A temperature-sensitive core-shell taste-masking microsphere and its preparation method

Abstract

This invention discloses a thermosensitive core-shell flavor-masking microsphere, its preparation method, and its application, belonging to the technical field of flavor-masking microspheres. The microsphere comprises a shell and a core. The shell is a thermosensitive hydrogel with an upper critical temperature of 25-45°C. The core comprises an oil-phase surfactant, sorbitan, and oil-wax components, and the melting point of the core is... T m The temperature is set at 35-55℃ to ensure the core layer remains in a semi-solid or solid state at room temperature. This invention prepares core-shell odor-masking microspheres with controlled odor release function using a microfluidic method. The core layer of these microspheres is semi-solid at room temperature and solid when frozen, forming a water-in-oil encapsulated solid biemulsion microsphere. This invention achieves controlled release of sorbitan odor by changing the state of the microsphere core layer, thus masking the odor, and the biemulsion microspheres maintain long-term stability. The shell layer can undergo thermosensitive conversion, facilitating the release of active ingredients and promoting sorbitan absorption.

Description

Technical Field

[0001] This invention belongs to the technical field of taste-masking microspheres, specifically relating to a temperature-sensitive core-shell type taste-masking microsphere and its preparation method. Background Technology

[0002] As consumers' demands for skincare product efficacy continue to rise, active ingredients with special functions have gradually become a research hotspot. For example, active ingredients such as sanshool, houttuynia cordata extract, and fish oil have been applied to skincare products, pharmaceuticals, and food. However, these active ingredients have distinctive odors, which can lead to a poor sensory experience for consumers if added to skincare products, pharmaceuticals, or food. Furthermore, active ingredients exhibit high instability in storage and application, limiting their widespread adoption.

[0003] Specifically, the sanshool, a natural active ingredient extracted from Sichuan pepper, promotes blood circulation and improves skin metabolism, effectively alleviating dullness and enhancing skin vitality. The fish oil, rich in omega-3 fatty acids and other nutrients, possesses anti-inflammatory, antioxidant, and moisturizing properties, repairing the skin barrier, reducing fine lines and wrinkles, and delaying skin aging, making it highly valuable in the skincare industry. However, the active ingredients, such as sanshool and fish oil, have a noticeable odor. This strong and distinctive smell not only affects the consumer experience and reduces product acceptance but may also raise questions about product quality among some consumers. Furthermore, the high activity of these active ingredients makes them easily deactivated under light and heat, resulting in poor stability and posing significant challenges to storage and application. Summary of the Invention

[0004] The purpose of this invention is to provide a temperature-sensitive core-shell odor-masking microsphere and its preparation method, in order to solve the above-mentioned problems.

[0005] This invention is mainly achieved through the following technical solutions:

[0006] A thermosensitive core-shell flavor-masking microsphere comprises a shell and a core. The shell is a thermosensitive hydrogel with an upper critical temperature of 25-45°C. The core comprises an oil-phase surfactant, sorbitan, and oil-wax components, and the melting point of the core is... T m The temperature is 35-55℃ to ensure the core layer is in a semi-solid or solid state at room temperature. Preferably, the melting point of the core layer is... T m The temperature is 35-45℃.

[0007] To better realize the present invention, the mass of the sanshool is 0.1wt%-10wt% of the total mass of the core layer; the mass of the oil phase surfactant is 0.1wt%-10.0wt% of the total mass of the core layer.

[0008] To better realize the present invention, further, the sanshool is hydroxy- α -Sansorcinol, hydroxyl- β -Sansorcinol, hydroxyl- γ - Any one or more of the following: saponins; the oily and waxy components are any one or more of the following: beeswax, candelilla wax, carnauba wax, coconut oil, cocoa butter, oleyl alcohol, jojoba oil, squalane, olive oil, and mineral oil.

[0009] To better realize the present invention, the shell layer is further described as a three-dimensional network structure hydrogel, comprising a UCST-type prepolymer and a crosslinking component, wherein the molar ratio of the UCST-type prepolymer to the crosslinking component is 2-4:1; the crosslinking material is any one or more of gelatin, sodium alginate, chitosan, sodium carboxymethyl cellulose, polyethylene glycol, and hyaluronic acid; and the UCST-type hydrogel is any one or more of polyacrylamide-acrylic acid, sodium polystyrene sulfonate-ethyl methacrylate, and polysulfobetaine.

