Dual-emulsion gel-based functional fat substitutes, their preparation methods and applications

Abstract

This invention discloses a dual-emulsion gel-based functional fat substitute, its preparation method, and its application. The preparation method includes the following steps: (1) dissolving hydrophobic active molecules in edible oil as the inner phase and water as the outer phase, emulsifying in the presence of an emulsifier to obtain a nanoemulsion; (2) adding the nanoemulsion to an aqueous solution of hydrophilic active molecules as the inner phase and edible oil as the outer phase, emulsifying in the presence of a solid particulate emulsifier to obtain an oil-in-water-in-oil dual-emulsion gel-based functional fat substitute. The dual-emulsion gel-based functional fat substitute of this invention is composed of a dual-emulsion gel with a multi-internal-phase structure, thereby co-encapsulating hydrophilic and hydrophobic active ingredients and simulating the semi-solid characteristics of fat, with a stable gel structure.

Description

Technical Field

[0001] This invention relates to the field of oil and food processing technology, and in particular to a dual emulsion gel-based functional fat substitute, its preparation method, and its application. Background Technology

[0002] The continued rise in meat consumption has exacerbated carbon dioxide emissions from livestock farming, making plant-based meat a growing focus of attention. In plant-based meat, the choice of fat substitutes is crucial because real adipose tissue contains cellular structures, including hydrophilic proteins and hydrophobic lipids. Therefore, structurally mimicking real adipose tissue requires fat substitutes with multiphase structures that encapsulate various active ingredients, simultaneously carrying both hydrophilic and hydrophobic functional active components to further simulate the flavor and applications of real fat.

[0003] Currently, fat substitutes are often prepared using gel structures, such as hydrogels, oleogels, emulsion gels, and dough mixtures. Gel-like substances can mimic the semi-solid characteristics of fat in terms of rheological properties and achieve a high degree of imitation in taste. However, single-medium gel systems such as hydrogels or oleogels can only carry active ingredients with the same solubility, and cannot simultaneously carry or encapsulate hydrophilic and hydrophobic active ingredients. Emulsion structures, with their multiphase characteristics, have become a very promising template for fat substitutes. However, traditional emulsions contain only one internal phase, making it impossible to simultaneously co-encapsulate hydrophilic and hydrophobic active ingredients. Dual emulsions, with their two internal phases with different properties, have become an effective way to solve the problem of co-encapsulating hydrophilic and hydrophobic active substances. However, the stability of dual emulsions poses a challenge to their application in food. Therefore, for primary and secondary emulsion systems of dual emulsions, appropriate emulsifiers and emulsification methods should be carefully selected.

[0004] Chinese patent document CN113383947B discloses a method and application of a phase-change tunable emulsion gel type fat substitute. Different types of emulsion gels are prepared by changing the oil-water ratio using oil-soluble polysaccharides and small molecule gelling agents. The emulsion gel contains only one specific internal phase, that is, it can only encapsulate hydrophilic or hydrophobic active substances, and cannot simultaneously encapsulate hydrophilic and hydrophobic active molecules in the internal phase of the emulsion.

[0005] Chinese patent document CN114468062B discloses a 3D / 4D printable dual-network zero-trans fat emulsion gel. It uses phytosterol nanoparticles as interface stabilizers and adds room-temperature solidified plant oils to the external phase to achieve the solidification of the emulsion gel. This water-in-oil emulsion structure only contains an aqueous internal phase and cannot simultaneously encapsulate hydrophobic active molecules inside the emulsion gel.

[0006] The aforementioned emulsion gel materials only contain a single emulsion structure and lack multiple internal phase structures, thus they cannot be used to simultaneously co-encapsulate hydrophilic and hydrophobic active ingredients. Therefore, there is an urgent need to develop a stable, semi-solid fat-like dual emulsion gel capable of co-encapsulating hydrophilic and hydrophobic active ingredients as a functional fat substitute. This would enhance the specific functions of the fat substitute through the encapsulated active ingredients and promote its application in the food industry. Summary of the Invention

[0007] This invention provides a dual emulsion gel-based functional fat substitute and its preparation method. The fat substitute is composed of a dual emulsion gel with a multi-phase structure, thereby co-encapsulating hydrophilic and hydrophobic active ingredients and simulating the semi-solid characteristics of fat. Excellent dual emulsion gel stability is achieved through the triple stabilization mechanism of thermodynamic stability of nanoemulsion, Pickering emulsification mechanism and gel structure.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing a dual emulsion gel-based functional fat substitute includes the following steps:

[0010] (1) Hydrophobic active molecules are dissolved in edible oil as the internal phase and water is used as the external phase. Emulsification is carried out in the presence of an emulsifier to obtain a nanoemulsion.

[0011] (2) The nanoemulsion is added to the aqueous solution of hydrophilic active molecules as the inner phase and edible oil as the outer phase. Emulsification is carried out in the presence of solid particulate emulsifier to obtain an oil-in-water-in-oil dual emulsion gel-based functional fat substitute.

