A biphasic gel based on microwave-modified soybean residue dietary fiber, its preparation method and application

Abstract

This invention relates to the field of food technology, and more particularly to a biphasic gel based on microwave-modified soybean residue dietary fiber, its preparation method, and its application. The biphasic gel is prepared from an olegel and a hydrogel, wherein the hydrogel comprises water and a hydrogeling agent, the hydrogeling agent being microwave-modified soybean residue soluble dietary fiber. This invention, a biphasic gel based on microwave-modified soybean residue dietary fiber, incorporates microwave-modified soybean residue soluble dietary fiber as a component of the hydrogel, which facilitates the high-value utilization of soybean residue, contributes to the development of biphasic gels, and reduces their cost.

Description

Technical Field

[0001] This invention relates to the field of food technology, and in particular to a biphasic gel based on microwave-modified soybean residue dietary fiber, its preparation method, and its application. Background Technology

[0002] Soybean residue is the largest byproduct in the production and processing of soy products such as tofu, soy skin, and soy protein, accounting for approximately 15% to 20% of the dry weight of soybean raw materials. For a long time, its primary use has been in animal feed, resulting in low utilization and significant resource waste. Soybean residue is rich in nutrients, with dietary fiber being the most abundant component, accounting for over 50% of its dry weight. Studies have shown that soybean residue dietary fiber is the most functional of all dietary fibers. Within a certain range of addition, it can not only increase the dietary fiber and protein content of products but also significantly improve the quality of high-fat foods. Soybean residue dietary fiber is easily absorbed by the human body and possesses excellent emulsifying and thickening properties. Years of clinical research have proven that soybean dietary fiber has significant physiological and medicinal functions. Therefore, soybean residue has potential and development value. It is readily available, inexpensive, and a highly functional source of dietary fiber. With the development of food science, people have gained new insights into its nutritional value. Using soybean residue to produce dietary fiber is a new way to comprehensively utilize soybeans. It can not only improve the nutritional health of the whole population, but also provide a new and effective way for soybean processing enterprises to comprehensively utilize resources.

[0003] Biphasic gels are two-phase systems created by shear mixing oleogels and hydrogels at a specific temperature. Biphasic gels combine the advantages of both oleogels and hydrogels, delivering both hydrophilic and lipophilic substances simultaneously. They also exhibit good moisturizing effects and better stability at room temperature. Current applications of biphasic gel systems are primarily concentrated in the cosmetics and pharmaceutical industries for the single or simultaneous delivery of lipophilic and hydrophilic compounds. Compared to single gels, biphasic gels demonstrate superior stability in terms of physical, rheological, mechanical, and microbiological properties, making them suitable materials for food applications. To date, different types of low-molecular-weight oleogels (such as beeswax, stearic acid, lecithin, and monoglycerides) can be combined with different oil media to prepare gels with varying structures, enabling biphasic gels to possess tunable properties.

[0004] Currently, there is almost no research on the preparation and application of biphasic gels based on soybean residue dietary fiber, which is of research value and is conducive to realizing the high-value utilization of soybean residue. Summary of the Invention

[0005] This invention provides a biphasic gel based on microwave-modified soybean residue dietary fiber, its preparation method, and its application, in order to solve the aforementioned technical problems existing in the prior art.

[0006] According to a first aspect of the present invention, the present invention provides a biphasic gel based on microwave-modified soybean residue dietary fiber, which is prepared from an oil gel and a hydrogel, wherein the hydrogel comprises water and a hydrogeling agent, and the hydrogeling agent is microwave-modified soybean residue soluble dietary fiber.

[0007] In the above scheme, soybean residue is readily available and inexpensive. This invention applies microwave-modified soybean residue soluble dietary fiber as a component of hydrogel to biphasic gel, which is beneficial for realizing the high-value utilization of soybean residue, and also helps in the development of biphasic gel and reduces the cost of biphasic gel.

[0008] To ensure the nutritional value of microwave-modified soybean residue soluble dietary fiber and improve the structural stability of the biphasic gel, the microwave-modified soybean residue soluble dietary fiber further satisfies at least one of the following characteristics (1) to (4): (1) The water-holding capacity of the microwave-modified soybean residue soluble dietary fiber is 3~16 g·g. -1 Preferably, it is 12~16 g·g -1 ; (2) The oil-holding capacity of the microwave-modified soybean residue soluble dietary fiber is 3~12 g·g. -1 Preferably 8~12 g·g -1 ; (3) The particle size of the microwave-modified soybean residue soluble dietary fiber is 212~1000 nm, preferably 212~400 nm; (4) The absolute value of the Zeta potential of the microwave-modified soybean residue soluble dietary fiber is 7~16 mV, preferably 13~15.34 mV.

[0009] In the preparation of oleogels and hydrogels, the type, amount, and composition of the gelling agent can affect the structure and physicochemical properties of the biphasic gel.

[0010] To realize the nutritional value of the biphasic gel and ensure its structural stability, the weight percentage of the microwave-modified soybean residue soluble dietary fiber in the hydrogel is further 3% to 10%, preferably 5%.

[0011] To ensure the structural stability of the biphase gel, the hydrogel in the biphase gel further comprises 10% to 90% by weight, preferably 30% to 70%, and more preferably 30%.

