A multi-spray device and a method for continuously preparing microcapsules

Abstract

The present invention discloses a multi-spray device, comprising the following components: a spray tank (G); a plurality of nozzles (P), arranged at the upper part of the inner wall of the spray tank (G); each nozzle is externally connected to a spray pipe (T) respectively; a plurality of stirring paddles (M), wherein at least one stirring paddle is arranged above or below the plurality of nozzles, and at least one stirring paddle is arranged at the lower part of the spray tank (G). The present invention also discloses a method for continuously preparing microcapsules by using the multi-spray device. By using the device of the present invention, the preparation of microcapsules can be carried out continuously, and the encapsulation rate of the obtained microcapsules is significantly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of spice preparation, and particularly relates to a multi-spray device and a method for continuously preparing microcapsules. Background Art

[0002] Microcapsules are a core-shell structure formed by encapsulating an embedded substance with a natural or synthetic, semi-synthetic polymer material as the capsule wall. The substance embedded in the polymer carrier can be slowly released, improving the utilization rate, action time and stability of the active ingredient.

[0003] Volatile fragrance substances mostly have the characteristics of strong volatility and easy oxidation and deterioration. Microcapsules can effectively protect the stability of fragrance molecules. By regulating the temperature, capsule wall material and the size of micropores on the capsule wall, the fragrance substances can diffuse from the inside to the capsule surface through the micropores of the capsule wall at different release rates, releasing the aroma components.

[0004] Fragrance substance microcapsules are mostly prepared by physical methods, mainly including complex coacervation method, single coacervation method and spray drying method, etc. Among them, the complex coacervation method uses two or several polymer materials as the wall material, disperses the fragrance substance into the wall material, and under the conditions of changing temperature, pH value or inorganic salt, etc., the wall material undergoes electrostatic interaction to reduce its solubility, and the wall material coagulates and wraps to form microcapsules; it operates at room temperature, and the inclusion rate and yield are relatively high. The spray drying method first prepares a mixed emulsion of fragrance substances and wall materials, and then sprays and dries the emulsion in a dryer. The wall material forms a network structure after being heated and wraps the fragrance substances in the mesh holes to form microcapsules; when heated, the fragrance substances are released through the "mesh holes" due to molecular thermal motion; the spray drying method is generally carried out within 100-300 °C, which is suitable for core materials with stable inclusion properties, but may not be suitable for highly volatile fragrance substances. The single coacervation method disperses the volatile fragrance substance in a polymer wall material to form an emulsion, prepares a uniform emulsion under high-speed dispersion conditions, adjusts the pH value, adds an ionized salt to reduce the solubility of the polymer material, and maintains a high salinity for capsule formation, and then coagulates to wrap the fragrance substance in it to form microcapsules; the single coacervation method uses a single wall material, has a high inclusion rate, operates at room temperature, is easy to operate, and is suitable for the encapsulation of fragrance substances and the enlarged production of the process. Currently, the relevant literature reports on the preparation of microcapsules by the single coacervation method are as follows: Liu Jun et al. adopted the single coacervation method to prepare and optimize the process scheme in the "Study on the Preparation and Release Performance of Citronella Oil-Loaded Microspheres for Mosquito-Repellent Fabrics". When the concentration of gelatin was 2%, the yield, encapsulation rate, oil loading amount and release rate of gelatin-citronella oil microspheres all reached relatively high values; among them, the release rate of citronella oil is related to the particle size of the microspheres. The smaller the particle size of the microspheres, the larger the release area of the encapsulated substance and the higher the release rate.

[0005] The above preparation methods such as complex coacervation method, simple coacervation method and spray drying method can all obtain microcapsules that can maintain the stability of fragrance molecules and can stably release aroma components at a certain temperature. The preparation method is simple and easy for industrial production. However, the above preparation methods are all batch operations, with poor controllability and unable to continuously prepare microcapsules; moreover, the encapsulation efficiency of the prepared microcapsules is not high.

