Hipes, hipes-lipid fortified surimi 3d printing ink and methods of making

Abstract

The application discloses HIPEs, HIPEs-lipid reinforced surimi 3D printing ink and a preparation method thereof, and belongs to the technical field of food processing.The application prepares fish scale gelatin particles (FSG) crosslinked by MTGase, and then uses the obtained FSG to stabilize HIPEs, and investigates the influence of FSG concentration on Zeta potential, interfacial adsorption characteristics, wettability, adsorbed protein percentage (AP, %), storage stability, micro-morphology and rheological behavior of the HIPEs.In addition, the application adds the obtained HIPEs into surimi to prepare food ink for 3D printing, and explores the influence of the HIPEs on the mechanical properties, rheological behavior, moisture distribution and printing performance of the surimi system, so that the content of healthy lipids in surimi products can be improved, the nutritional needs of consumers can be met, and the technical bottleneck for producing high-end surimi products can be solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food processing, and particularly relates to a polyunsaturated fatty acid high internal phase emulsion (HIPE) stabilized by an MTGase cross-linked FSG microgel particle system, a HIPE-lipid reinforced surimi 3D printing ink and a preparation method thereof. BACKGROUND

[0002] Exogenous lipid reinforcement and 3D printing technology are research hotspots in the production of new surimi products. Currently, solid fats of animal origin (such as mutton oil and lard) are usually added to surimi products in the industry to make up for product defects caused by the lack of fat. With the strengthening of consumers' concept of healthy diet, people are more cautious about choosing foods rich in saturated fatty acids, which have been proven to be associated with various disease risks and harmful to human health (Kris-Etherton & Krauss, 2020). In this regard, polyunsaturated fatty acids are a more promising choice than saturated fats (He et al., 2022). Fish oil, also known as deep-sea gold, is rich in various long-chain omega-3 PUFAs and is widely used in fortified foods due to its broad-spectrum health benefits (Y. Chen et al., 2022). Studies have shown that fish oil has excellent nutritional value and health benefits, plays an important role in promoting brain development, reducing the incidence of cardiovascular diseases, and reducing inflammation, and is suitable for consumption by the elderly and infant populations (W. Cao et al., 2022; de Oliveira et al., 2017; Sherratt et al., 2020). However, the addition of fish oil does not significantly improve the quality of surimi products. On the one hand, due to the thermodynamic instability of polyunsaturated fatty acids in fish oil, directly added oil and fat are prone to oxidative fission, causing surimi products to oxidize and deteriorate (Boran et al., 2006; M. Sun et al., 2022); on the other hand, the direct addition of fish oil cannot control the changes in surimi gel strength, which cannot meet the lipid reinforcement needs of different populations, especially the key needs of children and the elderly (Shi et al., 2014). Therefore, it is of great significance to find a processing method that can improve the stability of fish oil in surimi systems and adjust the texture according to different populations.

[0003] Zhou et al. (F.-Z. Zhou, Huang, et al., 2018) controlled the self-assembly and interfacial behavior of zein by utilizing the interaction between zein and pectin, and the stable HIPEs had excellent viscoelasticity and could protect curcumin from the external environment; Zhang et al. (Zhang et al., 2022) prepared HIPEs stabilized by SBP microgel particles using a simple one-step homogenization method, and the internal phase volume fraction was as high as 88% and showed excellent encapsulation efficiency for astaxanthin. In addition, studies have shown that the stability of protein-stabilized HIPEs can be enhanced by intermolecular covalent cross-linking (T. Feng et al., 2022), and some scholars have improved the thermal stability of gelatin-based HIPEs by using MTGase cross-linking. The HIPEs remained good appearance, small droplet size and high viscosity after sterilization at 121℃ for 20min, which was of great significance for the commercial sterilization and subsequent thermal processing of HIPEs (Du et al., 2021). However, most of the current researches are limited to the discussion of the performance of single HIPEs, and the research on the addition of HIPEs to surimi products has not been reported. At the same time, the effect of adding HIPEs to surimi products on its gel properties and 3D printing characteristics is also unclear.

[0004] Based on the above reasons, the present application is proposed. SUMMARY

[0005] Based on the above reasons, in view of the problems or defects in the prior art, the purpose of the present application is to provide a polyunsaturated fatty acid high internal phase emulsion HIPEs stabilized by a MTGase cross-linked FSG microgel particle system, a HIPEs-lipid fortified surimi 3D printing ink and a preparation method thereof, to solve or at least partially solve the above technical defects in the prior art.

[0006] In order to achieve the above first purpose of the present application, the technical solution adopted by the present application is as follows:

[0007] A polyunsaturated fatty acid high internal phase emulsion HIPEs stabilized by a MTGase cross-linked FSG microgel particle system, comprising a MTGase cross-linked FSG microgel particle system and fish oil.

[0008] Further, in the above technical solution, the volume of the fish oil is 50-90% of the volume of the HIPEs. In a preferred embodiment of the present application, the volume of the fish oil is 80% of the volume of the HIPEs.

[0009] Further, in the above technical solution, the MTGase cross-linked FSG microgel particle system is prepared by the following method, and the steps are as follows:

[0010] The fish scale gelatin (FSG) is dissolved in deionized water, swelled at room temperature, heated and stirred to obtain a gelatin solution, and then cooled to room temperature; then the pH value of the gelatin solution is adjusted to 5.5-6.5, transglutaminase (MTGase) is added, and the crosslinking reaction is carried out at 30-50℃ for 30-50min, and after the reaction is completed, the reaction system is continuously heated to 85-95℃ to inactivate the enzyme, homogenized, to obtain the TGase crosslinked FSG microgel particle system.

[0011] Further, in a preferred embodiment of the present application, the swelling time is 1h.

[0012] Further, in the above technical solution, the concentration of FSG in the gelatin solution is 10-60mg / mL.

[0013] Further, in a preferred embodiment of the present application, the pH value of the gelatin solution is 6.

[0014] Further, in a preferred embodiment of the present application, the addition amount of MTGase is 3.0U / g FSG.

[0015] The second object of the present application is to provide a preparation method of the above-mentioned HIPEs, specifically, fish oil is added to the MTGase crosslinked FSG microgel particles according to the ratio, and then homogenized.

[0016] The third object of the present application is to provide the application of the above-mentioned HIPEs in preparing a HIPEs-lipid fortified surimi 3D printing ink.

[0017] A HIPEs-lipid fortified surimi 3D printing ink, comprising HIPEs and surimi.

[0018] Further, in a preferred embodiment of the present application, the content of fish oil in the printing ink is 5wt%.

[0019] Further, in the above technical solution, the HIPEs are preferably 30-40mg / mL FSG stabilized HIPEs.