[0012] To realize the nutritional value of the biphasic gel and ensure its structural stability, the oleogel further comprises oil and an oleogeling agent, wherein the weight percentage of the oleogeling agent is 6% to 10%, preferably 9%. Preferably, the oil includes one or more of sunflower seed oil, soybean oil, corn oil, sesame oil, olive oil, cottonseed oil, grapeseed oil, rapeseed oil, and fish oil; and / or, the oil gelling agent includes one or more of palm wax, wood wax, soybean wax, beeswax, rice bran wax, and candelilla wax.

[0013] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described biphasic gel, comprising the following steps: Preparation of microwave-modified soybean residue soluble dietary fiber: Soybean residue and water are mixed evenly at a certain material-liquid ratio, then microwave-modified, dried, ground into powder, and extracted to obtain microwave-modified soybean residue soluble dietary fiber. Preparation of hydrogel: Water and the obtained microwave-modified soybean residue soluble dietary fiber were mixed and stirred evenly to obtain hydrogel; Preparation of oleogel: The oil and oleogel agent of the oleogel are mixed and stirred evenly to obtain the oleogel; Preparation of biphase gel: The obtained oleogel and hydrogel are stirred evenly in a certain proportion to obtain a biphase gel.

[0014] In the above scheme, microwaves, as an emerging modification process, can form dipole rotation in the solvent and rapidly increase the temperature, thereby increasing the solubility of the compound. Microwave energy directly penetrates the wall material to reach the center of the sample, making the sample heated more quickly and uniformly, thus saving more energy and time. It can also increase the intra-tissue pressure and release more active ingredients. The preparation method of the biphasic gel in this invention first uses microwave modification to obtain microwave-modified soybean residue soluble dietary fiber with excellent nutritional properties, and then uses it as a component of the hydrogel in the biphasic gel. This is beneficial for realizing the high-value utilization of soybean residue and also contributes to the development of biphasic gels. At the same time, because the raw material soybean residue is readily available and inexpensive, it can reduce the cost of biphasic gels. In addition, the preparation method of this invention is green, safe and simple.

[0015] Furthermore, in the process of preparing microwave-modified soybean residue soluble dietary fiber, the microwave power of the microwave modification is 500~900 W, the microwave time is 2~10 min, and the microwave temperature is 60~100 ℃; preferably, the microwave power of the microwave modification is 600 W, the microwave time is 4~6 min, and the microwave temperature is 70 ℃.

[0016] Furthermore, the ratio of soybean residue to water is 1:(5~15), preferably 1:10.

[0017] Further, the extraction includes a defatting step, an enzymatic hydrolysis step, an alcohol precipitation step, and a purification step; preferably, the enzyme used in the enzymatic hydrolysis step includes one or more of α-amylase, neutral protease, and amylase. More preferably, the enzyme used in the enzymatic hydrolysis step includes α-amylase, neutral protease, and amylase. More preferably, the weight ratio of α-amylase, neutral protease, and amylase is 1:(2~3):(5~8).

[0018] Experiments have shown that the ratio of soybean residue to water, microwave power, microwave time, and microwave temperature all affect the extraction rate, water retention, oil retention, particle size, and zeta potential of the modified soybean residue soluble dietary fiber (SDF) during the preparation of microwave-modified soybean residue soluble dietary fiber. These factors, in turn, influence the nutritional value of the modified soybean residue soluble dietary fiber and its stability when applied to biphasic gels. By limiting the ratio of soybean residue to water, microwave power, microwave time, and microwave temperature to a reasonable range, the nutritional value of the modified soybean residue soluble dietary fiber and its stability when applied to biphasic gels can be improved more effectively.

[0019] When preparing bigels by mixing oleogels and hydrogels, the ratio of the two, the mixing temperature, the mixing speed, and the storage conditions will all affect the structure and physicochemical properties of the bigels.

[0020] To further provide information on the structure and physicochemical properties of the biphase gel, the stirring temperature during hydrogel preparation was 50–70 °C, the stirring time was 5–10 min, and the stirring speed was 200–400 r / min.

[0021] To further provide information on the structure and physicochemical properties of the biphase gel, the stirring temperature during the preparation of the oleogel was 60-80 °C, the stirring time was 20-40 min, and the stirring speed was 200-400 r / min.

[0022] To further provide information on the structure and physicochemical properties of the biphase gel, the stirring temperature during preparation of the biphase gel is 60-80 °C, the stirring time is 1-5 min, and the stirring speed is 2000-3000 r / min.

[0023] According to a third aspect of the invention, the invention also provides the application of the above-described biphasic gel in food.

[0024] The biphasic gel of this invention has applications in the food industry, including: Encapsulation and delivery of bioactive substances: Common bioactive substances include polyphenols, flavonoids, plant pigments, vitamins, and probiotics.

[0025] Dysphagia-Guided Foods: Dysphagia is a swallowing dysfunction that makes it difficult for patients to transfer food from the mouth to the stomach. Patients with this condition tend to choose viscous foods, increasing the transit time of food from the mouth to the esophagus, thus allowing more reaction time for the muscles responsible for swallowing. Biphasic gels can modify their oral sensation and swallowing properties by adjusting their composition and structure.

