Preparation method and application of a dual-network emulsion gel with anti-freezing property

Abstract

The application provides a preparation method and application of a double-network emulsion gel with anti-freezing property, and belongs to the technical field of food processing. The application takes hydrophilic polysaccharide, plant protein, phytosterol, vegetable fat and water as main raw materials, and adopts a reverse solvent method to prepare an aqueous phase containing plant protein and polysaccharide, so as to form a first layer network structure by using the plant protein and the polysaccharide; then the oil solution of the phytosterol is mixed with the aqueous phase, and a second layer network structure is formed by using the plant protein and the phytosterol in the oil-water mixture; finally, high-speed homogenization is performed to make the double-network structure more compact, and self-assembly is formed during the cooling process to form an emulsion gel; the obtained emulsion gel can resist repeated freezing and thawing, has the health and nutritional characteristics of low saturated fat and reduced cholesterol, and can be widely used to replace animal fat or fat tissue partially or entirely.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a double-network emulsion gel with antifreeze properties, its preparation method, and its application as a substitute for animal fat or adipose tissue. Background Technology

[0002] The rising global obesity rate and diet-related chronic diseases (such as cardiovascular disease and diabetes) have prompted consumers and industry to increasingly focus on healthy and sustainable food solutions. Fat substitution technology has become a key focus, as animal fats are typically rich in saturated fatty acids, which are closely linked to health risks. While plant-based foods have made significant progress in mimicking muscle structure as an alternative, simulating animal fats still faces considerable challenges. This is mainly due to the poor stability, rough texture, and lack of flavor of existing alternatives, and their reliance on single structural agents, which limits their application. Structured lipid systems such as emulsion gels, oleogels, and dual gels have become cutting-edge research directions. Among them, emulsion gels can effectively mimic the hardness and water retention capacity of animal fats, making them a good alternative and providing a new pathway for plant-based fat substitution. Summary of the Invention

[0003] The purpose of this invention is to provide a double-network emulsion gel with antifreeze properties, its preparation method and application, which can partially or completely replace animal fat or adipose tissue for use in food processing.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A dual-network emulsion gel with antifreeze properties is prepared by the following steps: (1) Dissolve thermally reversible and thermally irreversible mixed polysaccharides in hot water by stirring to obtain an aqueous solution; (2) Dissolve the plant protein in an organic solvent by stirring to obtain a plant protein solution; (3) The plant protein solution obtained in step (2) is slowly added to the aqueous solution obtained in step (1) to obtain a mixed solution. Then, the organic solvent is removed by rotary evaporation of the mixed solution to obtain the aqueous phase. (4) Dissolve phytosterols in vegetable oil by stirring to obtain the oil phase; (5) The oil phase obtained in step (4) is mixed with the water phase obtained in step (3), and high-speed homogenization emulsification is carried out under heat preservation conditions. Then the resulting emulsion is cooled to room temperature to obtain the antifreeze double network emulsion gel.

[0005] Furthermore, the thermally reversible polysaccharide mentioned in step (1) is carrageenan.

[0006] Furthermore, the thermally irreversible polysaccharide mentioned in step (1) is at least one of konjac flour, sodium alginate, gellan gum, etc.

[0007] Furthermore, the mass ratio of thermally reversible polysaccharide to thermally irreversible polysaccharide used in step (1) is 1:1.

[0008] Furthermore, the temperature of the hot water in step (1) is 45~90℃.

[0009] Furthermore, the stirring time in step (1) is 10~240 min.

[0010] Furthermore, the mass concentration of the aqueous solution obtained in step (1) is 0.1~10%.

[0011] Furthermore, the plant protein mentioned in step (2) is one or more of zein, soy protein, wheat protein, etc.

[0012] Further, the organic solvent in step (2) is an ethanol solution with a volume concentration of 80% to 100%.

[0013] Furthermore, the stirring time in step (2) is 5 to 60 minutes.

[0014] Furthermore, the mass concentration of the plant protein solution obtained in step (2) is 0.1-15%.

[0015] Furthermore, the volume ratio of the plant protein solution to the aqueous solution used in step (3) is 1:10.