[0020] The fourth object of the present application is to provide a preparation method of the above-mentioned HIPEs-lipid fortified surimi 3D printing ink, specifically, frozen surimi is thawed, then subjected to air chopping and salt chopping in sequence, and then HIPEs are added to form.

[0021] A fifth object of the present invention is to provide a method for preparing a lipid-fortified surimi 3D printed product, comprising adding the HIPEs-lipid-fortified surimi 3D printing ink to the barrel of a 3D printer, and pre-designing or selecting a product printing structure model and printing program steps in the 3D printing device program; starting the printing program, and the 3D printing device extrudes the HIPEs-surimi mixture onto a work platform in a stacked printing manner according to the preset product structure model layering information. Under the control of the software system 3D model, by controlling the barrel temperature and printing speed, the material is extruded and stacked into a three-dimensional solid structure through an extrusion nozzle, thereby producing the lipid-fortified surimi product.

[0022] Furthermore, in a preferred embodiment of the present invention, the above technical solution is an extrusion 3D printer based on a dual-nozzle syringe.

[0023] Furthermore, in a preferred embodiment of the present invention, the printing parameters are as follows: nozzle diameter = 1.2 mm, syringe barrel diameter = 28 mm, layer height = 0.96 mm, first layer height = 0.8 mm, printing speed = 20 mm / s, retraction speed = 50 mm / s. The HIPE-surimi system models are a five-pointed star model (one outer layer, 0% infill, model height 10 mm) and a cylinder model (two outer layers, 80% infill, model height 10 mm, diameter 10 mm).

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This study prepared a fish scale gelatin (FSG) microgel particle system cross-linked by MTGase. Fish scale gelatin is a polymer mixture of polypeptide chains of varying lengths, derived from fish scales, a waste product of fish processing. Its unique physicochemical properties (gelation and emulsification), availability, and low cost make it suitable for the preparation of protein particles. Compared to mammalian gelatin, fish scale gelatin offers distinct advantages in that it is not subject to religious restrictions or mammalian diseases. The resulting MTGase-crosslinked FSG microgel particle system was then used to stabilize high-protein organic polymers (HIPEs). The effects of FSG concentration on the zeta potential, interfacial adsorption properties, wettability, adsorbed protein percentage (AP), storage stability, micromorphology, and rheological behavior of the HIPEs were investigated. Furthermore, the HIPEs were added to fish surimi to prepare food ink for 3D printing. The effects of HIPEs on the mechanical properties, rheological behavior, moisture distribution, and printing performance of the surimi system were investigated. This approach can increase the content of healthy lipids in surimi products, meeting consumer nutritional needs while also addressing the technical bottlenecks in the production of high-end surimi products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0027] Figure 1 (A) Pictures of HIPEs appearance stabilized by different concentrations of FSG; (B) Three-phase contact angle of FSG particles; (C) Interfacial tension of FSG with different concentrations; (D) Dependence of interfacial film surface pressure (π) on time (t1 / 2); (E) Molecular penetration and structural rearrangement steps of oil-water interface; (F) Interfacial protein adsorption amount of FSG with different concentrations; (G) Particle size change of HIPEs; (H) Zeta-potential of HIPEs stabilized by FSG particles with different concentrations;

[0028] Figure 2 HIPEs preparation flow chart;

[0029] Figure 3 Appearance of emulsions prepared at different oil phase volume fractions (φ = 10% ~ 90%), FSG concentration of 30 mg / mL. A: Freshly prepared appearance; B: Appearance of emulsions after standing at 25℃ for 60 min;

[0030] Figure 4 Environmental stability (B) Centrifugal stability; (C) Thermal stability; (D) Freeze-thaw stability of HIPEs stabilized by FSG particles with different concentrations;

[0031] Figure 5 Microstructure of HIPEs stabilized by FSG particles with different concentrations;

[0032] Figure 6 Rheological behavior of HIPEs and HIPEs-surimi systems;

[0033] Figure 7(A) HIPEs-lipid fortified surimi 3D printing ink transverse relaxation time spectrum distribution; (B) HIPEs-lipid fortified surimi 3D printing ink 3D printing precision and stability; (C) HIPEs-lipid fortified surimi 3D printing ink water holding capacity; (D) HIPEs-lipid fortified surimi 3D printing ink gel strength; (E) HIPEs-lipid fortified surimi 3D printing ink microstructure. (Blank sample: OG1-OG6: 10-60 mg / mL FSG-stabilized HIPE was added to surimi, respectively. Note: The control sample is a sample directly added with fish oil, and the experimental sample is a sample added with HIPE.

[0034] Figure 8 3D printing performance evaluation of HIPEs-lipid fortified surimi 3D printing ink with different concentrations. From top to bottom, respectively, are the vertical view and the side view. (Blank sample: OG1-OG6: 10-60 mg / mL FSG-stabilized HIPE was added to surimi, respectively. Note: The control sample is a sample directly added with fish oil, and the experimental sample is a sample added with HIPE.

[0035] Figure 9 3D printing performance evaluation of HIPEs-lipid fortified surimi 3D printing ink with different concentrations. From top to bottom, respectively, are the vertical view and the side view. (Blank sample: OG1-OG6: 10-60 mg / mL FSG-stabilized HIPE was added to surimi, respectively. Note: The control sample is a sample directly added with fish oil, and the experimental sample is a sample added with HIPE.

[0036] Figure 10 Correlation analysis. DETAILED DESCRIPTION

[0037] The application will be further described in detail through the following implementation cases. The implementation cases are implemented on the premise of the application technology, and the detailed implementation mode and specific operation process are given to illustrate the creativity of the application, but the protection scope of the application is not limited to the following implementation cases.

[0038] The equipment and raw materials used in the application can be purchased from the market or are commonly used in the art.

[0039] The frozen white silver carp surimi (AAA grade) involved in the following examples or application examples was purchased from Honghu City Jingli Aquatic Food Co., Ltd. in Hubei Province; deep sea fish oil (DHA+EPA≧70%) was provided by Shaanxi Kangzhou Biological Co., Ltd. (Xi'an, China); transglutaminase (activity: 100 units / g): Yiming Biological Products Co., Ltd.; other reagents: all were analytical pure, National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0040] Example 1

[0041] The method for preparing the MTGase-crosslinked fish scale gelatin (FSG) microgel particle system of the present embodiment specifically comprises the following steps:

[0042] The 200 g of dried grass carp scales were added to 2000 mL of NaOH solution (0.1 M) and mixed at room temperature for 4 h. Then, the pretreated fish scales were washed with distilled water until neutral. After that, hydrochloric acid (0.5 M) was added at a ratio of 1:10 (w / v), and the mixture was stirred at room temperature for 1.5 hours for decalcification treatment. The decalcified fish scales were further mixed with distilled water at a ratio of 1:3 (w / v) in a water bath at 60°C for 6 hours, and then filtered through four layers of gauze to obtain the first gelatin extract. The second gelatin extract was obtained by mixing the remaining residue with distilled water at a ratio of 1:3 (w / v) in a water bath at 70°C for 6 h, and then filtering through four layers of gauze. The third extract was obtained by the same procedure, except that the heating temperature was higher, at 80°C. After mixing the three gelatin extracts, freeze-drying treatment was performed to obtain FSG. The content of collagen in the freeze-dried gelatin was calculated according to the Woessner J method (hydroxyproline content) to be 99.97±0.37%.