[0012] The hydrophobic active molecule is at least one of curcumin, quercetin, lycopene, resveratrol, and tocopherol.

[0013] Preferably, the concentration of hydrophobic active molecules in the inner phase of step (1) is 1~500 mg / mL.

[0014] In dual emulsion gel-based functional fatty acid substitutes, the amount of hydrophobic active molecules encapsulated is limited by their solubility in the inner oil phase. Therefore, the concentration of hydrophobic active molecules in the inner phase has a certain optimal range. Exceeding this range may result in the hydrophobic active molecules not being completely dissolved in the inner phase, thus leading to encapsulation failure.

[0015] Further preferably, the concentration of hydrophobic active molecules in the inner phase of step (1) is 1~10 mg / mL; and even more preferably, it is 1~5 mg / mL.

[0016] The nanoemulsion in step (1) is an oil-in-water emulsion.

[0017] Preferably, in the nanoemulsion of step (1), the mass concentration of the emulsifier is 0.1-5%.

[0018] As the emulsifier concentration increases, the particle size of the nanoemulsion decreases significantly. However, once the emulsifier concentration reaches a certain value, the particle size reaches a critical value; beyond this point, further increases in concentration do not significantly reduce the droplet size. The viscosity of the nanoemulsion is also related to the emulsifier concentration. Too low a concentration leads to a significant increase in viscosity, which is detrimental to subsequent processing, while too high a concentration does not significantly reduce viscosity. The encapsulation efficiency of hydrophobic active molecules decreases with increasing emulsifier concentration. This is because the smaller droplet size exacerbates the exchange of matter between the hydrophobic active molecules and the external phase.

[0019] More preferably, in the nanoemulsion of step (1), the mass concentration of the emulsifier is 0.1-0.5%.

[0020] When the mass concentration of emulsifier is 0.1-0.5%, the nanoemulsion exhibits good emulsion particle size, viscosity, and encapsulation efficiency for hydrophobic active molecules.

[0021] In a further preferred step, the mass concentration of the emulsifier in the nanoemulsion of step (1) is 0.2-0.4%.

[0022] Preferably, in step (1), the emulsifier is at least one of Tween-20, Tween-40, Tween-60, Tween-80, and Tween-85.

[0023] Preferably, in the nanoemulsion of step (1), the volume fraction of the internal phase is 1-50%.

[0024] More preferably, in the nanoemulsion of step (1), the volume fraction of the internal phase is 1-10%. In step (1), if the volume of the internal phase is too large, the final product cannot maintain stability and cannot have a gel-like physical structure.

[0025] Preferably, step (1) includes: dissolving hydrophobic active molecules into oil as the inner phase, using water as the outer phase, mixing the inner phase, outer phase, and emulsifier, first obtaining a crude emulsion through high-speed shearing, and then emulsifying the crude emulsion under high pressure to obtain a nano-emulsion.

[0026] The high-speed shearing has a shearing rate of 8000-20000 rpm and a shearing time of 1-10 min.

[0027] The conditions for high-pressure emulsification are: 100-1000 bar emulsification cycle 1-10 times.

[0028] The edible oil mentioned is at least one of camellia oil, flaxseed oil, soybean oil, walnut oil, peanut oil, olive oil, rapeseed oil, sesame oil, corn oil, and sunflower seed oil.

[0029] The hydrophilic active molecule is at least one of anthocyanins, functional polysaccharides, ascorbic acid, amino acids, and nucleotides.

[0030] The dual emulsion gel-based functional fat substitute of the present invention is Pickering emulsion.

[0031] Preferably, in step (2), the solid particles are phytosterol particles with a particle size of less than 1 μm.

[0032] When the content of solid particulate emulsifier is insufficient, its emulsifying ability decreases, thus failing to form an effective emulsion and emulsion gel structure.

[0033] Preferably, in the dual emulsion gel-based functional fat substitute, the mass fraction of the solid particulate emulsifier is 1-10%.

[0034] Preferably, in step (2), the mass fraction of the hydrophilic active molecules containing nanoemulsion in the aqueous solution is 0.5-20%; and the volume fraction of the hydrophilic active molecules containing nanoemulsion in the dual emulsion gel-based functional fat substitute is 30-90%.

[0035] The encapsulation efficiency of hydrophobic active molecules in dual emulsion gels is relatively stable. However, as the content of nanoemulsions in the aqueous solution containing hydrophilic active molecules increases, the encapsulation efficiency of the prepared dual emulsion gel for hydrophilic active molecules gradually decreases. The liquid retention rate of the dual emulsion gel is a key parameter reflecting its stability; as the content of nanoemulsions in the aqueous solution increases, the liquid retention rate decreases significantly. Furthermore, when the content of hydrophilic active molecules in the aqueous solution containing nanoemulsions is insufficient, the final product cannot form a gel structure due to the low internal phase fraction.