[0026] 3D printed food: The semi-solid properties and stability of biphase gel systems make them potential applications in 3D printing, and the unique structure of biphase gels allows them to encapsulate lipophilic and hydrophilic nutrients, thereby improving the nutritional diversity of 3D printed food.

[0027] Fat Substitution: The use of biphasic gels can significantly reduce fat content while maintaining ideal texture and processing characteristics. Furthermore, the composition and manufacturing conditions of the biphasic gel can be adjusted to achieve textures specifically tailored to food requirements. In meat processing, animal fat plays a crucial role in the tenderness and juiciness of the product. Replacing animal fat in meat products with biphasic gels can produce novel health foods that are low in saturated fatty acids and cholesterol.

[0028] The technical solution provided by this invention has the following beneficial effects: This invention discloses a biphasic gel based on microwave-modified soybean residue dietary fiber. By incorporating microwave-modified soybean residue soluble dietary fiber as a component of the hydrogel into the biphasic gel, it is beneficial to realize the high-value utilization of soybean residue, and also helps in the development of biphasic gels and reduces their cost.

[0029] The present invention provides a green, safe and simple method for preparing biphasic gel based on microwave-modified soybean residue dietary fiber. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a graph showing the effect of different microwave modification conditions on the extraction rate of soluble dietary fiber from soybean residue in this invention.

[0032] Figure 2 This is a graph showing the effect of different microwave modification conditions on the water-holding capacity of soluble dietary fiber in soybean residue in this invention.

[0033] Figure 3This is a graph showing the effect of different microwave modification conditions on the oil-holding capacity of soluble dietary fiber in soybean residue in this invention.

[0034] Figure 4 This is a graph showing the effect of different microwave modification conditions on the particle size of soluble dietary fiber in soybean residue in this invention.

[0035] Figure 5 This is a graph showing the effect of different microwave modification conditions on the zeta potential of soluble dietary fiber from soybean residue in this invention.

[0036] Figure 6 The images show the microstructures of oleogel (a), hydrogel (b), and biphase gel (c) in the embodiments of the present invention.

[0037] Figure 7 This is a graph showing the effect of different biphase gel ratios on viscosity in this invention.

[0038] Figure 8 This is a graph showing the effect of different biphasic gel ratios on G' and G” in this invention.

[0039] Figure 9 This is a graph showing the effect of different biphasic gel ratios on G' and G” in this invention.

[0040] Figure 10 This is a graph showing the effect of different biphase gel ratios on G' and G” at different temperatures in this invention.

[0041] Figure 11 This is a graph showing the effect of different biphase gel ratios on G' and G” at different temperatures in this invention.

[0042] Figure 12 The graph shows the effect of different hydrogel agents on the viscosity of hydrogels (BK, MSDF) and biphasic gels (BK-7:3, MSDF-7:3) in this invention.

[0043] Figure 13 This is a graph showing the effect of hydrogels (BK, MSDF) and biphasic gels (BK-7:3, MSDF-7:3) with different hydrogel agents on G' and G” in this invention.

[0044] Figure 14 This is a graph showing the effect of hydrogels (BK, MSDF) and biphasic gels (BK-7:3, MSDF-7:3) with different hydrogel agents on G' and G” in this invention.

[0045] Figure 15 The graph shows the effect of hydrogels (BK, MSDF) and biphasic gels (BK-7:3, MSDF-7:3) with different hydrogel agents on G' and G” at different temperatures.

[0046] Figure 16This invention illustrates the effect of hydrogels (BK, MSDF) and biphasic gels (BK-7:3, MSDF-7:3) with different hydrogel agents on Tanδ at different temperatures. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0048] In this invention, unless specific techniques or conditions are specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Instruments and other equipment whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0049] The main reagents and instruments used in the following examples are as follows: Main reagents: soybean residue, deionized water, palm wax, sunflower seed oil, ethanol, phosphoric acid, sodium hydroxide.

[0050] Main instruments: Microwave catalytic synthesis / extraction system (XH-100A), constant temperature water bath, constant temperature incubator, rheometer (HR-1, Discovery), high-speed centrifuge (CR21N, Hitachi), microplate reader (Bio Tek Synergy H1).

[0051] This invention provides a method for preparing microwave-modified soybean residue dietary fiber. The preparation method is as follows: An appropriate amount of soybean residue SDF is weighed into a beaker, and deionized water is added at a material-to-liquid ratio of 1:10 g / mL. The mixture is stirred evenly and then placed in a magnetic rotor. The sample is subjected to microwave modification treatment under different conditions using a microwave catalytic synthesis / extraction instrument. The beaker is removed, and the sample is poured into a drying dish and placed in an oven (60 ℃, 18 h). After drying, the sample is ground into powder. The powder is then extracted through an 80-mesh sieve to obtain microwave-modified soybean residue soluble dietary fiber.

[0052] The microwave modification and extraction were carried out using three factors: different microwave power (500 W, 600 W, 700 W, 800 W, 900 W), time (2 M, 4 M, 6 M, 8 M, 10 M), and temperature (60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃). Single-factor and orthogonal experiments were conducted sequentially with the SDF extraction rate as the index to determine the optimal microwave modification conditions. The SDF under the optimal conditions was denoted as MSDF.

