation and control and a microcapsule embedding technology. According to the invention, the process limitation of traditional two-stage heating is broken through, texture improvement and nutrition retention are synchronously realized under a low-temperature condition, and a new technical scheme is provided for industrial production of high-quality surimi products.

Description

Technical Field

[0001] This invention relates to the field of aquatic food processing, specifically to a method for improving the nutritional stability of recombinant tuna products through synergistic enhancement of ultra-high pressure microcapsules. Background Technology

[0002] Surimi products are foods made primarily from fish protein, characterized by their rich nutrition, diverse flavors, and convenience. These products are not only low in fat but also rich in high-quality protein and various vitamins, while being low in cholesterol, making them a popular health food. Tuna, a typical deep-sea fish, has tender and delicious flesh, rich in high-quality protein, various minerals (such as calcium, phosphorus, and iron), and vitamin D. It also contains abundant unsaturated fatty acids, including DHA and EPA, making it a high-quality raw material for surimi products. However, in the production of surimi products, key technical bottlenecks such as low gel strength, insufficient elasticity, and poor water retention are commonly encountered, severely restricting the improvement of product quality and the expansion of its market application.

[0003] During tuna processing, byproducts comprise approximately 50%-70% of the whole fish, and are rich in high-quality fish oil. This fish oil is rich in Omega-3 fatty acids, which play important physiological roles such as promoting visual system development and enhancing nervous system function. By re-incorporating fish oil into surimi products, not only can the added value of the byproducts be increased, but the nutritional value of the products can also be improved. However, the highly unsaturated fatty acids in fish oil are highly susceptible to oxidation during processing and storage, which not only affects product quality but may also produce harmful substances. Summary of the Invention

[0004] [Technical Issues] It improves the gel strength and other quality properties of surimi products, while achieving low fat loss, reducing the nutritional loss of fish oil during processing, and maintaining a high retention rate of heat-sensitive nutrients such as ω-3 fatty acids.

[0005] [Technical Solution] In view of the aforementioned problems in the prior art, this invention provides a method for improving the nutritional stability of recombinant tuna products through a synergistic effect of ultra-high pressure (UHPP) and microcapsules. UHPP, as an emerging non-thermal processing technology, has been widely used in the field of aquatic product processing in recent years due to its advantages such as low processing cost, high safety, short processing time, and minimal nutrient loss. This technology significantly improves the gelation properties of surimi by disrupting non-covalent bonds in proteins and inducing conformational changes in protein molecules. Furthermore, this invention, based on specific and suitable UHPP treatment, can effectively improve the gelation ability of inferior surimi while maximizing the retention of heat-sensitive nutrients. Capsules, as a transport carrier, can effectively encapsulate and protect the active ingredients in fish oil. By forming a physical barrier to block oxygen contact, the oxidation rate of fish oil can be significantly slowed down, improving its stability and bioavailability. Combining UHPP and microcapsule technologies holds promise for developing novel surimi product processing techniques that combine excellent gelation properties with nutrient preservation, providing an innovative solution for improving the quality of surimi products.

[0006] The specific technical solution is as follows: A method for improving the nutritional stability of recombinant tuna products through synergistic effects of ultra-high pressure microcapsules includes the following steps: (i) Preparation of fish oil microcapsules: A composite hydrated solution containing gelatin and carrageenan was mixed with fish oil, and a primary emulsion was formed by high-speed shearing; the pH of the obtained primary emulsion was adjusted, and then gelatin and carrageenan were induced to coagulate under constant stirring to form a first wall material at the oil droplet interface, thus obtaining a monolayer microcapsule dispersion system; a carboxymethyl chitosan aqueous solution was mixed with the monolayer microcapsule dispersion system, the pH of the system was adjusted, and carboxymethyl chitosan was electrostatically adsorbed onto the first wall material under constant stirring to form a bilayer wall material structure, thus obtaining a bilayer microcapsule dispersion system; tannic acid was added to the obtained bilayer microcapsule dispersion system, cross-linked and cured, and stored at low temperature to obtain fish oil microcapsules; (II) Preparation of tuna reconstituted products: After thawing, skinning, deboning and removing the fascia of the tuna raw material, the fish meat is obtained. Then, it is first air-chopped, and salt and the obtained fish oil microcapsules are added in sequence during the chopping process and chopped until the fish meat paste becomes sticky. The chopped meat paste is filled into a mold to obtain a shaped reconstituted product. The shaped reconstituted product is then placed in the cavity of an ultra-high pressure equipment for ultra-high pressure treatment. After treatment, it is heated and cooked in a water bath to obtain the tuna reconstituted product.