[0010] To better realize the present invention, the UCST-type hydrogel is further described as polyacrylamide-acrylic acid, and the crosslinking material is chitosan; polyacrylamide-acrylic acid is obtained by reacting acrylic acid, acrylamide, initiator and deionized water, and the molar ratio is 5-10:10-20:0.01-0.1:40-80.

[0011] This invention is mainly achieved through the following technical solutions:

[0012] A method for preparing thermosensitive core-shell odor-masking microspheres includes the following steps:

[0013] Step S1: Prepare the inner phase solution for core layer preparation;

[0014] Step S2: Prepare an intermediate phase solution for shell preparation;

[0015] Step S3: Prepare the external phase solution;

[0016] Step S4: Assemble the microfluidic reaction device; fill the prepared internal phase solution, intermediate phase solution and external phase solution into the inlet bottles respectively, and connect the three inlet bottles to the internal phase inlet, intermediate phase inlet and external phase inlet of the chip respectively through the internal phase inlet pipeline, the intermediate phase inlet pipeline and the external phase inlet pipeline, and connect the chip outlet to the outlet pipeline.

[0017] Step S5: The internal phase pressure of the chip is 1.0-10.0 kPa, the intermediate phase pressure is 5.0-15.0 kPa, and the external phase pressure is 10.0-20.0 kPa;

[0018] Step S6: Use a 4℃ receiving phase to receive the microspheres.

[0019] To better realize the present invention, further, in step S3, the external phase solution includes a solvent and an oil phase surfactant, and the mass of the oil phase surfactant is 0.1wt%-10.0wt% of the total mass of the external phase solution; the solvent is any one of soybean oil, peanut oil, mineral oil, silicone oil, and liquid paraffin.

[0020] To better realize the present invention, further, in step S5, the internal phase pressure of the chip is 2.5-5.5 kPa, the intermediate phase pressure is 3.0-7.0 kPa, and the external phase pressure is 16.0-20.0 kPa.

[0021] The application of the above-mentioned temperature-sensitive core-shell odor-masking microspheres in washing and care products and skin care products.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) The core-shell odor-masking microspheres prepared in this invention are S / W / O biemulsion microspheres, wherein the core layer contains odorous salicornin. The odor of salicornin can be controlled by adjusting the state of the core layer of the microsphere (solid, semi-solid, liquid) to achieve the purpose of odor masking, and the biemulsion microspheres can maintain long-term stability (shelf life ≥ 24 months). Specifically, this invention prepares core-shell odor-masking microspheres with odor control function by microfluidic method. The core layer of the core-shell odor-masking microspheres is semi-solid at room temperature and solid at frozen state, and is a biemulsion microsphere in the form of water-in-oil-in-solid (S / W / O). Under frozen storage conditions, the core layer of the core-shell odor-masking microspheres is solid, which can restrict the flow of odorous salicornin in the core layer, reduce the volatilization and leakage of odor molecules, and at the same time improve the stability of salicornin inside the microspheres. Under normal operating conditions, the core layer of the core-shell flavor-masking microspheres is in a semi-solid and liquid state. It can be further converted into a liquid state by kneading and heating. At this point, the shell layer undergoes further temperature-sensitive conversion, facilitating the release of active ingredients. This invention allows control of the release of sanshool from the core layer by changing the operating temperature. Furthermore, the oily and waxy components within the core layer have moisturizing and soothing effects, promoting the absorption of sanshool.

[0024] (2) The shell of the core-shell odor-masking microsphere is a thermosensitive hydrogel with a three-dimensional network structure. Under the dynamic change of external temperature, the thermosensitive hydrogel of the shell can undergo sol-gel conversion according to the temperature change, and can expand or contract in response to temperature change. The shell and the waxy core layer in solid or semi-solid state have a synergistic effect, which can achieve a good encapsulation effect on the odorous active ingredients, improve the stability of the core layer, and accelerate the sustained release effect when the temperature rises.