[0053] The method for extracting SDF is as follows: Anhydrous ethanol was added to remove oil and pigment, and the precipitate was air-dried. The pretreated soybean residue powder (5.0 g) was mixed with 100 mL of MES-TRIS buffer solution (11.482 g MES + 7.176 g TRIS), and then 0.2 g α-amylase (6 x 10 g) was added. 6 (u / g) and 0.5 g neutral protease (6*10) 4 u / g), 1.2 g amylase (1*10) 5 (u / g) Enzymatic hydrolysis (35 min for each of the three enzymes) to remove starch and protein, followed by boiling for 10 min to inactivate the enzymes. Add 95% ethanol to the supernatant for 24 h to precipitate SDF, then add 80% ethanol for washing, followed by centrifugation. Dialyze and precipitate the washed sample with ethanol. The concentrated sample is then freeze-dried to obtain purified SDF. The SDF extraction rate is calculated using the following formula (1): SDF extraction rate (%) = m1 / m0 × 100 Formula (1). Where: m0 - weight of soybean residue, g; m1 - weight of modified SDF, g SDF property testing - water holding capacity (WHC), oil holding capacity (OHC): Weigh 1 g of sample into a 50 mL centrifuge tube, add 20 mL of distilled water (olive oil), let stand at room temperature for 24 h, then centrifuge at 4500 r / min for 10 min, and weigh the precipitate. WHC and OHC are calculated according to the following formula (2): WHC / OHC(g / g)=(m2-m1) / m0 Formula (2). Where: m0 - dry weight of sample, g; m1 - mass of centrifuge tube, g; m2 - mass of sample and centrifuge tube after water (oil) absorption, g.

[0054] SDF property testing - particle size: Weigh 20 mg of the sample into a 15 mL centrifuge tube, add 10 mL of distilled water, and after ultrasonic dispersion, use a laser particle size analyzer to determine the particle size distribution.

[0055] SDF property detection - potential: Weigh 20 mg of the sample into a 15 mL centrifuge tube, add 10 mL of distilled water, and after ultrasonic dispersion, determine the particle size distribution using a Zeta potential analyzer.

[0056] Results of the single-factor experiment: Depend on Figure 1It is evident that microwave power, time, and temperature all significantly affect the extraction rate of SDF from soybean residue. As microwave power, time, and temperature increase, the overall extraction rate of SDF from soybean residue shows a trend of first increasing and then decreasing. The gradual increase may be due to the increased microwave power, temperature, and time, leading to more thorough modification. The subsequent sharp decrease may be because excessive power, excessive time, and excessive temperature can cause excessively rapid evaporation of moisture within the system, resulting in overheating of the soybean residue and localized scorching. The results of single-factor microwave modification indicate that, under the combined effect of microwave power, time, and temperature, the extraction rate of SDF from soybean residue is highest at a microwave power of 600 W, a microwave time of 6 min, and a microwave temperature of 70℃.

[0057] Results of orthogonal experiment: Based on the single-factor results, with microwave power, microwave time, and microwave temperature as variables and SDF extraction rate as the indicator, L9(3) was used. 3 Orthogonal design was used to optimize the SDF extraction process. The factor level design is shown in Table 1, the results and analysis of the orthogonal experiment under microwave conditions are shown in Table 2, and the results of the analysis of variance are shown in Table 3.

[0058] Table 1. Factor Levels of Orthogonal Experiments under Microwave Conditions

[0059] Table 2 Results and Analysis of Orthogonal Experiments under Microwave Conditions Table 2 shows that A > B > C, with the order of influence being: power > time > temperature; the optimal reaction conditions are: power 600 W, time 4 min, and temperature 70 ℃. Verification showed that the SDF extraction rate under these conditions was 18.56%.

[0060] Table 3. Results of Analysis of Variance Source of variance Type III sum of squares Degrees of freedom Mean Square F value Significance A 29.948 2 14.974 72.338 0.014 B 20.196 2 10.098 48.783 0.020 C 10.455 2 5.228 25.255 0.038 error 0.414 2 0.207 Total after correction 61.014 8 Single-factor, orthogonal experiment - water holding capacity, oil holding capacity: Depend on Figure 2 , Figure 3 It can be seen that, compared with the unmodified group (BK, water holding capacity is 2.02 g·g), -1 Oil holding capacity is 2.45 g·g -1 Compared to other methods, microwave power, time, and temperature significantly improved the water-holding and oil-holding capacities of soybean residue SDF. As microwave power, time, and temperature increased, the water-holding and oil-holding capacities of soybean residue SDF generally showed a trend of first increasing and then decreasing. The water-holding capacity of MSDF (15.67 g·g) was... -1 Oil holding capacity (11.79 g·g) -1The best result is achieved by microwave treatment. The increase in microwave activity is likely due to the disruption and opening of the dense structure of dietary fiber during the microwave process, which increases the bonding between polysaccharides. The decrease is due to excessive microwave damage caused by excessive power, prolonged time, and excessive temperature, which negatively impacts the honeycomb structure of the SDF sample and affects WHC and OHC. This result demonstrates that modified soybean residue SDF can be effectively converted into valuable food ingredients.