[0007] In one embodiment of the present invention, the mass ratio of gelatin to carrageenan in the composite hydrated solution is 3:1.

[0008] In one embodiment of the present invention, the composite hydrated solution is prepared by mixing gelatin aqueous solution and carrageenan aqueous solution; the concentrations of gelatin aqueous solution and carrageenan aqueous solution are both 0.1 wt%-2 wt%, and the volume ratio of the two is 3:1.

[0009] In one embodiment of the present invention, the volume fraction of fish oil relative to the complex hydrated solution is 10%-40%.

[0010] In one embodiment of the present invention, the high-speed shearing speed is 6000-12000 rpm and the shearing time is 2-8 min.

[0011] In one embodiment of the present invention, the pH of the obtained primary emulsion is adjusted to 2-6, the stirring speed is 100-500 rpm, and the stirring time is 10-40 min to form a monolayer microcapsule dispersion system.

[0012] In one embodiment of the present invention, the pH of the carboxymethyl chitosan aqueous solution is 3-8.

[0013] In one embodiment of the present invention, the mass ratio of carboxymethyl chitosan to gelatin is 3:1.

[0014] In one embodiment of the present invention, a carboxymethyl chitosan aqueous solution is mixed with a single-layer microcapsule dispersion system, the pH of the system is adjusted to 3-8, the stirring speed is set to 100-500 rpm, and the stirring time is 10-40 min to form a double-layer wall structure, thereby obtaining a double-layer microcapsule dispersion system.

[0015] In one embodiment of the present invention, the amount of tannic acid added relative to the total wall material (gelatin, carrageenan and carboxymethyl chitosan) is 5 wt%-20 wt%.

[0016] In one embodiment of the present invention, the stirring speed is set to 100-500 rpm and the stirring time is set to 2-7 h for cross-linking and curing.

[0017] In one embodiment of the present invention, the storage temperature is 4-25 °C.

[0018] In one embodiment of the present invention, tuna includes yellowfin tuna, skipjack tuna, etc.

[0019] In one embodiment of the present invention, the tuna raw material is thawed at 4-10 °C for 3-5 hours.

[0020] In one embodiment of the present invention, the chopping process specifically includes: firstly, chopping in the air at 0-4 ℃, then adding salt and fish oil microcapsules in sequence and continuing to chop until the meat paste becomes viscous.

[0021] In one embodiment of the present invention, the air-cutting time is 1.5-3 minutes.

[0022] In one embodiment of the present invention, salt is added and chopping is continued for 1.5-3 minutes.

[0023] In one embodiment of the present invention, fish oil microcapsules are added and the mixture is further chopped for 1.5-3 minutes.

[0024] In one embodiment of the present invention, the amount of salt added relative to the total mass of the fish is 1.5 wt%-3 wt%.

[0025] In one embodiment of the present invention, the amount of fish oil microcapsules added relative to the total mass of fish meat is 5 wt%-30 wt%.

[0026] In one embodiment of the present invention, during the process of adding fish oil microcapsules and continuing to chop, auxiliary materials may also be added, and the amount of auxiliary materials added relative to the total mass of fish meat is 0-30 wt%.

[0027] In one embodiment of the present invention, the excipients may be selected from one or more of starch, seasonings, and food colloids.

[0028] In one embodiment of the present invention, the chopped minced meat is stuffed into casings, injected into molds, or extruded to form a block, column, or spherical molded body.

[0029] In one embodiment of the present invention, the conditions for ultra-high pressure treatment are: treatment pressure of 100-400 MPa and treatment time of 10-40 min.

[0030] In one embodiment of the present invention, the water bath heating and curing temperature is 70-100 ℃, and the processing time is 20-40 min.

[0031] In one embodiment of the present invention, step (ii) specifically includes: S2.1 Raw material pretreatment: Using tuna (yellowfin tuna, bonito, etc.) as raw material, after thawing, the fish meat is obtained by removing the skin, bones and tendons; S2.2 Chopping and Shaping Process: Chop the fish meat obtained in step S1, and then add salt and fish oil microcapsules in sequence during the chopping process until the fish meat paste becomes sticky; then, fill the chopped meat paste into the mold to obtain a reconstituted product of the preset shape. S2.3 Ultra-high pressure induced gelation treatment: The molded and reconstituted product obtained in step S2 is placed into the ultra-high pressure equipment cavity for ultra-high pressure treatment, in order to replace the first gelation process in the traditional two-stage water bath heating. S2.4. Curing treatment: The recombinant product after ultra-high pressure gelation in step S3 is subjected to water bath heating treatment to achieve curing of the product.