[0025] (3) In practical applications, the content of the sanshool is fixed. Therefore, the present invention uses the melting point T m The calculation formula (Gordon-Taylor equation) is used to control the composition and amount of oil and wax, selecting a mixed oil system that is semi-solid or liquid under the operating environment (30-40℃) and solid under the storage state (0-10℃), so that the melting point of the core layer is in the range of 35-45℃, achieving a semi-solid or solid state of the core layer at room temperature. Secondly, in order to control the surface tension of the internal phase, an oil-phase surfactant is added to the core layer.

[0026] (4) The cross-linked components in the shell of the core-shell flavor-masking microspheres are used to enhance the mechanical properties of the hydrogel, while obtaining an interpenetrating network structure shell. The shell has temperature-sensitive properties and functions such as flavor masking and sustained release. The swelling properties and gelation state of the shell can change with temperature. Specifically, when the temperature rises, the swelling properties of the shell increase accordingly. As the state of the core changes from solid to semi-solid to liquid, the hydrogel with increased internal space can provide sufficient space for the release of the core. When the temperature decreases, the gel shell shrinks and the swelling rate is low, which has a good encapsulation function for the internal solid core material. Attached Figure Description

[0027] Figure 1 This is a top view of the chip;

[0028] Figure 2 This is a schematic diagram of the chip's three-dimensional structure;

[0029] Figure 3 A schematic diagram of the core-shell type taste-masking microspheres prepared in Example 2;

[0030] Figure 4 This is a schematic diagram of the sorbitol release rate curve of the microspheres at 37℃.

[0031] Figure 5 This is a schematic diagram showing the change in the release rate of sanshool as a function of temperature.

[0032] Figure 6 A schematic diagram of the taste-masking sensory evaluation of microspheres.

[0033] The components are: 1. External phase inlet, 2. Mesophase inlet, 3. Internal phase inlet, 4. External phase solution annular pipe, 5. Outlet, 6. Mesophase solution annular pipe, 7. Internal phase solution linear pipe, 8. Outlet pipe after primary shearing, 9. Outlet pipe after secondary shearing, 10. Screw hole for screw fixing, 11. Acrylic cover plate, 12. PTFE membrane, 13. Base plate. Detailed Implementation

[0034] Example 1:

[0035] A method for preparing a temperature-sensitive core-shell odor-masking microsphere, as shown in Table 1, includes the following steps:

[0036] Step 1: Prepare the internal phase solution; Prepare the oil and wax components: According to the Gordon-Taylor equation, weigh 20.50g of beeswax and 30.00g of jojoba oil, add 1wt% of surfactant EM90, and dissolve the mixed oil phase in an oil bath at 45℃. Keep the dissolved oil solution warm for later use. Prepare a 5wt% hydroxy-α-sanshool solution.

[0037] Step 2: Preparation of the precursor for UCST hydrogel: 17.992 g of acrylic acid was neutralized with NaOH solution, followed by the addition of 10 mL of a 2.817 g / mol acrylamide solution. The mixture was then evacuated and purged with nitrogen for 30 minutes. 0.015 g of KPS was added as an initiator, and the reaction was allowed to proceed for 1 hour. 0.01% (m / V) hydroquinone was then added to terminate the polymerization reaction. After cooling to room temperature, the polyacrylamide-acrylic acid prepolymer was obtained.

[0038] Step 3: Weigh 1.0 g of chitosan and dissolve it in 100 mL of an aqueous solution containing 1 wt% acetic acid (pH≈4.0). Stir until transparent and set aside to prepare a 1 wt% chitosan solution.

[0039] Step 4: Slowly add chitosan solution to the polyacrylamide-acrylic acid prepolymer obtained in Step 2, with a molar ratio of polyacrylamide-acrylic acid to chitosan of 4:1. Adjust the pH to 5.0-6.0 with NaOH solution, mix well, and set aside to obtain an intermediate phase solution.

[0040] Step 5: Prepare the external phase solution; weigh 100g of soybean oil and add 5g of PGPR to it. Place it on a magnetic stirrer and mix well before use.

