Oil gel based on emulsion continuous phase transfer as well as preparation method and application of oil gel

Abstract

The invention provides a preparation method of oil gel based on emulsion continuous phase transfer. The preparation method comprises the following steps: preparing an oil-in-water emulsion from a water phase and an oil phase according to a certain proportion; under the condition of continuous stirring, adding edible and medicinal insoluble particles into the oil-in-water emulsion, and continuously stirring for a certain time to obtain oil gel; the edible and medicinal insoluble particles comprise one or a combination of more of cellulose, chitosan, starch, bean dregs, coffee grounds and poria cocos powder. According to the invention, the continuous phase of the emulsion is transferred among edible and medicinal insoluble particles, so that the fluidity of the continuous phase of the emulsion is reduced, and the oil gel with smooth and fine surface and good thixotropy and thermal stability is prepared. The preparation method provided by the invention is simple in process, a high-energy-consumption process of water removal (freeze-drying, drying and the like) is avoided, the production cost is reduced, and the prepared oleogel has a wide potential of replacing butter in baked foods.

Description

Technical Field

[0001] The invention belongs to the technical field of oil gel preparation, and specifically relates to an oil gel based on emulsion continuous phase transfer and a preparation method thereof, and also relates to the application of the oil gel based on emulsion continuous phase transfer in the food industry. Background Art

[0002] Oil gels are usually made from liquid oils and fats, and solid oil products are prepared by a structured method. The use of oil gels can effectively reduce the intake of saturated fatty acids and trans fatty acids, and reduce the risk of chronic diseases such as hyperlipidemia and coronary heart disease. In addition, oil gels have good processability and are widely used in chocolate, meat products, and baked products. At present, the preparation methods of oil gels can be divided into direct preparation and indirect preparation according to the gel mechanism. Among them, direct preparation is to add edible cross-linking agents (fatty alcohols, sodium stearoyl lactylate and natural wax, etc.) to the oil phase, and heat and melt to form an oil gel system with a three-dimensional network structure. Indirect preparation is most representative of the emulsion template method. Usually, an oil-in-water emulsion is prepared first, and then freeze-drying, drying, etc. are used to remove the water in the continuous phase of the emulsion, so that the dispersed oil droplets form a condensed state. However, the existing oil gel preparation methods all have problems such as poor quality and complex processes. The oil phase crosslinker in the direct preparation process needs to be dissolved under high temperature, which not only seriously affects the physical and chemical stability of the oil in the final product, but also the waxy taste limits the application of such oil gels. In order to remove the continuous phase in the emulsion, the indirect method often uses high-energy consumption processes such as freeze-drying and drying, which makes the product process complex and costly.

[0003] Chinese patent CN117546917A discloses a defatted coconut powder-based oil gel and a preparation method thereof, which uses defatted coconut powder as a stabilizer to prepare an emulsion, followed by freezing, vacuum freeze drying (-60°C), and finally low-speed shearing to obtain the defatted coconut powder oil gel. Although this solution avoids high-temperature treatment, thereby improving the stability and nutritional value of the oil, the freeze drying used is a high-energy consumption and complex dehydration process, which undoubtedly significantly increases the production cost of the oil gel. In addition, the rough and uneven surface quality of the oil gel prepared by this solution also limits its application scenarios.

[0004] Chinese patent CN114794251A discloses a vegetable oil gel fat substitute and its preparation and application, which disperses a composite gel containing ingredients such as β-sitosterol, lecithin, and oryzanol in corn oil, heats it to 100°C, and then cools it at 25°C for 24 hours to obtain a vegetable oil gel. The use of this oil gel in chocolate can not only improve the nutritional components and flavor characteristics of chocolate, but also improve the storage stability of chocolate. However, this solution requires the use of a high temperature of 100°C to promote the uniform dispersion of the composite gel in the oil phase, which not only requires high temperature resistant production equipment, but also the high temperature processing of vegetable oil may produce harmful components (oil peroxides, etc.). Therefore, the existing oil gel preparation scheme has defects such as high energy consumption and unstable product quality, and a preparation process with a clean label is urgently needed.

[0005] Chinese patent CN117337856A discloses a method for preparing a vegetable oil gel and its baking application, which uses inulin as a gelling factor to replace traditional wax, constructs a three-dimensional network through the strong hygroscopicity of inulin, and then adds vegetable oil mixed with inulin into the three-dimensional network to prepare an oil gel for biscuits. The biscuits prepared by the oil gel in this case have similar taste and texture characteristics to commercially available biscuits, while reducing the oil migration rate and GI value of the biscuits, fully demonstrating the application prospects of vegetable oil gel in baked products. However, the patent clearly points out that inulin has strong hygroscopicity and is very easy to clump, and additional starch and protein need to be added to improve the stability of the product.

