Preparation method of low-oil-phase high-viscoelasticity emulsion gel

Abstract

The invention belongs to the technical field of derived polysaccharide compositions and processing thereof, and discloses a preparation method of a low-oil-phase high-viscoelastic emulsion gel, which comprises the following steps: compounding hydroxypropyl methyl cellulose and flaxseed gum to prepare hydrogel, preparing candelilla wax-beewax mixture into oil gel, mixing the hydrogel and the oil gel by a one-step emulsification method, and preparing the low-oil-phase high-viscoelastic emulsion gel. And heating-cooling circulation treatment is carried out, such that the emulsion gel with an oil phase volume fraction of only 30-40% is prepared. The viscoelasticity of the gel is remarkably improved, the elastic modulus and the loss modulus of the gel are 2 orders of magnitude higher than those of traditional hydroxypropyl methyl cellulose-flaxseed emulsion gel, meanwhile, the gel has excellent storage stability and freeze-thaw stability, and the technical problem that a low-oil-phase system is prone to layering, water separation or oil separation is effectively solved. The method is simple in process, free of complex equipment and chemical modification, controllable in cost and suitable for industrial large-scale production, and has wide application prospects and market value in the fields of food, medicine and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of derivative polysaccharide compositions and processing thereof, and particularly relates to a method for preparing a low-oil-phase high-viscoelastic emulsion gel. Background Art

[0002] Emulsion gels are semisolid materials that combine the properties of both emulsions and gels. They are composed of dispersed emulsion droplets embedded in a three-dimensional gel network. Compared to traditional animal fats, emulsion gels are rich in polyunsaturated fatty acids and can partially or completely replace dietary fat. Furthermore, emulsion gels possess a unique semisolid texture and ideal viscoelastic properties. They can also encapsulate specific oil-soluble nutrients, offering broad application prospects in the food, pharmaceutical, and cosmetic sectors.

[0003] In the construction of emulsion gel systems, polysaccharides have attracted considerable attention due to their unique molecular structure and gelling properties. However, when polysaccharide-based emulsion gels are used as an alternative to animal fat, their mechanical properties and stability have become increasingly apparent. Existing research indicates that the properties of the oil phase play a crucial role in the performance and stability of emulsion gels. Against this backdrop, oil-phase gelation technology has emerged as an innovative oil-phase modification method. By manipulating the rheological behavior of the oil phase to construct a three-dimensional crystalline network, this technology effectively inhibits the migration and aggregation of oil droplets, thereby significantly improving the mechanical strength and stability of emulsion gels.

[0004] Although oil-phase gelation technology shows great potential, research on its effect on the performance of polysaccharide-based emulsion gels is still insufficient. In addition, traditional polysaccharide-based emulsion gels have the problem of high oil content, usually greater than 70%, which makes it difficult to meet the demand of modern consumers for low-fat and healthy foods. In view of this, the development of new polysaccharide-based emulsion gel systems with low oil phase content and the optimization of their viscoelastic properties and rheological behavior to simulate the texture properties of natural animal fat have become key technical difficulties that need to be overcome in the application of polysaccharide modification technology in the food and pharmaceutical fields. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a low-oil-phase, high-viscoelastic emulsion gel. The method is relatively simple to operate. The resulting emulsion gel has the characteristics of low oil phase and high viscoelasticity, and exhibits good storage stability and freeze-thaw stability. It can provide new technical ideas for the development of new healthy fat substitutes.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: In one aspect, the present invention provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, comprising the following steps: S1. preparing hydroxypropyl methylcellulose-flaxseed gum hydrogel; S2, preparing candelilla wax-beeswax oil gel; S3, heating and melting the candelilla wax-beeswax oil gel and homogenizing it with the hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 3:7 to 4:6 to prepare a low oil phase emulsion gel; S4. The low oil phase emulsion gel prepared in S3 was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0007] Furthermore, in the preparation method, the mass ratio of the hydroxypropyl methylcellulose aqueous solution to the flaxseed gum aqueous solution in the hydroxypropyl methylcellulose-flaxseed gum hydrogel in S1 is 3:1~1:3, the concentration of the hydroxypropyl methylcellulose aqueous solution is 1%~3% (w / w), and the concentration of the flaxseed gum aqueous solution is 1%~2% (w / w).

[0008] Furthermore, in the preparation method, the preparation method of the hydroxypropyl methylcellulose-linseed gum hydrogel in S1 includes dispersing hydroxypropyl methylcellulose and linseed in water respectively, stirring and dissolving them, and then hydrating them to obtain a hydroxypropyl methylcellulose aqueous solution and a linseed gum aqueous solution, mixing the hydroxypropyl methylcellulose aqueous solution and the linseed gum aqueous solution uniformly, and hydrating them overnight to obtain the hydroxypropyl methylcellulose-linseed gum hydrogel.

[0009] Furthermore, in the preparation method, the hydration time in the hydration after stirring and dissolving is 10h~14h.

[0010] Furthermore, in the preparation method, the preparation method of the candelilla wax-beeswax oil gel in S2 includes: mixing candelilla wax and beeswax and adding them to vegetable oil, placing them in a hot water bath and heating and stirring until they are completely dissolved, then quickly placing them in an ice water bath to cool, and then standing at 4°C overnight to obtain the candelilla wax-beeswax oil gel.