[0043] Subsequently, different amounts of FSG were dissolved in deionized water, swelled at 25°C for 1 h, and then stirred in a 40°C water bath for 30 min to obtain 10, 20, 30, 40, 50, and 60 mg / mL gelatin solutions. After cooling to room temperature, the pH was adjusted to 6.0 using 0.5 mol / L NaOH to achieve the optimal pH for MTGase, and then the amount of MTGase added was controlled at 3.0 U / g FSG, and the temperature was controlled at 40°C. After crosslinking for 40 min, the enzyme was inactivated by placing it in a 90°C water bath for 10 min to obtain an FSG-TG solution. The obtained FSG-TG solution was broken by an ULTRA-TURRAX® T18 digital homogenizer (IKA, Germany) at 10000 rpm for 2 min to obtain a microgel particle system. T18 digital homogenizer (IKA, Germany) at 10000 rpm for 2 min to obtain a microgel particle system.

[0044] Three-phase contact angle test of FSG

[0045] A drop shape analyzer (DSA 25, Hamburg, Germany) was used to measure the contact angle of the microgel particle system. The surface wettability of FSG was evaluated by three-phase contact angle analysis. First, freeze-dried FSG (0.025 g) was pressed into cylindrical tablets 1–2 mm thick. The tablets were soaked in fish oil for 10 minutes. The tablets were then placed on filter paper for 1 hour to remove excess fish oil. The tablets were then placed in an optical glass cuvette. 5 μL of Milli-Q pure water was slowly dripped from a syringe, allowing the tablets to adhere quickly to the surface. The shape of the water droplet was recorded by a camera, and the contact angle was numerically calculated using Advance software (Hamburg, KRUSS). Each measurement was performed in triplicate.

[0046] The droplet forms a three-phase contact angle (θ) at the oil-water interface, and θ is used as the main parameter to characterize wettability. Appropriate wettability can enhance the adsorption of particles at the interface, and the steric hindrance it provides can prevent the mutual aggregation of emulsions, thereby achieving the effect of stabilizing the emulsion. The wettability of FSG particles was studied based on the three-phase contact angle ( Figure 1 A) According to Young's equation E=πr 2 γ(1-|COSθ|) 2 (E is the desorption energy, r is the radius, θ is the three-phase contact angle, and γ is the oil-water interfacial tension) It can be seen that the closer the θ value is to 90°, the greater the energy required for the particles adsorbed to the oil-water interface to dissociate, which may lead to the formation of highly stable O / W emulsions.

[0047] In the present invention ( Figure 1 B) The three-phase contact angle observed for FSG at the oil-water interface was 67.2 ± 0.92°, indicating good wettability. However, compared with the three-phase contact angle values ​​reported in other studies, this measured value is lower. This may be because the concept and measurement method of contact angle are based on ideal spherical particles, while FSG particles are non-spherical. Therefore, the FSG θ is less useful in practical applications than its theoretical value. Further attention should be paid to evaluation indicators such as interfacial adsorption characteristics and emulsion stability.

[0048] FSG interface adsorption characteristics test

[0049] A fully automatic surface tensiometer (K100, KRUSS, Germany) was used to measure the interfacial tension of FSG at the oil-water interface over time using the Wilhelmy plate method. A low-density liquid was first added, and a platinum plate was placed. The instrument automatically calculated the buoyancy factor of the oil phase before replacing the beaker. The high-density liquid was added first, followed by the low-density liquid when prompted. The measurement time was set to 60 minutes, and the interfacial tension was monitored over time. The ambient temperature was maintained at 25°C, and external vibration interference was avoided.

[0050] The dynamic interface pressure (π) can be calculated using formula (1):

[0051] π=σ0-σ t (1)

[0052] Among them, σ0 represents the interfacial tension between pure water and fish oil; σ t It represents the interfacial tension value between gelatin solution and fish oil at time t.

[0053] In order to evaluate the role of FSG particle concentration in the formation dynamics of the oil-water interface film, the relationship between the interfacial adsorption behavior of FSG and its concentration was studied. Generally speaking, the adsorption dynamics of protein particles at the oil-water interface can be described by three main steps, namely (i) diffusion of particles from the bulk to the interface, (ii) penetration of particles at the interface, and (iii) rearrangement of adsorbed particles at the interface and formation of a viscoelastic film. Figure 1 As shown in Figure C, at 25°C, the interfacial tension values ​​of various FSG solutions (pH = 6.0) were significantly lower than that of pure water (pH = 6.0) / fish oil (22.17 mN / m). The decrease in interfacial tension caused by FSG particles can be attributed to the rapid diffusion of protein particles to the oil-water interface, forming an adsorption film. Upon reaching the oil-water interface, the particles expose their hydrophobic properties, at which point the interfacial tension rapidly decreases, and the particle adsorption film begins to form. Subsequently, the adsorption of particles at the interface reaches saturation, and the interfacial tension slowly decreases. During this process, the interfacial pressure (π) increases with adsorption time, but no plateau is observed in these curves. This is consistent with previous studies that have shown that protein adsorption equilibrium is not observed even after 2 or 3 days. When the interfacial pressure is low, the variation of the interfacial pressure (π) with adsorption time can be described by a modified form of the Ward and Tordai equation: Where C0 is the initial concentration of protein in the bulk solvent, K is the Boltzmann constant, T is the absolute temperature, and D is the diffusion coefficient. If the adsorption process is controlled by diffusion, then π is related to t 1 / 2 Linearly related (e.g. Figure 1 D 0-400s area), the slope of the curve is the diffusion rate constant (K diff ). K diff The larger the k is, the faster the protein particles are adsorbed to the interface. As shown in Table 1, with the increase of FSG concentration, k diff Significantly increased (R 2 >0.98), indicating that the diffusion rate of FSG is controlled by the FSG concentration, which is consistent with the fact that interfacial diffusion is a concentration-dependent process.