[0006] In summary, plant oil gel can replace animal fat and reduce the intake of saturated fatty acids and trans fatty acids, but the current oil gel preparation method has defects such as high energy consumption and unstable product quality. Therefore, establishing a new plant oil gel mechanism and how to develop oil gels with clean labels, suitable costs, and stable physical and chemical properties are technical problems that need to be solved urgently. Summary of the invention

[0007] One of the purposes of the present invention is to provide a method for preparing an oil gel based on emulsion continuous phase transfer, which has simple preparation process, low production cost and good stability.

[0008] The second object of the present invention is to provide an oil gel based on emulsion continuous phase transfer with good thixotropy and stability.

[0009] The third object of the present invention is to provide an oil gel based on emulsion continuous phase transfer with good thixotropy and stability for use in the food industry.

[0010] The technical solution adopted by the present invention to achieve one of the purposes is: to provide a method for preparing an oil gel based on emulsion continuous phase transfer, comprising the following steps: The water phase and the oil phase are prepared into an oil-in-water emulsion in a mass ratio of (2-2.5):10; under continuous stirring, the food-drug homologous insoluble particles are added into the oil-in-water emulsion in an amount of 20 wt.%-35 wt.%, and stirring is continued for a certain period of time to obtain an oil gel; The insoluble particles with food and medicine homology include one or more combinations of cellulose, chitosan, starch, bean dregs, coffee dregs, and tuckahoe powder; the particle size of the insoluble particles with food and medicine homology is 20-200 μm.

[0011] The present invention provides a method for preparing an oil gel based on emulsion continuous phase transfer, and its overall idea and inventive principle are as follows: In the existing plant oil gel preparation scheme, the use of oil phase gel factor easily leads to the deterioration of oil gel quality, and the oil gel-emulsion template preparation scheme adopts a high energy consumption process for dehydration, which is not only complex but also costly, and the obtained oil gel has quality problems such as rough surface or oil leakage. In view of the defects of the above process, the present invention provides a method for preparing oil gel based on emulsion continuous phase transfer, by adding water-insoluble food-grade particles of a certain proportion and size to the emulsion, and utilizing the capillary structure formed between the particles to transfer the continuous phase (water) in the emulsion system, inducing the dispersed phase (emulsion droplets) in the emulsion system to aggregate to form oil gel. Based on the capillary bridging network formed by the insoluble food-grade particles, the oil gel prepared by the present invention has good thixotropy and stability.

[0012] In the present invention, the insoluble food-grade particles are food-drug homology insoluble particles, including a combination of one or more of cellulose, chitosan, starch, bean dregs, coffee grounds, and Poria powder. Unlike other additives (such as gel factors, etc.), this type of food-drug homology insoluble particles belongs to food excipients. In addition to playing the capillary gel function, it also has certain functionality. For example, cellulose can be used to prepare high-fiber foods, and Poria powder can be used to prepare health conditioning foods. The addition of food-drug homology insoluble particles not only ensures the safety of the added raw materials and improves the stability of the oil gel, but also expands the application performance of the oil gel.

[0013] Furthermore, the amount of food-drug homology insoluble particles added to the emulsion and the particle size are key factors affecting the formation of capillary structures between particles. Among them, the use of food-drug homology insoluble particles with smaller particle size is conducive to the formation of more capillary structures; at the same time, the capillary structure is composed of water adsorbed between particles, and the particle concentration and water content jointly determine the stability of the capillary structure. When the particle concentration is too high, some particles lack adsorbed water and it is difficult to form a continuous capillary network; when the particle concentration is low, the particles are suspended in water and flow with the solvent, and a stable capillary network cannot be formed. Taking the above factors into consideration, the present invention sets the amount of food-drug homology insoluble particles added to the emulsion to 20 wt.%-35 wt.%, and controls the particle size of the food-drug homology insoluble particles to 20-200 μm on the basis of preparing an oil-in-water emulsion with a mass ratio of (2-2.5):10 for the water phase and the oil phase, so as to prepare an oil gel with higher stability.

[0014] Furthermore, in the preparation of the oil-in-water emulsion, the oil phase and the water phase containing the emulsifier are dispersed at a rotation speed of 10000-12000 rpm for 1-3 min to obtain the oil-in-water emulsion.

