An oil-in-water emulsion gel and its preparation method and application, and a fat substitute

Abstract

The present invention provides an oil-in-water emulsion gel, a preparation method and application thereof, and a fat substitute, belonging to the technical field of food processing. The oil-in-water emulsion gel provided by the present invention has preparation raw materials including nano-starch particles, gelling polysaccharides, oil and water. The content of the nano-starch particles is 8-40 g / L, the content of the gelling polysaccharides is 10-30 g / L, and the volume fraction of the oil is 10-30%. The present invention uses nano-starch particles as an emulsion gel stabilizer and simultaneously uses gelling polysaccharides in combination, so that the prepared oil-in-water emulsion gel has good stability, and a fat substitute can be prepared by using the same, especially suitable for preparing fat substitutes by 3D printing through various complex models, with high printing accuracy and good simulated fat effect.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to an oil-in-water emulsion gel, a preparation method and application thereof, and a fat substitute. Background Art

[0002] Traditional solid fats contain more saturated fatty acids, which can have adverse effects on human health. Fat substitutes, such as plant-based fat substitutes obtained by structuring liquid vegetable oils with polysaccharide macromolecules, have attracted widespread attention due to their good fat-like processing performance, sensory properties, and green and healthy advantages.

[0003] 3D printing technology, also known as additive manufacturing technology, is a process of manufacturing products with target models by layer-by-layer deposition. Food 3D printing is the process of manufacturing food using 3D printing technology. It has the advantages of personalized nutrition control, precise regulation of complex structures, digital production, optimization of food supply chain and reduction of food waste. It has been unprecedentedly developed due to its convenient customization and ultra-high degree of freedom.

[0004] The emulsion gel currently used to prepare fat substitutes based on 3D printing has poor stability and performs poorly in printing high-precision models. Summary of the invention

[0005] The purpose of the present invention is to provide an oil-in-water emulsion gel and a preparation method and application thereof, and a fat substitute. The oil-in-water emulsion gel provided by the present invention has good stability and can be used to prepare a fat substitute, and is particularly suitable for preparing a fat substitute by 3D printing with high printing accuracy.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides an oil-in-water emulsion gel. The raw materials for preparing the gel include nano starch particles, curd polysaccharide, oil and water. The content of the nano starch particles is 8-40 g / L, the content of the curd polysaccharide is 10-30 g / L, and the volume fraction of the oil is 10-30%.

[0008] Preferably, the particle size of the nano starch particles is 100 to 500 nm.

[0009] Preferably, the curdlan comprises one or more of carrageenan, xanthan gum and gellan gum.

[0010] Preferably, the oil comprises one or more of soybean oil, corn oil, peanut oil, sesame oil, wheat germ oil and fish oil.

[0011] The present invention provides a method for preparing the oil-in-water emulsion gel described in the above technical solution, comprising the following steps:

[0012] Mix the nano-starch particles with water and perform a first homogenization treatment to obtain a nano-starch dispersion;

[0013] Mix the nano-starch dispersion with oil and perform a second homogenization treatment to obtain an oil-in-water emulsion;

[0014] Mix the oil-in-water emulsion with gellan gum and perform a gelation treatment to obtain the oil-in-water emulsion gel.

[0015] Preferably, the conditions of the first homogenization treatment and the second homogenization treatment independently include: a rotation speed of 12,000 - 16,000 rpm and a time of 2 - 5 min.

[0016] Preferably, the temperature of the gelation treatment is 70 - 80 °C and the time is 50 - 70 min.

[0017] The present invention provides the application of the oil-in-water emulsion gel described in the above technical solution or the oil-in-water emulsion gel prepared by the preparation method described in the above technical solution in the preparation of a fat substitute.

[0018] Preferably, the preparation method of the fat substitute includes 3D printing.

[0019] The present invention provides a fat substitute, which is prepared by 3D printing the oil-in-water emulsion gel described in the above technical solution or the oil-in-water emulsion gel prepared by the preparation method described in the above technical solution.