[0054] Table 1 Dynamic adsorption characteristics of FSG particles at different concentrations on the oil-water interface

[0055]

[0056]

[0057] After the initial diffusion stage, the adsorption process is usually controlled by the penetration and rearrangement rate of the protein diffusing to the interface. The first-order kinetic equation for this stage is usually ln[(π 3600 -π t ) / (Ξ 3600 -π0)]=-Kt. 3600 -π t ) / (π 3600 -π0)], the permeation rate constant (K P ) is the slope of the first linear region obtained ( Figure 1 E), the slope of the following linear region is defined as the rearrangement rate constant (K R ). It can be seen from Table 1 that with the increase of FSG concentration, K P and K R It shows a trend of first increasing and then decreasing, indicating that the penetration and rearrangement rate of FSG particles at the oil-water interface increases with the increase of concentration within a certain concentration range. However, when the FSG concentration increases further, K P and K R This may be because when the FSG concentration is high, the steric hindrance generated by the FSG particles adsorbed on the interface and the interaction between the gelatin in the aqueous phase produce an energy barrier, thereby hindering the further penetration of FSG particles at the interface.

[0058] The interface pressure at equilibrium (π 3600 ) mainly depends on the amount of protein adsorbed on the interface at equilibrium, and the amount of protein adsorbed on the interface is related to the total amount of protein in the aqueous phase, the size of the protein, and the interaction between proteins. Therefore, as shown in Table 1 and Figure 1 As shown in C, under the condition that the FSG particle size remains consistent, π 3600 It increases with the increase of gelatin concentration, indicating that the amount of gelatin adsorbed on the interface at equilibrium increases with the increase of concentration. The increase of interfacial adsorbed protein may lead to a tighter stacking of proteins, thereby forming a more stable interfacial film, which is consistent with the results of the tested interfacial protein adsorption amount.

[0059] The results of dynamic interfacial adsorption characteristics show that the diffusion rate of FSG particles at the interface and the interfacial pressure at equilibrium increase with increasing concentration, indicating that when FSG particles are used to prepare emulsions, increasing their concentration will be beneficial to the formation and stability of the emulsion.

[0060] Example 2

[0061] This example investigates the potential of emulsions with varying oil phase volumes to simulate solid adipose tissue. Figure 3The macroscopic appearance of emulsions with different oil phase volume fractions (φ) stabilized by 30 mg / mL MTGase cross-linked FSG microgel particle system was shown. It can be seen that with the increase of φ (70% to 85%), the emulsion showed typical high internal phase emulsion characteristics. Due to the increase of the volume of the oil phase, the close packing of the emulsion caused the increase of its viscosity, thus forming an optically opaque semi-solid gel. When placed at a certain angle, the emulsion remained in the original position and did not flow to the bottom of the bottle. When φ was further increased to 85% and 90%, uniform and stable HIPEs could not be formed, and obvious phase separation occurred after standing for 60 min at 25°C Figure 3 B). Therefore, considering the optimal oil load efficiency and stability, HIPEs with an oil phase volume of 80% were selected for preparation and subsequent study.

[0062] The present embodiment also provides a method for preparing a polyunsaturated fatty acid high internal phase emulsion (HIPEs) stabilized by an MTGase cross-linked FSG microgel particle system, which specifically comprises the following steps:

[0063] The TGase cross-linked FSG microgel particle system was prepared by the same method as in Example 1; fish oil with a volume fraction of 80% was added to the solution containing different concentrations (FSG) of particles prepared in Example 1, and a high-speed disperser (T18, Germany IKA) was used to disperse at 15000 rpm for 60 s. The prepared HIPEs were photographed using a Nikon D780 digital camera and stored in a 4°C refrigerator for standby. The preparation process is shown in Figure 2 .

[0064] Characterization of HIPEs

[0065] 1. Environmental stability test

[0066] The centrifugal stability, thermal stability and freeze-thaw stability of the prepared HIPEs were determined by various experiments. Specifically, the FSG microgel particle stabilized HIPEs were centrifuged at 1000 rpm for 4 min at 4°C to show their centrifugal stability. Freshly prepared HIPEs were heated in a high-pressure steam sterilization pot at 121°C for 30 min to show their thermal stability. After analyzing the thermal stability of the HIPEs, they were frozen at -20°C for 24 h, and then taken out and placed at room temperature for 2 h to perform a freeze-thaw cycle for analyzing the freeze-thaw stability of the HIPEs. All the treated groups of HIPEs were photographed using a Nikon D780 digital camera.

[0067] Figure 4The stability of HIPEs stabilized by different concentrations of FSG was studied under the influence of centrifugal force, heating, freezing-thawing and other external factors. In the centrifugal field, the centrifugal acceleration can be much higher than the gravitational acceleration, so it can accelerate the instability process of HIPEs. The results are as follows Figure 4 As shown in FIG. B, the HIPEs stabilized by low concentration FSG (10 mg / mL-30 mg / mL) had serious phase separation after centrifugation at 10000 rpm for 45 min (4°C), and the emulsion structure was completely destroyed, and water and oil appeared in the bottom of the HIPEs. The HIPEs stabilized by high concentration FSG particles (40-60 mg / mL) did not have water and oil separation after centrifugation, and the emulsion structure remained intact. In the thermal stability test Figure 4 C), only the HIPEs stabilized by 10 mg / mL FSG particles had a small amount of liquid separated at the bottom, and the rest had obvious structure destruction, which showed that the HIPEs stabilized by FSG particles had good thermal stability. Related studies also confirmed this point, because TG enzyme crosslinking can effectively increase the melting transition temperature of gelatin, and the thermal stability of gelatin is enhanced. After a freeze-thaw cycle, it can be found that Figure 4 D), the HIPEs stabilized by low concentration (10-20 mg / ml) FSG particles had some oil separation. For the HIPEs stabilized by low concentration FSG particles, too low protein concentration is not enough to form a thick interfacial film, and the ice crystals formed by water phase crystallization destroy the interfacial film by physical penetration, so that the emulsion shows oil separation and demulsification when dissolved. The above results show that the HIPEs stabilized by FSG particles have good stability at a certain concentration, and can maintain good performance after heat, centrifugation, and freeze-thaw treatment, which is very suitable for the processing of surimi.

[0068] Particle size and potential test of HIPEs

[0069] The particle size of fresh HIPEs and HIPEs stored at 25°C for 7 days was measured by laser particle size analyzer (Mastersizer 2000, Malvern, UK), and the volume average particle size d 4,3 was used to represent the emulsion particle size.

[0070] The Zeta potential of the droplets was measured by a potential analyzer (Zetasizer Nano ZS, Malvern, UK). Before measurement, the freshly prepared HIPEs were diluted with phosphate buffer solution (0.01 M, pH 5.8) to eliminate multiple scattering effects.