[0061] Single-factor, orthogonal experiment - particle size: Depend on Figure 4 It can be seen that, compared with the unmodified group (BK, particle size 1014.77 nm), the particle size of soybean residue SDF was significantly reduced under the influence of microwave power and temperature. Figure 4 As shown in the upper left figure, with the increase of microwave power from 500 to 900 W, the SDF particle size decreased from 478.43 nm to 296.15 nm, and then increased to 602.07 nm. Figure 4 As shown in the upper right figure, the SDF particle size decreased from 992.3 nm to 299.00 nm over time, exhibiting a continuous decreasing trend. Figure 4 As shown in the lower left figure, as the microwave temperature increases from 60 to 100 °C, the SDF particle size decreases from 381.47 nm to 240.70 nm, and then increases again to 395.13 nm. Figure 4 As shown in the lower right figure, MSDF has the smallest particle size (212.76 nm). The reduced particle size is due to the increased soluble components in the modified soybean residue SDF, resulting in a looser and more porous microstructure. Microwaves disrupt the soybean residue fiber matrix, making it discontinuous and loose. As microwave power and temperature increase, the water-holding and oil-holding capacities of soybean residue SDF initially decrease and then increase. This may be because excessive microwaves cause water evaporation in the solution, leading to overheating and scorching of the soybean residue, which is detrimental to particle size reduction.

[0062] Single-factor experiment - potential: The absolute value of the zeta potential indicates the stability of soybean residue SDF; the larger the absolute value, the stronger the solution stability. The terms "increase" or "decrease" below refer to absolute values. Figure 5 It can be seen that, compared with the unmodified group (BK, the absolute value of the Zeta potential is 6.88 mV), the absolute value of the Zeta potential of soybean residue SDF is significantly increased under the influence of microwave power, time and temperature. p <0.05). As microwave power, time, and temperature continuously increase, the absolute value of the Zeta potential of soybean residue SDF generally shows a trend of first increasing and then decreasing. Specifically, from Figure 5It can be seen that as the microwave power increases from 500 to 900 W, the absolute value of the Zeta potential of SDF increases from 7.29 mV to 14.87 mV, and then decreases to 10.86 mV. With prolonged microwave time, the absolute value of the Zeta potential of SDF increases from 10.90 mV to 13.1 mV, and then decreases to 12.23 mV. As the microwave temperature increases from 60 to 100 °C, the absolute value of the Zeta potential of SDF increases from 11.65 mV to 13.1 mV, and then decreases to 11.55 mV. MSDF has the highest potential (absolute value of Zeta potential 15.14 mV). The increase in the absolute value of the Zeta potential indicates that the modification treatment promotes the stabilization of the attractive forces and van der Waals forces between SDF particles. This may be related to the degradation of the polymer matrix and the dissolution of hemicellulose during microwave treatment, as well as the increase in anionic charges (hydroxyl groups) on the SDF surface. Excessive microwave treatment leads to decreased stability, thus decreasing the absolute value of the Zeta potential.

[0063] Examples 1-3 This embodiment provides a biphasic gel based on microwave-modified soybean residue dietary fiber, which is prepared from an oil gel and a hydrogel. The weight ratios of the oil gel and the hydrogel are 7:3, 5:5, and 3:7, respectively. The hydrogel includes water and microwave-modified soybean residue soluble dietary fiber, with a weight ratio of 95:5. The oil gel includes sunflower seed oil and palm wax, with a weight ratio of 91:9.

[0064] The preparation method of biphasic gel is as follows: Preparation of microwave-modified soybean residue soluble dietary fiber: Soybean residue and water were mixed evenly at a material-to-liquid ratio of 1:10 and then microwave-modified (microwave power of 600 W, microwave time of 4 min, microwave temperature of 70 ℃). After drying, the mixture was ground into powder and extracted to obtain microwave-modified soybean residue soluble dietary fiber.

[0065] Preparation of hydrogel: Water and the obtained microwave-modified soybean residue soluble dietary fiber were mixed and stirred at 60 °C until completely dissolved to obtain hydrogel.

[0066] Preparation of oleogel: Sunflower seed oil and palm wax were mixed and stirred at 70 °C and 300 r / min for 30 min to obtain oleogel.

[0067] Preparation of biphase gel: The obtained oleogel and hydrogel were stirred at 70 °C and 2500 rpm / min for 3 min in a certain ratio, and then cooled at 4 °C for 12 h to obtain the biphase gel.

[0068] Comparative Examples 1-2 This comparative example provides a biphasic gel based on microwave-modified soybean residue dietary fiber, which differs from Example 1 in that the weight ratio of oil gel to hydrogel is 1:0 and 0:1, respectively. The preparation method of the biphasic gel is the same as in Example 1.

[0069] The following comparative tests were performed on the biphasic gels obtained in Examples 1-3 and Comparative Examples 1-2: (1) Gel optical microstructure detection: The microstructure of different gels was observed using an optical electron microscope with magnification settings of 10, 20, and 40.

[0070] (2) Rheological testing of gels with different proportions: The rheological properties of biphase gels prepared at different ratios were detected using a rheometer, including apparent viscosity, elastic modulus, viscous modulus, phase transition temperature, and power-law model.