[0036] Further preferably, in step (2), the mass fraction of the hydrophilic active molecules in the aqueous solution containing the nanoemulsion is 1-10%; and the volume fraction of the hydrophilic active molecules in the aqueous solution containing the nanoemulsion in the dual emulsion gel-based functional fat substitute is 60-70%. The dual emulsion gel-based functional fat substitute obtained by this technical solution has good encapsulation efficiency of both hydrophobic and hydrophilic active molecules, good liquid retention rate, and stable gel properties.

[0037] Preferably, in step (2), emulsification is performed by high-speed shearing; the shearing rate of high-speed shearing is 8000-15000 rpm and the shearing time is 1-10 min.

[0038] The present invention also provides a dual emulsion gel-based functional fat substitute prepared by the above preparation method.

[0039] The present invention also provides the application of the aforementioned dual emulsion gel-based functional fat substitute in the food industry.

[0040] The present invention also provides the application of the aforementioned dual emulsion gel-based functional fat substitute in pH-induced color-changing food 3D printing.

[0041] Food 3D printing applications use dual emulsion gel-based functional fat substitutes encapsulated with pH-sensitive hydrophilic active molecules as 3D printing raw materials to achieve food-grade 3D color-changing printing under conditions of adjusted aqueous phase pH.

[0042] Preferably, the application includes:

[0043] The hydrophilic active molecule is a pH-sensitive hydrophilic active molecule;

[0044] The pH of the aqueous solution containing hydrophilic active molecules in nanoemulsion was adjusted to 2-11 as the internal phase, and edible oil was used as the external phase. Emulsification was carried out in the presence of solid particulate emulsifier to obtain an oil-in-water-in-oil dual emulsion gel-based functional fat substitute.

[0045] 3D printing was performed using a dual emulsion gel-based functional fat substitute as a printing paste.

[0046] Preferably, during 3D printing, the print head diameter is 0.8-1.5 mm, the printer extrusion compensation is 120-200%, the printing temperature is room temperature, and the printing speed is 10-100 mm / s.

[0047] The present invention also provides the application of the aforementioned dual emulsion gel-based functional fat substitute in the controlled release of active molecules.

[0048] By co-encapsulating hydrophilic and hydrophobic active molecules within a dual emulsion gel system, the controlled release of active molecules from dual emulsion gel-based functional lipid substitutes is achieved.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) The fat substitute of the present invention is based on a dual emulsion gel structure. Its multi-phase characteristics enable it to co-encapsulate hydrophilic and hydrophobic active molecules and achieve controlled sustained release of active molecules during digestion.

[0051] (2) The dual emulsion gel structure of the fat substitute of the present invention uses nano-emulsion as primary emulsion and Pickering emulsion as secondary emulsion, which achieves a triple stability effect of thermodynamic stability, Pickering emulsification mechanism stability and gel structure stability, thus solving the weakness of poor stability of dual emulsion structure.

[0052] (3) The dual emulsion gel-based fat substitute of the present invention has adjustable semi-solid viscoelastic characteristics, can be used to replace traditional fat tissue in food, and the raw materials are not animal-derived, with healthy and green processing characteristics.

[0053] (4) The internal phase of the dual emulsion gel-based fat substitute of the present invention can dissolve pH-sensitive active pigments. Combined with good thixotropy and structural recovery ability, it can be used for pH-induced color change food 3D printing.

[0054] (5) The dual emulsion gel-based functional fat substitute of the present invention has low oil content, does not contain trans fatty acids, and the outermost phase is an oil phase, which can simulate the taste and texture of fat to a greater extent with lower oil addition. Attached Figure Description

[0055] Figure 1 This is a process flow diagram of the preparation of a dual emulsion gel-based functional lipid substitute co-encapsulated with hydrophobic quercetin and hydrophilic anthocyanin in Example 1.

[0056] Figure 2 The droplet size distribution (A), viscosity (B), and encapsulation efficiency (C) of the nanoemulsion prepared in step (1) of Example 1 are shown.

[0057] Figure 3 The rheological data for the fat substitutes prepared in Example 1 include strain scans (A), frequency scans (B), time scans (C), and temperature scans (D).

[0058] Figure 4 The encapsulation efficiency of quercetin (A), anthocyanin (B), and liquid retention rate (C) of the fat substitute prepared in Example 1 are given.

[0059] Figure 5 The FTIR spectrum is obtained by lyophilizing the fat substitute prepared in Example 1.

[0060] Figure 6 The FTIR spectra of all raw materials used in Example 1 for preparing a dual emulsion gel-based functional lipid substitute co-encapsulated with hydrophobic quercetin and hydrophilic anthocyanins are shown.

[0061] Figure 7Top and side views of the models after 3D color-changing printing of the fat substitutes in Example 2 and Comparative Example 6.