[0071] Comparing the changes in emulsion particle size during storage Figure 1 G), the droplet diameter d4,3 The droplet diameter was 53.98 μm and increased further with storage time, reaching 61.35 μm on the seventh day. In contrast, the droplet size of HIPEs stabilized with 30-60 mg / mL FSG did not exceed 50 μm during the seven-day storage period. In particular, the droplet size of HIPEs stabilized with 60 mg / mL FSG was 8.21 μm when fresh, increasing only slightly to 10.41 μm after seven days. This suggests that high concentrations of FSG can be directly used under appropriate dispersion conditions to form HIPEs with excellent storage stability, which is consistent with the dynamic interfacial adsorption results.

[0072] Zeta potential is the potential of the interfacial double layer at the particle interface and is an important indicator for evaluating the stability of colloidal dispersions. Proteins adsorbed on the surface of oil droplets in an emulsion may provide charge on the surface of the oil droplets. The zeta potential measurement determines the stability of the emulsion, where the most stable emulsions have the highest absolute zeta potential. The zeta potential of HIPEs at pH 6.0 is as follows: Figure 1 As shown in H. The Zeta-potential of HIPEs with an FSG concentration of 10 mg / ml is only -13.1 mV, indicating that the emulsion is not stable and is prone to flocculation. With the increase of FSG concentration, the absolute value of the Zeta-potential of the emulsion gradually increases and then decreases. The absolute values ​​of the Zeta-potential at protein concentrations of 40 mg / ml and 50 mg / ml are larger, indicating that HIPEs have stronger electrostatic repulsion at this time, are more stable, and are not prone to flocculation. The increase in the absolute value of the emulsion ζ-potential provides a high-energy barrier between the emulsion droplets, thereby providing good electrostatic repulsion. However, when the FSG concentration increases to 60 mg / mL, the absolute value of the potential drops to 18.9 mV. The change in the Zeta-potential of the colloidal particles is mainly attributed to the competition of adsorbed ions at the interface, the dissociation of surface groups, and the change in the thickness of the double layer caused by chemical surface reactions. For high-concentration protein solutions (60 mg mL -1) , the double layer thickness may dominate the Zeta-potential, resulting in a decrease in the absolute value of the Zeta-potential.

[0073] HIPEs interface protein adsorption (AP) test

[0074] HIPEs (20 g) were centrifuged at 15,000 g for 45 min at room temperature. After centrifugation, the aqueous phase at the bottom was collected and filtered through a 0.22 mm water filter. The filtrate was then assayed using the BCA method (using bovine serum albumin as a standard). f ) protein concentration. At the same time, the initial protein solution was centrifuged under the same conditions to determine the protein concentration in the supernatant (C s ). AP% is calculated according to formula (2):

[0075] AP (%) = (C s -C f )C0x 100% (2)

[0076] C0represents the concentration of FSG solution for the current HIPEs (10-60 mg / mL).

[0077] Microstructure test of HIPEs with different protein concentration

[0078] Optical microscope observation: Fresh emulsion was diluted with phosphate buffer solution (0.01 M, pH 5.8) and the droplet morphology was observed with an optical microscope equipped with a camera.

[0079] Laser confocal: 10 pL Nile red (1 mg / mL) and 10 pL Nile blue (1 mg / mL) were added into the prepared HIPEs (1 mL) respectively, and vortexed to mix well. After staining for 15 min at room temperature in the dark, the stained HIPEs were deposited on a concave microscope glass slide and covered with a cover glass. Nile red and Nile blue were excited by 488 nm argon laser and 647 nm He-Ne laser respectively. Green in the picture represents the oil phase, and blue represents the water phase.

[0080] The microstructure of HIPEs stabilized by FSG microgel particles with different concentrations was observed by laser confocal scanning microscope and inverted microscope Figure 5 A-D). FSG microgel particles and fish oil were stained with Nile blue (blue) and Nile red (green) respectively. As shown in Figure 5 A-D, green fluorescent M phase was observed inside the droplets, and blue fluorescent was observed on the droplet surface, further confirming the formation of O / W HIPEs. With the increase of FSG microgel particle concentration, the FSG particle layer became dense. This dense protein layer formed a physical barrier to prevent the accumulation of droplets and helped to stabilize the HIPEs. When the concentration of FSG microgel particles increased from 10 mg / ml to 60 mg / mL, the droplet size of the HIPEs gradually decreased, showing more uniform spherical droplets, which supported the experimental results of optical microscopy and particle size. Combined with dynamic interfacial adsorption and zeta potential analysis, it may be because at low FSG concentration, the amount of protein adsorbed on the interface at system equilibrium is low, which is not enough to cover all the oil droplets, and the interfacial membrane formed is thin and weak in rigidity. The low viscosity of the system leads to the easy floating of droplets after preparation, the collision of droplets leads to the damage of the interfacial membrane, and the internal oil droplets aggregate into larger large oil droplets. For HIPEs stabilized by higher concentration of FSG microgel particles, the particles are adsorbed on the oil-water interface to form a dense protein adsorption layer, and the excess particles are aggregated and cross-linked between the droplets to form a 3D network structure with strong rigidity on the droplet surface Figure 5B). HIPEs prepared with different concentrations of cod protein microgel particles were also found to have this cross-linked network. The FSG microgel particles in the continuous phase interacted with the droplet surface particles, fixing the position of the HIPEs droplets. This complex structure formed a strong physical barrier, and the steric hindrance of which improved the stability of the HIPEs.

[0081] Application Example

[0082] The application example is to use the 3D printing method to prepare the HIPEs-lipid fortified surimi 3D printing ink prepared in Example 2, and the specific preparation method is as follows:

[0083] Each group of 200g frozen surimi was thawed for 6h in a 4℃ environment, and then cut into cubes of 3cm x 3cm. After 2min of empty chopping with a chopper, 2wt% NaCl salt was added and chopped for 3min. Then the HIPEs were added to the surimi to form a series of different protein concentration stable HIPEs-lipid fortified surimi 3D printing inks (10mg / mL-60mg / mL). Then each group continued to chop for 3min. The blank group was the surimi sample without adding fish oil, and the control group was the sample directly adding liquid fish oil. The experimental group added HIPEs, and the fish oil content remained consistent with the control group, which was 5% of the mass of the surimi. Finally, the moisture content of all test groups of surimi was controlled at 80%. The whole process was carried out in a double-wall chopper with continuous circulation of cooling medium (ethanol: water 95:5), and was always kept at 4℃. Finally, a vacuum packaging machine was used for exhaust standby.