[0032] In one embodiment of the present invention, step (a) specifically includes: (1.1) Preparation of wall material hydration solution The wall materials carrageenan, gelatin and carboxymethyl chitosan were dissolved in water and mixed to obtain an aqueous phase, and the corresponding aqueous solutions were obtained. (1.2) Preparation of emulsion A composite hydrated solution was prepared by mixing aqueous solutions of gelatin and carrageenan. Fish oil was then added to the composite hydrated solution, and a primary emulsion was formed through high-speed shearing. (1.3) Preparation of monolayer microcapsules The pH of the primary emulsion obtained in step (1.2) was adjusted to 2-6, and then gelatin and carrageenan were induced to coagulate under constant stirring to form the first wall material at the oil droplet interface, thus obtaining a monolayer microcapsule dispersion system. (1.4) Preparation of bilayer microcapsules Adjust the pH of the carboxymethyl chitosan aqueous solution to 3-8, add it to the monolayer microcapsule dispersion system obtained in step (1.3) in proportion, adjust the pH of the system to 3-8 again, and under constant stirring, allow the carboxymethyl chitosan to be electrostatically adsorbed on the first wall material to form a double-layer wall material structure, thus obtaining a double-layer microcapsule dispersion system. (1.5) Solidification of microcapsules Tannic acid was added to the bilayer microcapsule dispersion system obtained in step (1.4) to solidify the wall material through cross-linking. After low-temperature storage, the final fish oil microcapsule product was obtained.

[0033] The present invention provides a recombinant tuna product prepared based on the above method.

[0034] The present invention also provides the application of the above-mentioned reconstituted tuna products in the food industry.

[0035] Beneficial effects (1) The ultra-high pressure non-thermal processing was used to replace the traditional water bath (40℃) gelation process, which reduced the damage to proteins caused by the processing temperature during gelation and improved the retention of nutrients. At the same time, the pressure induced denaturation and cross-linking of myofibril proteins, forming a gel matrix with a denser three-dimensional network structure, which improved the quality characteristics of the recombinant products and achieved the construction of a tuna recombinant system with low fat loss.

[0036] (2) By using ultra-high pressure processing combined with microencapsulation technology, a fish oil stabilization protection system was constructed, which significantly improved the stability of fish oil in recombinant tuna products. At the same time, the traditional antioxidant addition process was simplified, effectively reducing the nutritional loss of fish oil during processing and maintaining the retention rate of heat-sensitive nutrients such as ω-3 fatty acids by about 33%. Attached Figure Description

[0037] Figure 1 Gel strength diagrams of the reconstituted fish paste products of Comparative Examples 1-4 and Example 1; Figure 2 Elasticity diagrams of the reconstituted surimi products of Comparative Examples 1-4 and Example 1; Figure 3 Chewability graphs of the reconstituted fish paste products of Comparative Examples 1-4 and Example 1; Figure 4 Cohesiveness diagrams of the surimi reconstituted products of Comparative Examples 1-4 and Example 1; Figure 5 Figure showing the cooking loss of the reconstituted fish surimi products of Comparative Examples 1-4 and Example 1; Figure 6 The graph shows the fat loss of the reconstituted fish paste products of Comparative Examples 1-4 and Example 1. Figure 7 Moisture distribution diagrams of the reconstituted fish surimi products of Comparative Examples 1-4 and Example 1; Figure 8 Color diagrams of the reconstituted fish surimi products of Comparative Examples 1-4 and Example 1; Figure 9 Microstructure diagrams of the reconstituted fish surimi products of Comparative Examples 1-4 and Example 1; Figure 10 pH graphs of the reconstituted fish surimi products of Comparative Examples 5-7 and Example 2; Figure 11 TBARS diagrams of the reconstituted fish surimi products of Comparative Examples 5-7 and Example 2; Figure 12 Figure showing the carbonyl content of the reconstituted fish surimi products from Comparative Examples 5-7 and Example 2. Figure 13 The graph shows the DHA and EPA content of the recombinant fish surimi products of Comparative Examples 5-7 and Example 2; Figure 14 Gel strength diagrams of the reconstituted fish paste products of Comparative Examples 5-7 and Example 2; Figure 15 The graph shows the cooking loss and fat loss rate of the reconstituted fish surimi products of Comparative Examples 5-7 and Example 2. Detailed Implementation

[0038] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0039] Testing process: 1. Gel property test: The matured surimi gel was cut into cylindrical shapes (Φ20 mm × 25 mm), and the gel strength was measured using a TA-XT Plus texture analyzer (Stable Micro Systems, Godalming, UK).

