High-stability low-concentration fish protein adhesive emulsion and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a high-stability low-concentration fish protein adhesive emulsion and a preparation method thereof. The method comprises the following steps: mixing a fish protein glue solution, a microbial glutamine transaminase solution and a plant polysaccharide solution to obtain a mixed solution; then mixing with corn oil, and dispersing in a dispersion machine to obtain a mixed emulsion; and finally, carrying out steady-state cross-linking under the condition of 0-4 DEG C, and carrying out enzyme deactivation after the cross-linking is finished, so as to obtain the high-stability low-concentration fish protein adhesive emulsion. The microbial glutamine transaminase and the fish protein glue are cross-linked at low temperature, so that the problem that the fish protein glue emulsion is easy to layer is solved, and the prepared fish protein glue emulsion is relatively good in stability and meets the requirements of industrial production.

Description

Technical Field

[0001] This application belongs to the field of food processing technology, specifically relating to a high-stability, low-concentration fish protein latex and its preparation method. Background Technology

[0002] Fish protein gelatin, as an inexpensive raw material, has a low risk of zoonotic diseases, high safety, and similar physical and chemical properties to mammalian protein gelatin, making it a good alternative to mammalian protein gelatin. However, due to the poor emulsifying properties of fish protein gelatin (compared to mammalian gelatin), the stability of fish protein gelatin emulsions is poor.

[0003] Currently, modification strategies for fish protein gels include enzymatic, chemical, and physical methods. Microbial transglutaminase is a highly efficient enzymatic cross-linking agent; however, the typical reaction temperature for cross-linking fish protein gel emulsions with microbial transglutaminase is around 50°C. However, the fish protein gel emulsion itself is in a state of free thermal motion, exhibiting instability under these conditions. Cross-linking at this temperature (50°C) may lead to changes in protein structure, such as the breakdown from a more stable triple helix to an unstable single helix, which presents certain limitations. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly stable, low-concentration fish protein latex and its preparation method, specifically adopting the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a highly stable, low-concentration fish protein latex, comprising the following steps:

[0006] Fish protein gel solution, microbial transglutaminase solution and plant polysaccharide solution are mixed to obtain a mixed solution;

[0007] The mixed solution was mixed with corn oil and dispersed in a disperser to obtain a mixed emulsion;

[0008] The mixed emulsion was subjected to steady-state cross-linking at 0-4℃. After the cross-linking was completed, enzyme inactivation was performed to obtain the high-stability, low-concentration fish protein latex.

[0009] This invention utilizes biological transglutaminase as an enzyme cross-linking agent to achieve cross-linking in microorganisms under steady-state conditions (e.g., gelation at 4°C), forming a more uniform and stable emulsion system. By constructing a multi-dimensional index system of stability, rheological properties, emulsifying properties, physicochemical properties, and interaction forces, a technical solution for the scalable preparation of highly stable, low-concentration fish protein gel latex is proposed. Specifically, biological transglutaminase catalyzes the reaction between the ε-amino group of lysine residues and the γ-carboxamide group of glutamine residues in proteins, forming GL covalent bonds between intramolecular and intermolecular cross-links. Plant polysaccharides (konjac gum, sodium alginate, and guar gum) are natural high-molecular-weight polysaccharides. This invention effectively improves the stability of fish protein gel latex by utilizing microbial transglutaminase and polysaccharide composite modification.

[0010] As a further preferred embodiment, the volume ratio of the fish protein gel solution, the microbial transglutaminase solution, and the plant polysaccharide solution is 1:1:1.

[0011] As a further preferred embodiment, the fish protein gel solution and the microbial transglutaminase solution are obtained by the following steps:

[0012] Fish protein gelatin and microbial transglutaminase were heated at 40°C until completely dissolved.

[0013] As a further preferred embodiment, the plant polysaccharide solution is obtained by the following steps:

[0014] The plant polysaccharide was obtained by heating it at 50°C until it was completely dissolved.

[0015] As a further preferred embodiment, the plant polysaccharide is selected from at least one of konjac gum, sodium alginate, and guar gum.

[0016] As a further preferred embodiment, the volume ratio of the mixed solution to corn oil is 1:1.

[0017] As a further preferred embodiment, the speed of dispersion in the disperser is 12000 r / min and the time is 3 min.