[0084] In addition, the application example also provides a method for printing the above-mentioned HIPEs-lipid fortified surimi 3D printing ink into a HIPEs-lipid fortified surimi finished product by 3D printing, and the specific steps are as follows:

[0085] A SHINNOVE-D1 (SHIYIN Technologies Co. Ltd., Hangzhou, China) extrusion 3D printer based on double-nozzle injectors was used to print the HIPEs-lipid fortified surimi 3D printing ink at 25±1℃. The following 3D printing parameters were optimized in the pre-test: nozzle diameter = 1.2mm, injector barrel diameter = 28mm, layer height 0.96mm, first layer layer height 0.8mm, printing speed = 20mm / s, shrinkage speed = 50mm / s. The HIPEs-surimi system model is a five-point star model (outer layer number 1 layer, 0% filling, model height 10mm) and a cylindrical model (outer layer number 2 layers, filling density 80%, model height 10mm, diameter 10mm).

[0086] In addition, in order to obtain a model with more complex color and structure, the present application also constructs a double-nozzle 3D printing model similar to the texture of snowflake steak. Before printing, the printing support performance of the HIPEs emulsion is tested, and the better HIPEs emulsion is selected for double-nozzle 3D printing. The printed model is shown in the figure, and the red part is the surimi dyed with natural red koji pigment, and the white fat part is HIPEs.

[0087] Rheological behavior test

[0088] The rheological properties of the HIPEs and the HIPEs-surimi were measured using a DHR-3 rheometer (Waters, USA) equipped with a 40 mm parallel plate. The rheological measurements were as follows: (1) Strain sweep test: First, a dynamic strain sweep was performed at a strain range of 0.01%-100% at 1 Hz to establish the linear viscoelastic region (LVR). (2) Stress sweep test: The storage modulus (G') and loss modulus (G") were measured at a constant frequency of 1.0 Hz (1-1000 Pa) in oscillatory stress sweep mode. The yield stress was determined at the intersection point where G' = G'. (3) Frequency sweep test: The G' and G" of the material were measured at a strain of 0.1% in the frequency range of 0.01-100 Hz. (4) Shear rate sweep test: The apparent viscosity of the material was measured when the shear rate increased from 0.01 to 100 s -1 Unless otherwise specified, all samples were measured at 25°C and a gap of 1000 μm, and were equilibrated at 25°C for 120 s before measurement to eliminate the effects of loading the sample and trimming on the sample, so that the sample reached a stable state.

[0089] The rheological properties of the printing paste are key factors that indicate the microstructure, stability, and functionality of the material. In addition, during the 3D printing process, the material must exhibit shear thinning properties to enable it to pass through the narrow nozzle, and after printing, it needs to have sufficient mechanical strength to be self-supporting, and all these properties are reflected in the rheological properties. Therefore, the present application studies the rheological behavior of the HIPEs stabilized by different FSG particles and the changes in the rheological behavior after the HIPEs are added to the surimi. The rheological behavior is analyzed by oscillation tests (including strain sweep test, stress sweep test, and frequency sweep test), shear rate sweep test, and rheological parameter fitting.

[0090] Firstly, in Figure 6 In a and b, the G and G of the HIPEs and the HIPEs-surimi system exhibit a relatively stable state in a certain strain range. Within this range (i.e., LVR), a strain value of 0.1% is determined and applied to the following tests.

[0091] The apparent viscosity and shear thinning properties of the printing paste were evaluated. η = K × γ n-1The equation can quantitatively describe the shear thinning characteristics of the printing paste, where η is the apparent viscosity, K is the consistency coefficient (Pa·sn), and γ is the shear rate (s -1 ), n is the flow behavior index, where n>1 indicates that the test sample is a dilatant fluid, and n<1 indicates that the test sample is a pseudoplastic fluid, and the smaller n is, the stronger the shear thinning ability is. -1 Increase to 100s -1 , FSG-stabilized HIPEs exhibit shear thinning ( Figure 6 c, Table 2), and their n values ​​are all less than 1. This may be due to the deformation and rearrangement of individual droplets or droplet clusters, which also means that the prepared HIPEs are all pseudoplastic fluids. It was found that the K value increased with the FSG concentration, indicating that increasing the FSG concentration level can enhance the apparent viscosity of HIPEs. It can be seen from the combination that the protein particles interact with each other, thereby increasing the viscosity. In the surimi system with HIPEs stabilized by adding different FSG concentrations, the ink showed a shear thinning phenomenon with increasing shear rate ( Figure 6 D, Table 3), the n values ​​are all less than 1, the control group with direct addition of fish oil has the largest apparent viscosity, and with the addition of different HIPEs, the apparent viscosity and K value of the surimi system show a gradually decreasing trend, indicating that the addition of HIPEs has a dilution effect on the surimi system, which will interfere with the cohesion of the system. This is because the change in apparent viscosity reflects the cross-linking characteristics of the internal structure of the surimi gel and the ability of the internal structure to resist deformation, indicating that compared with the direct addition of oils and fats, the addition of HIPEs hinders the formation of the surimi gel network. Yield stress is an indicator of the extrudability and self-supporting properties of ink. It should be noted at this time that the HIPEs ink studied in this experiment was smoothly extruded through the extrusion system of the printer, indicating that the critical yield stress for the HIPEs ink to start flowing is lower than the rated yield stress of the printer. In Figure 6 In E and F, within the lower stress range, the ink's G' is always greater than G". As the stress increases, the ink's structure is destroyed, and G' begins to decrease until G' is less than G". The intersection of G' and G" is the critical point where the ink changes from solid to liquid. As the FSG concentration increases, the yield stress gradually increases. A higher yield stress is more conducive to the self-support of the shape (Table 3), thereby ensuring high fidelity of the printed product. This conclusion can be confirmed by the photos of the 3D printed products of HIPEs. In addition to yield stress, G' and G" are generally used to reflect the mechanical strength of the ink. Inks with higher mechanical strength can exhibit superior self-supporting properties.

[0092] Moisture distribution of HIPEs-lipid-enhanced surimi 3D printing ink

[0093] The water distribution and composition of surimi samples were determined by proton relaxation time in low-field nuclear magnetic resonance (LF-NMR). The proton resonance frequency was 20 MHz, the magnet strength was 0.52 T, and the measurement temperature was 32℃. The surimi was accurately weighed and recorded, then placed in a nuclear magnetic tube with a diameter of 30 mm, and then placed in a low-field nuclear magnetic resonance analyzer. The Carr-Purcell-Meiboom-Gill (CPMG) sequence was used to determine the relaxation time T2 value of the sample. The measurement parameters: τ value (time between 90° pulse and 180° pulse) was 91 μs, repeated sampling 8 times, echo number 5000, the obtained CPMG exponential decay curve was inverted by MultiExp Inv Analysis software to obtain T2 value.