[0041] Step 6: The prepared phase solutions and hydroxy-α-sanshool solution are respectively placed into the inlet bottles. Each inlet bottle and chip are placed inside a 45°C oven for microsphere shearing. To ensure the stability of the active component hydroxy-α-sanshool, it is placed outside the oven.

[0042] Preferably, such as Figure 1 and Figure 2 As shown, the chip includes an acrylic cover plate, a PTFE membrane, and a base plate arranged sequentially from top to bottom. One end of the top of the acrylic cover plate has an outer phase inlet, an intermediate phase inlet, and an inner phase inlet arranged sequentially from left to right, while the other end has an outlet. The top periphery of the acrylic cover plate and the base plate has several screw holes for fixing. The top of the base plate has an outer phase solution annular pipe, an intermediate phase solution annular pipe, and an inner phase solution linear pipe arranged sequentially from the outside to the inside. One side of the inner phase solution linear pipe is connected to a primary shear outlet pipe and a secondary shear outlet pipe, and the secondary shear outlet pipe is connected to the outlet. The outer phase solution annular pipe, the intermediate phase solution annular pipe, and the inner phase solution linear pipe are respectively connected to the outer phase inlet, the intermediate phase inlet, and the inner phase inlet.

[0043] Step 7: Connect the chip and the inlet bottle using a Teflon tube. After checking the airtightness, use a constant pressure pump to adjust the flow rates of the four solutions: internal phase pressure 2.7 kPa, intermediate phase pressure 6.0 kPa, and external phase pressure 18.2 kPa, until a stable oil-in-water-in-solid (S / W / O) biemulsion microsphere is prepared. Finally, the prepared microspheres are received in a 4℃ solution containing 3% (m / v) CaCl2 and crosslinked for 30 min. After filtration, the microspheres are washed with isopropanol to remove excess external oil phase, resulting in composite microspheres. The composite microspheres are then heated in a 45℃ physiological saline water bath for a period of time. It is observed that the shell of the composite microspheres swells, and the oil phase in the core layer melts and leaks out, indicating that the core melting point and the UCST of the shell material are both 45℃.

[0044] Example 2:

[0045] A method for preparing a temperature-sensitive core-shell odor-masking microsphere, as shown in Table 1, includes the following steps:

[0046] Step 1: Prepare the internal phase solution; Prepare the oil and wax components: According to the Gordon-Taylor equation, weigh 14.99g of beeswax and 30.00g of jojoba oil, add 1wt% EM90, and dissolve the mixed oil phase in an oil bath at 40℃. Keep the dissolved oil solution warm for later use. Prepare a 5wt% hydroxy-α-sanshool solution.

[0047] Step 2: Preparation of the precursor for UCST hydrogel: 10.341 g of acrylic acid was neutralized with NaOH solution, followed by the addition of 7 mL of a 2.817 g / mol acrylamide solution. The mixture was then evacuated and purged with nitrogen for 30 minutes. 0.015 g of KPS was added as an initiator, and the reaction was allowed to proceed for 1 hour. 0.01% (m / V) hydroquinone was then added to terminate the polymerization reaction. After cooling to room temperature, the polyacrylamide-acrylic acid prepolymer was obtained.

[0048] Step 3: Weigh 1.0 g of chitosan and dissolve it in 100 mL of an aqueous solution containing 1 wt% acetic acid (pH≈4.0). Stir until transparent and set aside to prepare a 1 wt% chitosan solution.

[0049] Step 4: Slowly add chitosan solution to the polyacrylamide-acrylic acid prepolymer obtained in Step 2, with a molar ratio of polyacrylamide-acrylic acid to chitosan of 4:1. Adjust the pH to 5.0-6.0 with NaOH solution, mix well, and set aside to obtain an intermediate phase solution.

[0050] Step 5: Prepare the external phase solution; weigh 100g of soybean oil and add 5g of PGPR to it. Place it on a magnetic stirrer and mix well before use.

[0051] Step 6: The prepared phase solutions and hydroxy-α-sanshool solution are respectively placed into the inlet bottles. Each inlet bottle and chip are placed inside a 40°C oven for microsphere shearing. To ensure the stability of the active component hydroxy-α-sanshool, it is placed outside the oven.