[0040] 。

[0041] 2. Texture Properties Testing: The texture properties of reconstituted products subjected to different pressure treatments were determined using a TA-XT Plus texture analyzer. The samples were placed on the testing stage and tested in TPA mode. The texture analyzer probe was model P50, and the testing parameters were: pre-test speed 2 mm / s, test speed 1 mm / s, post-test speed 1 mm / s, strain 30%, and trigger force 5 g.

[0042] 3. Cooking loss test: The result is calculated by the weight ratio of the sample before and after heat treatment, where M0 is the mass of the sample before heat treatment, and M1 is the mass of the sample after the surface moisture is wiped off. The final result is the average of three repeated tests.

[0043] The formula for calculating cooking loss is as follows: Cooking loss (%) = [(M0-M1) / M0] × 100%.

[0044] 4. Fat Loss Test: Weigh approximately 8 g of sample (M0), wrap it in filter paper (M1), and place it in a 50 mL centrifuge tube. Centrifuge at 8000 rpm for 15 min. After centrifugation, weigh the sample (M2) and the filter paper (M3). Then, place the filter paper in an oven at 60℃ and dry for 4 h. Weigh the dried filter paper (M4).

[0045] The formula for calculating fat loss is as follows: Fat loss (%) = [(M3-M1) / (M0-M2)] × 100%.

[0046] 5. Moisture Distribution Test: A cylindrical sample with a diameter of 2.0 cm and a height of 2.5 cm was weighed, wrapped in plastic wrap, and placed in a 40 mm NMR tube for measurement. The transverse relaxation time T2 was determined using a CPMG pulse sequence with the following parameters: TE = 0.50 ms, TW = 4000.00 ms, NS = 8.00, NECH = 8000.00. The obtained data were used to invert the T2 spectrum using specialized software.

[0047] 6. Whiteness Test: The color of the sample was measured using a HunterLab colorimeter. The colorimeter was turned on, the colorimetric software was entered, and after calibration, the sample was placed in front of the light-transmitting aperture for color measurement. All measurements were performed at three random locations on each sample surface. The sample luminance value (L*), red-green hue value (a*), and yellow-blue hue value (b*) were recorded, and the whiteness was calculated.

[0048] The formula for calculating whiteness (W) is: 。

[0049] 7. Microstructure Testing: The microstructure of the reconstituted product was tested using a thermal scanning electron microscope. After freeze-drying, the sample was fixed on the sample stage of the scanning electron microscope and sputtered with gold. The sample was then placed in the observation chamber and magnified at 1000× to observe the microstructure of the sample.

[0050] 8. pH test: Weigh about 5 g of sample, add 50 ml of 0.1 mol / L potassium chloride solution, homogenize at 8000 r / min for 1 min, filter with filter paper and measure the pH value of the filtrate.

[0051] 9. TBARS test: Weigh about 2 g of sample, add 10 mL of trichloroacetic acid solution, homogenize at 10000 r / min for 1 min, place on a shaker for 30 min, filter with filter paper, take 5 mL of filtrate, add 5 mL of 0.02 mol / L thiobarbituric acid, incubate in a 95 ℃ water bath for 10 min, cool to room temperature, and measure the absorbance A0 at a wavelength of 532 nm.

[0052] The formula for calculating TBARS is: TBARS = A0 × 2.77.

[0053] 10. Carbonyl group test: Weigh approximately 0.5 g of the sample, add 1 mL of 10 mmol dinitrophenylhydrazine solution, homogenize at 10000 rpm for 1 min, and react in the dark for 1 h. To terminate the reaction, add 1 mL of 20% trichloroacetic acid solution, centrifuge at 8000 rpm for 10 min at 4 ℃, and collect the precipitate. Wash the precipitate with 1 mL of ethanol-ethyl acetate (1:1, v / v) solution, repeating three times. Add 3 mL of 6 mol / L guanidine hydrochloride solution to the precipitate, mix well, react at 37 ℃ for 15 min, centrifuge at 8000 rpm for 10 min, and measure the absorbance of the supernatant at 370 nm.

[0054] Carbonyl content (C) 羰基 The calculation formula is:

[0055] Where A1 refers to the absorbance at 370 nm, C refers to the protein mass concentration in mg / mL, and ε refers to the molar extinction coefficient of 22000 mol / (L·cm).

[0056] 11. DHA and EPA Content Test: Take 10g of sample and add chloroform-methanol (2:1, v / v) mixed solution at a material-to-liquid ratio of 1:20. Homogenize at 8000rpm for 2min, then let stand at 4℃ for 24h. After filtration, add 30ml of 0.9% NaCl solution to the filtrate and shake for 2min to promote separation. Transfer the mixture to a separatory funnel and let stand for 3h. Collect the lower chloroform phase and dry it with anhydrous Na2SO4. Finally, remove the organic solvent by rotary evaporation at 40℃ to obtain total lipids. Determination is performed using gas chromatography-flame ionization detector.