[0062] Figure 8 This is an example of the release of quercetin (A), anthocyanins (B), and free fatty acids (C) from camellia oil after simulated digestion in Example 3. Detailed Implementation

[0063] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0064] Test method:

[0065] 1. The particle size of the nanoemulsion was tested using a Zeta-nanoparticle size analyzer. The data were presented in the form of average particle size and polydispersity index, and the frequency of particle size distribution was statistically analyzed.

[0066] 2. The viscosity of the nanoemulsion was tested using a rotational rheometer in flow curve mode, with shear rates starting from 0.1 s⁻¹. -1 Increase to 100 s -1 The test temperature was 25℃.

[0067] 3. The encapsulation efficiency of quercetin was quantitatively tested by ultraviolet spectrophotometry. Unencapsulated quercetin in the nanoemulsion was extracted by dilution, filtration, and mixing with anhydrous ethanol. The quantification was performed by ultraviolet spectrophotometer. The absorption wavelength of quercetin was 373 nm.

[0068] 4. The rheological properties of the dual emulsion gel-based functional fat substitute were tested using an advanced rotational rheometer. In the strain scan, the strain value was increased from 0.01% to 100%, the frequency was set to 1 Hz, and the temperature was 25℃. In the frequency scan, the frequency was increased from 0.1% to 10 Hz, the strain was set to 0.1%, and the temperature was 25℃. In the time scan, the strain was rapidly switched between 0.1% and 100%, each stage was held for 150 s, the frequency was set to 1 Hz, and the temperature was 25℃. In the temperature scan, the temperature was increased from 5℃ to 90℃ and then decreased back to 5℃, the strain was set to 0.1%, the frequency was 1 Hz, and the temperature was 25℃.

[0069] 5. The encapsulation efficiency of quercetin and anthocyanins in the dual-emulsion gel-based functional fat substitute was determined by ultraviolet spectrophotometry. The dual-emulsion gel was first centrifuged at 4000 rpm for 15 min. After centrifugation, the supernatant was filtered and mixed with anhydrous ethanol to extract the unencapsulated quercetin and anthocyanins. The quantification was performed using an ultraviolet spectrophotometer, and the absorption wavelength of anthocyanins was 535 nm.

[0070] 6. The liquid retention rate of the dual emulsion gel-based functional fat substitute was tested by centrifugation. The sample was placed in a centrifuge tube and centrifuged at 8000 rpm for 30 minutes. The leaked liquid was removed and weighed to calculate the liquid retention rate.

[0071] 7. Fourier transform infrared (FTIR) spectra of dual emulsion gel-based functional fat substitutes and their raw materials were measured using an FTIR spectrometer with wavenumbers ranging from 500 to 4000 cm⁻¹. -1 The test method is attenuated total reflection mode, and the sample needs to be freeze-dried to remove moisture before testing.

[0072] 8. The full texture test of the 3D printed model was carried out by a texture analyzer. The TPA mode was used, and a 50 mm diameter probe was selected for TPA mode extrusion. The extrusion strain was 30%, and the probe speed was 1 mm / s.

[0073] 9. The release rates of quercetin and anthocyanins during simulated digestion were tested using ultraviolet spectrophotometry. After simulated gastric digestion, the digestive fluid was centrifuged at 4000 rpm for 15 min. The supernatant was collected, filtered, and anhydrous ethanol was added for extraction of active substances. The final mixture was tested and quantified using an ultraviolet spectrophotometer, and the release rate was calculated. The release rate of camellia oil was determined by measuring the amount of NaOH required to maintain the pH of the digestive fluid at 7 during simulated intestinal digestion, thus measuring the content of free fatty acids.

[0074] Examples 1-5: A method for preparing dual emulsion gel-based functional fat substitutes

[0075] (1) 0.1 g, 0.2 g, 0.3 g, 0.4 g and 0.5 g of Tween-80 were dissolved in 5 mL of camellia oil heated in a water bath at 45 °C. Then 25 mg of hydrophobic active molecule quercetin was added and stirred until completely dissolved to prepare an oil solution of quercetin. 5 mL of the oil solution was mixed with 95 mL of water and a crude emulsion was prepared by high-speed emulsification at a shear rate of 12000 rpm for 5 min. The crude emulsion was further subjected to high-pressure emulsification at 600 bar for 5 cycles to finally obtain a nanoemulsion encapsulated with hydrophobic active molecule quercetin.

[0076] (2) Dissolve anthocyanins in water at pH 7 at a concentration of 5 mg / mL to prepare anthocyanin aqueous solution. Take 1 mL (1%, Example 1), 3 mL (3%, Example 2), 5 mL (5%, Example 3), 7 mL (7%, Example 4), and 9 mL (9%, Example 5) of the nanoemulsion emulsified with 0.3 g Tween-80 in step (1), and make up to 100 mL with anthocyanin aqueous solution. Stir thoroughly until uniform and set aside.