[0071] The rheometer is equipped with a flat plate clamp (50 mm in diameter, 1000 µm gap). The sample is placed on the base plate, and a thin layer of silicone oil is applied to the edges of the sample to prevent moisture loss during the rheological measurement. The TRIOS software package (TAInstruments, New Castle, DE, USA) is used to control the equipment and acquire rheological parameters. First, a steady-state shear scan test is performed at a set temperature of 25 °C, with a shear rate range of 1–1000 s⁻¹. -1 The viscoelasticity of the samples was measured at 1 Hz and oscillations of 0.1–20% (within the linear viscoelastic region). Next, in frequency scanning tests, the temperature was maintained at 25 °C, and the modulus (G', G”, Tanδ) was measured as a function of frequency (0.1–100 Hz) at a strain of 0.01% within the linear viscosity region. Finally, temperature scanning tests were performed to evaluate the thermal stability of the gel in the range of 25 °C to 90 °C, with a linear heating rate of 5 °C / min, a shear strain of 0.01%, and a Hz setting. Data for each sample were obtained by averaging three experiments.

[0072] In frequency scanning experiments, the dynamic modulus of the sample changes with frequency mainly depends on the relationship between the storage modulus G' and frequency. This relationship can be described and fitted using a power-law model, and the power-law model equation is as follows: G'=K'ω n' , In the formula: K' - power law model constant, Pa·sn / rad; n' - power law exponent of frequency, dimensionless; ω - angular frequency, rad / s.

[0073] The n' value can be used to describe the sensitivity of the elastic modulus of a sample to frequency within a defined frequency range, and it can effectively provide information on the viscoelastic properties of food raw materials.

[0074] (3) Rheological testing of hydrogels and biphasic gels with different hydrogel agents (unmodified SDF, microwave-modified SDF).

[0075] The rheological properties of unmodified SDF hydrogel (BK) and microwave-modified SDF hydrogel (MSDF), as well as the rheological properties of unmodified SDF biphase gel (BK-7:3) and microwave-modified SDF biphase gel (MSDF-7:3), were tested, including apparent viscosity, elastic modulus, viscous modulus, and phase transition temperature. The ratio of oleogel to hydrogel in the biphase gel was the optimal ratio (7:3) in (2), and the other experimental conditions and procedures were consistent with (2).

[0076] Optical microstructure diagram: Figure 6 The images shown are optical micrographs of the biphasic gel of Example 1 and the oleogel and hydrogel used in its preparation process, as follows: Figure 6 As shown, the microstructures of the oleogel, hydrogel, and biphasic gel are significantly different. It can be observed that in the oleogel and hydrogel, the palm wax oil gelling agent and MSDF hydrogelling agent are relatively uniformly distributed, forming dense network structures with the oil phase and aqueous phase, respectively. Under 10, 20, and 40x magnification, the oleogel in the biphasic gel is pale yellow and uniformly mixed with the hydrogel, forming a bicontinuous structure. Therefore, the present invention prepares a bicontinuous biphasic gel based on a single-phase, single-gelling agent.

[0077] Rheology of biphase gels with different proportions: like Figure 7 As shown, the rheological properties of biphase gels differ significantly under different concentration conditions.

[0078] Through shear scan test, by Figure 7 As can be seen, the apparent viscosity decreases, indicating that all gels exhibit shear-thinning behavior. During the preparation process, due to the homogenizing emulsification, the oleogel and hydrogel particles are broken down and then re-aggregate and cross-link to form a network. With the increase of oleogel in the gel system, the incorporated SDF gel particles become smaller and can act as active fillers in the matrix, increasing its viscoelasticity. However, with the rapid increase of the shear rate, the network structure of the gel is destroyed, the oil droplets deform and break, exhibiting liquid properties, thereby reducing the flow resistance and viscosity of the gel.

[0079] Through frequency scanning test, by Figure 8 It can be seen that after the oleogel and hydrogel mixture treatment, the elastic modulus G' and viscous modulus G” of each gel are improved. The higher the proportion of oleogel in the biphasic gel system, the larger the G' and G” of the gel. G' is directly related to the hardness of food; therefore, increasing the proportion of oleogel can improve the mechanical strength of the biphasic gel sample. Figure 9It can be seen that for all gels, G' is higher than G” across the entire frequency range, indicating that elastic behavior is dominant and the gel is more inclined to solid properties. G' and G” do not overlap, which is typical behavior of elastic networks, indicating that the mixture of oleogels and hydrogels produces a gel with stable properties.

[0080] The thermodynamic properties of the biphase gel were evaluated using temperature scanning tests. Figure 10 It can be seen that the modulus of the oleogel system decreases with increasing temperature. This indicates that the interaction between SDF and water can delay the instability of the system. The modulus of the hydrogel increases, which is related to the evaporation of water during the heating process. Starting from 25 ℃, the modulus of gels G' and G” decreases slowly. When the temperature reaches about 65 ℃ (1:0), the modulus of the gel decreases rapidly, and around 75 ℃ (7:3) and (5:5), the modulus of the gel decreases rapidly. Until 85~90 ℃, the modulus of the hydrogel increases. Figure 11 It can be seen that the tanδ values ​​of the (1:0), (7:3), and (5:5) gels are greater than 1, indicating that phase transitions occur successively, and the systems have become viscous or fluid. With the melting of the oleogel crystals (or the structural breakdown of the oleogel system), SDF may dissociate at higher temperatures, including evaporation of the gel's physical bound water and changes in hydrogen bonds. Table 4 shows that the phase transition temperature increases with the increase of the hydrogel ratio, indicating that the hydrogel has a positive impact on the thermal stability of the gel. The phase transition temperature can be adjusted by changing the hydrogel ratio.