[0011] Furthermore, in the preparation method, the mass ratio of the candelilla wax to beeswax is 3:1 to 1:3, and the amount added after the two are mixed is 3% to 5% of the total mass of the candelilla wax, beeswax and vegetable oil.

[0012] Furthermore, in the preparation method, the vegetable oil is selected from rapeseed oil, linseed oil, and sunflower oil.

[0013] Furthermore, in the preparation method, the hot water bath temperature is 70° C. to 85° C., and the stirring time is 30 min to 50 min.

[0014] Furthermore, in the preparation method, the homogenization speed in S3 is 10000 rpm to 12000 rpm, and the homogenization time is 2 min to 5 min.

[0015] Finally, a low-oil-phase high-viscoelastic emulsion gel prepared by the preparation method of the present invention is also provided.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages: (1) The present invention successfully prepares a highly viscoelastic emulsion gel through the synergistic emulsification of candelilla wax-beeswax oil gel and hydroxypropyl methylcellulose-linseed gum hydrogel, combined with a specific heating-cooling process. Compared with traditional preparation methods, the elastic modulus and loss modulus of the emulsion gel have both increased by two orders of magnitude, enabling the emulsion gel to exhibit superior deformation resistance and energy dissipation capabilities when subjected to external forces, providing a more solid performance foundation for the application of emulsion gel in high-end food, cosmetics, and pharmaceutical fields.

[0017] (2) The oil phase of the emulsion gel prepared by the preparation method provided by the present invention is only 30% to 40%, which is much lower than that of traditional high-fat emulsion gel. While maintaining excellent texture performance, the fat content is effectively reduced, providing new ideas for the development of low-fat functional foods.

[0018] (3) The emulsion gel prepared by the preparation method provided by the present invention has both good storage stability and freeze-thaw stability. During storage, it can effectively resist the influence of temperature and humidity, maintain a uniform and stable texture for a long time, and will not delaminate, separate out water or oil. Even after experiencing freeze-thaw cycles, it can still quickly restore its original structure and performance, ensuring the stability of product quality. This characteristic successfully overcomes the stability problem commonly encountered in low-oil phase systems and expands the application of emulsion gels in the field of refrigerated and frozen foods.

[0019] (4) The present invention adopts a one-step emulsification method combined with a programmed temperature control process, making the entire preparation process simple, easy to operate, and easy to control. It does not require the use of complex equipment or chemical modification, greatly reducing production costs and difficulty. This feature makes the preparation method suitable for industrial large-scale production and can meet the huge market demand for emulsion gel products. At the same time, since no chemical modification is involved, the prepared emulsion gel meets the requirements of clean labeling, providing a scalable technical solution for the development of safe and healthy fat substitutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Temperature scanning curves of low-oil-phase, high-viscoelastic emulsion gels prepared in different examples, where (a) is heating and (b) is cooling.

[0021] Figure 2The appearance image and microstructure of biowax-based oil gel. (a) is the appearance image; (b) is the microstructure.

[0022] Figure 3 The rheological properties of biowax-based oil gel are shown in Figure 1. (a) shows the flow scan result, (b) shows the strain scan result, (c) shows the frequency scan result, and (d) shows the creep recovery curve.

[0023] Figure 4 The visual appearance and microstructure analysis results of the low-oil-phase, high-viscoelastic emulsion gel. (a) is the visual appearance; (b) is the microstructure.

[0024] Figure 5 The curves of the elastic modulus (G') and viscous modulus (G'') of the low-oil phase high-viscoelastic emulsion gel with temperature during the heating-cooling process, where (a) is the heating process and (b) is the cooling process.

[0025] Figure 6 The visual appearance and microstructure of the low-oil phase high-viscoelastic emulsion gel after storage at room temperature; (a) is the visual appearance; (b) is the microstructure.

[0026] Figure 7 The visual appearance and microstructure of the low-oil phase high-viscoelastic emulsion gel after freeze-thaw treatment; (a) is the visual appearance; (b) is the microstructure. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention are described below with reference to the following embodiments; however, the present invention is not limited to the following embodiments.