[0057] Example 1 A method for preparing recombinant tuna products based on ultra-high pressure physical field regulation to inhibit fat loss includes the following steps: (1) Raw material pretreatment: The tuna (yellowfin tuna, skipjack tuna, etc.) is thawed at 4 ℃ for 4 hours, and then the skin, bones and fascia are removed to obtain the fish meat.

[0058] (2) Chopping and mixing Place the fish meat obtained in step (1) into a meat grinder. First, chop it in the air at 4°C for 2 minutes. Then, add 1.5% of the total mass of the fish meat with salt and continue chopping for 2 minutes until the fish meat paste becomes sticky.

[0059] (3) Molding process The chopped fish paste from step (2) is stuffed into collagen casings to make cylindrical fish paste sausages with a diameter of about 2.0 cm and a height of about 2.5 cm, for subsequent ultra-high pressure treatment and heat treatment.

[0060] (4) Ultra-high pressure induced gelation treatment The reconstituted product formed in step (3) was placed in an ultra-high pressure chamber and treated with a pressure of 300 MPa for 30 minutes.

[0061] (5) Aging treatment The recombinant product after ultra-high pressure gelation in step (4) was placed in a 90 ℃ water bath and heated for 30 min, and then cooled to obtain the finished product.

[0062] Example 2 A method for improving the nutritional stability of recombinant tuna products through synergistic effects of ultra-high pressure microcapsules includes the following steps: (I) Preparation of fish oil microcapsules (1.1) Preparation of wall material hydration solution Carrageenan, gelatin, and carboxymethyl chitosan were dissolved in water and mixed to form 1 wt% carrageenan aqueous solution, 1 wt% gelatin aqueous solution, and 1 wt% carboxymethyl chitosan aqueous solution.

[0063] (1.2) Preparation of emulsion A composite hydrated solution was prepared by mixing gelatin aqueous solution and carrageenan aqueous solution at a ratio of 3:1 (v / v). Then, fish oil with a relative volume fraction of 20% of the composite hydrated solution was added to the composite hydrated solution, and a primary emulsion was formed by high-speed shearing at 10,000 rpm for 4 min.

[0064] (1.3) Preparation of monolayer microcapsules The pH of the primary emulsion obtained in step (1.2) was adjusted to 3.5, and then gelatin and carrageenan were induced to coagulate under constant stirring at 300 rpm for 30 min to form the first layer of wall material at the oil droplet interface.

[0065] (1.4) Preparation of bilayer microcapsules Adjust the pH of the carboxymethyl chitosan aqueous solution to 5.0. Add the gelatin to carboxymethyl chitosan mass ratio of 3:1 in the composite hydrated solution of gelatin and carboxymethyl chitosan in step (1.2) to the monolayer microcapsule dispersion system obtained in step (1.3). Adjust the pH of the system to 5.0 again. Then, under constant stirring at 300 rpm for 30 min, the carboxymethyl chitosan is electrostatically adsorbed onto the first wall material to form a bilayer structure.

[0066] (1.5) Solidification of microcapsules Add 7 wt% tannic acid relative to the total wall material (carrageenan, gelatin and carboxymethyl chitosan) to the bilayer microcapsule dispersion system obtained in step (1.4), and solidify the wall material through cross-linking under constant stirring at 300 rpm for 4 h. After storage at 4°C, the final fish oil microcapsule product is obtained.

[0067] (II) Preparation of recombinant fish products Except for the chopping step, the remaining preparation operations of the recombinant product, including raw material pretreatment, ultra-high pressure induced gelation treatment, and maturation treatment, are the same as in Example 1. The difference between this example and Example 1 is that fish oil microcapsules are added during the chopping process described in step (2), and the amount of fish oil microcapsules added is 15% of the fish meat mass. The specific steps are as follows: (2.1) Raw material pretreatment: Same as in Example 1.

[0068] (2.2) Chopping and mixing: The fish meat obtained in step (2.1) is placed in a meat grinder. First, it is chopped in the air at 4°C for 2 minutes. Then, 1.5% of the total mass of the fish meat is added and chopped for 2 minutes. Next, 15% of the total mass of the fish meat is added and fish oil microcapsules (obtained in Part (I)) are added and chopped for 2 minutes until the fish meat paste becomes viscous.

[0069] (2.3) Molding process: Same as in Example 1.

[0070] The chopped fish paste from step (2.2) is stuffed into collagen casings to form cylindrical fish paste sausages with a diameter of about 2.0 cm and a height of about 2.5 cm, for subsequent ultra-high pressure processing and heat treatment.