[0016] Furthermore, the temperature of rotary evaporation in step (3) is 25~75℃.

[0017] Furthermore, the phytosterols mentioned in step (4) are selected from one or more of β-sitosterol, stigmasterol, campesterol, and sitosterol.

[0018] Furthermore, the vegetable oil mentioned in step (4) is selected from one or more of soybean oil, corn oil, peanut oil, sunflower seed oil, palm oil, etc.

[0019] Furthermore, the temperature for stirring and dissolving in step (4) is 60~90℃, and the stirring time is 10~60 min.

[0020] Furthermore, the mass concentration of the oil phase obtained in step (4) is 0.1~10%.

[0021] Furthermore, the mass ratio of the oil phase to the water phase used in step (5) is 1:9 to 4:6.

[0022] Further, in step (5), the high-speed homogenization emulsification temperature is 45~90℃, the emulsification speed is 10000~30000rpm, and the emulsification time is 1~5 min.

[0023] The resulting emulsion gel has a double-network self-assembled structure and can maintain good and stable gel properties after repeated freeze-thaw cycles. It can be used as a substitute for animal fat or adipose tissue to achieve partial or complete replacement.

[0024] The beneficial effects of this invention are as follows: (1) This invention mainly uses plant proteins such as zein, soybean protein, and wheat protein, and hydrophilic polysaccharides such as carrageenan, konjac flour, sodium alginate, and gellan gum as raw materials to construct an aqueous network structure; and uses plant sterols such as β-sitosterol, stigmasterol, campesterol, and sitosterol as raw materials to construct an oil network structure. Without adding emulsifiers or structural agents, the aqueous and oil phases are self-assembled by high-temperature and high-speed homogenization emulsification followed by natural cooling to obtain an emulsion gel. The resulting emulsion gel has a dual network structure that not only gives it good stability, preventing emulsion breakage and stratification under high temperature conditions, but also improves its own freeze-thaw stability, enabling it to withstand repeated freeze-thaw cycles (the loss rate can be controlled within 5% after three repeated freeze-thaw cycles). Moreover, it has structural characteristics similar to high-saturated fats and oils, and can be used to partially or completely replace animal fats or adipose tissues in frozen and prepared aquatic and meat products, with healthy nutritional characteristics of low saturated fat and reduced cholesterol.

[0025] (2) The dual-network low-saturated fat emulsion gel of the present invention can encapsulate physiologically active substances or flavor substances in the aqueous phase or oil phase, which can greatly improve the digestibility of physiologically active substances and the sustained-release performance of flavor substances.

[0026] (3) The emulsion gel of the present invention is constructed with plant-based raw materials, has low saturated fat content, is rich in phytosterols that have cholesterol-lowering function, and is low-carbon and environmentally friendly. It is healthier than traditional animal fat and has good application and commercial value. Attached Figure Description

[0027] Figure 1 The images show a comparison of the physical samples of different emulsion gels prepared in Example 1.

[0028] Figure 2 Polarized light microscope images of different emulsion gel samples prepared in Example 1.

[0029] Figure 3 This is a comparison chart of the freeze-thaw loss rates of different emulsion gel samples prepared in Example 1 after repeated freeze-thaw cycles.

[0030] Figure 4 The rheological properties of different emulsion gel samples prepared in Example 1 are compared.

[0031] Figure 5 The Fourier transform infrared spectra of different emulsion gel samples prepared in Example 1 are compared.

[0032] Figure 6 The results of 3D printing characteristic simulation tests were performed on the emulsion gel prepared in Example 2.