[0015] In the present invention, the water phase and the oil phase are prepared into an oil-in-water emulsion according to a mass ratio of (2-2.5):10. The water content in this high-oil phase emulsion is low, and a gel structure is more likely to appear during the water migration process. In addition, the lower water content in the emulsion avoids the subsequent dehydration process such as freeze drying or high temperature treatment, simplifies the preparation process, and reduces production costs and energy consumption.

[0016] Furthermore, the oil phase includes one or more combinations of soybean oil, peanut oil, corn oil, and sunflower oil.

[0017] Furthermore, the emulsifier is selected from one of Tween-80, Tween-20 and OSA-starch.

[0018] Furthermore, the concentration of the emulsifier in the water phase is 1.4wt.%-2wt.%.

[0019] Furthermore, the rotation speed of the continuous stirring is 100-800 rpm.

[0020] Furthermore, the stirring time is 5-10 minutes. Specifically, the stirring speed and the stirring time can be adjusted according to the total amount of the sample to ensure that the sample is mixed evenly. During the continuous shearing process, the continuous phase in the emulsion is induced to transfer between the particles to obtain a stable oil gel morphology.

[0021] Furthermore, in the present invention, the use of food and medicine homologous insoluble particles with a smaller particle size is conducive to forming more capillary structures. At the same time, considering the factors of controlling raw materials, the particle size of the food and medicine homologous insoluble particles is not easy to be too small. Preferably, the particle size of the food and medicine homologous insoluble particles is 20-50 μm.

[0022] The technical solution adopted by the present invention to achieve the second purpose is: to provide an oil gel based on emulsion continuous phase transfer, which is prepared by the preparation method according to one of the purposes of the present invention.

[0023] The oil gel prepared by the invention has a smooth and delicate surface and good thixotropy and thermal stability. The mass fraction of oil is 55-65%, the mass fraction of water is 11.5%-16.5%, and the mass fraction of food-drug homology insoluble particles is 20%-35%.

[0024] The technical solution adopted by the present invention to achieve the third purpose is: to provide an application of the oil gel based on emulsion continuous phase transfer according to the second purpose of the present invention in the food industry.

[0025] Furthermore, the application includes: adding the oil gel based on emulsion continuous phase transfer to baked products to replace animal fats such as butter. Compared with animal fats such as butter, the oil gel prepared by the present invention can effectively reduce the intake of saturated fatty acids and trans fatty acids, and reduce the risk of chronic diseases such as hyperlipidemia and coronary heart disease. The addition of food and medicine homologous insoluble particles in the oil gel can give baked products a certain healthiness and functionality while ensuring the stability of the oil gel.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a method for preparing an oil gel based on emulsion continuous phase transfer, wherein an oil-in-water emulsion is prepared by using an oil-in-water emulsifier, and the oil gel is prepared by adding food-drug homologous insoluble particles to the emulsion system. The capillary structure between the particles is utilized to transfer the continuous phase (water) of the emulsion system, and the dispersed phase (emulsion droplets) of the emulsion system are induced to aggregate to form a gel, thereby significantly enhancing the strength of the oil gel and improving the stability of the oil gel.

[0027] (2) The present invention provides a method for preparing an oil gel based on emulsion continuous phase transfer. The preparation process is simple and avoids high energy consumption dehydration processes (freeze drying, drying, etc.), which significantly simplifies the preparation process and reduces production costs.

[0028] (3) The surface of the oil gel based on the emulsion continuous phase transfer prepared by the present invention is smooth and delicate, and has good thixotropy and thermal stability. No obvious oil leakage occurs after centrifugation at 5000 rpm×3 min, and its performance and appearance can be maintained after storage at 75°C for 30 min. The above properties make it have broad promotion and application prospects in the food industry, especially in baked products. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The appearance morphology of the oil gel prepared in Examples 1-4 of the present invention during storage at 25° C. and after centrifugation; Figure 2 The morphological diagrams of the oil gels prepared in Comparative Examples 1 and 2 of the present invention during storage at 25° C. and after centrifugation. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] The present invention provides a method for preparing an oil gel based on emulsion continuous phase transfer, comprising the following steps: Step 1: Prepare an oil-in-water emulsifier as the water phase (the mass concentration of the emulsifier in the water phase is 1.4%-2.0%), then mix the water phase and the oil phase at a mass ratio of 2.0-2.5:10, and disperse them in a high-speed shear machine (10000-12000 rpm) for 1-3 minutes to obtain a uniform emulsion with an emulsion particle size of 20-50μm.