[0077] (3) Take 65 mL of the mixed liquid obtained in step (2), add 35 mL of camellia oil and 5 g of phytosterol nanoparticles with an average particle size of 800 nm, and emulsify using a high-speed emulsification method with a shear rate of 12000 rpm for 5 min to finally obtain a dual emulsion gel-based functional fat substitute co-encapsulated with hydrophilic anthocyanins and hydrophobic quercetin. A method for preparing a dual emulsion gel-based functional fat substitute, the flowchart of which is shown below. Figure 1 As shown.

[0078] Figure 2 The droplet size distribution, polydispersity index (A), viscosity (B), and encapsulation efficiency (C) of the nanoemulsion encapsulated with the hydrophobic active molecule quercetin prepared in step (1) are analyzed. With increasing Tween-80 concentration, the droplet size of the nanoemulsion significantly decreases. However, when the concentration reaches 0.3%, a critical value is reached, and concentrations exceeding 0.3% do not significantly reduce the droplet size. The viscosity of the nanoemulsion also has a 0.3% Tween-80 concentration as a dividing line. Too low a concentration leads to a significant increase in viscosity, which is detrimental to subsequent processing, while concentrations exceeding 0.3% do not significantly reduce the viscosity. The encapsulation efficiency of quercetin decreases continuously with increasing Tween-80 concentration. This is because the droplet size decreases, thus intensifying the exchange of substances between quercetin and the external phase.

[0079] Figure 3 These are rheological test results for a dual-emulsion gel-based functional fat substitute. As a fat substitute, the rheological properties of the dual-emulsion gel can reflect its ability to mimic the sensory properties of fat. Traditional fat is typically a plastic semi-solid with a crystalline structure, and its elastic modulus (G') is higher than its viscous modulus (G''). However, when fat is subjected to strong pressure, G'' will briefly exceed G'. In strain scans ( Figure 3In step (2), when the amount of nanoemulsion in step (2) is 1 mL, the dual emulsion gel exhibits the largest linear viscoelastic region (LVR) and the highest G' and G'' reversal points (~5%), indicating that this dual emulsion gel has the highest yield stress. With increasing nanoemulsion in step (2), the LVR of the dual emulsion gel continuously decreases, while the G' and G'' reversal points decrease. From 1% to 9% of the nanoemulsion in the W phase, the G' and G'' of the dual emulsion gel in the LVR decrease from 22400 Pa and 4700 Pa to 7500 Pa and 1550 Pa, respectively, implying that increasing the amount of nanoemulsion leads to a decrease in the solid properties of the dual emulsion gel. In the frequency scan ( Figure 3 In the time-scanning (B), the G' and G'' of the dual emulsion gel remain on the same order of magnitude, indicating that the rheological properties of the dual emulsion gel are stable as the frequency increases from 0.1 Hz to 10 Hz. Modular stability during frequency scanning is fundamental to the suitability of dual emulsion gels for food processing. The modulus recovery capability of dual emulsion gels is crucial for food applications, such as food 3D printing. Figure 3 The dual-emulsion gel underwent continuous strain cycles between 0.1% and 100%. After several cycles, the G' and G'' of the dual-emulsion gel recovered to over 90%, which means that the dual-emulsion gel can quickly recover its semi-solid properties and achieve structural recoverability after structural damage caused by strong strain. Figure 3 Figure D shows the change in modulus of the dual emulsion gel with temperature. As the temperature rises from 5°C to 90°C and then falls back to 5°C, when the amount of nanoemulsion in step (2) is 1 mL, the decrease in G' and G'' of the dual emulsion gel is the smallest at 90°C, and the degree of modulus recovery is the highest at 5°C. However, the continuous increase in the amount of nanoemulsion in step (2) greatly affects the temperature stability of the dual emulsion gel. Higher nanoemulsion concentrations will significantly reduce the G' and G'' of the dual emulsion gel at 90°C, as well as the structural recoverability at 5°C, meaning that the rheological properties of the dual emulsion gel cannot be restored to their original state after temperature cycling. This also means that the rheological properties of the dual emulsion gel can be easily controlled by changing the amount of nanoemulsion added.

[0080] Table 1 shows the droplet size distribution of the prepared dual emulsion gel when the amount of nanoemulsion added in step (2) is 1-9 mL. D 90 , D 50 , D 10 ), and polydispersity index ( SPAN As the concentration of nanoemulsions continues to increase, the emulsion droplets of the dual emulsion gel continue to grow larger, and the particle size dispersion also continues to increase.

[0081] Table 1 shows the relationship between the concentration of the internal phase nanoemulsion and the droplet size in the dual emulsion gel.

[0082]

[0083] Figure 4 The encapsulation efficiency and liquid retention rate (C) of the dual emulsion gel for quercetin (A) and anthocyanins (B) are shown. The encapsulation efficiency of quercetin in the dual emulsion gel is relatively stable, consistently maintaining above 90%. With the continuous increase of nanoemulsion in step (2), the encapsulation efficiency of the prepared dual emulsion gel for anthocyanins decreases from 85.6% to 80.7%. The liquid retention rate of the dual emulsion gel is a key parameter reflecting its stability. With the increase of nanoemulsion, the liquid retention rate decreases significantly. The liquid retention rate of the dual emulsion gel containing 9% nanoemulsion in the inner phase is less than 60%, while the liquid retention rate of the dual emulsion gel containing 1% nanoemulsion in the middle and inner phases can reach over 95%. Therefore, it should be considered whether excessive nanoemulsion will adversely affect the stability and performance of the dual emulsion gel in practical applications.