[0094] The water distribution reflects the tightness between myofibrillar protein and water molecules, and studies have also shown that the water distribution state of the slurry is closely related to the 3D printing performance, so by measuring the T2 relaxation time of surimi slurry to characterize the distribution and migration of water in surimi slurry. As shown in Figure 7 A, three peaks were observed in the curve, indicating that myofibrillar proteins restrict the mobility of water at different amplitudes. By AT 2b , AT 21 , AT 22 representing various water peaks (T 2b , T 21 , T 22 ), the area ratio can reflect the content and change of water in different states in surimi slurry. As can be seen from Table 4, the bound water (AT 2b ) accounts for 1.0-3.82%, the free water (AT 22 ) accounts for 2.1-3.39%, and the water that is not easy to flow (AT 21 ) accounts for as high as 94.09-96.79%, becoming the highest water state in surimi slurry. Compared with the blank group without adding oil, the AT 2b of the surimi slurry directly added with 5% wt fish oil increased significantly, and the AT 21 and AT 22 decreased, indicating that part of the water that is not easy to flow and free water in the slurry was converted into bound water, indicating that the direct addition of oil increased the binding capacity of surimi. This may be because the oil added forms a hydrophobic interaction with myofibrillar proteins, and liquid oil droplets can act as fillers for surimi networks, resulting in a more dense and less void microstructure Figure 7 E). Compared with the control group, the AT 2b of the surimi slurry added with HIPEs was significantly lower than that of the control group, and the AT 21The higher than the control group shows that the addition of HIPEs weakens the ability of myofibril protein to bind water. Studies have shown that emulsion gel acts as a filler or copolymer in surimi matrix, and the steric hindrance it produces reduces the formation of the three-dimensional network of myofibril protein matrix. Therefore, there is not enough three-dimensional network space to restrict the movement of water molecules in the matrix. As can be seen from the rheological analysis, the greater the concentration of FSG particles, the stronger the rigidity of the HIPEs, which leads to the inability of the HIPEs to stably exist in the surimi matrix during mixing with the surimi, causing damage to the spatial network of the surimi. The surimi microstructure slice confirms this point. This can be used to explain why the G', τ f , and η of the HIPEs-surimi system decrease.

[0095] Table 2 K value, n value and yield stress in the fitting model of HIPE

[0096]

[0097] Table 3 K value, n value and yield stress in the fitting model of HIPEs-lipid fortified surimi 3D printing ink

[0098]

[0099] Table 4 Low-field nuclear magnetic resonance analysis of HIPEs-lipid fortified surimi 3D printing ink

[0100]

[0101] 3D printing display

[0102] In order to evaluate the effect of the addition of oil on the printability of surimi, the ink system was printed into a five-point star without filling and a cylinder with 80% filling, and the center height of the printed product was measured (which can reduce the error caused by object deformation due to extrusion expansion and broken filaments). The accuracy of the 3D printed product was determined by formula (2), the center height of the product was measured again after 2h, and the stability of the product was determined by formula (3). The results are shown in Figure 8 It can be seen that the control group directly adding fish oil has uneven extrusion during printing. Combined with the rheological fitting parameters, it can be seen that under the current printing parameters (1.2mm diameter), the yield stress and consistency coefficient of the material have exceeded the maximum driving force range of the stepping motor of the printer, resulting in poor flowability of the sample, causing extrusion difficulty, and even plugging the nozzle, resulting in low printing accuracy. However, the strong mechanical properties of the sample result in good self-supporting performance and high printing stability. The self-supporting performance of OG5 and OG6 is poor, the printed lines are thick, and the printing accuracy and printing stability are low. In summary, OG3-OG4 is a slurry formulation that can have both printing accuracy and printing stability.

[0103] In addition, rheological analysis of the HIPEs showed that the FSG particle-stabilized HIPEs had excellent rheological properties and were an excellent 3DP material, and the 3D printing effect of the HIPEs was as shown in Figure 9 A. The 10 mg / mL FSG particle-stabilized HIPEs collapsed in the hollow square block of the printing demonstration, indicating that the FSG concentration at this time was not enough to support the HIPEs to carry out higher support 3DP, and with the increase of the FSG concentration, the yield stress, G' and apparent viscosity of the ink gradually increased, and even in the case of multi-layer continuous printing, fine printing shapes gradually close to the target size were obtained, which was also confirmed in other studies, which showed that the HIPEs exhibited good printability and could be used to program different types of 3D structures. In addition to 3D printing, another important application is that the HIPEs are a good substitute for fat containing trans fatty acids and animal back fat. This can bring an infinite number of new types of food, especially in combination with 3D printing technology. However, reports of 3D printing using a dual material system (HIPEs + other food matrix) are relatively rare, so the present application attempts to construct a steak-like model with a marbled pattern by using HIPEs as an animal fat mimic and surimi as a protein matrix for dual material 3D printing. The printing results are as shown in Figure 9 B. The results show that all concentrations of FSG-stabilized HIPEs groups can print structures with white texture, but as the FSG concentration increases, the printed fat texture becomes clearer and smoother. The design goal of this model is that the fat texture of the entire model is 40% (w / w), and this size and fat ratio can be adjusted by computer programs, so it is not only possible to reproduce complex meat texture by using dual nozzle printing, but also to adjust the fat content according to the consumer's own taste and health status.

[0104] Characterization of the finished product of HIPEs-lipid fortified surimi 3D printing

[0105] (I) Water holding capacity test

[0106] The water holding capacity (WHC) of surimi gel was determined by using a hardness meter method. The test steps are as follows: cut the surimi gel into 5 mm thin slices, weigh and record as W1, then wrap it with filter paper and place it in the center of the hardness meter, press it with 5 g force for 1 min, then remove the filter paper, weigh the pressed gel and record it as W2, test in parallel for 6 times. The water holding capacity of the surimi gel was calculated using formula (6):

[0107]

[0108] Water holding capacity (WHC) is the ability of surimi gel to retain its own water, which is an important attribute of surimi gel and directly affects the texture, mouthfeel and stability during storage. For example, Figure 7 The WHC trends of control and experimental samples were similar to the results of water distribution. The WHC of surimi gel was related to the state of lipid, which indicated that the direct addition of lipid within a certain range was beneficial to the formation of myofibrillar protein hydration network structure, which made water and lipid more dispersedly filled in the gel matrix. This may be because the hydrophobic residues of proteins were embedded in the interior of oil acyl chains to some extent, which increased the interaction between lipid and protein. However, when HIPEs were added, FSG particles would wrap oil, which hindered the interaction between lipid and protein, and the steric hindrance of HIPEs would increase the distance between proteins, which had a negative impact on their interaction, thus reducing the compactness and uniformity of the three-dimensional network structure.