[0033] The oil phase comprises one or more of soybean oil, peanut oil, corn oil and sunflower oil; the emulsifier is selected from one of Tween-80, Tween-20 and octenyl succinate starch (OSA-starch).

[0034] Step 2: Slowly add the food-drug homologous insoluble particles to the emulsion at a speed of 100-800 rpm, and control the mass ratio of the added particles to the emulsion to be (2.0-3.5):10. After all the particles are added, continue to shear the mixture for 5-10 min (100-800 rpm) to obtain a uniform oil gel.

[0035] The insoluble particles with food and medicine homology include one or more of cellulose, chitosan, starch, bean dregs, coffee grounds, and Poria powder; and the particle size of the insoluble particles with food and medicine homology is 20-50 μm.

[0036] The present invention is further described below in conjunction with specific examples, but is not intended to be limiting of the present invention. The reagents used in the examples and comparative examples can be purchased from the market unless otherwise specified. The equipment used in the examples and comparative examples: The homogenizer model is T18 homogenizer (IkA).

[0037] The main experimental conditions and parameters of the embodiments and comparative examples of the present invention are shown in Table 1 below: Table 1

[0038] Example 1 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-20 solution with a concentration of 2.0wt.% as the water phase, then mix the water phase and the oil phase at a mass ratio of 2.5:10, disperse in a 10000 rpm high-speed shearing machine for 1.5 min to obtain a uniform emulsion.

[0039] Step 2: Slowly add cellulose particles to the emulsion, wherein the mass ratio of the added particles to the emulsion is 2.5:10. At the same time, the mixture is continuously sheared while the particles are added. After all the particles are added, the mixture is sheared at 200 rpm×10 min to obtain a uniform oil gel.

[0040] Example 2 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-80 solution with a concentration of 1.4 wt.% as the water phase, then mix the water phase and the oil phase in a mass ratio of 2:10, disperse in a 12000 rpm high-speed shearing machine for 3 min to obtain a uniform emulsion.

[0041] Step 2: Slowly add cellulose particles to the emulsion, wherein the mass ratio of the added particles to the emulsion is 3:10. At the same time, the mixture is continuously sheared while the particles are added. After all the particles are added, the mixture is sheared at 400 rpm × 6 min to obtain a uniform oil gel.

[0042] Example 3 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-80 solution with a concentration of 1.8 wt.% as the water phase, then mix the water phase and the oil phase in a mass ratio of 2.2:10, disperse in a high-speed shearing machine at 11000 rpm for 2 min to obtain a uniform emulsion.

[0043] Step 2: Slowly add starch particles to the emulsion, wherein the mass ratio of the added particles to the emulsion is 3.5:10. At the same time, the mixture is continuously sheared while the particles are added. After all the particles are added, the mixture is sheared at 300 rpm × 8 min to obtain a uniform oil gel.

[0044] Example 4 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare an OSA-starch solution with a concentration of 2 wt.% as the water phase, then mix the water phase and the oil phase at a mass ratio of 2.5:10, and disperse in a high-speed shearing machine at 10,000 rpm for 2 min to obtain a uniform emulsion.

[0045] Step 2: Slowly add okara to the emulsion, where the mass ratio of added particles to emulsion is 2.0:10. At the same time, the mixture is continuously sheared while adding the particles. After all the particles are added, the mixture is sheared at 800 rpm×5 min to obtain a uniform oil gel.

[0046] Example 5 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-80 solution with a concentration of 1.8 wt.% as the water phase, then mix the water phase and the oil phase in a mass ratio of 2.2:10, disperse in a high-speed shearing machine at 11000 rpm for 2 min to obtain a uniform emulsion.

[0047] Step 2: Slowly add chitosan particles to the emulsion, wherein the mass ratio of the added particles to the emulsion is 2:10. At the same time, the mixture is continuously sheared while the particles are added. After all the particles are added, the mixture is sheared at 400 rpm × 6 min to obtain a uniform oil gel.

[0048] Example 6 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-80 solution with a concentration of 1.8 wt.% as the water phase, then mix the water phase and the oil phase in a mass ratio of 2.2:10, disperse in a high-speed shearing machine at 11000 rpm for 2 min to obtain a uniform emulsion.

[0049] Step 2: Slowly add coffee ground particles to the emulsion, where the mass ratio of added particles to emulsion is 2.5:10. At the same time, the mixture is continuously sheared while adding the particles. After all the particles are added, the mixture is sheared at 600 rpm×6 min to obtain a uniform oil gel.