[0084] Figure 5 The image shows the FTIR spectrum of the lyophilized double emulsion gel. Key characteristic peaks of the double emulsion gel appear at 3420, 3281, 2922, 2852, 1743, and 1158 cm⁻¹. -1 Location. At 3420 and 3281 cm -1 The characteristic peak at this point is caused by OH groups, and the absorption intensity increases with increasing nanoemulsion concentration. Figure 6 These are the FTIR spectra of various components in the double emulsion gel. CH4 (2922 and 2852 cm⁻¹) in the double emulsion gel. -1 C=O (1743 cm) -1 ) and CO (1158 cm -1 The stretching vibrations of the OH groups are mainly caused by camellia oil. The sources of OH groups in the double emulsion gel are diverse, including phytosterols, Tween-80, quercetin, and anthocyanins. The absorption peaks of OH groups differ among different components. Notably, phytosterol nanoparticles show absorption peaks at 3303 and 3426 cm⁻¹. -1 The bimodal peaks at OH groups may be related to the 3420 and 3281 cm⁻¹ peaks in the double emulsion gel. -1 The bimodal distribution is related to the bimodal distribution of OH groups in phytosterol nanoparticles. Compared to the bimodal distribution of OH groups in the two-emulsion gel, these two peaks are located at 3303 and 3426 cm⁻¹, respectively. -1 Moved to 3281 and 3420 cm -1The peak shift of OH groups to lower wavenumbers is always caused by hydrogen bonding. Rheological data analysis shows that the concentration of the nanoemulsion is key to the rheological properties of the dual-emulsion gel, with Tween-80 being the main variable component. Therefore, it can be inferred that the peak shift of OH groups in the dual-emulsion gel is related to Tween-80 (~3508 cm⁻¹). -1 The disappearance of the OH group in Tween-80 is caused by hydrogen bonds between Tween-80 and phytosterol nanoparticles.

[0085] Comparative Example 1

[0086] Step (1) in Example 1 was modified by dissolving 1 g, 2 g, 3 g, 4 g, and 5 g of Tween-80 in 50 mL of camellia oil heated in a 45°C water bath, respectively. Then, 250 mg of the hydrophobic active molecule quercetin was added and stirred until completely dissolved to prepare an oil solution of quercetin. 50 mL of the oil solution was mixed with 10 mL of water and emulsified at a shear rate of 12000 rpm for 5 min to prepare a crude emulsion. The crude emulsion was further subjected to high-pressure emulsification at 600 bar for 5 cycles to finally obtain an emulsion encapsulated with the hydrophobic active molecule quercetin. The prepared emulsion had an oil phase fraction exceeding 80%, resulting in micron-sized emulsion droplets and excessive viscosity, making it unsuitable for subsequent preparation of a double emulsion gel.

[0087] Comparative Example 2

[0088] Step (1) in Example 1 was modified by dissolving 0.01 g of Tween-80 in 5 mL of camellia oil heated in a 45°C water bath, followed by adding 25 mg of the hydrophobic active molecule quercetin and stirring until completely dissolved to prepare an oil solution of quercetin. 5 mL of the oil solution was mixed with 95 mL of water and emulsified at a shear rate of 12000 rpm for 5 min to prepare a crude emulsion. The crude emulsion was further subjected to high-pressure emulsification at 600 bar for 5 cycles to finally obtain an emulsion encapsulated with the hydrophobic active molecule quercetin. Due to insufficient emulsifier, the emulsion droplet size reached the micrometer level, making it unsuitable for subsequent preparation of double emulsion gels.

[0089] Comparative Example 3

[0090] Step (2) in Example 1 was modified to dissolve anthocyanins in water at a concentration of 5 mg / mL to prepare an anthocyanin aqueous solution. 30 mL of the nanoemulsion emulsified with 0.3 g Tween-80 in step (1) was taken and made up to 100 mL with the anthocyanin aqueous solution, and stirred thoroughly until homogeneous. The remaining steps remained unchanged from Example 1. The final product could not maintain stability and could not possess a gel-like physical structure.

[0091] Comparative Example 4

[0092] In Example 1, step (3) was modified to take 20 mL of the mixed liquid obtained in step (2), add 80 mL of camellia oil and 5 g of phytosterol nanoparticles with an average particle size of 800 nm, and emulsify using a high-speed emulsification method with a shear rate of 12000 rpm for 5 min. The final product could not form a gel structure due to the low internal phase fraction.

