Composite minced fish and shellfish gel as well as preparation method and application thereof

Abstract

The invention relates to composite minced fish and shellfish gel as well as a preparation method and application thereof, and belongs to the technical field of aquatic product processing. The invention provides composite minced fish and shellfish gel which comprises the following components in parts by mass: 80-120 parts of fish meat, 80-120 parts of shellfish meat, 0.5-1.5 parts of calcium salt and 0.5-1.5 parts of sodium chloride, and the calcium salt is calcium citrate or calcium chloride. The fish meat and the shellfish meat are mixed to prepare meat paste, metal calcium ions are added, the composite minced fish and shellfish gel is prepared through two-stage heating, and the content of a umami substance IMP in the gel is increased by activating AMP deaminase. Meanwhile, paramyosin in the shellfish meat also improves the gel property of the product. The invention provides a method for improving the delicate flavor of the surimi product, and provides a new theory for developing high-quality aquatic products.

Description

Technical Field

[0001] The present invention relates to the technical field of aquatic product processing, and in particular to a composite fish and shellfish minced gel, a preparation method and application thereof. Background Art

[0002] As an important aquatic resource, the unique umami flavor of fish and shellfish directly determines consumer acceptance and the economic value of the product. Inosine-5′-monophosphate (IMP) is a key umami flavoring substance in fish and shellfish. Its umami-enhancing ability is 40 times stronger than that of monosodium glutamate (MSG), and it is considered the primary umami flavoring substance. However, studies have shown significant differences in the amount of IMP accumulated after death in fish and shellfish, which directly affects the flavor characteristics of each.

[0003] After fish die, oxygen is cut off, and normal cellular metabolic activity gradually ceases. ATP, unable to regenerate through aerobic respiration, rapidly degrades into adenosine diphosphate (ADP) and adenylate (AMP). Subsequently, it is rapidly degraded into inosine phosphate (IMP) by various endogenous enzymes. IMP, under the combined action of microbial enzymes and endogenous phosphohydrolases, generates inosine (HxR) and hypoxanthine (Hx). The accumulation of HxR and Hx leads to a bitter taste, depriving the fish of its original umami flavor. This degradation process follows a typical metabolic pathway: ATP → ADP → AMP → IMP → HxR → Hx. The degradation of IMP to HxR proceeds very slowly, and IMP accumulates at high levels in fish for a period of time. This step is considered the most critical and rate-limiting step. Unlike fish, shellfish exhibit significant differences in their AMP metabolic pathways. Kawashima et al. discovered two AMP degradation pathways in scallop muscle: AMP → adenosine (AdR) → HxR → Hx, and AMP → IMP → HxR → Hx. AMP phosphorylase (AMPP) catalyzes the rapid conversion of AMP to AdR and HxR, resulting in the accumulation of IMP (IMP) far below that found in fish (maintaining only trace levels). However, as a key flavoring substance (with a threshold of 0.025 g / 100 mL), IMP is often added exogenously to processed products to enhance umami flavor. Therefore, by regulating the activity of AMP-degrading enzymes (such as AMP deaminase and AMP phosphorylase), IMP production can be targeted, reducing the addition of exogenous substances and meeting current label cleanliness requirements. This may become a key strategy for enhancing the umami flavor of processed shellfish products.

[0004] Based on this, the present invention is proposed. Summary of the Invention

[0005] The application aims to provide a compound fish and shellfish surimi gel, a preparation method thereof and an application thereof, so as to solve the problem of improving umami by adding umami substances from outside.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The application provides a compound fish and shellfish surimi gel, which comprises the following components in mass fractions:

[0008] 80-120 parts of fish meat, 80-120 parts of shellfish meat, 0.5-1.5 parts of calcium salt and 0.5-1.5 parts of sodium chloride;

[0009] The calcium salt is calcium citrate or calcium chloride.

[0010] Preferably, the fish meat is one or more of the following: carp, silver carp, Hexagrammos otakii and Sebastiscus alternatus.

[0011] Preferably, the shellfish meat is one or more of the following: Chlamys variegata, Chlamys variegata and Patinopecten yessoensis.