[0020] The present invention provides an oil-in-water emulsion gel, and the preparation raw materials include nano-starch particles, gellan gum, oil and water. The content of the nano-starch particles is 8 - 40 g / L, the content of the gellan gum is 10 - 30 g / L, and the volume fraction of the oil is 10 - 30%. The present invention uses nano-starch particles as an emulsion gel stabilizer and simultaneously uses gellan gum in combination, so that the prepared oil-in-water emulsion gel has good stability, and a fat substitute can be prepared by using it, especially suitable for 3D printing of various complex models to prepare a fat substitute, with high printing accuracy and good simulation of the fat effect.

[0021] The present invention provides a method for preparing the oil-in-water emulsion gel, which comprises the following steps: mixing nano starch particles with water, and performing a first homogenization treatment to obtain a nano starch dispersion; mixing the nano starch dispersion with oil, and performing a second homogenization treatment to obtain an oil-in-water emulsion; mixing the oil-in-water emulsion with gellan gum, and performing a gelation treatment to obtain the oil-in-water emulsion gel. The present invention uses nano starch particles and oil as raw materials, and obtains a nano starch dispersion and an oil-in-water emulsion (i.e., a Pickering emulsion stabilized by nano starch particles) through two-step homogenization treatment, and then obtains the oil-in-water emulsion gel through a gelation treatment under the action of gellan gum, realizing the structuring treatment of oil. The oil-in-water emulsion gel prepared by the method of the present invention has good rheological properties and emulsion stability, and can be used for preparing a fat substitute with controllable structure, especially suitable for preparing a fat substitute by 3D printing, with high printing accuracy and high printing strength, showing good application potential. In addition, the preparation process of the method provided by the present invention is simple and efficient, does not involve harmful reagents and chemical components, is green and environmentally friendly, realizes obtaining a more stable structured oil system under the condition of a lower oil phase ratio, can completely or partially replace traditional solid fat, and expands the practical application range of low-fat and healthy fat substitutes in the food field. Description of the Drawings

[0022] Figure 1 Photograph, optical microscope image and confocal microscope image of the O / W emulsion gel prepared in Example 1;

[0023] Figure 2 Rheological property comparison diagram of the O / W emulsion gels prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2;

[0024] Figure 3 Emulsion stability property comparison diagram of the O / W emulsion gels prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2;

[0025] Figure 4 3D printing product comparison diagram of the O / W emulsion gels prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. Detailed Embodiments

[0026] The present invention provides an oil-in-water emulsion gel, and the preparation raw materials include nano starch particles, gellan gum, oil and water. The content of the nano starch particles is 8-40 g / L, the content of the gellan gum is 10-30 g / L, and the volume fraction of the oil is 10-30%.

[0027] The present invention endows the emulsion gel with excellent stability through the Pickering mechanism, which refers to a novel green emulsion construction mechanism in which solid particles replace small molecule surfactants to form a coating on the surface of droplets. Specifically, the present invention uses nano-starch particles as the emulsion gel stabilizer and simultaneously uses gellan gum, so that the prepared oil-in-water emulsion gel has good stability, and can be used to prepare fat substitutes, especially suitable for preparing fat substitutes by 3D printing through various complex models, with high printing accuracy and high printing strength, and can achieve a good simulated fat effect. The oil-in-water emulsion gel of the present invention will be described in detail below.

[0028] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art or prepared by methods well-known to those skilled in the art.

[0029] In the present invention, the raw materials for preparing the oil-in-water emulsion gel include nano-starch particles; based on the raw materials, the content of the nano-starch particles is 8-40 g / L, preferably 15-35 g / L, and more preferably 25-32 g / L. In the present invention, the particle size of the nano-starch particles is preferably 100-500 nm. In the present invention, the nano-starch particles are used as the emulsion gel stabilizer and simultaneously gellan gum is used, so that the prepared oil-in-water emulsion gel has good stability. In the present invention, the nano-starch particles are preferably prepared by the nano-precipitation method, which specifically includes the following steps:

[0030] Mix natural starch with NaOH solution and perform the third homogenization treatment to obtain natural starch paste;

[0031] Drop the natural starch paste into ethanol and perform the fourth homogenization treatment to obtain a starch alcohol precipitation solution;

[0032] Centrifuge the starch alcohol precipitation solution, collect the precipitate, wash, dry, grind and sieve it in sequence to obtain the nano-starch particles.