[0028] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0029] The experimental methods and detection methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0030] Example 1 This embodiment provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, the method comprising the following steps: Step S1, preparing hydroxypropyl methylcellulose-linseed gum hydrogel: Hydroxypropyl methylcellulose and flaxseed gum powder were dispersed in distilled water, stirred magnetically until completely dissolved, and then hydrated in a refrigerator at 4°C for 12 h to obtain 1% (w / w) hydroxypropyl methylcellulose and 2% (w / w) flaxseed gum aqueous solutions, respectively. A 1% (w / w) hydroxypropyl methylcellulose aqueous solution and a 2% (w / w) flaxseed gum aqueous solution were mixed in a mass ratio of 3:1, stirred evenly, and then hydrated in a refrigerator at 4°C for 10 h to prepare a hydroxypropyl methylcellulose-flaxseed gum hydrogel. Step S2, preparing candelilla wax-beeswax oil gel: Candelilla wax and beeswax were mixed in a mass ratio of 3:1, and then the candelilla wax and beeswax mixture was added to linseed oil in an amount of 3% of the total mass of the candelilla wax, beeswax and linseed oil, and the mixture was placed in a 70°C hot water bath and continuously heated and stirred for 30 minutes until completely dissolved, and then the mixture was quickly transferred to an ice water bath for cooling, and then allowed to stand at 4°C overnight to prepare a candelilla wax-beeswax oil gel; Step S3, preparing a low oil phase emulsion gel: The candelilla wax-beeswax hydrogel was heated and melted in a hot water bath, and then mixed with the hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 3:7, homogenized at 10,000 rpm using a high-speed disperser for 5 minutes, and then rapidly cooled to room temperature to prepare a low oil phase emulsion gel; Step S4: Preparation of low oil phase high viscoelastic emulsion gel: The prepared low oil phase emulsion gel was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0031] Example 2 This embodiment provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, the method comprising the following steps: Step S1, preparing hydroxypropyl methylcellulose-linseed gum hydrogel: Hydroxypropyl methylcellulose and flaxseed gum powder were dispersed in distilled water, stirred magnetically until completely dissolved, and then hydrated in a refrigerator at 4°C for 11 hours to obtain 3% (w / w) hydroxypropyl methylcellulose and 1% (w / w) flaxseed gum aqueous solutions, respectively. A 3% (w / w) hydroxypropyl methylcellulose aqueous solution and a 1% (w / w) flaxseed gum aqueous solution were mixed in a mass ratio of 1:1, stirred evenly, and then hydrated in a refrigerator at 4°C for 14 hours to prepare a hydroxypropyl methylcellulose-flaxseed gum hydrogel; Step S2, preparing candelilla wax-beeswax oil gel: The candelilla wax and beeswax were mixed in a mass ratio of 1:1, and then the candelilla wax and beeswax mixture was added to rapeseed oil in an amount of 5% of the total mass of the candelilla wax, beeswax and rapeseed oil, and the mixture was placed in a 70°C hot water bath and continuously heated and stirred for 50 minutes until completely dissolved, and then the mixture was quickly transferred to an ice water bath for cooling, and then allowed to stand at 4°C overnight to prepare a candelilla wax and beeswax oil gel; Step S3, preparing a low oil phase emulsion gel: The candelilla wax-beeswax hydrogel was heated and melted in a hot water bath, and then mixed with hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 4:6, homogenized at 12000 rpm for 2 minutes using a high-speed disperser, and then rapidly cooled to room temperature to prepare a low oil phase emulsion gel; Step S4: Preparation of low oil phase high viscoelastic emulsion gel: The prepared low oil phase emulsion gel was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0032] Example 3 This embodiment provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, the method comprising the following steps: Step S1, preparing hydroxypropyl methylcellulose-linseed gum hydrogel: Hydroxypropyl methylcellulose and flaxseed gum powder were dispersed in distilled water, stirred magnetically until completely dissolved, and then hydrated in a refrigerator at 4°C for 10 h to obtain 4% (w / w) hydroxypropyl methylcellulose and 0.5% (w / w) flaxseed gum aqueous solutions, respectively. A 4 (w / w)% hydroxypropyl methylcellulose aqueous solution and a 0.5% (w / w) flaxseed gum aqueous solution were mixed in a mass ratio of 1:3, stirred evenly, and then hydrated in a refrigerator at 4°C for 10 h to prepare a hydroxypropyl methylcellulose-flaxseed gum hydrogel; Step S2, preparing candelilla wax-beeswax oil gel: Candelilla wax and beeswax are mixed in a mass ratio of 1:3, and then the candelilla wax and beeswax mixture is added to sunflower oil in an amount of 3% of the total mass of the candelilla wax, beeswax and sunflower oil, and the mixture is placed in a 70°C hot water bath and continuously heated and stirred for 40 minutes until completely dissolved, and then the mixture is quickly transferred to an ice water bath for cooling, and then allowed to stand at 4°C overnight to prepare a candelilla wax-beeswax oil gel; Step S3, preparing a low oil phase emulsion gel: The candelilla wax-beeswax hydrogel was heated and melted in a hot water bath, and then mixed with hydroxypropyl methylcellulose-linseed gum hydrogel at a mass ratio of 4:6, homogenized at 13,000 rpm for 2 minutes using a high-speed disperser, and then rapidly cooled to room temperature to prepare a low oil phase emulsion gel; Step S4: Preparation of low oil phase high viscoelastic emulsion gel: The prepared low oil phase emulsion gel was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0033] Example 4 This embodiment provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, the method comprising the following steps: Step S1, preparing hydroxypropyl methylcellulose-linseed gum hydrogel: Hydroxypropyl methylcellulose and flaxseed gum powder were separately dispersed in distilled water, magnetically stirred until completely dissolved, and then hydrated in a refrigerator at 4°C for 12 h to obtain 3% (w / w) hydroxypropyl methylcellulose and 1% (w / w) flaxseed gum aqueous solutions, respectively. A 3% (w / w) hydroxypropyl methylcellulose aqueous solution and a 1% (w / w) flaxseed gum aqueous solution were mixed in a mass ratio of 1:3, stirred evenly, and then hydrated in a refrigerator at 4°C for 13 h to prepare a hydroxypropyl methylcellulose-flaxseed gum hydrogel; Step S2, preparing candelilla wax-beeswax oil gel: Candelilla wax and beeswax were mixed in a mass ratio of 1:2, and then the candelilla wax and beeswax mixture was added to linseed oil in an amount of 4% of the total mass of the candelilla wax, beeswax and linseed oil, and the mixture was placed in an 80°C hot water bath and continuously heated and stirred for 45 minutes until completely dissolved, and then the mixture was quickly transferred to an ice water bath for cooling, and then allowed to stand at 4°C overnight to prepare a candelilla wax-beeswax oil gel; Step S3, preparing a low oil phase emulsion gel: The candelilla wax-beeswax hydrogel was heated and melted in a hot water bath, and then mixed with the hydroxypropyl methylcellulose-linseed gum hydrogel at a mass ratio of 4:6, homogenized at 12000 rpm for 2 minutes using a high-speed disperser, and then rapidly cooled to room temperature to prepare a low oil phase emulsion gel; Step S4: Preparation of low oil phase high viscoelastic emulsion gel: The prepared low oil phase emulsion gel was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0034] Example 5 This embodiment provides a method for preparing a low-oil-phase high-viscoelastic emulsion gel, the method comprising the following steps: Step S1, preparing hydroxypropyl methylcellulose-linseed gum hydrogel: Hydroxypropyl methylcellulose and flaxseed gum powder were separately dispersed in distilled water, magnetically stirred until completely dissolved, and then hydrated in a refrigerator at 4°C for 11 h to obtain 3% (w / w) hydroxypropyl methylcellulose and 1% (w / w) flaxseed gum aqueous solutions, respectively. A 3% (w / w) hydroxypropyl methylcellulose aqueous solution and a 1% (w / w) flaxseed gum aqueous solution were mixed in a mass ratio of 1:2, stirred evenly, and then hydrated in a refrigerator at 4°C for 10 h to prepare a hydroxypropyl methylcellulose-flaxseed gum hydrogel; Step S2, preparing candelilla wax-beeswax oil gel: Candelilla wax and beeswax are mixed in a mass ratio of 1:3, and then the candelilla wax and beeswax mixture is added to sunflower oil in an amount of 3% of the total mass of the candelilla wax, beeswax and sunflower oil, and the mixture is placed in an 85°C hot water bath and continuously heated and stirred for 50 minutes until completely dissolved, and then the mixture is quickly transferred to an ice water bath for cooling, and then allowed to stand at 4°C overnight to prepare a candelilla wax-beeswax oil gel; Step S3, preparing a low oil phase emulsion gel: The candelilla wax-beeswax oil gel was heated and melted in a hot water bath, and then mixed with the hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 3:7, homogenized at 11000 rpm for 3 minutes using a high-speed disperser, and then rapidly cooled to room temperature to prepare a low oil phase emulsion gel; Step S4: Preparation of low oil phase high viscoelastic emulsion gel: The prepared low oil phase emulsion gel was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