[0050] Example 7 A method for preparing an oil gel based on emulsion continuous phase transfer comprises the following steps: Step 1: Prepare a Tween-80 solution with a concentration of 1.8 wt.% as the water phase, then mix the water phase and the oil phase in a mass ratio of 2.2:10, disperse in a high-speed shearing machine at 11000 rpm for 2 min to obtain a uniform emulsion.

[0051] Step 2: Slowly add the tuckahoe powder particles to the emulsion, wherein the mass ratio of the added particles to the emulsion is 3:10. At the same time, the mixture is continuously sheared while the particles are added. After all the particles are added, the mixture is sheared at 500 rpm × 6 min to obtain a uniform oil gel.

[0052] Comparative Example 1 The difference between this comparative example and Example 2 is that no emulsifier is added to the aqueous phase in step 1, and the other conditions and steps remain unchanged.

[0053] Comparative Example 2 The difference between this comparative example and Example 3 is that the mass ratio of the water phase to the oil phase in step 1 is 1.5:10, and the other conditions and steps remain unchanged.

[0054] Performance testing and result discussion The stability test of the oil gel products prepared in Examples 1-4 and Comparative Examples 1 and 2 was carried out. The relevant test results are shown in the attached Figure 1 and 2 .

[0055] Examples 1-4 and Comparative Examples 1-2 all use insoluble particles of food and medicine homology to prepare oil gels. Among them, Examples 1-4 and Comparative Example 2 use the oil gel preparation method of the present invention, first prepare an oil-in-water emulsion, then add the insoluble particles of food and medicine homology to the emulsion, and stir to form an oil gel form. In Comparative Example 1, no emulsifier is added, and the oil, water, and particles are mixed and sheared in a one-step method. Figure 1 and 2It can be found from the comparative examples that the oil gels prepared in Examples 1-4 have no obvious oil leakage and a smooth and delicate surface; while comparative example 1 has obvious oil leakage, indicating that emulsification can effectively improve the morphology and physical stability of the oil gel. In addition, although comparative example 2 adopts an emulsification process, it reduces the amount of water phase in the preparation stage of the water-in-oil emulsion. When the water content is insufficient, the content of the food-drug homologous insoluble particles is excessive relative to water, resulting in the collapse of the capillary bridge network, and thus the inability to lock the oil.

[0056] Furthermore, after centrifugation (5000 rpm×3 min), it was more clearly observed that Examples 1-4 had a stable gel structure without obvious oil separation; Comparative Example 1-2 had an obvious oil layer, indicating that the emulsification process and particle addition range used in this solution are necessary prerequisites to ensure that the oil gel has good stability.

[0057] In summary, the method for preparing oil gel based on emulsion continuous phase transfer provided by the present invention has an outstanding effect in improving the quality of oil gel. The oil gel preparation process has the advantage of simple preparation process, avoids water removal (freeze drying, drying and other high energy consumption processes), and has broad potential to replace butter in baked foods.

[0058] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an oil gel based on emulsion continuous phase transfer, characterized in that: The following steps are involved: The water phase and the oil phase are prepared into an oil-in-water emulsion in a mass ratio of (2-2.5):10; under continuous stirring, the food-drug homology insoluble particles are added into the oil-in-water emulsion in an amount of 20 wt.%-35 wt.%, and stirring is continued for a certain period of time to obtain an oil gel; The insoluble particles with food and medicine homology include one or more combinations of cellulose, chitosan, starch, bean dregs, coffee dregs, and tuckahoe powder; the particle size of the insoluble particles with food and medicine homology is 20-200 μm.

2. The preparation method according to claim 1, characterized in that In the preparation of the oil-in-water emulsion, the oil phase and the water phase containing the emulsifier are dispersed at a rotation speed of 10000-12000 rpm for 1-3 min to obtain the oil-in-water emulsion.

3. The preparation method according to claim 2, characterized in that: The oil phase includes one or more combinations of soybean oil, peanut oil, corn oil, and sunflower oil.

4. The preparation method according to claim 2, characterized in that: The emulsifier is selected from one of Tween-80, Tween-20 and OSA-starch.

5. The preparation method according to claim 2, characterized in that: The concentration of the emulsifier in the water phase is 1.4 wt.%-2 wt.%.

6. The preparation method according to claim 1, characterized in that The rotation speed of the continuous stirring is 100-800 rpm.

7. The preparation method according to claim 1, characterized in that: The stirring time is 5-10 min.

8. The preparation method according to claim 1, characterized in that: The particle size of the food-drug homology insoluble particles is 20-50 μm.

9. An oil gel based on emulsion continuous phase transfer, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the oil gel based on emulsion continuous phase transfer according to claim 9 in the food industry.

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