[0018] As a further preferred embodiment, the steady-state cross-linking temperature is 4°C and the time is 18h; the enzyme inactivation temperature is 90°C and the time is 10min.

[0019] Secondly, the present invention provides a highly stable, low-concentration fish protein latex, which is prepared by the above-described preparation method.

[0020] As a further preferred embodiment, the high-stability, low-concentration fish protein gel latex contains 0.5% fish protein gel, 0.05% microbial transglutaminase, and 0.05% plant polysaccharides by weight percentage.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention provides a method for preparing a high-stability, low-concentration fish protein gel latex. By using microbial transglutaminase to crosslink fish protein gel at low temperature, the problem of easy separation of fish protein gel latex is solved, and the prepared fish protein gel latex has good stability, meeting the needs of industrial production. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The figures show the storage stability (3 hours-21 days) of the microbial glutamine transaminase and polysaccharide-modified fish protein gelatin emulsions in examples of the present invention; wherein, ① fish protein gelatin, ② fish protein gelatin + 50℃ microbial glutamine transaminase, ③ fish protein gelatin + 4℃ microbial glutamine transaminase, ④ fish protein gelatin + konjac gum, ⑤ fish protein gelatin + konjac gum + 50℃ microbial glutamine transaminase, ⑥ fish protein gelatin + konjac gum + 4℃ microbial glutamine transaminase, ⑦ fish protein gelatin + sodium alginate, ⑧ fish protein gelatin + sodium alginate + 50℃ microbial glutamine transaminase, ⑨ fish protein gelatin + sodium alginate + 4℃ microbial glutamine transaminase, ⑩ fish protein gelatin + guar gum, Fish protein gelatin + guar gum + 50℃ microbial transglutaminase Fish protein gelatin + guar gum + 4℃ microbial transglutaminase.

[0025] Figure 2 The figures show the storage stability (6 hours-28 days) of the microbial glutamine transaminase and polysaccharide-modified fish protein gelatin emulsions in examples of the present invention; wherein, ① fish protein gelatin, ② fish protein gelatin + 50℃ microbial glutamine transaminase, ③ fish protein gelatin + 4℃ microbial glutamine transaminase, ④ fish protein gelatin + konjac gum, ⑤ fish protein gelatin + konjac gum + 50℃ microbial glutamine transaminase, ⑥ fish protein gelatin + konjac gum + 4℃ microbial glutamine transaminase, ⑦ fish protein gelatin + sodium alginate, ⑧ fish protein gelatin + sodium alginate + 50℃ microbial glutamine transaminase, ⑨ fish protein gelatin + sodium alginate + 4℃ microbial glutamine transaminase, ⑩ fish protein gelatin + guar gum, Fish protein gelatin + guar gum + 50℃ microbial transglutaminase Fish protein gelatin + guar gum + 4℃ microbial transglutaminase.

[0026] Figure 3 The images show the thermal stability (A) and freeze-thaw stability (B) of the microbial glutamine transaminase and polysaccharide-modified fish protein gelatin emulsions in the embodiments of the present invention. From left to right, the samples in each image are: fish protein gelatin, fish protein gelatin + 50℃ microbial glutamine transaminase, fish protein gelatin + 4℃ microbial glutamine transaminase, fish protein gelatin + konjac gum, fish protein gelatin + konjac gum + 50℃ microbial glutamine transaminase, fish protein gelatin + konjac gum + 4℃ microbial glutamine transaminase, fish protein gelatin + sodium alginate, fish protein gelatin + sodium alginate + 50℃ microbial glutamine transaminase, fish protein gelatin + sodium alginate + 4℃ microbial glutamine transaminase, fish protein gelatin + guar gum, fish protein gelatin + guar gum + 50℃ microbial glutamine transaminase, and fish protein gelatin + guar gum + 4℃ microbial glutamine transaminase.

[0027] Figure 4 The figures show the apparent viscosity of the microbial transglutaminase and polysaccharide-modified fish protein latex in this embodiment of the invention. A: Apparent viscosity of all samples in this embodiment; B: Apparent viscosity of the microbial transglutaminase and konjac gum-modified fish protein latex; C: Apparent viscosity of the microbial transglutaminase and sodium alginate-modified fish protein latex; D: Apparent viscosity of the microbial transglutaminase and guar gum-modified fish protein latex.