[0035] Test Example 1 This test example is to test the stability of a low oil phase high viscoelastic emulsion gel.

[0036] The low-oil-phase, high-viscoelastic emulsion gels prepared in Examples 1 to 5 were used as samples. Temperature scanning was used to test the changes in elastic modulus (G') and viscous modulus (G'') with temperature during the heating-cooling process of the low-oil-phase, high-viscoelastic emulsion gels prepared in different examples, and the stability of the low-oil-phase, high-viscoelastic emulsion gels prepared in Examples 1 to 5 was evaluated.

[0037] The results are as follows Figure 1 As shown. Figure 1As shown in Figure (a), at low temperatures (<35°C), the G' of all samples was significantly higher than their G'', indicating typical gel-like behavior. With the exception of Example 3, the G' and G'' of Examples 1, 2, 4, and 5 remained essentially stable below 35°C, indicating that their gel network structure did not undergo significant changes within this temperature range. When the temperature rose above 35°C, the G' and G'' of Examples 1, 2, and 5 rose rapidly, reaching a peak around 45°C. Thereafter, they slowly decreased with further temperature increases, with Example 2 exhibiting the highest G' value. In contrast, the G' and G'' of Example 4 showed a continuous downward trend above 35°C, while those of Example 3 showed a slow decrease throughout the entire heating process. These differences may be related to the HPMC content in the different examples. The higher HPMC content in Examples 1, 2, and 5 exposed the hydrophobic groups of the molecular chains when heated to 45°C, forming stronger intermolecular crosslinks with flaxseed gum, thereby enhancing the gel network strength. However, in Examples 3 and 4, due to the low HPMC content, when the temperature exceeds the melting point of the oil gel component (CW-BW), the crystal network structure is destroyed, resulting in a significant decrease in G' and G".

[0038] Figure 1 The results in (b) show that G' and G'' for all samples remained essentially stable during the cooling phase (80°C → 45°C). When the temperature dropped below 45°C, G' and G'' increased dramatically, indicating that the crystalline particles in the system reformed into a three-dimensional network structure through intermolecular interactions. The increase was most significant for the low-oil-phase, high-viscoelastic emulsion gel prepared in Example 2. This confirms the excellent thermal reversibility of the low-oil-phase, high-viscoelastic emulsion gels prepared in Examples 1–5, with the low-oil-phase, high-viscoelastic emulsion gel prepared in Example 2 exhibiting the best thermal reversibility.