[0071] (2.4) Ultra-high pressure induced gelation treatment: Same as in Example 1.

[0072] (2.5) Curing treatment: Same as in Example 1.

[0073] Comparative Example 1 Step (4) of Example 1 was adjusted to be heated in a water bath at 40 °C for 30 min, while the rest remained the same as in Example 1, to obtain the tuna recombinant product.

[0074] Comparative Example 2 Step (4) of Example 1 was adjusted to be treated with ultra-high pressure of 100 MPa for 30 min, while the rest remained the same as in Example 1, and the tuna reconstituted product was obtained.

[0075] Comparative Example 3 Step (4) of Example 1 was adjusted to be treated with ultra-high pressure of 200 MPa for 30 min, while the rest remained the same as in Example 1, and the tuna recombinant product was obtained.

[0076] Comparative Example 4 Step (4) of Example 1 was adjusted to be treated with ultra-high pressure of 400 MPa for 30 min, while the rest remained the same as in Example 1, and the tuna reconstituted product was obtained.

[0077] Comparative Example 5 A method for preparing recombinant tuna products without ultra-high pressure processing or microencapsulation technology includes the following steps: The amount of unmicroencapsulated fish oil added during the chopping process in step (2.2) of Part 2 of Example 2 was adjusted (the amount added was the same as the fish oil content in the fish oil microcapsules), and step (2.4) was adjusted to be heated in a water bath at 40 °C for 30 min. Everything else remained the same as in Example 2, and the reconstituted tuna product was obtained.

[0078] Comparative Example 6 A method for preparing recombinant tuna products without ultra-high pressure processing and solely using microencapsulation technology includes the following steps: Step (2.4) in Part 2 of Example 2 was adjusted to be heated in a water bath at 40 °C for 30 min, and ultra-high pressure treatment was no longer used. Everything else remained the same as in Example 2, and the reconstituted tuna product was obtained.

[0079] Comparative Example 7 A method for preparing recombinant tuna products using only ultra-high pressure processing without microencapsulation technology includes the following steps: Adjust the amount of unmicroencapsulated fish oil added during the chopping process in step (2.2) of Part 2 of the embodiment (the amount added is the same as the fish oil content in the fish oil microcapsules), and keep everything else the same as in Example 2 to obtain the tuna recombinant product.

[0080] The recombinant tuna products prepared in the above embodiments and comparative examples were tested, and the test results are as follows: Figures 1-4 The graphs show the gel strength and textural properties of the reconstituted surimi products from Comparative Examples 1-4 and Example 1. From... Figures 1-4 It can be seen that, under the same temperature and time conditions, the gel strength of the samples showed a significant upward trend with increasing pressure. When the treatment pressure was increased to 200 MPa, significant differences in gel strength began to appear, reaching a maximum at 400 MPa. Texture analysis showed that the key indicators such as chewiness and cohesiveness of the ultra-high pressure heat-treated samples were significantly improved compared to the atmospheric pressure-treated group. At 300 MPa and higher pressures, the cohesiveness of the gel was significantly better than the control group, reflecting a denser and more uniform network structure, which helps improve the morphological stability of the product during processing and consumption, reducing breakage or loosening.

[0081] Figures 5-6 The images show cooking loss and fat loss graphs for the reconstituted fish surimi products of Comparative Examples 1-4 and Example 1. Figures 5-6 It can be seen that, compared with traditional water bath treatment (Comparative Example 1), ultra-high pressure treatment can significantly reduce the cooking loss, moisture loss, and fat loss of surimi products, indicating that ultra-high pressure treatment effectively improves the gelation properties of surimi. Among them, the 300 MPa ultra-high pressure treatment group had the lowest cooking loss and fat loss, which was significantly better than other groups. As the pressure continued to increase, the degree of protein denaturation increased, leading to excessive protein aggregation or structural collapse, which partially weakened the gelation properties.

[0082] Figure 7 This is a moisture distribution diagram of the reconstituted fish surimi products from Comparative Examples 1-4 and Example 1. From... Figure 7 It can be seen that the ultra-high pressure treatment group showed significant changes compared to the atmospheric pressure group. T 21 ,T 22 , T 23 The relaxation time showed a decreasing trend. With increasing pressure, the fixed water content of the sample ( T 22 Increased content and free water ( T 23 The content decreased.

[0083] Figure 8 Color diagrams of the reconstituted fish surimi products from Comparative Examples 1-4 and Example 1. From... Figure 8 It can be seen that, compared with traditional water bath treatment, the reconstituted surimi products treated with ultra-high pressure have a higher whiteness value, indicating that appropriate ultra-high pressure treatment can effectively improve the color quality of surimi products.