[0028] Figure 5 The figures show the emulsifying activity index (A) and emulsion stability index (B) of the microbial glutamine transaminase and polysaccharide modified fish protein gel latex in the embodiments of the present invention.

[0029] Figure 6 The figures show the particle size (A) and zeta potential (B) of the microbial glutamine transaminase and polysaccharide-modified fish protein latex in an embodiment of the present invention.

[0030] Figure 7 The figures show the surface hydrophobicity of microbial transglutaminase and polysaccharide-modified fish protein latex in embodiments of the present invention. A: Surface hydrophobicity of all samples in this work; B: Surface hydrophobicity of microbial transglutaminase and konjac gum-modified fish protein latex; C: Surface hydrophobicity of microbial transglutaminase and sodium alginate-modified fish protein latex; D: Surface hydrophobicity of microbial transglutaminase and guar gum-modified fish protein latex. Detailed Implementation

[0031] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0032] The experimental materials used in the following examples are as follows (unless otherwise specified, all are commercially available):

[0033] Fish protein gelatin (a company in Jiangsu); plant polysaccharides (konjac gum, sodium alginate, guar gum) (a company in Jiangxi); microbial transglutaminase (a company in Jiangsu); corn oil (a grain and oil group in Jiangxi); deionized water was used in the experiment.

[0034] In the following examples, the fish protein gel solution, microbial transglutaminase solution, and plant polysaccharide (konjac gum, sodium alginate, guar gum) solution used are obtained by heating and dissolving the fish protein gel, microbial transglutaminase, and plant polysaccharide (konjac gum, sodium alginate, guar gum), respectively. The heating temperature for the fish protein gel and microbial transglutaminase is 40°C, and the heating temperature for the plant polysaccharide (konjac gum, sodium alginate, guar gum) is 50°C, with a rotation speed of 300 r / min.

[0035] Example 1

[0036] A method for preparing a highly stable, low-concentration fish protein latex, the specific preparation process of which includes the following steps:

[0037] (1) Mix 3% fish protein gelatin solution, 0.3% microbial transglutaminase solution and 0.3% plant polysaccharide solution (konjac gum) with a volume ratio of 1:1:1 to obtain a mixed solution;

[0038] (2) The mixed solution obtained in step (1) is mixed with corn oil at a volume ratio of 1:1 and dispersed in a high-speed disperser at 12000 rpm for 3 minutes to obtain a fish protein gel mixed emulsion.

[0039] (3) Crosslink the fish protein gel mixture emulsion obtained in step (2) at 4°C for 18 hours, and then inactivate the enzyme at high temperature (the enzyme inactivation condition is 90°C for 10 min) to finally obtain a high-stability low-concentration fish protein gel emulsion (denoted as FG+KGM+4°CMTG).

[0040] Example 2

[0041] A method for preparing a high-stability, low-concentration fish protein gel latex is described. The specific preparation process is similar to that in Example 1, except that the "konjac gum" in step (1) is replaced with "sodium alginate". The final result is a high-stability, low-concentration fish protein gel latex (denoted as FG+SA+4℃MTG).

[0042] Example 3

[0043] A method for preparing a high-stability, low-concentration fish protein gel latex is described. The specific preparation process is similar to that in Example 1, except that the "konjac gum" in step (1) is replaced with "guar gum". The final result is a high-stability, low-concentration fish protein gel latex (denoted as FG+GG+4℃MTG).

[0044] Comparative Example 1

[0045] A method for preparing fish protein latex is similar to that in Example 1, except that “4℃” in step (3) is changed to “50℃” and “crosslinking for 18 hours” is changed to “crosslinking for 60 minutes” to obtain fish protein latex (denoted as FG+KGM+50℃MTG).

[0046] Comparative Example 2

[0047] A method for preparing fish protein latex is similar to that in Example 2, except that “4℃” in step (3) is changed to “50℃” and “crosslinking for 18 hours” is changed to “crosslinking for 60 minutes” to obtain fish protein latex (denoted as FG+SA+50℃MTG).

[0048] Comparative Example 3

[0049] A method for preparing fish protein latex is similar to that in Example 3, except that “4℃” in step (3) is changed to “50℃” and “crosslinking for 18 hours” is changed to “crosslinking for 60 minutes” to obtain fish protein latex (denoted as FG+GG+50℃MTG).