[0033] The present invention mixes natural starch with an NaOH solution and performs a third homogenization treatment to obtain a natural starch paste. In the present invention, the natural starch preferably includes one or more of corn starch, tapioca starch, and rice starch, more preferably corn starch, tapioca starch, or rice starch; the concentration of the NaOH solution is preferably 0.01 - 0.05 g / mL, more preferably 0.01 - 0.03 g / mL; the dosage ratio of the natural starch to the NaOH solution is preferably 2 - 10 g:100 mL, more preferably 4 - 5 g:100 mL. In the present invention, the rotation speed of the third homogenization treatment is preferably 1500 - 3000 rpm, more preferably 2500 - 3000 rpm; the time is preferably 1 - 3 min, more preferably 2 - 3 min.

[0034] After obtaining the natural starch paste, the present invention drops the natural starch paste into ethanol and performs a fourth homogenization treatment to obtain a starch alcohol precipitation solution. In the present invention, the ethanol is preferably anhydrous ethanol; the volume ratio of the natural starch paste to the ethanol is preferably 1:1 - 3, more preferably 1:1 - 2. The present invention preferably drops the natural starch paste into the ethanol drop by drop. In the present invention, the rotation speed of the fourth homogenization treatment is preferably 3000 - 15000 rpm, more preferably 10000 - 15000 rpm; the time of the fourth homogenization treatment is preferably 2 - 5 min, more preferably 4 - 5 min, and the time of the fourth homogenization treatment starts from the completion of the dropping of the natural starch paste. The present invention preferably drops the natural starch paste into the ethanol under the rotation speed condition of the fourth homogenization treatment, and maintains the above rotation speed for the fourth homogenization treatment after the dropping is completed. The present invention preferably performs the fourth homogenization treatment under the above conditions, which is beneficial to promoting the formation of nano starch particles.

[0035] After obtaining the starch alcohol precipitation solution, the present invention centrifuges the starch alcohol precipitation solution, collects the precipitate, and successively performs washing, drying, grinding, and sieving to obtain the nano starch particles. In the present invention, the rotation speed of the centrifugation is preferably 1000 - 2000 rpm, more preferably 1500 - 2000 rpm; the time is preferably 5 - 10 min, more preferably 8 - 10 min. In the present invention, the reagent used for washing is preferably ethanol, more preferably anhydrous ethanol. In the present invention, the drying temperature is preferably 35 - 75 °C, more preferably 40 - 50 °C; the present invention has no special limitation on the drying time, as long as it is sufficiently dried. The present invention has no special limitation on the grinding and sieving, as long as nano starch particles meeting the particle size requirements can be obtained; in the examples of the present invention, the mesh number of the sieve used for sieving is specifically 200 meshes.

[0036] In the present invention, the raw materials for preparing the oil-in-water emulsion gel include gellan gum; based on the raw materials, the content of gellan gum is 10 to 30 g / L, preferably 15 to 25 g / L, and more preferably 20 g / L. In the present invention, the gellan gum preferably includes one or more of carrageenan, xanthan gum, and gellan gum, and more preferably carrageenan, xanthan gum, or gellan gum. The present invention preferably uses the above types of gellan gum, which has a fast gelation rate and good gelation effect.

[0037] In the present invention, the raw materials for preparing the oil-in-water emulsion gel include oil; based on the raw materials, the volume fraction of the oil is preferably 10 to 30%, more preferably 15 to 25%, and further preferably 20%. In the present invention, the oil preferably includes one or more of soybean oil, corn oil, peanut oil, sesame oil, wheat germ oil, and fish oil, and more preferably soybean oil, corn oil, peanut oil, sesame oil, wheat germ oil, or fish oil.

[0038] In the present invention, the raw materials for preparing the oil-in-water emulsion gel include water, and the amount of water used is only required to ensure that the contents of the nano starch particles and gellan gum and the volume fraction of the oil meet the above requirements.

[0039] In the present invention, the oil-in-water emulsion gel contains oil droplets formed by oil, and the size of the oil droplets is preferably 5 to 60 μm.

[0040] The present invention provides a method for preparing the oil-in-water emulsion gel according to the above technical solution, comprising the following steps:

[0041] Mix the nano starch particles with water and perform a first homogenization treatment to obtain a nano starch dispersion;

[0042] Mix the nano starch dispersion with oil and perform a second homogenization treatment to obtain an oil-in-water emulsion;

[0043] Mix the oil-in-water emulsion with gellan gum and perform a gelation treatment to obtain the oil-in-water emulsion gel.