[0052] Step 7: Connect the chip and the inlet bottle using a Teflon tube. After checking the airtightness, use a constant pressure pump to adjust the flow rates of the four solutions: internal phase pressure 3.4 kPa, intermediate phase pressure 6.8 kPa, and external phase pressure 17.4 kPa, until a stable oil-in-water-in-solid (S / W / O) biemulsion microsphere is prepared. Finally, the prepared microspheres are received in a 4℃ solution containing 3% (m / v) CaCl2 and crosslinked for 30 min. After filtration, the microspheres are washed with isopropanol to remove excess external oil phase, resulting in composite microspheres. The composite microspheres are then heated in a 40℃ physiological saline water bath for a period of time. It is observed that the shell of the composite microspheres swells, and the oil phase in the core layer melts and leaks out, indicating that the core melting point and the UCST of the shell material are 40℃ and 37℃, respectively.

[0053] like Figure 3As shown, (a) is the microspheres prepared in Example 2 just received under a microscope; (b) is the microspheres prepared in Example 2 after washing under a microscope; and (c) is the microspheres prepared in Example 2 after curing under a camera. Analysis shows that this example has successfully prepared regular core-shell odor-masking microspheres with uniform particle size.

[0054] Example 3:

[0055] A method for preparing a temperature-sensitive core-shell odor-masking microsphere, as shown in Table 1, includes the following steps:

[0056] Step 1: Prepare the internal phase solution; Prepare the oil and wax components: According to the Gordon-Taylor equation, weigh 9.98g of beeswax and 30.00g of jojoba oil, add 1wt% EM90, and dissolve the mixed oil phase in an oil bath at 35℃. Keep the dissolved oil solution warm for later use. Prepare a 5wt% hydroxy-α-sanshool solution.

[0057] Step 2: Preparation of the precursor for UCST hydrogel: 10.341 g of acrylic acid was neutralized with NaOH solution, followed by the addition of 7 mL of a 2.817 g / mol acrylamide solution. The mixture was then evacuated and purged with nitrogen for 30 minutes. 0.015 g of KPS was added as an initiator, and the reaction was allowed to proceed for 1 hour. 0.01% (m / V) hydroquinone was then added to terminate the polymerization reaction. After cooling to room temperature, the polyacrylamide-acrylic acid prepolymer was obtained.

[0058] Step 3: Weigh 2.0 g of sodium alginate and dissolve it in 100 mL of aqueous solution; weigh a certain amount of anhydrous calcium chloride and dissolve it in ultrapure water to prepare a 2 mol / L calcium chloride solution; accurately weigh a certain amount of sodium hydroxide and dissolve it in ultrapure water to prepare a 2 mol / L sodium hydroxide solution; then mix the 2 mol / L calcium chloride solution with a 0.5 mol / L EDTA solution (pH=7.42) at a volume ratio of 1:4, and adjust the pH of the mixed solution to 8.13 using the 2 mol / L sodium hydroxide solution. Mix the pH-adjusted Ca-EDTA solution and 2 wt% sodium alginate solution at a volume ratio of 1:1 and stir until homogeneous, to prepare a 1 wt% sodium alginate solution.

[0059] Step 4: Slowly add sodium alginate solution to the polyacrylamide-acrylic acid prepolymer obtained in Step 2, with the molar ratio of polyacrylamide-acrylic acid to sodium alginate being 4:1. Mix well and set aside to obtain an intermediate phase solution.

[0060] Step 5: Prepare the external phase solution; weigh 100g of soybean oil and add 5g of PGPR to it. Place it on a magnetic stirrer and mix well before use.

[0061] Step 6: The prepared phase solutions and hydroxy-α-sanshool solution are respectively placed into the inlet bottles. Each inlet bottle and chip are placed inside a 35°C oven for microsphere shearing. To ensure the stability of the active component hydroxy-α-sanshool, it is placed outside the oven.