[0050] Comparative Example 4

[0051] A method for preparing a fish protein gel latex, the specific preparation process of which is as follows:

[0052] (1) Mix 3% fish protein gel solution, 0.3% microbial transglutaminase solution and water at a volume ratio of 1:1:1 to obtain a mixed solution;

[0053] (2) The mixed solution obtained in step (1) is mixed with corn oil at a volume ratio of 1:1 and dispersed in a high-speed disperser at 12000 rpm for 3 minutes to obtain a fish protein gel mixed emulsion.

[0054] (3) Crosslink the fish protein gel mixture obtained in step (2) at 4°C for 18 hours, and then inactivate the enzyme at high temperature (the enzyme inactivation condition is 90°C for 10 minutes) to finally obtain the fish protein gel emulsion (denoted as FG+4°CMTG).

[0055] Comparative Example 5

[0056] A method for preparing fish protein latex is similar to that of Comparative Example 4, except that “4℃” in step (3) is changed to “50℃” and “crosslinking for 18 hours” is changed to “crosslinking for 60 minutes”, and finally fish protein latex (denoted as FG+50℃MTG) is obtained.

[0057] Comparative Example 6

[0058] A method for preparing fish protein gel latex is similar to that of Comparative Example 4, except that the "0.3% microbial transglutaminase solution" in step (1) is replaced with "0.3% plant polysaccharide solution (konjac gum)" to obtain fish protein gel latex (denoted as FG+KGM).

[0059] Comparative Example 7

[0060] A method for preparing fish protein latex is similar to that of Comparative Example 4, except that the "0.3% microbial transglutaminase solution" in step (1) is replaced with "0.3% plant polysaccharide solution (sodium alginate)" to obtain fish protein latex (denoted as FG+SA).

[0061] Comparative Example 8

[0062] A method for preparing fish protein gel latex is similar to that of Comparative Example 4, except that the "0.3% microbial transglutaminase solution" in step (1) is replaced with "0.3% plant polysaccharide solution (guar gum)" to obtain fish protein gel latex (denoted as FG+GG).

[0063] Example 4

[0064] The fish protein gelatin emulsions and fish protein gelatin (FG) prepared in Examples 1-3 and Comparative Examples 1-8 were subjected to performance testing, and the specific process is as follows:

[0065] (1) Storage stability test

[0066] The prepared emulsion was placed in a separate glass bottle and stored indoors at an ambient temperature of 25°C. The emulsion was photographed periodically (at 3 hours, 6 hours, 9 hours, 12 hours, 24 hours, 48 ​​hours, 7 days, 14 days, 21 days, and 28 days) to observe its morphology and for any layering or flocculation.

[0067] The result is as follows Figure 1-Figure 2 As shown in the figure, both pure fish protein latex and the single-modified fish protein latex exhibited stratification after 48 hours, while the fish protein latex modified with a combination of microbial transglutaminase and polysaccharides at 4℃ did not show stratification. Notably, at 3 and 9 hours, and at 4 and 50℃, the synergistic effect of sodium alginate incorporation and microbial transglutaminase-mediated cross-linking caused the fish protein latex to gel sequentially. Furthermore, at 4℃, the synergistic effect of sodium alginate incorporation and microbial transglutaminase-mediated cross-linking extended the storage stability of the fish protein latex from the initial 3 hours to the current 28 days (672 hours), a 224-fold increase, demonstrating optimal storage stability.

[0068] (2) Thermal stability test

[0069] Place the prepared emulsion into a separate glass bottle. Then, heat the emulsion in an 80°C water bath for 1 hour, and allow it to cool to ambient temperature. Take a photograph and observe the emulsion for any color change or layering.

[0070] The result is as follows Figure 3 As shown in Figure A, compared to pure fish protein gelatin at 50°C, the composite modification effect was more pronounced at 4°C, and the fish protein gelatin emulsion modified with sodium alginate and microbial transglutaminase at 4°C exhibited the mildest stratification. Figure 3 (Marked in red in the image). The results showed that polysaccharides and microbial transglutaminase were effective in preventing the accumulation and stratification of fish protein latex under heating conditions at 4℃.