[0044] In the present invention, the nano starch particles are mixed with water and a first homogenization treatment is performed to obtain a nano starch dispersion. In the present invention, the conditions of the first homogenization treatment preferably include: the rotation speed is preferably 12000 to 16000 rpm, more preferably 15000 rpm; the time is preferably 2 to 5 min, more preferably 3 min.

[0045] After obtaining the nano-starch dispersion, the present invention mixes the nano-starch dispersion with oil and performs a second homogenization treatment to obtain an oil-in-water emulsion. In the present invention, the conditions of the second homogenization treatment preferably include: the rotation speed is preferably 12,000 - 16,000 rpm, more preferably 15,000 rpm; the time is preferably 2 - 5 min, more preferably 3 min. In the present invention, in the oil-in-water emulsion, the oil is the dispersed phase and the nano-starch dispersion is the continuous phase.

[0046] After obtaining the oil-in-water emulsion, the present invention mixes the oil-in-water emulsion with gellan gum and performs a gelation treatment to obtain the oil-in-water emulsion gel. In the present invention, the mixing of the oil-in-water emulsion and gellan gum is preferably carried out under stirring conditions. The rotation speed of the stirring is preferably 100 - 120 rpm, more preferably 110 rpm; the time is preferably 1 - 2 min. In the present invention, the temperature of the gelation treatment is preferably 70 - 80 °C, more preferably 70 - 75 °C; the time is preferably 50 - 70 min, more preferably 55 - 60 min. In the present invention, during the gelation treatment, gellan gum gradually dissolves in the oil-in-water emulsion and cross-links with each other to produce a gel network. In the present invention, after the gelation treatment, it preferably further includes: cooling the material obtained after the gelation treatment to room temperature; the present invention has no special limitation on the cooling method, and it can be cooled by a water bath or naturally cooled at room temperature. The present invention preferably heats the mixture of the oil-in-water emulsion and gellan gum in a water bath for gelation treatment, and then naturally cools it to room temperature at room temperature to obtain the oil-in-water emulsion gel.

[0047] The present invention provides the application of the oil-in-water emulsion gel described in the above technical solution or the oil-in-water emulsion gel prepared by the preparation method described in the above technical solution in the preparation of fat substitutes. In the present invention, the preparation method of the fat substitute preferably includes 3D printing. The present invention can obtain customized fat substitute products with certain self-supporting properties through 3D printing. In the present invention, the method for preparing a fat substitute by 3D printing using the oil-in-water emulsion gel preferably includes the following steps:

[0048] Preheat the oil-in-water emulsion gel to a flowing state and then fill it into a 3D printing syringe;

[0049] Adjust the printing nozzle to a predetermined temperature and load the 3D printing needle, and reset the X-axis, Y-axis, and Z-axis of the 3D printer to zero through program settings;

[0050] Design a 3D model using data modeling software, generate a corresponding number of three-dimensional slices using slicing software to obtain a slice model, calculate the path for each layer of three-dimensional slice using programming G code and import it into the 3D printer;

[0051] The 3D printer performs 3D printing by means of air pump extrusion or mechanical extrusion according to preset 3D printing parameters to obtain the fat substitute.

[0052] In the present invention, the oil-in-water emulsion gel is preheated to a flowing state and then filled into a 3D printing syringe. There is no special limitation on the preheating temperature in the present invention, as long as the oil-in-water emulsion gel can be in a flowing state. Preferably, the flowing oil-in-water emulsion gel is filled into the 3D printing syringe without introducing air bubbles, and it is ensured that the oil-in-water emulsion gel in the 3D printing syringe is in a homogeneous and non-stratified state. In the present invention, the capacity of the 3D printing syringe is preferably 10 mL; the needle of the 3D printing syringe is preferably a conical needle, and the diameter of the needle is preferably 0.26 - 0.6 mm.

[0053] After completing the above steps, the printing nozzle of the present invention is adjusted to a predetermined temperature and the 3D printing needle is loaded, and the X-axis, Y-axis, and Z-axis of the 3D printer are all set to zero through program settings. In the present invention, the temperature of the printing nozzle is preferably 4 - 35 °C, more preferably 10 - 25 °C.