[0006] The present invention is proposed to solve the above problems. Summary of the Invention

[0007] The present invention discloses a multi-spray device and a method for continuously preparing microcapsules using the multi-spray device. Using the multi-spray device of the present invention, microcapsules can be continuously prepared, and the encapsulation efficiency of the obtained microcapsules is significantly improved. The device of the present invention is simple and easy to operate and is easy for industrial production.

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

[0009] The first aspect of the present invention discloses a multi-spray device, which includes the following components:

[0010] A spray tank G;

[0011] A plurality of nozzles P, arranged at the upper part of the inner wall of the spray tank G; each nozzle is externally connected to a spray pipe T respectively;

[0012] A plurality of stirring paddles M, at least one of which is arranged above or below the plurality of nozzles, and at least one of which is arranged at the lower part of the spray tank G.

[0013] Preferably, an even number of the nozzles are arranged in the same horizontal plane and are opposite to each other in pairs.

[0014] Preferably, there are 2 of the plurality of stirring paddles, the stirring paddle arranged above or below the plurality of nozzles is the first stirring paddle M1, and the one arranged at the lower part of the spray tank G is the second stirring paddle M2.

[0015] Preferably, the first stirring paddle M1 and the second stirring paddle M2 share a stirring shaft M, and a driving device D is connected to the stirring shaft M.

[0016] Preferably, there is a feed port J in the middle of the spray tank G and a discharge port C at the bottom.

[0017] The second aspect of the present invention discloses a method for continuously preparing microcapsules using the multi-spray device, which includes the following steps:

[0018] ① Prepare an emulsion containing a fragrance substance and a wall material, and connect the emulsion to the nozzle through a spray pipe;

[0019] ② Prepare two portions of salt solutions, one with a higher concentration and the other with a lower concentration; connect the salt solution with the higher concentration to the nozzle through a spray pipe; the nozzle connected to the salt solution with the higher concentration is opposite to the nozzle connected to the emulsion;

[0020] ③ Inject the salt solution with the lower concentration prepared in step ② into the spray tank G through the feed port J;

[0021] ④ Start the driving device D to turn on the stirring paddle M, turn on the nozzle P, and regulate the droplet size for spraying;

[0022] ⑤ After fully mixing the solution at the bottom of the spray tank G, discharge it into the intermediate storage tank through the discharge port C;

[0023] ⑥ The materials continue to be mixed in the intermediate storage tank;

[0024] ⑦ Filter and freeze-dry to obtain the microcapsules.

[0025] Preferably, the flavor substance in step ① is one or more of peppermint oil, perilla oil, or citronella oil; the wall material is gelatin.

[0026] Preferably, the salt solution in step ② is one or more of sodium sulfate, potassium sulfate, sodium chloride, or potassium chloride salt solutions; the concentration of the salt solution with the higher concentration is 20-40 wt%; the concentration of the salt solution with the lower concentration is 10-15 wt%.

[0027] Preferably, the rotation speed of the stirring paddle M in step ④ is 500-1000 rpm.

[0028] The specific steps of using the multi-spray device of the present invention for continuously preparing microcapsules are as follows, taking gelatin as the wall material and peppermint oil as the flavor substance as an example for illustration:

[0029] Step 1, dissolve an appropriate amount of gelatin in distilled water at 40-70 °C to prepare a gelatin solution with a concentration of 1-10 wt%; add an appropriate amount of peppermint oil, control the mass ratio of peppermint oil to gelatin to be 1:1-1:4, adjust the pH value to 3.5-3.8 with acetic acid, and emulsify at 13000-18000 rpm for 2-3 min and ultrasonicate for 3-5 min to obtain a peppermint oil gelatin emulsion; the frequency of ultrasonication is 20-30 kHz and the power is 200-250 W;

[0030] Step 2, dissolve one or more of an appropriate amount of anhydrous sodium sulfate, potassium sulfate, sodium chloride, or potassium chloride in water to prepare a concentrated salt solution with a concentration of 20-40 wt% and a dilute salt solution with a concentration of 10-15 wt%, and adjust the pH value to 3.5-3.8 with acetic acid respectively for standby;

[0031] Step 3: Inject the dilute salt solution with a concentration of 10 - 15 wt% prepared in Step 2 into the spray tank G through the feed port J;