[0012] The application provides a preparation method of the compound fish and shellfish surimi gel, comprising the following steps:

[0013] (1) mixing fish meat, shellfish meat, sodium chloride and calcium salt, and chopping and stirring to obtain mixed meat paste;

[0014] (2) performing two-stage heating on the mixed meat paste, and cooling to obtain a compound fish and shellfish surimi gel product.

[0015] Preferably, the chopping and stirring in step (1) is performed at a temperature of 2-6 DEG C for 15-25 min.

[0016] Preferably, the first-stage heating in the two-stage heating in step (2) is performed at a temperature of 35-45 DEG C for 15-25 min.

[0017] Preferably, the second-stage heating in the two-stage heating in step (2) is performed at a temperature of 85-95 DEG C for 25-35 min.

[0018] The application provides an application of the compound fish and shellfish surimi gel or the compound fish and shellfish surimi gel prepared by the preparation method in the preparation of high-quality seafood food.

[0019] The application has the following technical effects and advantages:

[0020] The present invention has demonstrated through experiments that the IMP content in mixed minced meat can be significantly increased by utilizing the AMP deaminase enzyme present in fish meat. Adding calcium ions significantly increases the activity of AMP deaminase, further increasing the amount of flavor compounds in the minced meat. Furthermore, calcium ions provide nutritional reinforcement and enhance gelation. By comparing the effects of different heating temperatures and times on flavor compounds, the optimal first heating temperature and time were determined. This ultimately increased the IMP content and gel strength of the composite fish and shellfish minced meat product, providing a method for enhancing the flavor of seafood and offering a new theory for developing high-quality minced fish products. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the experimental flow chart for the dynamic changes of IMP content in fish and shellfish under the treatment of exogenous AMP deaminase;

[0022] Figure 2 is the change of flavor nucleotide content in the control group during storage;

[0023] Figure 3 is the change of flavor nucleotide content in the enzyme-added group during storage;

[0024] Figure 4 is the content of IMP in minced meat under different heating conditions;

[0025] Figure 5 The status of gel in different treatment groups;

[0026] Figure 6 The texture test results of gels in different treatment groups;

[0027] Figure 7 The results of gel strength test of gels in different treatment groups are shown;

[0028] Figure 8 The results of gel strength test of gels in different metal ion treatment groups are shown;

[0029] Figure 9 These are the results of determination of total thiol content in the gels of different metal ion treatment groups. DETAILED DESCRIPTION

[0030] The present invention provides a composite fish and shellfish surimi gel, comprising the following components in parts by weight:

[0031] 80-120 parts of fish, 80-120 parts of shellfish, 0.5-1.5 parts of calcium salt and 0.5-1.5 parts of sodium chloride;

[0032] The calcium salt is calcium citrate or calcium chloride;

[0033] The fish meat is preferably 100 parts; the shellfish meat is preferably 100 parts; the calcium salt is preferably 1 part; and the sodium chloride is preferably 1 part.

[0034] In the present invention, the fish meat is one or more of carp, silver carp, otaki hexapod and xu's flathead.

[0035] In the present invention, the shellfish meat is one or more of bay scallop, Chlamys farreri and Yesso scallop.

[0036] The present invention provides a method for preparing the composite fish and shellfish surimi gel, comprising the following steps:

[0037] (1) fish meat, shellfish meat, sodium chloride and calcium salt are mixed and chopped to obtain a mixed minced meat;

[0038] (2) The mixed minced meat is heated in two stages and cooled to obtain a composite fish and shellfish minced gel product.

[0039] In the present invention, the chopping temperature in step (1) is 2-6°C, preferably 4°C, and the chopping time is 15-25 minutes, preferably 20 minutes.

[0040] In the present invention, the temperature of the first stage of the two-stage heating in step (2) is 35-45° C., preferably 40° C., and the heating time is 15-25 min, preferably 20 min.

[0041] In the present invention, the temperature of the second stage heating in the two-stage heating in step (2) is 85-95° C., preferably 90° C., and the heating time is 25-35 min, preferably 30 min.

[0042] The present invention provides the use of the composite fish and shellfish minced gel or the composite fish and shellfish minced gel prepared by the preparation method in preparing high-quality seafood.