[0071] (3) Freeze-thaw stability test

[0072] The prepared emulsion was placed in a clear glass bottle and then placed in a -20°C freezer for approximately 20 hours each time. The sample was then thawed at 20°C for approximately 4 hours. This cycle was repeated, with photographs taken each time to observe for oil separation or emulsion cracking, thus determining the freeze-thaw stability of the emulsion.

[0073] The result is as follows Figure 3 As shown in Figure B, compared to pure fish protein latex and fish protein latex cross-linked with microbial transglutaminase at 50°C, the microbial transglutaminase-modified fish protein latex exhibited significantly reduced phase separation and droplet aggregation at 4°C after a single freeze-thaw cycle, indicating enhanced structural stability under low-temperature conditions. Furthermore, with increasing freeze-thaw cycles, the composite modification showed the best antifreeze effect at 4°C, with the fish protein latex modified with sodium alginate and microbial transglutaminase at 4°C exhibiting the best freeze-thaw stability (marked in yellow in the figure).

[0074] (4) Apparent viscosity measurement

[0075] The apparent viscosity of the fish protein gelatin latex was determined according to the method of Huang Tao et al. The above-mentioned fish protein gelatin latex was tested using a shear rate controlled rheometer with a 50mm stainless steel parallel plate. The viscosity was measured at 25℃ with a shear rate range of 0.01-100s. -1 Continuous shear tests were conducted at the shear rate. A gap of 0.1 mm was fitted to obtain the apparent viscosity of the emulsion.

[0076] The result is as follows Figure 4 As shown, by Figure 4 As shown in A, the apparent viscosity of the fish protein latex cross-linked with microbial transglutaminase at 4℃ is higher than that of the fish protein latex cross-linked with microbial transglutaminase at 50℃ and the pure fish protein latex. This is because low-temperature cross-linking slows down Brownian motion, increasing apparent viscosity. Simultaneously, microbial transglutaminase catalyzes the formation of intramolecular and intermolecular covalent bonds in the fish protein latex, reducing water flowability and increasing the apparent viscosity of the latex. Figure 4 B- Figure 4 As shown in Figure D, among all the fish protein latexes with added polysaccharides, the apparent viscosity of microbial transglutaminase at 4°C was greater than that at 50°C. These results indicate that fish protein latexes modified with polysaccharides and crosslinked with microbial transglutaminase at 4°C exhibited the highest apparent viscosity and best stability. Furthermore, under low shear rate conditions, the synergistic combination of sodium alginate incorporation and microbial transglutaminase-mediated crosslinking resulted in the highest apparent viscosity at 4°C.

[0077] (5) Emulsification performance test

[0078] At 0 and 30 minutes, 50 μL of emulsion samples were removed from the bottom of the emulsion and diluted with 5 mL of 0.1% sodium dodecyl sulfate (SDS). The absorbance of the solution at 500 nm was then measured using a U-2910 spectrophotometer to measure the emulsifying ability. The emulsifying activity index (EAI) and emulsifying stability index (ESI) were calculated using the following formulas:

[0079]

[0080] In the above formula, A0 is the absorbance of the homogenized diluted emulsion; DF is the dilution factor (100); and c is the weight of protein per volume (1,000 g / m³). 3 ); θ is the oil volume fraction of the emulsion (0.5); θ is the optical path length of the cuvette (0.01 m); ΔA is the time from 0 to 30 minutes (A0-A). 30 The change in absorbance between Δt and Δt is the time interval, 30 minutes.

[0081] The result is as follows Figure 5 As shown, by Figure 5 As shown in Figure A, the EAI value of fish protein latex cross-linked with microbial transglutaminase at 4℃ is significantly higher than that of fish protein latex cross-linked with microbial transglutaminase at 50℃ and pure fish protein latex. This phenomenon originates from the compaction induced by cross-linking of the fish protein latex wall matrix at 4℃, where covalent bonds promote a tighter triple helix structure. Therefore, fish protein latex cross-linked with microbial transglutaminase at 4℃ exhibits better emulsifying properties. Notably, for fish protein latex with added polysaccharides, the EAI value of cross-linking with microbial transglutaminase at 4℃ is also increased. This is because, under the action of microbial transglutaminase, the fish protein latex forms a network structure, effectively preventing droplet aggregation, and the steady-state cross-linking at 4℃ makes the structure of the fish protein latex more compact, preventing droplet aggregation and increasing the EAI value.