[0081] Table 4 Different gel phase transition temperatures Biphasic gel ratio Phase transition temperature (°C) 1:0 69.89 7:3 85.87 5:5 87.94 3:7 / 0:1 / The data obtained from frequency scanning can be regressed using a power-law model, and the regression parameters are shown in Table 5. The table shows that the K' value in the biphasic gel significantly increases with increasing oleogel concentration, indicating that both the elasticity and viscosity of the oil-water mixed gel are enhanced with the addition of oleogel. Simultaneously, the n' values ​​for oleogel and hydrogel are significantly greater than those for the biphasic gel, with the (5:5) ratio gel having the smallest n' value in the biphasic gel. The trend in n' value variation indicates that the frequency dependence of the elastic characteristics of oleogel and hydrogel is greater than that of the biphasic gel. The significant change in n' value due to the mixing of oil and hydrogel indicates that it has a significant impact on the frequency dependence of the elastic characteristics of the mixed gel, with the biphasic gel exhibiting better frequency stability.

[0082] Table 5. Regression Analysis of Power Law Model Biphasic gel ratio K' n' <![CDATA[R 2 ]]> 1:0 136.5 0.1925 0.9019 7:3 3196 0.07888 0.9945 5:5 1463 0.06816 0.9945 3:7 1099 0.07756 0.9968 0:1 128.3 0.1162 0.9217 In summary, the rheological measurements show that the biphasic gel exhibits better viscoelasticity, a more stable network structure, and better thermal and frequency stability at a ratio of (7:3).

[0083] Biphasic gel rheology of different hydrogel agents (unmodified SDF, microwave-modified SDF): Depending on the hydrogel agent, hydrogels include unmodified SDF (BK) and microwave-modified SDF (MSDF), while biphasic gels include unmodified SDF (BK-7:3) and microwave-modified SDF (MSDF-7:3). Figures 12-16 As shown, the rheological properties of hydrogels and lower biphase gels prepared with different hydrogelating agents differ significantly.

[0084] Through shear scan test, by Figure 12 The apparent viscosity shows a decreasing trend, indicating that all gels exhibit shear-thinning behavior. The viscosity of the biphasic gels (BK-7:3, MSDF-7:3) is greater than that of the hydrogels (BK, MSDF). This is because during the preparation of the biphasic gels, the oleogel and hydrogel particles are broken down by homogenization and then re-aggregate and cross-link to form a network. With the increase of oleogel in the gel system, the incorporated SDF gel particles become smaller, which can act as active fillers in the matrix, increasing its viscoelasticity. For both hydrogels and biphasic gels, the viscosity of microwave-modified SDF is greater than that of unmodified SDF. This indicates that microwave modification increases the water-holding capacity of SDF, making it more capable of binding water and forming a more stable network structure, thus increasing the gel viscosity.

[0085] Through frequency scanning test, by Figure 13 It can be seen that, compared with unmodified SDF, the elastic modulus G' and viscous modulus G" of microwave-modified SDF hydrogels and biphasic gels are improved. G' is directly related to the hardness of food; therefore, microwave-modified SDF can improve the mechanical strength of gel samples. Figure 14 It can be seen that for all gels, across the entire frequency range, the G' of the hydrogel (MSDF) and biphasic gels (BK-7:3, MSDF-7:3) is higher than G", indicating that elastic behavior is dominant and the gel is more inclined towards a solid state. The absence of overlap between G' and G" is typical behavior of elastic networks, indicating the formation of a stable gel. However, the hydrogel (BK) shows a significant increasing trend in both G' and G"; G' changes from being less than G" to being greater than G", exhibiting an overlap phenomenon. This indicates that the hydrogel prepared from unmodified SDF shifted from a liquid-like state to a solid-like state, failing to form an elastic network and resulting in system instability. Therefore, microwave modification makes the SDF hydrogel system more inclined towards a solid state, leading to greater system stability.

[0086] Thermodynamic properties were evaluated using temperature scanning tests. Figure 15 It can be seen that with increasing temperature, the elastic modulus G' and viscous modulus G” of the microwave-modified SDF hydrogel and biphase gel all increase compared to unmodified SDF. This indicates that the interaction between microwave-modified SDF and water can delay the instability of the system. The increasing trend in hydrogel is related to water evaporation during the heating process. Figure 16As shown in Table 6, the tanδ of BK decreases with increasing temperature. At 36.92 ℃, tanδ of BK < 1, indicating a phase transition from liquid to solid. MSDF maintains tanδ < 1 throughout, tending towards a solid state without undergoing a phase transition. This suggests that compared to unmodified SDF, microwave-modified SDF has better water binding ability, forming a uniform gel network structure with strong resistance to high-temperature changes. From 25 ℃ to 90 ℃, both BK-7:3 and MSDF-7:3 gels successively exhibit tanδ > 1, indicating a phase transition and the system becoming viscous or fluid. Compared to BK-7:3, MSDF-7:3 has a higher phase transition temperature, suggesting that microwave modification has a positive impact on the thermal stability of SDF biphase gels.