[0043] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] Composite fish and shellfish surimi gel

[0046] 500g of Otaki hexapod dorsal muscle, 500g of Yesso scallop adductor muscle, 5g of calcium chloride and 5g of sodium chloride.

[0047] Preparation method of composite fish and shellfish surimi gel

[0048] (1) 500 g of dorsal muscle of Otaki croaker, 500 g of adductor muscle of Yesso scallop, 5 g of sodium chloride and 5 g of calcium chloride were mixed and chopped at 4°C for 20 min to obtain a mixed meat paste;

[0049] (2) The mixed minced meat is heated in two stages, with the first stage heating temperature being 40°C and the heating time being 20 min, and the second stage heating temperature being 90°C and the heating time being 30 min, and then rapidly cooled with running water to obtain a composite fish and shellfish minced meat gel product.

[0050] Example 2

[0051] Composite fish and shellfish surimi gel

[0052] 400g of Otaki hexapod dorsal muscle, 500g of Yesso scallop adductor muscle, 3g of calcium citrate and 6g of sodium chloride.

[0053] Preparation method of composite fish and shellfish surimi gel

[0054] (1) 400 g of dorsal muscle of Otaki croaker, 500 g of adductor muscle of Yesso scallop, 6 g of sodium chloride and 3 g of calcium citrate were mixed and chopped at 4°C for 20 min to obtain a mixed meat paste;

[0055] (2) The mixed minced meat is heated in two stages, with the first stage heating temperature being 40°C and the heating time being 20 min, and the second stage heating temperature being 90°C and the heating time being 30 min, and then rapidly cooled with running water to obtain a composite fish and shellfish minced gel.

[0056] Example 3

[0057] Composite fish and shellfish surimi gel

[0058] 600g of Otaki hexapod dorsal muscle, 500g of Yesso scallop adductor muscle, 5g of calcium citrate and 4g of sodium chloride.

[0059] Preparation method of composite fish and shellfish surimi gel

[0060] (1) 600 g of dorsal muscle of Otaki croaker, 500 g of adductor muscle of Yesso scallop, 4 g of sodium chloride and 5 g of calcium citrate were mixed and chopped at 4°C for 20 min to obtain a mixed meat paste;

[0061] (2) The mixed minced meat was mixed with 40 g of calcium citrate, allowed to stand at 4°C for 20 min, and then heated in two stages. The first stage was heated at 45°C for 20 min, and the second stage was heated at 90°C for 30 min. The mixture was then rapidly cooled with running water to obtain a composite fish and shellfish minced gel.

[0062] Experimental Example 1: Effect of AMP Deaminase on Flavor Nucleotides in Surimi and Surimi

[0063] The dynamic changes of IMP content in fish and shellfish under the treatment of exogenous AMP deaminase were compared experimentally. The experimental process is as follows: Figure 1 The specific method is as follows:

[0064] The back muscle of the big six-line fish and the adductor muscle of the yesso scallop were taken respectively, 3.0 g of muscle tissue was accurately weighed, 15.0 mL of pre-cooled 53 mmol / L sodium citrate buffer solution (pH = 6.0) was added, and homogenized at 35000 rpm for 30 seconds using a high-speed homogenizer under ice bath conditions. The operation was repeated 3 times to fully disrupt the tissue. The homogenate was then centrifuged at 10000g for 20 minutes at 4°C, and the supernatant was collected as the crude enzyme of AMP deaminase. Under stirring in an ice bath at 0°C, an equal volume of anhydrous ethanol was slowly added to each crude enzyme solution to a final concentration of 60% to obtain a mixed solution. The mixed solution was placed at 4°C for 1 hour, and then the precipitate was collected by centrifugation and freeze-dried to obtain FAMPD (big six-line fish AMP deaminase) and SAMPD (yesso scallop AMP deaminase) for use.