[0082] Depend on Figure 5 As shown in Figure B, at 4℃, the ESI of the fish protein latex cross-linked with microbial transglutaminase was significantly higher than that of the pure fish protein latex and the fish protein latex cross-linked with microbial transglutaminase at 50℃. Furthermore, with the addition of polysaccharide modification, the ESI value of the fish protein latex cross-linked with microbial transglutaminase at 4℃ was higher than that at 50℃. This may be because the fish protein latex cross-linked with microbial transglutaminase at 4℃ is in a stable state compared to the one at 50℃. Therefore, the fish protein latex formed a more homogeneous and stable system.

[0083] (6) Particle size and potential

[0084] Particle size and potential were measured using a nanoparticle size and potential analyzer. The refractive indices of the emulsion particles and the aqueous dispersion medium were 1.46 and 1.33, respectively. The diluted emulsion was added dropwise into the detection container until the sample concentration reached the detection limit.

[0085] The result is as follows Figure 6 As shown, particle size and zeta potential are key indicators for evaluating emulsion stability. This can be achieved by observing... Figure 6As shown in Figure A, the particle size of the fish protein gelatin latex significantly decreased after incorporation with microbial transglutaminase. At 4°C, the fish protein gelatin latex cross-linked with microbial transglutaminase exhibited smaller particle sizes. Compared to pure fish protein gelatin latex, the particle size of the fish protein gelatin latex cross-linked with microbial transglutaminase at 50°C and 4°C decreased by 18.13% and 62.50%, respectively. Interestingly, when polysaccharides were added to the fish protein gelatin latex and simultaneously cross-linked with microbial transglutaminase, the particle size of the fish protein gelatin latex slightly increased at both 50°C and 4°C. This is because, on the one hand, the polysaccharides and microbial transglutaminase adsorb onto the surface of the protein droplets, leading to an increase in particle size. On the other hand, the electrostatic interaction between the polysaccharides and the fish protein gelatin also contributes to the increase in particle size. Studies have shown that the highest stability can be achieved within an appropriate range of latex particle size. These results indicate that the synergistic combination of polysaccharide incorporation and microbial transglutaminase-mediated cross-linking provides the most suitable particle size and optimal stability at 4°C.

[0086] observe Figure 6 B. The zeta potential of fish protein latex cross-linked with microbial transglutaminase at 4°C was significantly higher than that of pure fish protein latex and the zeta potential of fish protein latex cross-linked with microbial transglutaminase at 50°C. Studies have shown that this may be because the structure of the fish protein latex changes when cross-linked with microbial transglutaminase at 50°C, with some components breaking down into single chains. At 4°C, the structure of the fish protein latex is unaffected by temperature and transforms into a triple helix structure. Furthermore, the fish protein latex cross-linked with polysaccharides and microbial transglutaminase at 4°C exhibited the highest zeta potential, and the synergistic combination of sodium alginate incorporation and microbial transglutaminase-mediated cross-linking also showed the highest zeta potential at 4°C. Research indicates that the greater the electrostatic repulsion between droplets, the larger the absolute value of the zeta potential, which is beneficial for forming a stable and homogeneous system. Therefore, the system of fish protein latex cross-linked with polysaccharides and microbial transglutaminase at 4°C is the most stable.

[0087] (7) Surface hydrophobicity

[0088] The surface hydrophobicity of the emulsion was measured using an 8-phenyl-1-naphthalenesulfonic acid fluorescent probe (ANS). 0.5 mL of the emulsion was mixed with 25 μL of 8 mM ANS and 4.5 mL of deionized water. The mixture was incubated at room temperature in the dark for 30 min, and measurements were taken at λex = 370 nm and λem = 400–600 nm.

[0089] The result is as follows Figure 7 As shown, by Figure 7As shown in Figure A, the peak fluorescence intensity of pure fish protein gel at an emission wavelength of 474 nm is 288.6. The fluorescence intensity of fish protein gel cross-linked with microbial transglutaminase significantly increased to 359.2 at 50℃ and reached 385.6 at 4℃, indicating that the surface hydrophobicity of the fish protein gel emulsion modified by microbial transglutaminase is enhanced, with modification at 4℃ being superior to modification at 50℃. This increase is due to the formation of a covalent ε-(γ-glutamyl)-lysine isopeptide bond between glutamine and lysine residues catalyzed by microbial transglutaminase, and the loss of the ε-amino group catalyzed by microbial transglutaminase also increases the hydrophobicity of the protein.