[0039] The rheological properties of emulsion gels are primarily determined by the composition and ratio of the hydrogel to the oleogel. A high HPMC content significantly enhances the formation of a three-dimensional network during heating, resulting in a more pronounced elastic enhancement effect. Meanwhile, the melting and crystallization behavior of the oleogel component during temperature fluctuations dominates the rheological response during the cooling phase. The synergistic effect of these two mechanisms determines the ultimate viscoelastic properties of the emulsion gel system.

[0040] The test results of this example show that the low-oil-phase, high-viscoelastic emulsion gels prepared in Examples 1, 2, 4, and 5 exhibit good stability. The low-oil-phase, high-viscoelastic emulsion gel prepared in Example 2 exhibits both high-temperature melting resistance and rapid low-temperature recovery, resulting in the best stability. Further research will be conducted on Example 2.

[0041] Comparative Example 1 Hydroxypropyl methylcellulose and flaxseed gum powders were dispersed in distilled water, stirred magnetically until completely dissolved, and then hydrated in a 4°C refrigerator for 12 h to obtain 3% hydroxypropyl methylcellulose and 1% flaxseed gum aqueous solutions, respectively. 3% hydroxypropyl methylcellulose aqueous solution and 1% flaxseed gum aqueous solution were mixed in a 1:1 mass ratio, stirred evenly, and then hydrated in a 4°C refrigerator for 12 h to obtain hydroxypropyl methylcellulose-flaxseed gum hydrogel. Rapeseed oil and hydroxypropyl methylcellulose-flaxseed gum hydrogel were mixed in a 4:6 mass ratio and homogenized in a high-speed disperser at 12,000 rpm for 2 min to obtain an emulsion gel, which was labeled as the E / CO group.

[0042] Comparative Example 2 Hydroxypropyl methylcellulose and linseed gum powders were dispersed in distilled water, stirred magnetically until completely dissolved, and then hydrated in a 4°C refrigerator for 12 hours to obtain 3% hydroxypropyl methylcellulose and 1% linseed gum aqueous solutions, respectively. The 3% hydroxypropyl methylcellulose aqueous solution and the 1% linseed gum aqueous solution were mixed in a mass ratio of 1:1, stirred evenly, and hydrated in a 4°C refrigerator for 12 hours to obtain a hydroxypropyl methylcellulose-linseed gum hydrogel. 5% candelilla wax was mixed into 95% rapeseed oil according to mass percentage, placed in a 75°C hot water bath, and heated and stirred continuously for 30 minutes until completely dissolved. The mixed system was then quickly transferred to an ice-water bath for cooling and then allowed to stand at 4°C overnight to form an oil gel. The candelilla wax oil gel was heated in a hot water bath to melt and then mixed with the hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 4:6. The mixture was homogenized at 12,000 rpm using a high-speed disperser for 2 minutes and then rapidly cooled to room temperature to obtain an emulsion gel, which was labeled as the E / CW group.

[0043] Comparative Example 3 Under the same conditions as Comparative Example 2, 5% of the candelilla wax in Comparative Example 2 was replaced by 5% of beeswax, by mass percentage, and mixed into 95% rapeseed oil. The mixture was placed in a 75°C hot water bath and continuously heated and stirred for 30 min until completely dissolved. The mixture was then quickly transferred to an ice-water bath for cooling and then allowed to stand at 4°C overnight to form an oil gel. The oil gel was then mixed with hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 4:6 and emulsified, and then rapidly cooled to room temperature to prepare an emulsion gel, which was labeled as the E / BW group.

[0044] Test Example 2 2.1 Analysis of the appearance and crystal morphology of oil gel Oil gel samples prepared with candelilla wax (CW), beeswax (BW), and their blend (CW-BW, 1:1, w / w) as gelling agents were stored at 4°C overnight and then taken out. The formation of self-sustaining gel was determined by inverting the small glass containing the sample. The samples were photographed and their appearance was observed. The results were as shown in Figure 2As shown in (a), when the total gelling agent concentration was 5% (w / w), all samples (CW, BW, and CW-BW) formed a stable solid-like morphology. When the vials containing the samples were inverted, all samples remained at the bottom of the vials without flowing, indicating that a dense crystalline network structure had formed within them. This indicates that single or composite wax-based gelling agents can effectively induce the formation of oleogels at low concentrations. This result is consistent with the findings of Hong et al. (Food Chemistry, 2022), who found that single CW could form solid-like oleogels at concentrations as low as 3%. In addition, Shi et al. (Food Chemistry, 2024) reported that when the BW concentration was greater than 3% (w / w), the oil binding capacity of the oleogels reached 100%. It is worth noting that the single component concentration of the CW-BW blended oil gel system in this method is only 2.5% (w / w), which is lower than the minimum effective gelation concentration of a single component reported in the literature, indicating that CW and BW may have a synergistic effect in the oil gel formation process.

[0045] The composition and crystal structure of biowax have an important influence on the mechanical properties and thermal stability of oil gel. The microscopic crystal morphology of different biowax-based oil gels was observed by polarizing microscopy. Figure 2 As shown in (b). The crystals in the CW-based oleogel exhibited a larger snowflake-like aggregate morphology, while the crystals in the BW-based oleogel exhibited a uniformly distributed needle-like or fibrous structure. This is consistent with the findings of Shi et al. (Food Chemistry, 2024), who found that the network structure of the fibrous crystals in the BW-based oleogel system could effectively bind liquid oil molecules, ultimately forming a semisolid oleogel with viscoelasticity. The difference in crystal morphology between CW and BW may be the key structural factor leading to the difference in rheological properties between the two oleogels. Notably, when CW and BW were blended, the needle-like crystals of BW were intercalated into the snowflake-like aggregate structure of CW, forming a hybrid three-dimensional network structure. This optimized crystal arrangement significantly enhanced the network strength of the oleogel, effectively encapsulating and fixing the rapeseed oil in the three-dimensional network structure, restricting its fluidity.