[0065] The dorsal muscle of the fish (Otaki ocellaris) and the adductor muscle of the Japanese scallop (Yokohama scallop) were chopped and processed at 4°C for 2 minutes to obtain fish and shellfish mince, respectively. The enzyme-added group and the control group were set up. The enzyme-added group added exogenous AMPD (fish mince + SAMPD, shellfish mince + FAMPD), while the control group did not receive any treatment (all operations were completed at a low temperature of 4°C to ensure the stability of enzyme activity). The treated samples were stored at 4°C and samples were taken at 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 minutes. The changes in the content of flavor nucleotides AMP and IMP in the samples were determined by HPLC. The specific method is as follows:

[0066] Accurately weigh 0.2g of minced meat for each group, add 2.0mL of pre-cooled 5% (w / v) perchloric acid (HClO4) solution, and put in grinding steel balls. Use a high-throughput tissue grinder to homogenize at 800rpm for 60s, and repeat the homogenization 3 times. After the sample is fully broken, use 2M KOH solution to adjust the pH to 3.0, and finally use ultrapure water to make up to 4mL. After centrifugation at 3000g for 5min, take 0.8mL of supernatant and add 0.2mL of 0.1mol / L phosphate buffer (pH=7.5) and shake well. After passing through a 0.45μm filter membrane, place it at -40℃ for testing. The entire operation is carried out at 4℃ or in an ice bath, and the sample is determined by high-performance liquid chromatography. Analytical conditions: SinoChrom ODS-BP (4.6 mm × 250 mm, 5 μm) chromatographic column; using an ODS-BP column (4.6 mm × 250 mm, 5 μm), methanol-phosphate buffer (0.05 mol / L, pH = 6.4) as the mobile phase, DAD detector (254 nm), column temperature 30°C, flow rate 0.8 mL / min, injection volume 10 μL.

[0067] Changes in the content of flavor nucleotides in the control group during storage Figure 2 As shown, the horizontal axis represents time (min), and the vertical axis represents the AMP and IMP content (μmol / g). The changes in the flavor nucleotide content of the enzyme-added group during storage are shown in Figure 3 As shown, the abscissa represents time (min), and the ordinate represents AMP and IMP content (μmol / g).

[0068] according to Figure 2 and Figure 3 The results show that during storage, the accumulation of IMP in shellfish minced meat was significantly lower than that in fish minced meat. This difference stems from the fundamental differences in the AMP metabolic pathways of the two. Highly active endogenous AMP deaminase in fish muscle drives the efficient conversion of AMP to IMP, while in shellfish, competition with AMP phosphorylase results in a higher conversion of AMP to AdR rather than IMP. However, when FAMPD was added to shellfish minced meat, the IMP content rapidly increased to 3.45 μmol / g within 0 to 20 minutes and continued to increase to a peak of 5.42 μmol / g (a 57% increase).

[0069] In contrast, the IMP content in surimi was 7.12 μmol / g at the beginning of storage and remained at approximately 7 μmol / g after 120 minutes, directly related to the high activity of endogenous AMP deaminase. However, the addition of SAMPD had no significant effect on the IMP content in surimi. This not only confirms the significant enhancement of the AMP→IMP pathway by FAMPD but also suggests that FAMPD can be an effective flavor enhancer for shellfish. This confirms that the addition of fish-derived AMP deaminase to shellfish surimi significantly increases the IMP content after 20 minutes of storage.

[0070] In summary, adding AMPD extracted from fish to shellfish minced meat significantly increases the IMP content, so fish minced meat is added to shellfish minced meat to increase its IMP content.

[0071] Experimental Example 2: Determination of the Temperature for Promoting IMP Formation in Gel Preparation

[0072] The experiment was divided into three groups, namely, fish mince group (FS), shellfish mince group (SS) and mixed fish and shellfish mince group (MFS). The fish mince group used the back muscle of the bigeye croaker, the shellfish mince group used the adductor muscle of the Hokkaido scallop, and the mixed fish and shellfish mince group used the back muscle of the bigeye croaker and the adductor muscle of the Hokkaido scallop, with a mass ratio of 1:1. 500 g of meat was taken from each group, 5 g of sodium chloride was added, and minced for 20 minutes at 4°C to obtain minced meat. The prepared minced meat was put into a polyethylene casing with a diameter of 3 cm and the two ends were tied tightly. The three groups of samples were subjected to low-temperature gelation treatment for 60 minutes in a water bath at 30°C and 40°C, respectively. Samples were taken at 0, 10, 20, 40, and 60 minutes of heating, respectively. The content of IMP in the minced meat was determined by the method in Experimental Example 1. The detection results of the content of IMP in the minced meat under different heating conditions are shown in the figure below. Figure 4 shown.