[0062] Step 7: Connect the chip and the inlet bottle using a Teflon tube. After checking the airtightness, use a constant pressure pump to adjust the flow rates of the four solutions: internal phase pressure 2.9 kPa, intermediate phase pressure 6.5 kPa, and external phase pressure 18.0 kPa, until a stable oil-in-water-in-solid (S / W / O) biemulsion microsphere is prepared. Finally, the prepared microspheres are received in a 4℃ solution containing 3% (m / v) CaCl2 and crosslinked for 30 min. After filtration, the microspheres are washed with isopropanol to remove excess external oil phase, resulting in composite microspheres. The composite microspheres are then heated in a 35℃ saline water bath for a period of time. It is observed that the shell of the composite microspheres swells, and the oil phase in the core layer melts and leaks out, indicating that the core melting point and the UCST of the shell material are 35℃ and 32℃, respectively.

[0063] Comparative Example 1:

[0064] A method for preparing thermosensitive core-shell flavor-masking microspheres is shown in Table 1. Hydroxy-α-sanshool / sodium alginate biemulsion microspheres were prepared using a microfluidic method. The specific preparation steps are as follows:

[0065] Step 1: Prepare the internal phase solution; the oily and waxy component is oleyl alcohol, and 5 wt% hydroxy-α-sanshool is added to it. Stir at room temperature for 30 min to completely mix sanshool into the oleyl alcohol to obtain the internal oil phase solution.

[0066] Step 2: Accurately weigh a certain amount of sodium alginate and prepare it into a 2wt% homogeneous solution for later use;

[0067] Accurately weigh a certain amount of anhydrous calcium chloride and dissolve it in ultrapure water to prepare a 2 mol / L calcium chloride solution. Accurately weigh a certain amount of sodium hydroxide and dissolve it in ultrapure water to prepare a 2 mol / L sodium hydroxide solution. Next, mix the 2 mol / L calcium chloride solution with a 0.5 mol / L EDTA solution (pH=7.42) at a volume ratio of 1:4. Adjust the pH of the mixed solution to 8.13 using the 2 mol / L sodium hydroxide solution. Mix the pH-adjusted Ca-EDTA solution and a 2 wt% sodium alginate solution at a volume ratio of 1:1 and stir until homogeneous to obtain an intermediate phase solution.

[0068] Step 3: The external phase solution is soybean oil, and 5.0 wt% PGPR is added to it and stirred evenly for later use.

[0069] Step 4: The receiving phase solution is soybean oil, and 3.0 wt% glacial acetic acid is added to it to provide acidic conditions for microsphere solidification.

[0070] Step 5: Pour the prepared inner phase solution, intermediate phase solution, and outer phase solution into the inlet bottle. Then connect the power source device and the chip through Teflon tubing. Connect the inner phase inlet pipe to the inner phase inlet, the intermediate phase inlet pipe to the intermediate phase inlet, the outer phase inlet pipe to the outer phase inlet, and the chip outlet to the outlet pipe. Check the airtightness of the entire pipeline.

[0071] Step 6: Adjust the pressure of the internal phase of the power source to 5.5 kPa, the pressure of the intermediate phase to 7.8 kPa, and the pressure of the external phase to 19.0 kPa.

[0072] Step 7: The prepared microspheres are received into the prepared receiving phase for solidification. After solidification for 30 minutes, the excess oil phase on the upper layer of the receiving phase is removed. Then, ethyl acetate is added to the remaining microspheres at the bottom. After gentle shaking and washing, the microspheres are filtered through a 500-mesh sieve. The microspheres are then washed 2-3 times with ethyl acetate. After washing with ethyl acetate, the microspheres are washed with ultrapure water. The above steps are repeated 2-3 times. The microspheres are then collected and dispersed in ultrapure water.

[0073] Comparative Example 2:

[0074] A method for preparing thermosensitive core-shell flavor-masking microspheres is shown in Table 1. Hydroxy-α-sanshool / sodium alginate@sodium carboxymethyl cellulose biemulsion microspheres were prepared using a microfluidic method. The specific preparation steps are as follows:

[0075] Step 1: Prepare the internal phase solution; the oily and waxy component is oleyl alcohol, and 5 wt% hydroxy-α-sanshool is added to it. Stir at room temperature for 30 min to completely mix sanshool into the oleyl alcohol to obtain the internal oil phase solution.