[0054] After completing the above steps, the present invention designs a 3D model using data modeling software, generates a corresponding number of three-dimensional slices using slicing software to obtain a sliced model, calculates the path for each layer of three-dimensional slice using programming G code and imports it into the 3D printer. In the present invention, the data modeling software is preferably the CAD 2007 version, and the exported 3D model is in the stl format; the slicing software is preferably the slic3r 1.3.1 version, and the file format after slicing is the gcode format.

[0055] After completing the above steps, the 3D printer of the present invention performs 3D printing by means of air pump extrusion or mechanical extrusion according to preset 3D printing parameters to obtain the fat substitute. Preferably, the air pump extrusion method is used for 3D printing in the present invention; the parameters of the 3D printing include: the printing layer height is preferably 0.2 - 0.4 mm, more preferably 0.2 - 0.3 mm; the filling density is preferably 80 - 100%, more preferably 90 - 100%; the air pump extrusion pressure is 10 - 25 kPa, more preferably 10 - 20 kPa; the printing rate is preferably 8 - 15 mm / s, more preferably 9 - 11 mm / s.

[0056] The present invention provides a fat substitute, which is prepared by 3D printing the oil-in-water emulsion gel described in the above technical solution or the oil-in-water emulsion gel prepared by the preparation method described in the above technical solution. In the present invention, the method and operating conditions for preparing the fat substitute by 3D printing the oil-in-water emulsion gel are preferably the same as those in the above technical solution, and will not be elaborated here.

[0057] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0058] The characterization and performance testing methods involved in the following examples and comparative examples are as follows:

[0059] Optical microstructure test: An optical microscope (Leica dmi1) was used to observe the microstructure of the O / W emulsion gel.

[0060] Confocal microstructure test: A laser confocal microscope (Leica TCS SP8) was used to observe the microstructure of the O / W emulsion gel, where the oil phase was stained with Nile red and appeared red in the results.

[0061] Rheological property test: Viscosity test was carried out in the shear rate range of 1 - 500 s -1 ; Modulus test was carried out in the angular frequency range of 0.1 - 100 rad / s while maintaining a constant strain of 2%. In addition, all tests were performed using an aluminum plate (diameter 25 mm), and the gap value was set to 1 mm.

[0062] Emulsion stability value test: Using an emulsion stabilizer ( Lab equipment, FormulationSmart Scientific Analysis) to monitor the change of optical signal in the O / W emulsion gel every 45 s, and calculate the emulsion stability value (TSI).

[0063] Example 1

[0064] 5 g of natural corn starch was mixed with 100 mL of a NaOH solution with a concentration of 0.01 g / mL, and shear homogenization treatment was carried out at a rotation speed of 3000 rpm for 3 min to dissolve the natural starch in the NaOH solution and completely gelatinize it, obtaining a natural starch paste; at a rotation speed of 15000 rpm, 100 mL of the natural starch paste was gradually dropped into 100 mL of absolute ethanol drop by drop. After dropping, homogenization treatment was carried out at a rotation speed of 15000 rpm for 5 min. Then, the obtained feed liquid was centrifuged at a rotation speed of 2000 rpm for 10 min. The precipitate was washed with absolute ethanol and dried at 50 °C, and then ground through a 200-mesh sieve to obtain nano-starch particles with a particle size of 100 - 500 nm;

[0065] Mix the nano-starch particles with water, and perform homogenization treatment at 15,000 rpm for 3 min to obtain a nano-starch dispersion with a concentration of 4 wt.%.

[0066] Add 20 mL of soybean oil to 80 mL of the nano-starch dispersion, and perform homogenization treatment at 15,000 rpm for 3 min to obtain an oil-in-water (O / W) emulsion. In the O / W emulsion, soybean oil is the dispersed phase and the nano-starch dispersion is the continuous phase.

[0067] Add 2 g of carrageenan to 100 mL of the O / W emulsion, stir at 110 rpm for 2 min, then heat-treat in a water bath at 70 °C for 1 h, and cool to room temperature to obtain an O / W emulsion gel.