[0073] according to Figure 4 As shown, the IMP production in all three groups of samples heated at 40°C was significantly higher than that in the 30°C treatment group. The SS group reached a maximum IMP content of 0.45 μmol / g after heating at 40°C for 20 minutes, while the MFS group significantly increased IMP content to 1.89 μmol / g under the same conditions, approximately 4.2 times that of the SS group alone. This suggests that heating at 40°C for 20 minutes is the optimal condition for IMP production, and that the mixed fish and shellfish treatment significantly increased IMP production, thereby better preserving the umami characteristics of shellfish.

[0074] In order to fully induce gelation in the FS, SS and MFS groups and ensure their texture characteristics, a two-stage heating method was used. The first stage heating (low temperature gelation) was heating in a constant temperature water bath at 40°C for 20 min; the second stage heating (high temperature setting) was heating in a water bath at 90°C for 30 min to obtain gels in different treatment groups. The state characteristics of the gels in different treatment groups are shown in the figure below. Figure 5 shown.

[0075] according to Figure 5Significant differences in gel characteristics were observed among the FS, SS, and MFS groups after the first and second heating stages. The FS group formed a dense gel with a relatively smooth surface and a uniform, fine texture. This characteristic stems from the heat-induced denaturation, aggregation, and cross-linking of myofibrillar proteins in the surimi. The resulting three-dimensional network imparts excellent elasticity and mechanical strength to the surimi, enabling it to maintain a stable morphology. In contrast, the SS group also formed a dense gel after heating, but its appearance differed from that of the FS group. Its surface was slightly rough, its texture was relatively loose, and its structural integrity was poor. The MFS group formed a regular, uniform gel after heating, with a surface smoothness intermediate between the FS and SS groups and a dense, elastic texture. This improved gel is attributed to the synergistic interaction of the protein components during heating, resulting from the combination of fish and shellfish surimi: the fish surimi proteins provide a stable gel network framework, while the shellfish surimi proteins likely enhance the strength of the gel network through specific molecular interactions. This synergistic effect not only mitigates the gel defects of shellfish surimi alone but also preserves the unique flavor and nutritional properties of shellfish proteins.

[0076] Experimental Example 3: Effects of Components on Gel Flavor Properties and Quality

[0077] The experiment was divided into three groups: surimi (FS), surimi (SS), and mixed fish and shellfish (MFS). The surimi group used dorsal muscle from taki (Six-line fish), the surimi group used adductor muscle from the Japanese scallop (Scallop ocellaris), and the mixed fish and shellfish (MFS) group used dorsal muscle from taki (Six-line fish), adductor muscle from the Japanese scallop (Scallop ocellaris), with a mass ratio of 1:1. 1000g of meat from each group was minced and processed at 4°C for 20 minutes with 5g of sodium chloride. The minced meat was then placed into 3cm-diameter polyethylene casings and tightly tied at both ends. The three groups of samples were heated in two stages: the first at 40°C for 20 minutes and the second at 90°C for 30 minutes. After rapid cooling under running water, the gels from surimi (FS), surimi (SS), and mixed fish and shellfish (MFS) were obtained and stored in a refrigerated environment at 4°C.

[0078] 1. Flavor characteristics determination

[0079] 1.1 Determination of flavor nucleotides

[0080] Accurately weigh 0.2 g of gel sample for each group, and use the method in Example 1 to determine the content of flavor nucleotides AMP and IMP in the sample.