[0046] 2.2 Rheological properties analysis of oil gel The rheological properties of the oil gel were tested using a rotational rheometer equipped with a 40 mm flat plate fixture. The test gap was set to 1000 μm and the trimming height was 1050 μm. An appropriate amount of sample was placed on the test platform and allowed to equilibrate for 2 minutes after trimming. The rheological properties of the sample were then analyzed through a series of test procedures. Steady-state shear scan: By changing the shear rate (0.1s -1 ~100s -1) to record changes in the sample's apparent viscosity. Dynamic strain sweep: With a fixed frequency of 1.0 Hz, the changes in the sample's storage modulus (G') and loss modulus (G'') are recorded by varying the strain range (0.01% to 100%) to determine the sample's linear viscoelastic region. Frequency sweep: With a fixed strain of 0.1%, the changes in the sample's G' and G'' with frequency (0.1 Hz to 10 Hz) are recorded. Creep recovery test: A stress of 10 Pa is applied to the sample for 300 seconds, the stress is removed, and the sample is allowed to stabilize for 300 seconds. The strain changes in the sample are recorded throughout the entire process.

[0047] like Figure 3 As shown in (a), at a shear rate of 0.1s -1 ~100s -1 Within the range of , the viscosity of all oil gel samples gradually decreases with increasing shear rate, showing typical shear thinning behavior characteristics. This phenomenon may be related to the directional rearrangement of the oil gel crystal structure under high shear rate, which in turn leads to a decrease in the flow resistance of the system. This research result is consistent with the behavioral characteristics of oil gels reported by ZHOU et al. (LWT, 2025), indicating that shear action will lead to the destruction of crystal aggregates in the oil gel network structure. It is worth noting that the viscosity of the CW-BW composite oil gel is slightly higher than that of the single CW or BW oil gel system, which may be due to the synergistic effect between the CW and BW components, thereby enhancing the mechanical strength and stability of the oil gel network structure.

[0048] Figure 3 (b) shows the dynamic strain sweep results of oleogels constructed with different gelation factors. As shown in the figure, the elastic modulus (G') of all samples within the linear viscoelastic region (LVR) is significantly higher than the viscous modulus (G''), indicating that all oleogels exhibit elastic, solid-like behavior. Notably, the CW oleogels exhibit the widest LVR range but the lowest G' value. Meanwhile, the BW oleogels, while possessing a narrower LVR, exhibit slightly higher G' values ​​than the CW oleogels. When the strain exceeds a critical value, all samples exhibit an intersection point (G'=G''), indicating a gel-sol transition within the oleogels' three-dimensional crystalline network. Subsequently, G' and G'' drop sharply, indicating a degree of damage to the crystalline structure within the system. However, mixing CW with BW yields a significantly higher G' value for the resulting composite oleogels than for the individual components, further demonstrating a synergistic effect between CW and BW in improving the rheological properties of the oleogels.

[0049] Frequency scanning results of different oil gels are as follows Figure 3As shown in (c). The G' of all samples is much greater than G'', indicating that the formed oil gel system has typical solid gel characteristics. In addition, the G' and G'' of the three oil gel samples did not show frequency dependence. Under the same frequency conditions, the G' and G'' values ​​of the CW-BW composite oil gel are significantly higher than those of the single CW or BW oil gel. The reason for the difference in G' between the CW oil gel and BW oil gel systems is mainly due to the different crystal forms of the two. The crystal structure of CW is mainly orthorhombic, the molecules are tightly arranged, and a highly ordered layered structure is formed, while the crystal structure of BW is mainly triclinic, the molecules are relatively loosely arranged, and the interlayer bonding force is weak. In addition, compared with the single component, the CW-BW composite oil gel presents the highest G', indicating that the composite of CW and BW can optimize the mechanical properties of the oil gel through the eutectic effect.

[0050] The creep-recovery curves of different oil gel samples are as follows: Figure 3 As shown in (d) in the figure, after the instantaneous application of constant stress, all oil gel samples deformed to varying degrees, and the strain value gradually increased with the extension of the action time. Among them, the CW oil gel showed the largest strain response value, indicating that its internal three-dimensional network structure was relatively loose and its mechanical strength was weak, which was not conducive to resisting external forces. In contrast, after the same stress was applied, the strain response value of the BW oil gel was significantly reduced, while the composite oil gel formed by mixing CW and BW showed the lowest strain response value. Their creep-recovery curves basically overlapped, indicating that the internal structure of the composite oil gel was relatively compact and had good deformation resistance. This is consistent with the results of microstructural analysis, indicating that the synergistic effect between CW and BW significantly enhanced the oil gel's deformation resistance.