[0093] Comparative Example 5

[0094] In Example 1, step (3) was modified to take 65 mL of the mixed liquid obtained in step (2), add 35 mL of camellia oil and 0.5 g of phytosterol nanoparticles with an average particle size of 800 nm, and emulsify using a high-speed emulsification method with a shear rate of 12000 rpm for 5 min. The final product could not form an effective emulsion and emulsion gel structure due to the lack of phytosterol nanoparticles, resulting in a decrease in emulsification ability.

[0095] Example 6: Dual-emulsion gel-based functional fat substitutes for pH-induced color-changing food 3D printing applications

[0096] Step (2) in Example 1 was modified by dissolving anthocyanins in water at a concentration of 5 mg / mL to prepare anthocyanin aqueous solutions, and adjusting the pH to 3, 5, 7, and 9 respectively. 1 mL of the nanoemulsion emulsified with 0.3 g Tween-80 in step (1) was taken and made up to 100 mL with the anthocyanin aqueous solution, and stirred thoroughly until homogeneous. The remaining steps remained the same as in Example 1, resulting in the final dual-emulsion gel-based functional fat substitute. This fat substitute was then filled into a 3D printing injection cylinder for 3D printing. The printed model is shown below. Figure 7 As shown, at pH 3, the prepared double emulsion gel exhibits a pink appearance after 3D printing because the anthocyanin aqueous solution is red. As the pH increases to 5, the red color of the 3D-printed model fades to a pale purple. As the pH rises to 7, the 3D-printed model exhibits a slight yellow hue. With the pH increasing to 9, due to the fading reaction of anthocyanins under alkaline conditions, the 3D-printed model turns a deep yellow.

[0097] The dual emulsion gel-based functional fat substitute prepared in Example 1 was used as a 3D printing material. After 3D printing, a full texture test was conducted, and the test results are shown in Table 2.

[0098] Table 2. Full texture analysis data of the 3D printed model

[0099]

[0100] The overall texture analysis data revealed that, from Examples 1 to 5, as the concentration of the nanoemulsion in the aqueous phase increased from 1% to 9%, the hardness of the 3D printed model decreased from 20.06 g to 11.96 g, and the adhesion decreased from 94.89 to 50.14, while the elasticity and resilience showed relatively little change. Similarly, with increasing nanoemulsion concentration, chewiness, viscosity, and cohesion decreased from 12.98, 13.60, and 0.73 to 8.18, 8.85, and 0.67, respectively. The regulation of the overall structural strength by the nanoemulsion concentration is mainly achieved by influencing the stabilizer at the interface between the outer oil phase and the aqueous phase.

[0101] Comparative Example 6

[0102] Step (2) in Example 1 was modified by taking 1 mL of the nanoemulsion emulsified with 0.3 g of Tween-80 in step (1) and adding pure water to bring the volume to 100 mL, stirring thoroughly until homogeneous. The remaining steps remained the same as in Example 1, resulting in the final dual-emulsion gel-based functional fat substitute. After 3D printing, the 3D-printed model appeared white because the dual-emulsion gel did not contain pH-sensitive anthocyanins. Figure 7 ).

[0103] Example 7: Application of dual emulsion gel-based functional lipid substitutes in the controlled release of co-encapsulated hydrophilic / hydrophobic active molecules

[0104] The dual emulsion gel-based functional fat substitutes co-encapsulated with hydrophobic quercetin and hydrophilic anthocyanins prepared in Examples 1-5 were subjected to simulated oral, gastric, and intestinal digestion tests. The release of the active molecules obtained from the tests is as follows: Figure 8 As shown. The specific simulated digestion experiment is as follows:

[0105] (1) Simulated chewing: 0.4 g of double emulsion gel was mixed with 50 μL of CaCl2(H2O)2 (0.3 mmol / L), 6 mL of oral simulated digestive fluid and 3.95 mL of water and shaken for 2 h in a shaker (60 rpm) with a constant temperature water bath (37℃).

[0106] (2) Simulated gastric digestion: Lipase (31.26 mg), 6 mL of simulated gastric digestion fluid, 1.93 mL of water and a moderate concentration of HCl (5 mol / L) were mixed to prepare a mixture with a pH of 3. The sample (0.4 g) obtained after simulated chewing was added to the mixture and shaken in a shaker (100 rpm, 37 °C) for 2 h.

[0107] (3) Simulated intestinal digestion: 0.762 g porcine pancreatic lipase, 0.18 g bile salts, 6 mL of simulated intestinal digestion solution, 1.96 mL of water, and an appropriate concentration of NaOH (5 mol / L) were mixed to prepare a mixture with a pH of 7. 2 mL of the simulated gastric digestion solution was added to the mixture in a shaker (100 rpm, 37℃) for 2 h. During the simulated intestinal digestion process, the pH of the mixed solution was continuously adjusted with NaOH (0.5 mol / L) to maintain it at 7.