[0076] Step 2: Accurately weigh a certain amount of sodium alginate and carboxymethyl cellulose, and prepare them into a 2wt% homogeneous solution for later use;

[0077] Accurately weigh a certain amount of anhydrous calcium chloride and dissolve it in ultrapure water to prepare a 2 mol / L calcium chloride solution. Accurately weigh a certain amount of sodium hydroxide and dissolve it in ultrapure water to prepare a 2 mol / L sodium hydroxide solution. Next, mix the 2 mol / L calcium chloride solution with a 0.5 mol / L Ca-EDTA solution (pH=7.42) at a volume ratio of 1:4. Adjust the pH of the mixed solution to 8.13 using the 2 mol / L sodium hydroxide solution. Mix the pH-adjusted Ca-EDTA solution with a 2 wt% sodium alginate and carboxymethyl cellulose solution at a volume ratio of 1:1 and stir until homogeneous to obtain an intermediate phase solution.

[0078] Step 3: The external phase solution is soybean oil, and 5.0% PGPR is added to it. Stir well and set aside.

[0079] Step 4: The receiving phase solution is soybean oil, and 3.0% glacial acetic acid is added to it to provide acidic conditions for microsphere solidification.

[0080] Step 5: Pour the prepared inner phase solution, intermediate phase solution, and outer phase solution into the inlet bottle. Then connect the power source device and the chip through Teflon tubing. Connect the inner phase inlet pipe to the inner phase inlet, the intermediate phase inlet pipe to the intermediate phase inlet, the outer phase inlet pipe to the outer phase inlet, and the chip outlet to the outlet pipe. Check the airtightness of the entire pipeline.

[0081] Step 6: Adjust the pressure of the internal phase of the power source to 4.8 kPa, the pressure of the intermediate phase to 7.8 kPa, and the pressure of the external phase to 19.0 kPa.

[0082] Step 7: The prepared microspheres are received into the prepared receiving phase for solidification. After solidification for 30 minutes, the excess oil phase on the upper layer of the receiving phase is removed. Then, ethyl acetate is added to the remaining microspheres at the bottom. After gentle shaking and washing, the microspheres are filtered through a 500-mesh sieve. The microspheres are then washed 2-3 times with ethyl acetate. After washing with ethyl acetate, the microspheres are washed with ultrapure water. The above steps are repeated 2-3 times. The microspheres are then collected and dispersed in ultrapure water.

[0083] Release curves of sanshool from microspheres prepared in Examples 1-3 and Comparative Examples 1-2 at 37°C were tested. The microspheres were placed in dry iodine flasks, and the total amount of sanshool in the samples was measured every hour. The results were repeated three times, and the average value was taken. Release curves for different samples were then plotted and compared. The calculation formula was used as follows:

[0084] Release rate (%) = (1- m t / m 0) ×100%;

[0085] in, m t The total amount of sanshool in the sample measured at time t (g);

[0086] m 0 represents the total amount of sanshool (g) originally measured in the sample.

[0087] like Figure 4 As shown, at 37°C, compared with the sanshool release rates of Comparative Examples 1 and 2, the sanshool release rates of Examples 1-3 were significantly reduced, effectively decreasing the release of the microsphere flavor. Figure 5 As shown, the release rate of sanshool in Examples 1-3 and Comparative Example 1 increased with temperature, and the release of sanshool increased with increasing operating temperature. Overall, Example 1, with the same melting point of the core layer and UCST of the shell material, showed the best sustained-release effect.

[0088] Sensory evaluation: One method for assessing the aroma of microcapsules. Microsphere samples from Examples 1-3 and Comparative Examples 1 and 2 were placed in sealed, light-protected sample bottles at 37°C. Ten sensory evaluators (4 males and 6 females, aged 22-37 years) conducted sensory evaluations on each sample. All participants received professional perfumer training before the formal experiment; all selected sensory evaluators had received sensory evaluation training and answered questions independently during the evaluation. All sensory evaluators smelled the odor of the sanshool standard sample and scored the sample based on odor intensity. The odor intensity scoring standard was 0-5 points (accurate to 0.1), with the weakest odor intensity (no aroma detectable) at 0 points and the strongest odor intensity (strong, pungent aroma) at 5 points. Three replicates were set up for each sample group. The sensory results of all evaluators were statistically analyzed. After removing the maximum and minimum values ​​for each sample group, the average value was calculated as the sensory evaluation aroma intensity of the sample. Figure 6 As shown, at 37°C, the odor intensity of Examples 1 to 3 was relatively weak, close to 0 points; while the odor intensity of Comparative Examples 1 and 2 was stronger, close to 5 points, indicating that the microspheres prepared in this application have a better odor masking effect.