[0033] Figure 7 Comparison images of the emulsion gels prepared in Examples 2 and 3 and commercially available pork fat. Detailed Implementation

[0034] A dual-network emulsion gel with antifreeze properties is prepared by the following steps: (1) Mix thermally reversible polysaccharides and thermally irreversible polysaccharides at a mass ratio of 1:1, and stir in hot water at 45~90℃ for 10~240 min to dissolve them, so as to obtain an aqueous solution with a mass concentration of 0.1~10%; (2) Dissolve the plant protein in an ethanol solution with a volume concentration of 80% to 100% by stirring for 5 to 60 minutes to obtain a plant protein solution with a mass concentration of 0.1% to 15%. (3) The plant protein solution obtained in step (2) is slowly added to the aqueous solution obtained in step (1) at a volume ratio of 1:10. The resulting mixed solution is then evaporated at 25~75℃ to remove the organic solvent, and an aqueous phase is obtained. (4) Add phytosterols to the plant oil and stir at 60-90℃ for 10-60 min to dissolve them, so as to obtain an oil phase with a mass concentration of 0.1-10%; (5) The oil phase obtained in step (4) and the aqueous phase obtained in step (3) are mixed at a mass ratio of 1:9 to 4:6. The mixture is homogenized and emulsified at a speed of 10,000 to 30,000 rpm for 1 to 5 minutes under the heat preservation condition of 45 to 90°C. The resulting emulsion is then cooled to room temperature to obtain a double network emulsion gel with antifreeze properties.

[0035] In step (1), the thermally reversible polysaccharide is carrageenan. The thermally irreversible polysaccharide is at least one of konjac flour, sodium alginate, gellan gum, etc.

[0036] The plant protein mentioned in step (2) is one or more of zein, soy protein, wheat protein, etc.

[0037] The phytosterols mentioned in step (4) are selected from one or more of β-sitosterol, stigmasterol, campesterol, and sitosterol. The plant oils are selected from one or more of soybean oil, corn oil, peanut oil, sunflower oil, and palm oil.

[0038] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0039] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods. Example 1

[0040] The preparation of a dual-network low-emulsion gel with antifreeze properties includes the following steps: (1) Weigh 0.5 parts of carrageenan and 0.5 parts of konjac powder into 98 parts of hot water at 80℃, stir for 120 min to obtain an aqueous solution; (2) Weigh 1 part of zein and dissolve it in 9 parts of anhydrous ethanol. Stir at 500 rpm for 30 min to obtain zein solution. (3) The corn protein solution obtained in step (2) is slowly added to the aqueous solution in step (1) at a rate of 5 ml / min to obtain a mixed solution. Then, the mixed solution is rotary evaporated at 50°C to remove ethanol and obtain an aqueous phase. (4) Weigh 2 parts of stigmasterol into 98 parts of soybean oil at 80℃, stir and dissolve for 30 min to obtain the oil phase; (5) The oil phase obtained in step (4) and the aqueous phase obtained in step (3) are mixed evenly at mass ratios of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, and 7:3, respectively. The mixture is then homogenized and emulsified at 80°C for 3 min at a speed of 15000 rpm. The resulting liquid emulsion is cooled to room temperature to obtain emulsion gel, which are numbered a to g in sequence.

[0041] The prepared emulsion gel samples were tested using the following methods: 1. Texture determination: At room temperature, the emulsion gel was molded into a cylinder with a diameter of 20 mm and a height of 10 mm, and the TPA mode was used for determination, with a compression ratio of 30%.

[0042] 2. Microstructure: At room temperature, 10 μl of the emulsion gel was placed on a glass slide using a pipette, covered with a coverslip, and observed using a polarizing microscope at 400x magnification.

[0043] 3. Freeze-thaw loss rate determination: Weigh the original weight m1 of the emulsion gel, then freeze it in a -18℃ freezer for 24 hours. After thawing, remove it and let it thaw until the core temperature reaches room temperature. Wipe the surface with filter paper. Repeat the freeze-thaw cycle 3 times, and weigh it again m2. Calculate the freeze-thaw loss rate according to the formula: Freeze-thaw loss rate = (m1-m2) / m1×100%.

[0044] 4. Rheological properties: An aluminum plate with a diameter of 20 mm was used as a fixture to test the emulsion gel. Static scanning program, oscillation frequency test angular frequency 0.1~100 rad / s, strain 1%, temperature 25℃; flow scanning program, equilibrium time 30s, shear rate 0.1~1000 1 / s, equilibrium time 5s, averaging time 30s.