[0081] 1.2 Determination of free amino acid content

[0082] Each group of 2.5 g of gel sample was accurately weighed, 15.0 mL of pre-cooled 15% trichloroacetic acid solution was added, and homogenized in an ice bath for 2 min. Then the mixture was centrifuged at 8000 g for 10 min at 4°C, and the supernatant was collected. The pH value was adjusted using the gradient adjustment method: first adjust to pH = 8.5 with 2 mol / L KOH solution, and then adjust to pH 9.0 with 1 mol / L KOH solution. The Elite AAK amino acid kit was used, and the volume was made up to 25 mL by adding the derivative buffer (preparation method: accurately weigh solid component A 1.24 g and solid component B 7.63 g, and make up to 500 mL with ultrapure water), and vortex for 30 seconds. Take 1 mL of the above solution, add 0.5 mL of derivatization reagent, mix well, seal, and derivatize in a 60°C water bath for 1 hour. After derivatization, add 1 mL of equilibration buffer (preparation method: accurately weigh solid component A 0.91 g and solid component B 3.58 g, and make up to 250 mL with ultrapure water), filter through a 0.22 μm microporous filter, and reserve for use. Determination: gradient elution determination analysis was performed using high performance liquid chromatography (HPLC). Analysis conditions: mobile phase A: 50% acetonitrile solution, ultrasonic for 30 min; mobile phase B: weigh 4.1 g of solid component B, dissolve in 950 mL of ultrapure water, adjust the pH to 6.4-6.8, then add 10 mL of N,N-dimethylformamide, make up to 1 L, filter and degas for 30 min; column: Dalian Elite Analytical Instruments Co., Ltd. amino acid analysis column (Elite AAK, 5 μm, 4.6 mm x 250 mm); detector: diode array detector (DAD); detection wavelength: 360 nm; injection volume: 10 μL, mobile phase flow rate: 1 mL / min.

[0083] The content of taste compounds in the gels of different treatment groups is shown in Table 1.

[0084] Table 1 Content of taste compounds in gels of different treatment groups

[0085]

[0086]

[0087]

[0088] According to Table 1, there are significant differences in the content of taste nucleotides in the three meat paste gel samples, and the content of IMP changes significantly: the content of IMP in SS is the lowest, only 0.03 mg / g, while the content of IMP in FS reaches 3.76 ± 0.32 mg / g (p < 0.05), but the content of IMP increases to 3.36 ± 0.51 mg / g after mixing, and TAV > 1, which is significantly higher than that of single abalone paste raw material.

[0089] Free amino acids, as one of the main flavoring substances in food, exhibit three taste characteristics: umami, sweet, and bitter. Their content and composition are important indicators of the flavor of aquatic products. Based on their different structural characteristics, amino acids are mainly divided into three categories: umami amino acids (DAA), sweet amino acids (SAA), and bitter amino acids (BAA). The higher the flavor amino acid content, the stronger and richer the flavor. Compared with the SS group gel and the FS group gel, the alanine and glutamic acid contents in the MFS group gel increased to 1.49±0.10mg / g and 0.52±0.17mg / g, respectively. Glutamic acid, as the main umami amino acid in aquatic products, has a synergistic effect when coexisting with alanine, which can enhance the umami flavor of fish.

[0090] 2. Texture determination

[0091] The TMS-PRO texture analyzer, equipped with a TA4 (20 mm diameter) cylindrical probe, was used to measure the gel samples, each measuring 20 mm in diameter. The test parameters were set as follows: TPA-1000N mode, an initial force of 2.5 N, a speed of 60 mm / min before, during, and after the test, and a compression ratio of 30%. The gels were measured for hardness (N), chewiness (mJ), elasticity (mm), and cohesion (Raito). Each sample was measured in six replicates.

[0092] The texture test results of gels in different treatment groups are as follows Figure 6 As shown in the figure, A represents the hardness of different minced meat gels, B represents the chewiness of different minced meat gels, C represents the elasticity of different minced meat gels, and D represents the cohesion of different minced meat gels.

[0093] The elasticity of surimi products mainly comes from the three-dimensional network structure of surimi gel, which can directly reflect the degree of gelation in surimi. Cohesion refers to the degree to which the internal components (such as proteins, polysaccharides, etc.) of food are bound together by intermolecular forces during chewing or cutting. Chewing property is the product of hardness, elasticity coefficient and cohesion. Figure 6 The hardness and chewiness of the MFS gel were higher than those of the single SS and FS gels, reaching 8.7 N and 7.36 mJ, respectively. This improvement may be due to the formation of a denser gel network between scallop paramyosin and fish myofibrillar proteins through hydrophobic interactions or disulfide bonds. Both exhibited the same pattern of change, as hardness and chewiness are linearly correlated within a certain range. Elasticity reflects the gel's ability to recover after the extrusion force is removed and is closely related to changes in the protein network structure within the surimi gel. The elasticity of the FS, SS, and MFS gels was 1.33 mJ, 1.55 mJ, and 1.64 mJ, respectively. The MFS gel had slightly higher elasticity than the individual components. This phenomenon may be due to the synergistic effect of fish and shellfish proteins, which optimizes the gel network structure. These results indicate that the mixed fish and shellfish surimi system effectively improves the texture of single meat surimi.