[0108] After simulating gastric digestion, the quercetin release was lowest (9.12%) in step (2) of Example 1 when 1 mL of nanoemulsion was used to prepare the double emulsion gel. As the concentration of the nanoemulsion increased to 9 mL, the quercetin release rate during simulated gastric digestion significantly increased to 37.29%. Figure 8 (A). After simulated intestinal digestion, the release rate of quercetin in each group was significantly increased. In Example 1, step (2), the release of quercetin in the preparation of a double emulsion gel using 1 mL of nanoemulsion only increased to 17.43%, which means that the structure of this double emulsion gel remained stable and may promote the interaction between the nanoemulsion and the small intestinal epithelial cells, making quercetin better absorbed by the human body. In Example 5, step (2), 9 mL of nanoemulsion was used to prepare a double emulsion gel, and 65.34% of quercetin was released into the water environment of the intestine after simulated intestinal digestion. Structural stability determines the integrity of the double emulsion gel. A double emulsion gel with better structural stability is more conducive to protecting the stability of the nanoemulsion and improving the absorption efficiency of quercetin. For anthocyanins, since the addition of nanoemulsion weakened the structural stability of the double emulsion gel, after total simulated digestion, in Example 5, step (2), 9 mL of nanoemulsion was used to prepare a double emulsion gel, and the release of anthocyanins increased from 62.39% to 98.89%. Figure 8 (B) The digestion and absorption rate of anthocyanins is positively correlated with their release rate. The release rate of free fatty acids reflects the bioavailability of camellia oil in the double emulsion gel during simulated digestion. In the intestinal simulation experiment, as the concentration of nanoemulsion increased, the structural stability of the double emulsion gel decreased, and the release rate of free fatty acids increased significantly. In the double emulsion gel prepared by taking 1 mL of nanoemulsion in step (2) of Example 1, only about 40% of the free fatty acids were released after 180 min of simulated intestinal digestion. Figure 8(C). The high elastic modulus and stable semi-solid properties allow for high binding of camellia oil, preventing contact with lipases. However, 78.06% of the free fatty acids were released in the dual emulsion gel, which exhibited the highest nanoemulsion concentration. As an oil-in-water-in-oil dual emulsion gel, hydrophobic interactions during simulated digestion led to aggregation, significantly impacting the digestion and absorption of the dual emulsion gel. In conclusion, the high structural stability of the dual emulsion gel facilitates quercetin delivery, while its weak stability is more conducive to the release and absorption of camellia oil and anthocyanins.

[0109] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a dual emulsion gel-based functional fat substitute, characterized in that, Includes the following steps: (1) Hydrophobic active molecules are dissolved in edible oil as the internal phase and water is used as the external phase. The internal phase, external phase and emulsifier are mixed and a crude emulsion is obtained by high-speed shearing. The crude emulsion is then subjected to high-pressure emulsification to obtain a nanoemulsion. In the nanoemulsion, the volume fraction of the internal phase is 1-10% and the mass concentration of the emulsifier is 0.2-0.4%. The emulsifier is at least one of Tween-20, Tween-40, Tween-60, Tween-80, and Tween-85. (2) The nanoemulsion is added to the aqueous solution of hydrophilic active molecules as the inner phase, and edible oil is used as the outer phase. Emulsification is carried out in the presence of a solid particulate emulsifier to obtain an oil-in-water-in-oil dual emulsion gel-based functional fat substitute. In the inner phase, the mass fraction of the nanoemulsion is 0.5-20%. In the dual emulsion gel-based functional fat substitute, the volume fraction of the aqueous solution containing the hydrophilic active molecules of the nanoemulsion is 30-90%, and the mass fraction of the solid particulate emulsifier is 1-10%. The solid particulate emulsifier is a phytosterol particle with a particle size of less than 1 μm.

2. The method for preparing the dual emulsion gel-based functional fat substitute according to claim 1, characterized in that, The hydrophobic active molecule is at least one of curcumin, quercetin, lycopene, resveratrol, and tocopherol; the hydrophilic active molecule is at least one of anthocyanin, functional polysaccharide, ascorbic acid, amino acid, and nucleotide; and the edible oil is at least one of camellia oil, flaxseed oil, soybean oil, walnut oil, peanut oil, olive oil, rapeseed oil, sesame oil, corn oil, and sunflower seed oil.

3. The method for preparing the dual emulsion gel-based functional fat substitute according to claim 1 or 2, characterized in that, In the inner phase of step (1), the concentration of hydrophobic active molecules is 1~500 mg / mL.

4. A dual emulsion gel-based functional fat substitute, characterized in that, It is prepared by the preparation method described in any one of claims 1-3.

5. The application of a dual emulsion gel-based functional fat substitute as described in claim 4 in the food industry.

6. The application according to claim 5, characterized in that, include: 3D printing was performed using a dual emulsion gel-based functional fat substitute as a printing paste. During 3D printing, the print head diameter is 0.8-1.5 mm, the printer extrusion compensation is 120-200%, the printing temperature is room temperature, and the printing speed is 10-100 mm / s.

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