[0089] Table 1

[0090]

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A temperature-sensitive core-shell type taste-masking microsphere, characterized in that, It comprises a shell and a core layer. The shell is a thermosensitive hydrogel with an upper critical temperature of 25-45°C. The core layer comprises an oil-phase surfactant, sorbitan, and oil-wax components, and the melting point of the core layer is... T m The temperature is 35-55℃, so that the core layer can be in a semi-solid or solid state at room temperature; The oil and wax components are beeswax and jojoba oil; The thermosensitive hydrogel is a three-dimensional network structure hydrogel, and includes a UCST-type prepolymer and a crosslinking component, wherein the molar ratio of the UCST-type prepolymer and the crosslinking component is 2-4:

1. The UCST-type hydrogel is polyacrylamide-acrylic acid, which is obtained by reacting acrylic acid, acrylamide, an initiator and deionized water, with a molar ratio of 5-10:10-20:0.01-0.1:40-80; the crosslinking component is sodium alginate or chitosan.

2. The temperature-sensitive core-shell type taste-masking microsphere according to claim 1, characterized in that, The mass of the sanshool is 0.1wt%-10wt% of the total mass of the core layer; the mass of the oil phase surfactant is 0.1wt%-10.0wt% of the total mass of the core layer.

3. A temperature-sensitive core-shell type taste-masking microsphere according to claim 1 or 2, characterized in that, The sanshool is a hydroxyl- α -Sansorcinol, hydroxyl- β -Sansorcinol, hydroxyl- γ - Any one or more of the saponins.

4. A method for preparing thermosensitive core-shell type taste-masking microspheres, used to prepare the thermosensitive core-shell type taste-masking microspheres according to any one of claims 1-3, characterized in that, Includes the following steps: Step S1: Prepare the inner phase solution for core layer preparation; Step S2: Prepare an intermediate phase solution for shell preparation; Step S3: Prepare the external phase solution; Step S4: The prepared internal phase solution, intermediate phase solution and external phase solution are respectively loaded into the inlet bottles, and the three inlet bottles are connected to the internal phase inlet, intermediate phase inlet and external phase inlet of the chip through the internal phase inlet pipe, the intermediate phase inlet pipe and the external phase inlet pipe respectively. The chip outlet is connected to the outlet pipe. Step S5: The internal phase pressure of the chip is 1.0-10.0 kPa, the intermediate phase pressure is 5.0-15.0 kPa, and the external phase pressure is 10.0-20.0 kPa; Step S6: Use a 4℃ receiving phase to receive the microspheres.

5. The method for preparing a thermosensitive core-shell type taste-masking microsphere according to claim 4, characterized in that, In step S3, the external phase solution includes a solvent and an oil-phase surfactant, and the mass of the oil-phase surfactant is 0.1 wt%-10.0 wt% of the total mass of the external phase solution; the solvent is any one of soybean oil, peanut oil, mineral oil, and silicone oil.

6. The method for preparing a thermosensitive core-shell type taste-masking microsphere according to claim 4, characterized in that, In step S3, the external phase solution includes a solvent and an oil-phase surfactant, and the mass of the oil-phase surfactant is 0.1 wt%-10.0 wt% of the total mass of the external phase solution; the solvent is liquid paraffin.

7. The method for preparing a thermosensitive core-shell type taste-masking microsphere according to claim 4, characterized in that, In step S5, the internal phase pressure of the chip is 2.5-5.5 kPa, the intermediate phase pressure is 3.0-7.0 kPa, and the external phase pressure is 16.0-20.0 kPa.

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