[0094] 3. Gel Strength Determination

[0095] The gel sample was cut into a cylinder with a diameter of 25 mm and a height of 25 mm. A P / 5s cylindrical probe was used with a penetration distance of 10 mm, a trigger force of 5 g, and a test speed of 60 mm / min to measure the breaking force (g) and breaking distance (mm). Each group was measured 6 times and the average value was taken. The formula for calculating the gel strength is as follows:

[0096] Gel strength (g·mm) = breaking force (g) × breaking distance (mm).

[0097] The gel strength test results of the gels in different treatment groups are shown in Figure 2. Figure 7 shown.

[0098] The gel strength of minced meat directly characterizes the mechanical properties of its gel network structure and is the core parameter for evaluating the quality of minced meat. Figure 7 The gel strength of the FS group was the highest at 98.0 g·cm, while the gel strength of the SS group was the lowest at only 61.1 g·cm. The gel strength of the MFS group increased to 83.62 g·cm, a significant 36.8% improvement compared to the surimi alone. This indicates that the addition of surimi effectively improved the gel properties of surimi.

[0099] Experimental Example 4: Effects of different metal ions on the quality and flavor of mixed fish and shellfish surimi gel

[0100] The experiment was divided into four groups: control group, K + Treatment group, Zn 2+ Treatment groups and Ca 2+ Treatment groups, wherein the control group was prepared by adding 5 g of sodium chloride to 1000 g of dorsal muscle of Otaki six-line fish and adductor muscle of Yesso scallop in a mass ratio of 1:1, and chopping and blending them at 4°C for 20 min to obtain a mixed minced meat. The mixed minced meat was put into a polyethylene casing with a diameter of 3 cm, and the two ends were tightly tied. The mixed minced meat was heated in two stages, the first stage was heated at 40°C for 20 min, and the second stage was heated at 90°C for 30 min, and then quickly cooled in running water to obtain mixed fish and shellfish minced meat gels; K + In the treatment group, 5g of potassium chloride was added to the mixed minced meat, and the rest of the steps were the same; Zn 2+ In the treatment group, 5g zinc chloride was added to the mixed minced meat, and the rest of the steps were the same; Ca 2+ In the treatment group, 5g of calcium chloride was added to the mixed minced meat, and the rest of the steps were the same. The gel strength and total thiol content of the different treatment groups were measured. The gel strength was measured in the same way as in Example 3, and the total thiol content was measured as follows:

[0101] Take 1g (accurate to 0.0001g) of minced gel sample and homogenize it with 9mL of 0.6M KCl solution (10000rpm, 3×10s), filter it with double-layer absorbent cotton gauze, take 100μL of filtrate, add 2.5mL phosphate buffer (0.1M KH2PO4 / K2HPO4, 1mM EDTA, pH=8.0, containing 8M urea) and 50μL of 10mM DTNB, vortex mix, keep it away from light for 15min, and then centrifuge it (4500g, 5min). Take the supernatant, measure the absorbance at 412nm, and calculate the total thiol content. The calculation formula is as follows:

[0102]

[0103] Where A is the absorbance at 412 nm, and C is the protein concentration (mg / mL).