[0051] Test Example 3 The low-oil-phase, high-viscoelastic emulsion gel (E / CW-BW) prepared in Example 2, the emulsion gel (E / CO) prepared in Comparative Example 1, the emulsion gel (E / CW) prepared in Comparative Example 2, and the emulsion gel (E / BW) prepared in Comparative Example 3 were used as test objects. The appearance and microstructure of the above samples were analyzed, and their viscoelasticity, storage stability, and freeze-thaw stability were tested.

[0052] 3.1 Visual appearance and microstructural analysis of low-oil-phase high-viscoelastic emulsion gel The hydroxypropyl methylcellulose-linseed gum latex gels prepared by gelling oil phase with different gel factors were photographed to observe the visual appearance; the microstructure was observed by optical microscopy. Figure 4 shown. Figure 4 (a) shows the visual appearance of the emulsion gel obtained by gelling the oil phase with different gel factors. Figure 4As shown in (a), the emulsion gels prepared by gelling the oil phase with different gelling factors all have a milky white appearance and a fine and smooth texture. When the glass vials containing the samples are inverted, all samples can adhere to the bottom of the glass vial without flowing, showing good self-supporting properties, which may be a typical feature of emulsion gels. Figure 4 (b) shows the microstructure of emulsion gels obtained by gelling the oil phase with different gelation factors. As shown in the figure, the droplets of all emulsion gels exhibit a regular spherical morphology with a relatively uniform size distribution and no obvious coalescence. Compared with the emulsion gel in which the oil phase was not gelled (E / CO group), the average droplet size of the emulsion gel with the addition of CW oil gel (E / CW group) significantly decreased from 35.75 μm to 31.30 μm, while the introduction of BW oil gel resulted in a slight increase in the droplet size of the emulsion gel (E / BW group). Notably, the emulsion gel containing the CW-BW composite oil gel (low oil phase, high viscoelasticity emulsion gel, E / CW-BW group) exhibited the smallest droplet size, at only 28.82 μm. This is likely due to the synergistic effect of CW and BW, which enhances the mechanical strength of the interfacial film.

[0053] 3.2 Changes of elastic modulus (G') and viscous modulus (G'') of low-oil phase high-viscoelastic emulsion gel with temperature during heating-cooling process The temperature sweep test was used to test the changes of elastic modulus (G') and viscous modulus (G'') of low oil phase high viscoelastic emulsion gel with temperature during the heating-cooling process. The results are as follows Figure 5 As shown, Figure 5Panel (a) shows that when the temperature is below 35°C, the G' of the emulsion gel (E / CO group) in which the oil phase has not gelled is significantly higher than G'', and both values ​​do not change with increasing temperature. Above 35°C, the G' and G'' of the E / CO group increase rapidly with increasing temperature. After reaching 45°C, the growth rates of G' and G'' gradually slow and stabilize. This is primarily because when the temperature approaches the gelation temperature of hydroxypropyl methylcellulose (HPMC) (approximately 40°C-50°C), the hydrophobic groups on the molecular chains are exposed and strengthen intermolecular associations, forming a dense network structure. Simultaneously, the linear polysaccharide chains of flaxseed gum stretch during the heating process, cross-linking with HPMC through hydrogen bonds or hydrophobic interactions, thereby strengthening the gel network structure and ultimately leading to a significant increase in the G' of the emulsion gel. Compared with the E / CO group, the G' and G'' values ​​of the E / CW, E / BW, and E / CW-BW groups (low-oil-phase, high-viscoelastic emulsion gels) showed similar trends within the temperature range of 20°C to 55°C, with the G' and G'' values ​​of the E / CW-BW group increasing more significantly. Above 55°C, the G' and G'' values ​​of the E / CW, E / BW, and E / CW-BW groups gradually decreased, with the decrease being more pronounced in the E / CW group. This may be because temperatures above 55°C reach the melting point of CW and BW, disrupting the crystalline network structure in the CW, BW, or CW-BW oil gels and thus reducing the viscoelasticity of the emulsion gel system. Figure 5 The structure in (b) shows that the G' and G'' of the E / CO group decrease slowly as the temperature decreases from 80°C. In contrast, the G' and G'' of the E / CW, E / BW, or E / CW-BW emulsion gels remain essentially unchanged within the temperature range of 80°C to 45°C. However, they increase rapidly below 45°C, with the G' and G'' increasing most significantly in the E / CW-BW group. This indicates that the crystal particles within the system reform into a three-dimensional network structure through intermolecular interactions. More importantly, the G' and G'' of the E / CW-BW emulsion gels subjected to the heating-cooling treatment are significantly higher (approximately two orders of magnitude) than those of the initial emulsion gels (E / CO group). These results demonstrate that oil-phase gelation exhibits excellent thermoreversibility and that the heating-cooling treatment can further enhance the viscoelasticity of the emulsion system.

[0054] 3.3 Stability analysis of low oil phase high viscoelastic emulsion gel The storage stability of the emulsion gel system is a key indicator for evaluating its applicability. The storage stability was evaluated by comparing the changes in the appearance and microstructure of the emulsion gel constructed by gelling oil phase with different gel factors after storage at room temperature for 20 days. The appearance was observed by taking pictures and the microstructure after storage was observed by optical microscopy. The results are as follows: Figure 6 As shown by Figure 6As shown in (a), all the emulsion gel samples did not undergo obvious changes in appearance after long-term storage at room temperature, and no water or oil separation occurred. The macroscopic morphology remained intact, indicating that the system still maintained a good gel network structure. Figure 6 As shown in (b), it is further shown that the droplets of all samples after long-term storage at room temperature are still relatively evenly distributed, without obvious coalescence, and the droplet size does not change much compared with the fresh emulsion, indicating that all emulsion gel samples have good storage stability.