[0084] Figure 9 Microstructure diagrams of the reconstituted fish surimi products from Comparative Examples 1-4 and Example 1. From... Figure 9 It can be seen that the samples treated under normal pressure exhibit a loose and unevenly distributed gel network with numerous irregular large pores inside. The samples treated under ultra-high pressure show a significantly increased density of the gel network, a gradually more uniform distribution, and smaller pores.

[0085] Figure 10 pH graphs for the reconstituted fish surimi products of Comparative Examples 5-7 and Example 2. From... Figure 10 It can be seen that the addition of different forms of fish oil and processing techniques have a significant impact on the oxidation degree of reconstituted fish paste products. The sample with directly added fish oil after traditional heat treatment (Comparative Example 5) had the lowest pH value, indicating the most severe oxidation. In contrast, both microencapsulation and ultra-high pressure technologies significantly inhibited protein oxidation, with pH values ​​increasing by 0.84% ​​and 0.67%, respectively. Notably, the sample using both microencapsulation and ultra-high pressure technologies showed a significantly higher pH increase (1.68%) than the sum of the increases in the microencapsulation and ultra-high pressure groups, exhibiting the best oxidative stability. Ultra-high pressure treatment and microencapsulation technology produced a synergistic effect in this system. The low-temperature environment of ultra-high pressure eliminated thermal oxidizing factors, while the physical barrier effect of microcapsules blocked the lipid-protein interaction oxidation pathway. Together, they constructed a dual-protection system with the best inhibitory effect on protein oxidation.

[0086] Figure 11 TBARS diagrams for the reconstituted fish surimi products of Comparative Examples 5-7 and Example 2. From... Figure 11As can be seen, compared with Comparative Example 5, using microencapsulation technology alone reduced the TBARS value by 21.77%. Using ultra-high pressure technology alone reduced the TBARS value by 34.51%, indicating that both technologies can inhibit the occurrence and development of lipid oxidation to a certain extent. The combination of ultra-high pressure and microencapsulation resulted in the lowest TBARS, with a reduction of up to 67.27%. Specific test data are shown in Table 1: Table 1

[0087] The results show that the TBARS value of the product obtained by combining the two technologies in Example 2 significantly exceeds the effect of each individual technology and is significantly higher than the sum of the effects of the two individual technologies, indicating that ultra-high pressure treatment and microcapsule encapsulation technology have a synergistic effect in this system.

[0088] Figure 12 This is a graph showing the carbonyl content of the reconstituted fish surimi products from Comparative Examples 5-7 and Example 2. From... Figure 12 As can be seen, compared with the samples treated with direct addition of fish oil and traditional water bath treatment (Comparative Example 5), the use of microencapsulation technology alone reduced the carbonyl content by 14.85%, and the use of ultra-high pressure technology alone reduced the carbonyl content by 16.05%, indicating that microencapsulation and ultra-high pressure treatment can effectively protect fish oil and slow down its induced protein oxidation. The sample with the best overall effect was the one treated with ultra-high pressure combined with microencapsulation, which reduced the carbonyl content by 18.80%, significantly lower than the two single-technology treatment groups, showing a synergistic effect in inhibiting oxidation.

[0089] Figure 13 This is a graph showing the DHA and EPA content of the reconstituted fish surimi products from Comparative Examples 5-7 and Example 2. From... Figure 13 As can be seen, compared with Comparative Example 5, using only ultra-high pressure treatment (Comparative Example 7) increased the retention rates of DHA and EPA by 10.60% and 16.98%, respectively, while using only microencapsulation technology (Comparative Example 6) increased the retention rates of DHA and EPA by 11.20% and 4.73%, respectively. In Example 2, the retention rate of DHA increased by 33.40%, and the retention rate of EPA increased by 33.17%. Specific test data are shown in Table 2. Table 2

[0090] The results show that the product obtained by the method in Example 2 is significantly better than each individual technology in terms of fatty acid retention, and significantly better than the sum of the effects of the two individual technologies. This fully demonstrates that ultra-high pressure and microencapsulation technology have a clear synergistic effect in protecting ω-3 fatty acids, ultimately increasing the overall retention rate of key nutrients by about 33%.

[0091] Figure 14 The gel strength graphs are for the reconstituted fish paste products of Comparative Examples 5-7 and Example 2. From... Figure 14 It can be seen that, compared with the direct addition of fish oil, the gel strength of the samples treated with fish oil microcapsules and ultra-high pressure was significantly improved. Among them, the sample treated with ultra-high pressure and microcapsules (Example 2) had the highest gel strength, which was similar to that of Example 1. p <0.05). This combined technology, when used with liquids such as fish oil, contributes to a denser and more stable gel network structure, enhancing gel performance.