[0104] The gel strength test results of the gels in the different metal ion treatment groups are as follows: Figure 8 As shown. Figure 8 It can be seen that there are significant differences in the gel strength of the gels treated with different metal ions. Compared with the control group (81.69 g·cm), K + 、Zn 2+ and Ca 2+ The gel strengths of the treated groups were significantly improved, reaching 169.85 g·cm, 107.62 g·cm, and 334.34 g·cm, respectively, with increases of 108%, 32%, and 309%, respectively. 2+ The enhancement effect of K is the most significant, which may be because divalent metal ions cause changes in protein conformation and interact with the negative charges on the protein polypeptide chain to form a double layer of ionic groups, reducing the electrostatic interaction between protein molecules, thereby changing the protein-protein and protein-water interactions. + and Zn2 + The promoting effect of metal ions is relatively weak. This may be because different metal ions carry different amounts of positive charge and diameters, which can change the electrostatic repulsion between proteins or shield the charge of proteins, so that the attractive and repulsive forces are in a balanced state, significantly affecting the interactions between proteins, protein-protein and protein-solvent, and thus affecting the denaturation, unfolding and aggregation process of proteins. On the other hand, ionic strength has a significant effect on protein solubility, resulting in changes in the protein content in the product, thereby affecting the protein gel properties.

[0105] Thiol is one of the most active reactive groups in myofibrillar protein. Its content reflects the degree of protein oxidation and denaturation. Its content change can be used as a key indicator to characterize protein oxidation and denaturation and gel network construction. The results of total thiol content determination in gels treated with different metal ions are shown in Figure 2. Figure 9 As shown. Figure 9 It can be seen that K + 、Zn 2+ and Ca 2+ The total thiol content in the treated group gels decreased significantly (p < 0.05). This may be because the addition of metal ions caused the myosin structure to unfold, resulting in the exposure of embedded thiol groups, which then underwent cross-linking reactions in an oxidative environment to induce the formation of disulfide bonds. The formation of disulfide bonds is positively correlated with density and gel strength, which is mutually verified by the gel strength. 2+ The total thiol content in the treated group was significantly reduced, with a decrease of 55.2%.

[0106] In summary, K + 、Zn 2+ and Ca 2+ The gel strength, flavor nucleotides and total thiol content of the treated group were better than those of the control group, among which Ca 2+ The treatment group was the best.

[0107] As can be seen from the above examples, the present invention provides a composite fish and shellfish minced gel, as well as its preparation method and application. Experiments have shown that adding fish-derived AMP phosphorylase can significantly increase the IMP content in shellfish minced meat. Fish and shellfish meat are mixed to prepare minced meat. The addition of metallic calcium ions not only increases the activity of AMP phosphorylase, further increasing the flavor compounds in the minced meat, but also improves the quality of the gel. A two-stage heating method is used. By comparing the effects of different heating temperatures and times on the gel flavor compounds, the optimal first-stage heating temperature and time are determined, ultimately increasing the content of flavor compounds in the composite fish and shellfish minced gel and the quality of the gel. This provides a method for enhancing the umami flavor of seafood and offers a new theory for developing high-quality aquatic products.

[0108] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A composite fish and shellfish minced gel, characterized in that: The composition includes the following parts by mass: 80-120 parts of fish, 80-120 parts of shellfish, 0.5-1.5 parts of calcium salt and 0.5-1.5 parts of sodium chloride; The calcium salt is calcium citrate or calcium chloride.

2. The composite fish and shellfish surimi gel according to claim 1, characterized in that The fish meat is one or more of carp, silver carp, otaki hexapod and xu's flathead.

3. The composite fish and shellfish surimi gel according to claim 1, characterized in that The shellfish meat is one or more of bay scallop, chlamys farreri and scallop.

4. The method for preparing the composite fish and shellfish surimi gel according to any one of claims 1 to 3, characterized in that: The steps include: (1) fish meat, shellfish meat, sodium chloride and calcium salt are mixed and chopped to obtain a mixed minced meat; (2) The mixed minced meat is heated in two stages and cooled to obtain a composite fish and shellfish minced gel product.

5. The preparation method according to claim 4, characterized in that The chopping temperature in step (1) is 2-6° C., and the chopping time is 15-25 min.

6. The preparation method according to claim 4, characterized in that The temperature of the first stage of the two-stage heating in step (2) is 35-45° C., and the heating time is 15-25 minutes.

7. The preparation method according to claim 4, characterized in that The temperature of the second stage of the two-stage heating in step (2) is 85-95° C., and the heating time is 25-35 minutes.

8. Use of the composite fish and shellfish surimi gel according to any one of claims 1 to 3 or the composite fish and shellfish surimi gel prepared by the preparation method according to any one of claims 4 to 7 in the preparation of high-quality seafood.

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