[0109] Color

[0110] The lightness, red-green, blue-yellow and whiteness of HIPEs-surimi gel stabilized by FSG with different concentrations were shown in Table 5. Compared with the blank group, the L* and whiteness of the group with direct addition of oil increased significantly, because after the direct addition of oil, the oil droplet size was large, suspended on the surface of surimi gel, which enhanced the light scattering effect of surimi gel, resulting in more light being reflected, which increased the brightness and whiteness of surimi. The low concentration of stabilized HIPEs would also have oil precipitate during the surimi chopping process, which would be dispersed in the surimi gel network, and its whiteness and brightness would also increase significantly, but with the increase of protein concentration, HIPEs would completely wrap the oil, and its own light yellow appearance would also reduce its whiteness and brightness, but its indicators were within the range of sensory acceptance.

[0111] Table 5 Whiteness and texture properties of HIPEs-lipid fortified surimi 3D printing ink

[0112]

[0113] Texture properties

[0114] Food texture is highly dependent on textural attributes, which significantly affect consumer preference and acceptance behavior, and studies have shown that the textural properties of 3D-printed products are related to the effort and risk of obstruction in swallowing and pushing food chunks through the throat. In order to explore the effect of the addition of oil on the textural properties of 3D-printed surimi products, the present invention uses penetration experiments and TPA tests (double bite compression mode) to determine the gel strength, hardness, elasticity and chewiness of the samples. The gel strength, hardness, elasticity and chewiness of the control group with direct addition of fish oil are the highest, and studies have shown that omega-3 rich oils (flaxseed oil, algal oil, herring oil, etc.) can increase the mechanical properties of surimi gel, because within a certain range of oil addition, liquid oil is first broken into small droplets during chopping, and then interacts with salt-soluble myofibrillar proteins (MP) to form a semi-rigid interfacial protein film (IPF), which limits the movement of the protein matrix in the gel network structure, forming a more compact gel network structure, and studies have shown that direct addition of oil will adversely affect the mechanical properties of surimi, which is inconsistent with this study, which may be due to the difference in oil content, and studies have shown that the textural properties of emulsified meat products depend largely on the type and concentration of oil. Excessive oil addition reduces the concentration of surimi myofibrillar proteins, reducing the protein content of the gel network structure, resulting in a poor gel network structure, and the oil content of all groups in this study is consistent. The addition of HIPEs significantly reduces the textural properties of 3D surimi products, because as the FSG concentration increases, it is easier to form a more rigid emulsion gel, and FSG encapsulates fish oil droplets, preventing them from filling the myofibrillar protein network, and the mechanical strength of the emulsion gel is much lower than that of surimi itself, and the physical filling of the emulsion gel in the surimi matrix hinders the formation of the myofibrillar protein spatial network, thereby reducing the mechanical properties of the system. Studies have shown that foods for swallowing disorders and the elderly should exhibit low gel strength, hardness, elasticity and chewiness. This indicates that 3D-printed surimi products with added HIPEs have the potential to be selected and consumed by consumers with chewing or swallowing disorders.

[0115] Correlation analysis

[0116] The key task of the present invention is to evaluate the effect of FSG particles on the performance of HIPEs and the effect of adding HIPEs to surimi on its 3D printing properties, so a correlation graph is established between the performance of HIPEs, rheology, LF-NMR and 3D printing performance. The graph is a graphical representation of the Pearson correlation coefficient (r) -1 and 1, and a color scale is used to better understand the degree of correlation. In Figure 10 the FSG particle concentration and π 3600, AP, n(HIPEs), K(HIPEs), Tf(HIPEs) were positively correlated (p<0.05), indicating that the performance of HIPEs had obvious concentration dependence. FSG particle concentration, π 3600 , AP, n(HIPEs), K(HIPEs), Tf(HIPEs) were negatively correlated with the gel properties and rheological properties of the surimi system, indicating that the addition of HIPEs weakened the mechanical properties of the surimi system, but a certain FSG concentration of stable HIPEs made the surimi have higher 3D printing accuracy and stability under this 3D printing parameter condition.

Claims

1. A HIPEs-lipid-enhanced surimi 3D printing ink, characterized by: The invention comprises a polyunsaturated fatty acid high internal phase emulsion HIPEs stabilized by an FSG microgel particle system cross-linked by MTGase and fish paste; the HIPEs comprise a fish scale gelatin (FSG) microgel particle system cross-linked by transglutaminase (MTGase) and fish oil; the volume of the fish oil is 50-90% of the volume of the HIPEs; the HIPEs are HIPEs stabilized by 30-40 mg / mL of fish scale gelatin (FSG); and the fish paste contains 10-60 mg / mL of FSG-stabilized HIPEs.

2. The HIPEs-lipid-enhanced surimi 3D printing ink according to claim 1, characterized in that: The MTGase-crosslinked FSG microgel particle system was prepared by the following method, the steps being as follows: Fish scale gelatin (FSG) is dissolved in deionized water, swelled at room temperature, heated and stirred to obtain a gelatin solution, and cooled to room temperature; the pH value of the gelatin solution is then adjusted to 5.5-6.5, transglutaminase (MTGase) is added, and the solution is heated to 30-50°C for a cross-linking reaction for 30-50 minutes. After the reaction is completed, the reaction system is further heated to 85-95°C to inactivate the enzyme and homogenize to obtain the TGase-crosslinked FSG microgel particle system.

3. The HIPEs-lipid-enhanced surimi 3D printing ink according to claim 2, characterized in that: The added amount of the MTGase was 3.0 U / g FSG.

4. The method for preparing the HIPEs-lipid-enhanced surimi 3D printing ink according to any one of claims 1 to 3, characterized in that: Specifically, the frozen surimi is thawed, chopped by air and then by salt, and then HIPEs are added to form it.

5. A method for preparing a lipid-enhanced surimi 3D printed product, characterized in that: The HIPEs-lipid-fortified surimi 3D printing ink according to any one of claims 1 to 3 is added to the barrel of a 3D printer, and a product printing structure model and printing program steps are pre-designed or selected in the 3D printing device program; the printing program is started, and the 3D printing device extrude the HIPEs-surimi mixture onto a work platform in a stacked printing manner according to the preset product structure model layering information. Under the control of the software system 3D model, by controlling the barrel temperature and printing speed, the material is extruded and stacked into a three-dimensional solid structure through an extrusion nozzle, thereby producing the lipid-fortified surimi finished product.

6. The preparation method according to claim 5, characterized in that: The printing parameters were set as follows: nozzle diameter = 1.2 mm, syringe barrel diameter = 28 mm, layer height = 0.96 mm, first layer height = 0.8 mm, printing speed = 20 mm / s, and retraction speed = 50 mm / s.

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