[0090] Furthermore, after the addition of konjac gum and guar gum, the fluorescence intensity of the fish protein gelatin latex cross-linked with microbial transglutaminase at 4°C reached 604.4 and 611.7, respectively, both higher than the fluorescence intensity at 50°C. It is worth noting that, as... Figure 7 As shown in Figure C, the fluorescence intensity of the three emulsions—including the emulsion without microbial transglutaminase, the microbial transglutaminase cross-linked emulsion at 50°C, and the microbial transglutaminase cross-linked emulsion at 4°C—showed a sequential decrease in fluorescence intensity after the addition of sodium alginate. This may be because the molecular structure of sodium alginate contains highly hydrophilic hydroxyl groups. The colloidal network or surface activity formed by sodium alginate in the emulsion increases the hydrophilicity of the emulsion, leading to hydrophobicity and a decrease in peak value, thereby reducing hydrophobic interactions. Under the action of microbial transglutaminase, the hydrophilic hydroxyl groups in sodium alginate are further induced onto the fish protein glue, resulting in a further decrease in hydrophobicity. These results indicate that the main force improving the stability of sodium alginate-modified fish protein glue emulsion may not be hydrophobic interactions, but rather electrostatic interactions.

[0091] In summary, this invention solves the problem of instability and easy stratification of low-concentration fish protein latex by optimizing the cross-linking temperature of microbial transglutaminase. Specifically, the fish protein latex cross-linked with microbial transglutaminase at 4°C, with the addition of sodium alginate, exhibits the best freeze-thaw stability, thermal stability, and storage stability. Furthermore, the addition of polysaccharides results in the highest apparent viscosity, surface hydrophobicity, and ESI value of the fish protein latex cross-linked with microbial transglutaminase at 4°C. Moreover, with the addition of polysaccharides, the particle size of the fish protein latex cross-linked with microbial transglutaminase at 4°C is reduced by 74.13%, 74.06%, and 79.73% compared to the latex without added microbial transglutaminase, respectively, while the potential increases by 45.42%, 46.06%, and 37.39%, respectively.

[0092] The embodiments of this application have been described above with reference to the accompanying drawings. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the core ideas of this application. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for preparing a highly stable, low-concentration fish protein latex, characterized in that, Includes the following steps: Fish protein gel solution, microbial transglutaminase solution and plant polysaccharide solution are mixed to obtain a mixed solution; The mixed solution was mixed with corn oil and dispersed in a disperser to obtain a mixed emulsion; The mixed emulsion was subjected to steady-state cross-linking at 0-4℃. After the cross-linking was completed, enzyme inactivation was performed to obtain the high-stability, low-concentration fish protein latex.

2. The preparation method according to claim 1, characterized in that, The volume ratio of the fish protein gel solution, the microbial glutamine transaminase solution, and the plant polysaccharide solution is 1:1:

1.

3. The preparation method according to claim 2, characterized in that, The fish protein gel solution and the microbial transglutaminase solution were obtained through the following steps: Fish protein gelatin and microbial transglutaminase were heated at 40°C until completely dissolved.

4. The preparation method according to claim 2, characterized in that, The plant polysaccharide solution was obtained through the following steps: The plant polysaccharide was obtained by heating it at 50°C until it was completely dissolved.

5. The preparation method according to claim 4, characterized in that, The plant polysaccharide is selected from at least one of konjac gum, sodium alginate, and guar gum.

6. The preparation method according to claim 1, characterized in that, The volume ratio of the mixed solution to corn oil is 1:

1.

7. The preparation method according to claim 1, characterized in that, The dispersion process in the disperser is carried out at a speed of 12000 r / min for 3 min.

8. The preparation method according to claim 1, characterized in that, The steady-state cross-linking temperature is 4℃ and the time is 18-20h; the enzyme inactivation temperature is 90-100℃ and the time is 5-10min.

9. A highly stable, low-concentration fish protein latex, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The high-stability, low-concentration fish protein latex according to claim 9, characterized in that, By mass percentage, the high-stability, low-concentration fish protein gel latex contains 0.5% fish protein gel, 0.05% microbial transglutaminase, and 0.05% plant polysaccharides.

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