[0055] Freeze-thaw stability refers to a food's ability to maintain its physical, chemical, and sensory properties during repeated freezing and thawing. It is a key indicator of frozen food quality. Good freeze-thaw stability reduces water loss, texture deterioration, and flavor loss, ensuring consistent food quality during storage and transportation. Figure 7 The changes in appearance and microstructure of emulsion gels constructed by gelling oil phase with different gelling factors after freeze-thaw treatment. Figure 7 As shown in (a), the emulsion gel in which the oil phase was not gelled (E / CO group) showed water and oil separation after freeze-thaw treatment. This is mainly attributed to the fact that the oil phase and water phase of the emulsion gel will crystallize to varying degrees during the freezing process, which may pierce the oil-water interface layer, resulting in oil floating, demulsification or phase separation in the system during the thawing stage. In contrast, the emulsion gels with different gelling factors for the oil phase (E / CW, E / BW and E / CW-BW groups) did not undergo significant changes in appearance after freeze-thaw treatment, nor did they show water and oil separation. The microstructure of the emulsion gel is shown in Figure 2. Figure 7 As shown in (b), the droplets in the E / CO group exhibited significant aggregation, with most droplets exhibiting irregular shapes and a slight presence of floating oil within the system. While the droplet aggregation in the E / CW and E / BW groups was slightly reduced, a significant number of irregular droplets remained, with the E / CW group exhibiting a more pronounced pattern. Notably, the droplets in the E / CW-BW group maintained a regular spherical structure, exhibiting no significant coalescence and a relatively uniform droplet distribution, indicating excellent freeze-thaw stability. These results demonstrate that oil phase gelation, particularly the gelation of the composite gelling factor, can effectively enhance the interfacial strength of the emulsion gel, thereby significantly improving its freeze-thaw stability.

[0056] As described above, the basic principles, main features and advantages of the present invention are well described. The above embodiments and descriptions are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the scope of protection determined by the present invention.

Claims

1. A method for preparing a low-oil-phase high-viscoelastic emulsion gel, characterized in that: The following steps are involved: S1. preparing hydroxypropyl methylcellulose-flaxseed gum hydrogel; S2, preparing candelilla wax-beeswax oil gel; S3, heating and melting the candelilla wax-beeswax oil gel and homogenizing it with the hydroxypropyl methylcellulose-linseed gum hydrogel in a mass ratio of 3:7 to 4:6 to prepare a low oil phase emulsion gel; S4. The low oil phase emulsion gel prepared in S3 was heated from 20°C to 80°C at a heating rate of 5°C / min, and then cooled from 80°C to 20°C at a cooling rate of 5°C / min to obtain a low oil phase high viscoelastic emulsion gel.

2. The preparation method according to claim 1, characterized in that The mass ratio of the hydroxypropyl methylcellulose aqueous solution to the flaxseed gum aqueous solution in the hydroxypropyl methylcellulose-flaxseed gum hydrogel in S1 is 3:1-1:3, the concentration of the hydroxypropyl methylcellulose aqueous solution is 1%-3% (w / w), and the concentration of the flaxseed gum aqueous solution is 1%-2% (w / w).

3. The preparation method according to claim 2, characterized in that The preparation method of the hydroxypropyl methylcellulose-linseed gum hydrogel in S1 comprises dispersing hydroxypropyl methylcellulose and linseed in water respectively, stirring and dissolving them, and then hydrating them to obtain a hydroxypropyl methylcellulose aqueous solution and a linseed gum aqueous solution, uniformly mixing the hydroxypropyl methylcellulose aqueous solution and the linseed gum aqueous solution, and hydrating them overnight to obtain the hydroxypropyl methylcellulose-linseed gum hydrogel.

4. The preparation method according to claim 3, characterized in that The hydration time in the hydration after stirring and dissolving is 10h~14h.

5. The preparation method according to claim 1, characterized in that The preparation method of the candelilla wax-beeswax oil gel in S2 includes: mixing candelilla wax and beeswax, adding the mixture to vegetable oil, heating and stirring the mixture in a hot water bath until the mixture is completely dissolved, then quickly cooling the mixture in an ice water bath, and then standing the mixture at 4° C. overnight to obtain the candelilla wax-beeswax oil gel.

6. The preparation method according to claim 5, characterized in that The mass ratio of the candelilla wax to the beeswax is 3:1-1:3, and the amount of the mixed candelilla wax to be added is 3%-5% of the total mass of the candelilla wax, beeswax and vegetable oil.

7. The preparation method according to claim 6, characterized in that The vegetable oil is selected from rapeseed oil, linseed oil and sunflower oil.

8. The preparation method according to claim 5, characterized in that The temperature of the hot water bath is 70° C. to 85° C., and the stirring time is 30 min to 50 min.

9. The preparation method according to claim 1, characterized in that The homogenization speed in S3 is 10000 rpm to 12000 rpm, and the homogenization time is 2 min to 5 min.

10. The low-oil-phase high-viscoelastic emulsion gel prepared by the preparation method according to any one of claims 1 to 9.

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