[0045] 5. Fourier transform infrared spectroscopy: Tested using a modified attenuated total reflectance (ATR) method. Absorption spectra are in the range of 400 to 4000 cm⁻¹. -1 Recording was performed within the specified range, with 64 scans and a spectral resolution of 4 cm⁻¹. -1 .

[0046] 6. 3D printing characteristic simulation test: The liquid emulsion gel was piped onto the surface of the petri dish using a piping bag, cooled to room temperature, and then photographed and recorded.

[0047] Figure 1 The images show physical samples of different emulsion gels prepared in Example 1. As can be seen from the images, sample g is in a liquid state and cannot form a solid emulsion gel; therefore, only sample af will be tested subsequently.

[0048] Figure 2 The images show polarized light micrographs of different emulsion gel samples prepared in Example 1. The images reveal that the formed emulsion gels are oil-in-water emulsions, with oil droplets evenly distributed in the aqueous phase, and significant phytosterol crystals present in the oil phase.

[0049] Figure 3 The figure shows a comparison of the freeze-thaw loss rates of different emulsion gel samples prepared in Example 1 after repeated freeze-thaw cycles. As can be seen from the figure, the freeze-thaw loss rate of all samples is within 10%, and the freeze-thaw loss rates of samples b, c, and d are within 5%.

[0050] Table 1 shows the textural test results of different emulsion gels prepared in Example 1 before and after repeated freeze-thaw cycles. As can be seen from Table 1, sample ad maintained good textural properties after repeated freeze-thaw cycles, while the textural properties of samples e and f deteriorated significantly after repeated freeze-thaw cycles.

[0051] Table 1

[0052] Figure 4 The figure shows a comparison of the rheological properties of different emulsion gel samples prepared in Example 1. As can be seen from the figure, the loss modulus of samples e and f is significantly higher than that of other samples, indicating that they have stronger irreversible deformation ability and are more likely to undergo permanent deformation that cannot be recovered under external force.

[0053] Figure 5The image shows a comparison of the Fourier transform infrared spectra of different emulsion gel samples prepared in Example 1. As can be seen from the image, at 2924 cm⁻¹... -1 and 2853 cm -1 The characteristic peak at 743 cm⁻¹ is attributed to the stretching vibration of the CH groups in triglycerides and monoglycerides, while the peak at 743 cm⁻¹ is attributed to the stretching vibration of the CH groups in triglycerides and monoglycerides. -1 and 1159 cm -1 The characteristic peak at 1636 cm⁻¹ is attributed to the C=O stretching vibration of triglycerides in the oil. -1 The peak at the specified position represents hydrogen bonding and is related to the OH stretching vibration of water molecules. All of these characteristic peaks confirm that the prepared emulsion gel has a physically integrated double network structure. Furthermore, with increasing oil phase content, the intensity of the hydrogen-related characteristic peaks first flattens out and then becomes significant, while the characteristic peaks related to the oil phase show the opposite trend. This indicates that physical hydrogen bonding is affected by the water / oil mass ratio, consistent with the results of texture and rheological tests.

[0054] As can be seen from the above, emulsion gels prepared by oil phase and water phase at a mass ratio of 2:8 to 4:6 have good comprehensive properties, among which the emulsion gel prepared by oil phase and water phase at a mass ratio of 3:7 has the best performance. Example 2

[0055] Replace the soybean oil used in step (4) of Example 1 with sunflower oil, and set the mass ratio of oil phase to water phase in step (5) to 3:7. Other operations are the same as in Example 1.

[0056] The obtained emulsion gel was evaluated through 3D printing property simulation tests, and the results are shown below. Figure 6 As shown in the figure, the obtained samples can be clearly shaped into numbers, letters, and simple Chinese characters, indicating that they have good plasticity and ductility and have the potential for 3D printing. Example 3

[0057] The soybean oil used in step (4) of Example 1 was replaced with palm oil and coconut oil respectively. The mass ratio of oil phase to water phase in step (5) was set to 3:7. Other operations were the same as in Example 1.