[0068] Figure 1 Figures of the O / W emulsion gel prepared in Example 1 are shown, including a physical image, an optical microscope image, and a confocal microscope image. Among them, A is the physical image, B is the optical microscope image, and C is the confocal microscope image. As can be seen from Figure 1 A in, the emulsion gel prepared in Example 1 exhibits semi-solid characteristics, does not flow when inverted, and has a uniform milky white morphology, simulating the effect of fat in appearance. As can be seen from Figure 1 B and C in, the emulsion gel prepared in Example 1 is an oil-in-water emulsion gel, and the oil droplet size is 5 - 60 μm.

[0069] Perform 3D printing on the O / W emulsion gel prepared in Example 1, which specifically includes the following steps:

[0070] Preheat the O / W emulsion gel to a flowing state, then fill it into a 3D printing syringe without introducing air bubbles, and ensure that the oil-in-water emulsion gel in the 3D printing syringe is in a homogeneous and non-stratified state. Among them, the capacity of the 3D printing syringe is 10 mL, a conical needle head is used, and the needle head diameter is 0.26 mm.

[0071] Adjust the printing nozzle to 25 °C and load the 3D printing needle head, and set the X-axis, Y-axis, and Z-axis of the 3D printer to zero through program settings.

[0072] Design a 3D model using data modeling software, generate corresponding several layers of three-dimensional slices using slicing software to obtain a slice model, and calculate the path for each layer of three-dimensional slice using programming G code and import it into the 3D printer. Among them, the data modeling software is the CAD 2007 version, and the exported 3D model is in stl format; the slicing software is the slic3r1.3.1 version, and the file format after slicing is in gcode format.

[0073] The 3D printer performs 3D printing by means of air pump extrusion according to preset 3D printing parameters to obtain a fat substitute product with self-supporting properties; the 3D printing parameters include: a printing layer height of 0.2 mm; a filling density of 100%; an air pump extrusion pressure of 20 kPa; and a printing rate of 11 mm / s.

[0074] Example 2

[0075] Prepare the O / W type emulsion gel according to the method of Example 1, except that the soybean oil is replaced with fish oil.

[0076] Perform 3D printing on the O / W type emulsion gel prepared in this example according to the method of Example 1, except that the air pump extrusion pressure is 10 kPa.

[0077] Comparative Example 1

[0078] Prepare the O / W type emulsion gel according to the method of Example 1, except that the nano-starch dispersion is replaced with water.

[0079] Perform 3D printing on the O / W type emulsion gel prepared in this comparative example according to the method of Example 1, except that the air pump extrusion pressure is 15 kPa.

[0080] Comparative Example 2

[0081] Prepare the O / W type emulsion gel according to the method of Example 1, except that the nano-starch particles are replaced with natural corn starch.

[0082] Perform 3D printing on the O / W type emulsion gel prepared in this comparative example according to the method of Example 1.

[0083] Test Example 1

[0084] Perform rheological property tests on the emulsion gels prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2, and the results are as Figure 2 shown, where A is a graph of viscosity versus shear rate, B is a graph of modulus versus frequency, and the relevant detection data are shown in Table 1. As can be seen from Figure 2 A in, all four emulsion gels prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 have good shear thinning properties and can be used for extrusion-based 3D printing. As shown in Table 1, the emulsion gels prepared in Example 1, Comparative Example 1 and Comparative Example 2 have a shear rate of 0.01 s -1The viscosities under the conditions are 3839.4 Pa·s, 8092.8 Pa·s, and 6109.6 Pa·s respectively, indicating that the addition of nano-starch particles reduces the viscosity of the emulsion gel system, enabling it to be extruded more smoothly from the extrusion head, thereby improving the accuracy of 3D printing. The frequency sweep graph can reflect the internal structure information of the printing ink. Among them, the storage modulus (G') represents the stored energy caused by elastic materials, while the loss modulus (G”) reflects the energy loss caused by viscous deformation in rheology. According to Figure 2 As shown in B of

[0085] Table 1 Rheological property test results of emulsion gels prepared in examples and comparative examples

[0086]

[0087] Test Example 2

[0088] The emulsion gels prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were tested for emulsion stability value. The results are as Figure 3 shown in and Table 1. Turbiscan calculates the overall stability value (TSI) by detecting the backscattered light signal in real time and comparing it with the initial value through a built-in program. The closer the TSI is to 0, the better the stability of the emulsion gel. As can be seen from Figure 3 , the TSI values of the four emulsion gels increase with the passage of time, indicating that the emulsion gels are slowly destabilizing. Among them, the TSI value of the emulsion gel prepared in Example 1 is the smallest, always less than 0.1, indicating that this emulsion gel has high stability and is not easily deformed and destabilized during long-term storage. While the TSI values of the emulsion gels in Comparative Example 1 without nano-starch particles and Comparative Example 2 containing ordinary corn starch are both greater than 0.2, indicating that the emulsion gel prepared based on nano-starch particles has better stability and can better maintain the shape and accuracy of 3D printed products.