[0092] Figure 15 The graph shows the cooking loss and fat loss rates of the reconstituted fish surimi products from Comparative Examples 5-7 and Example 2. Figure 15 As can be seen, under the same processing method, the groups with added fish oil microcapsules all exhibited lower cooking loss and fat loss rates. Compared with Comparative Example 5, the fat loss rate of Comparative Example 6 was significantly reduced by 38.77%. Compared with Comparative Example 7, the fat loss rate of Example 2 was reduced by 19.61%. Example 2 had the lowest cooking loss among all groups, and its fat loss rate was not significantly different from that of Example 1. This indicates that, based on the addition of fish oil, the combined use of microcapsule technology and ultra-high pressure technology can further effectively reduce cooking loss and significantly inhibit fat loss.

[0093] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for improving the nutritional stability of recombinant tuna products through synergistic enhancement of ultra-high pressure microcapsules, characterized in that, Includes the following steps: (i) Preparation of fish oil microcapsules: A composite hydrated solution containing gelatin and carrageenan was mixed with fish oil, and a primary emulsion was formed by high-speed shearing; the pH of the obtained primary emulsion was adjusted, and then gelatin and carrageenan were induced to coagulate under constant stirring to form a first wall material at the oil droplet interface, thus obtaining a monolayer microcapsule dispersion system; a carboxymethyl chitosan aqueous solution was mixed with the monolayer microcapsule dispersion system, the pH of the system was adjusted, and carboxymethyl chitosan was electrostatically adsorbed onto the first wall material under constant stirring to form a bilayer wall material structure, thus obtaining a bilayer microcapsule dispersion system; tannic acid was added to the obtained bilayer microcapsule dispersion system, cross-linked and cured, and stored at low temperature to obtain fish oil microcapsules; (II) Preparation of tuna reconstituted products: After thawing, skinning, deboning and removing the fascia of the tuna raw material, the fish meat is obtained. Then, it is first air-chopped, and salt and the obtained fish oil microcapsules are added in sequence during the chopping process and chopped until the fish meat paste becomes sticky. The chopped meat paste is filled into a mold to obtain a shaped reconstituted product. The shaped reconstituted product is then placed in the cavity of an ultra-high pressure equipment for ultra-high pressure treatment. After treatment, it is heated and cooked in a water bath to obtain the tuna reconstituted product.

2. The method according to claim 1, characterized in that, The mass ratio of gelatin to carrageenan in the composite hydrated solution is 3:

1.

3. The method according to claim 1, characterized in that, The complex hydrated solution was prepared by mixing gelatin aqueous solution and carrageenan aqueous solution; the concentrations of gelatin aqueous solution and carrageenan aqueous solution were both 0.1 wt%-2 wt%; the volume fraction of fish oil in the complex hydrated solution was 10%-40%.

4. The method according to claim 1, characterized in that, A carboxymethyl chitosan aqueous solution was mixed with a single-layer microcapsule dispersion system, the pH of the system was adjusted to 3-8, the stirring speed was set to 100-500 rpm, and the stirring time was 10-40 min to form a double-layer wall structure, thus obtaining a double-layer microcapsule dispersion system; the mass ratio of carboxymethyl chitosan to gelatin was 3:

1.

5. The method according to claim 1, characterized in that, The amount of tannic acid added relative to the total mass of gelatin, carrageenan and carboxymethyl chitosan is 5 wt%-20 wt%.

6. The method according to claim 1, characterized in that, The chopping process specifically includes: first, chopping in the air at 0-4 ℃, then adding salt and fish oil microcapsules in sequence and continuing to chop until the minced meat becomes viscous; the process of adding fish oil microcapsules and continuing to chop also includes adding auxiliary materials, which can be one or more of starch, seasonings and food colloids.

7. The method according to claim 6, characterized in that, The amount of salt added relative to the total mass of fish meat is 1.5wt%-3wt%; the amount of fish oil microcapsules added relative to the total mass of fish meat is 5wt%-30wt%; and the amount of excipients added relative to the total mass of fish meat is 0-30wt%.

8. The method according to any one of claims 1-7, characterized in that, The conditions for ultra-high pressure treatment are: treatment pressure of 100-400 MPa and treatment time of 10-40 min; water bath heating and curing temperature of 70-100 ℃ and treatment time of 20-40 min.

9. A reconstituted tuna product prepared by the method according to any one of claims 1-8.

10. The application of the reconstituted tuna product according to claim 9 in the food industry.

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