[0058] Figure 7 The figures show a comparison between the emulsion gels prepared in Examples 2 and 3 and commercially available pork fat. As can be seen from the figures, the apparent hardness of the emulsion gels varies significantly with increasing saturated fatty acid content of the added oils; the hardness of Example 2 is significantly lower than that of Example 3.

[0059] Table 2 compares the saturated fatty acid content of the emulsion gels prepared using different vegetable oils in Examples 2 and 3 with that of commercially available pork fat. As shown in Table 2, the emulsion gel prepared using coconut oil has a higher saturated fatty acid content.

[0060] Table 2 Example 4

[0061] The addition rates of corn protein solution in step (3) of Example 1 were adjusted to 8 ml / min and 20 ml / min, respectively. The mass ratio of oil phase to water phase in step (5) was set to 3:7. Other operations were the same as in Example 1.

[0062] The results showed that a stable emulsion gel could be obtained by adding corn protein solution at a rate of 8 ml / min, while an emulsion obtained by adding it at a rate of 20 ml / min would form a large amount of corn gliadin flocculent material and would not form a stable emulsion gel. Example 5

[0063] The homogenization speeds in step (5) of Example 1 were adjusted to 25,000 rpm and 5,000 rpm, respectively. The mass ratio of oil phase to water phase in step (5) was set to 4:6. Other operations were the same as in Example 1.

[0064] The results showed that a homogenization speed of 25,000 rpm could produce a stable emulsion gel, while a homogenization speed of 5,000 rpm resulted in obvious stratification of the emulsion, which could not form a stable emulsion gel.

[0065] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a double-network emulsion gel with antifreeze properties, characterized by comprising the following steps: (1) Dissolve and mix thermally reversible polysaccharides and thermally irreversible polysaccharides in hot water to obtain an aqueous solution; (2) Dissolve the plant protein in an organic solvent to obtain a plant protein solution; (3) The plant protein solution obtained in step (2) is slowly added to the aqueous solution obtained in step (1) to obtain a mixed solution. Then, the organic solvent is removed by rotary evaporation of the mixed solution to obtain the aqueous phase. (4) Dissolve phytosterols in vegetable oil to obtain the oil phase; (5) The oil phase obtained in step (4) is mixed with the water phase obtained in step (3), and high-speed homogenization emulsification is carried out under heat preservation conditions. Then the resulting emulsion is cooled to room temperature to obtain the dual-network emulsion gel.

2. The method for preparing a dual network emulsion gel according to claim 1, characterized in that, The thermally reversible polysaccharide mentioned in step (1) is carrageenan, and the thermally irreversible polysaccharide is at least one of konjac flour, sodium alginate, and gellan gum, with a mass ratio of 1:1; the mass concentration of the resulting aqueous solution is 0.1~10%.

3. The method of preparing a dual network emulsion gel according to claim 1, characterized in that, The plant protein in step (2) is one or more of zein, soy protein, and wheat protein; the organic solvent is an ethanol solution with a volume concentration of 80% to 100%; and the mass concentration of the resulting plant protein solution is 0.1% to 15%.

4. The method of preparing a dual network emulsion gel according to claim 1, characterized in that, The volume ratio of the plant protein solution to the aqueous solution used in step (3) is 1:

10.

5. The method of preparing a dual network emulsion gel according to claim 1, characterized in that, The phytosterols mentioned in step (4) are selected from one or more of β-sitosterol, stigmasterol, campesterol, and sitosterol; the plant oils are selected from one or more of soybean oil, corn oil, peanut oil, sunflower oil, and palm oil; and the mass concentration of the obtained oil phase is 0.1-10%.

6. The method of preparing a dual network emulsion gel according to claim 1, characterized in that, The mass ratio of oil phase to water phase used in step (5) is 1:9 to 4:6; the temperature of high-speed homogenization emulsification is 45 to 90°C, the emulsification speed is 10,000 to 30,000 rpm, and the emulsification time is 1 to 5 min.

7. A dual-network emulsion gel prepared by the method according to any one of claims 1 to 6.

8. The use of a dual-network emulsion gel as described in claim 7 as a substitute for animal fat or adipose tissue.

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