[0089] Figure 4The comparison chart of 3D printed products prepared by using the emulsion gels in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 shows that the emulsion gels in Example 1 and Example 2 have good 3D printing performance and printing accuracy, and can successfully print smooth, high-precision circles, five-pointed stars and the shape of the Zhejiang University Qiushi Eagle. However, when the emulsion gel in Comparative Example 1 3D prints circles and five-pointed stars, the top of the printed product is rough and some lines are distorted. When the emulsion gel in Comparative Example 2 prints the Zhejiang University Qiushi Eagle model with complex details, the printed lines are uneven and the surface of the entire printed product is uneven, affecting the visual aesthetics. By measuring and calculating the length, width and height of the printed products of the embodiment and the comparative example, and comparing them with the original printed model, the results are shown in Table 2. The printing accuracy of Example 1 can reach 94.33±3.30%, while the printing accuracy of Comparative Example 1 and Comparative Example 2 are 91.23±2.89% and 88.70±3.62%, respectively, indicating that the O / W emulsion gel stabilized by nano starch particles in the present invention has excellent 3D printing performance and can meet various high-precision food 3D printing requirements.

[0090] Table 2 Emulsion stability and printing accuracy test results of emulsion gels prepared in Examples and Comparative Examples

[0091]

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oil-in-water emulsion gel, characterized in that, The raw materials for preparation are nano-starch particles, gellan gum, oil and water. The content of the nano-starch particles is 25 - 40 g / L, the content of the gellan gum is 10 - 30 g / L, and the volume fraction of the oil is 10 - 30%. The gellan gum is carrageenan; the oil is soybean oil or fish oil. The preparation method of the nano-starch particles includes the following steps: mixing natural starch with NaOH solution, performing a third homogenization treatment to obtain a natural starch paste; dropping the natural starch paste into ethanol and performing a fourth homogenization treatment to obtain a starch alcohol precipitation solution; centrifuging the starch alcohol precipitation solution, collecting the precipitate, and successively performing washing, drying, grinding and sieving to obtain the nano-starch particles. The oil-in-water emulsion gel includes oil droplets formed by the oil, and the size of the oil droplets is 5 - 60 μm.

2. The oil-in-water emulsion gel according to claim 1, characterized in that, The particle size of the nano-starch particles is 100 - 500 nm.

3. The preparation method of the oil-in-water emulsion gel according to any one of claims 1 to 2, characterized in that, It includes the following steps: Mixing the nano-starch particles with water and performing a first homogenization treatment to obtain a nano-starch dispersion. Mixing the nano-starch dispersion with the oil and performing a second homogenization treatment to obtain an oil-in-water emulsion. Mixing the oil-in-water emulsion with the gellan gum and performing a gelation treatment to obtain the oil-in-water emulsion gel.

4. The preparation method according to claim 3, characterized in that, The conditions of the first homogenization treatment and the second homogenization treatment independently include: the rotation speed is 12000 - 16000 rpm, and the time is 2 - 5 min.

5. The preparation method according to claim 3 or 4, characterized in that, The temperature of the gelation treatment is 70 - 80 °C, and the time is 50 - 70 min.

6. The application of the oil-in-water emulsion gel according to any one of claims 1 - 2 or the oil-in-water emulsion gel prepared by the preparation method according to any one of claims 3 - 5 in the preparation of a fat substitute, and the preparation method of the fat substitute includes 3D printing.

7. A fat substitute, characterized in that, It is prepared by 3D printing of the oil-in-water emulsion gel according to any one of claims 1 - 2 or the oil-in-water emulsion gel prepared by the preparation method according to any one of claims 3 - 5.

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