[0087] Table 6 Different gel phase transition temperatures Gel types Phase transition temperature (°C) BK 36.92 MSDF / BK-7:3 78.04 MSDF-7:3 85.87 In summary, the rheological measurements show that, compared with unmodified SDF, gels (including hydrogels and biphasic gels) prepared by microwave-modified SDF have better viscoelasticity, more stable network structure, and better thermal and frequency stability.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biphasic gel based on microwave-modified soybean residue dietary fiber, characterized in that, It is prepared from oleogels and hydrogels, wherein the hydrogels include water and a hydrogelating agent, and the hydrogelating agent is microwave-modified soybean residue dietary fiber; The water retention capacity of the microwave modified okara dietary fiber is 12-16 g·g -1 The oil retention capacity of the microwave modified okara dietary fiber is 8-12 g·g -1 The particle size of the microwave modified okara dietary fiber is 212-400 nm; and the absolute value of the Zeta potential of the microwave modified okara dietary fiber is 13-15.34 mV. Preparation of microwave-modified soybean residue dietary fiber: Soybean residue and water are mixed evenly at a certain material-to-liquid ratio, then microwave-modified, dried, ground into powder, and extracted to obtain microwave-modified soybean residue dietary fiber; in the preparation of microwave-modified soybean residue dietary fiber, the microwave power of the microwave modification is 500~900 W, the microwave time is 2~10 min, and the microwave temperature is 60~100℃; the material-to-liquid ratio of soybean residue to water is 1:(5~15); the extraction includes defatting, enzymatic hydrolysis, alcohol precipitation, and purification steps; the enzymes used in the enzymatic hydrolysis step include α-amylase, neutral protease, and amylase.

2. The biphasic gel according to claim 1, characterized in that, In the hydrogel, the weight percentage of the microwave-modified soybean residue dietary fiber is 3% to 10%.

3. The biphasic gel according to claim 2, characterized in that, In the hydrogel, the microwave-modified soybean residue dietary fiber accounts for 5% by weight.

4. The biphasic gel according to claim 1, characterized in that, In the biphasic gel, the hydrogel accounts for 10% to 90% by weight.

5. The biphasic gel according to claim 4, characterized in that, In the biphasic gel, the hydrogel accounts for 30% to 70% by weight.

6. The biphasic gel according to claim 5, characterized in that, In the biphasic gel, the hydrogel accounts for 30% by weight.

7. The biphasic gel according to claim 1, characterized in that, The oleogel comprises oil and an oleogeling agent, wherein the oleogeling agent comprises 6% to 10% by weight.

8. The biphasic gel according to claim 7, characterized in that, The oleogel has a weight percentage of 9%.

9. The biphasic gel according to claim 7, characterized in that, The oil includes one or more of sunflower oil, soybean oil, corn oil, sesame oil, olive oil, cottonseed oil, grapeseed oil, rapeseed oil, and fish oil; and / or the oil gelling agent includes one or more of palm wax, wood wax, soybean wax, beeswax, rice bran wax, and candelilla wax.

10. The method for preparing the biphasic gel according to any one of claims 1 to 9, characterized in that, Includes the following steps: Preparation of microwave-modified soybean residue dietary fiber: Soybean residue and water are mixed evenly at a certain material-to-liquid ratio, then microwave-modified, dried, ground into powder, and extracted to obtain microwave-modified soybean residue dietary fiber; in the preparation of microwave-modified soybean residue dietary fiber, the microwave power of the microwave modification is 500~900 W, the microwave time is 2~10 min, and the microwave temperature is 60~100℃; the material-to-liquid ratio of soybean residue to water is 1:(5~15); the extraction includes defatting, enzymatic hydrolysis, alcohol precipitation, and purification steps; the enzymes used in the enzymatic hydrolysis step include α-amylase, neutral protease, and amylase. Preparation of hydrogel: Water and the obtained microwave-modified soybean residue dietary fiber were mixed and stirred evenly to obtain hydrogel; Preparation of oleogel: The oil and oleogel agent of the oleogel are mixed and stirred evenly to obtain the oleogel; Preparation of biphase gel: The obtained oleogel and hydrogel are stirred evenly in a certain proportion to obtain a biphase gel.

11. The preparation method according to claim 10, characterized in that, The microwave power for the microwave modification is 600 W, the microwave time is 4-6 min, and the microwave temperature is 70 ℃.

12. The preparation method according to claim 10, characterized in that, The ratio of soybean residue to water is 1:

10.

13. The preparation method according to claim 10, characterized in that, During the preparation of the hydrogel, the stirring temperature was 50~70 ℃, the stirring time was 5~10 min, and the stirring speed was 200~400 r / min; And / or, during the preparation of oleogel, the stirring temperature is 60~80 ℃, the stirring time is 20~40 min, and the stirring speed is 200~400 r / min.

14. The preparation method according to claim 10, characterized in that, During the preparation of biphasic gels, the stirring temperature was 60-80 ℃, the stirring time was 1-5 min, and the stirring speed was 2000-3000 r / min.

15. The use of the biphasic gel according to any one of claims 1 to 9 or the biphasic gel prepared by the preparation method according to any one of claims 10 to 14 in food.

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