[0032] Step 4: Start the drive device D, and the first stirring paddle M1 and the second stirring paddle M2 stir at a speed of 500 - 1000 rpm respectively; start the nozzle spraying;

[0033] Step 5: Spray the peppermint oil gelatin emulsion obtained in Step 1 and the concentrated salt solution obtained in Step 2 into the spray tank G through the first nozzle P1 and the second nozzle P2 respectively, and the diameter of the sprayed droplets is 300 - 1000 μm; the two nozzles are arranged at the horizontally opposite positions on the inner wall of the spray tank G as Figure 1 shown. The sprayed droplets collide and mix with each other, and under the action of the first stirring paddle M1, the above two kinds of droplets are fully mixed. Under the action of the concentrated salt solution, gelatin coagulates, and the peppermint oil is wrapped therein to form microcapsules. Under the action of gravity and the inertial force of the first stirring paddle M1, it settles or flows along the inner wall of the spray tank G to Figure 1 the bottom of the spray tank G in; at the same time, the second stirring paddle M2 stirs the above liquid droplets and the dilute salt solution fully at a speed of 500 - 1000 rpm and continues to stir for 5 - 15 min;

[0034] Step 6: Discharge the liquid substance in Step 5 through the discharge port C and place it in the intermediate storage device, continue to stir at a speed of 500 - 1000 rpm, and cool down to 0 - 10°C; continue to stir, slowly dropwise add 10 - 15 M formaldehyde solution, and then slowly dropwise add 15 - 25 wt% sodium hydroxide solution to adjust the pH value to 8 - 9, keep the temperature at 0 - 10°C unchanged, and continue to stir for 2 - 5 h. Adding formaldehyde is to solidify the microcapsules. Its reaction mechanism is that under alkaline conditions, formaldehyde reacts with NH2 in gelatin, which is an irreversible chemical reaction, and a solidified colloid is formed after the reaction to avoid the depolymerization of gelatin.

[0035] Step 7: Filter, wash the filter cake with water until the filtrate cannot change the color of the hydroxylamine phosphate solution from light yellow to pink, and freeze-dry to obtain the finished product, which is the microcapsule; the obtained microcapsule has a particle size of 10 - 50 μm. If the microcapsule remains formaldehyde, the hydroxylamine phosphate solution is pink, and if there is no residue, the solution is light yellow.

[0036] The beneficial effects of the present invention:

[0037] 1. The multi-spray device of the present invention is the first to set multiple nozzles, and the number and relative positions of the multiple nozzles can be set according to the properties of the emulsion and the salt solution, so that the sprayed emulsion droplets and salt solution droplets are fully mixed.

[0038] 2. The multi-spray device of the present invention is provided with at least two stirring paddles, and at least one stirring paddle is used for mixing the droplets, ensuring that the ejected emulsion droplets and concentrated salt solution droplets are further mixed.

[0039] 3. The encapsulation rate of the microcapsule fragrance prepared by the multi-spray device of the present invention is significantly improved.

[0040] 4. The multi-spray device of the present invention can continuously prepare microcapsules. Compared with the intermittent operation of the prior art, it has strong controllability and improved production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the multi-spray device of Example 1.

[0042] Figure 2 It is a top view of the multi-spray device of Example 2.

[0043] Figure 3 It is an SEM image of the gelatin peppermint oil microcapsules prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The present invention will be further described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited to the content described.

[0045] Example 1

[0046] The schematic diagram of the multi-spray device used in this example is as Figure 1 shown. It includes the following components: a spray tank G with a discharge port C at the bottom, two nozzles, namely the first nozzle P1 and the second nozzle P2, which are oppositely arranged on the same horizontal plane; there is a feed port J below the nozzle P; two stirring paddles, among which the stirring paddle arranged below the nozzle is the first stirring paddle M1, and the stirring paddle arranged in the lower part of the spray tank G is the second stirring paddle M2. The two stirring paddles share a stirring shaft M, and a driving device D is connected to the stirring shaft M.

[0047] The steps for preparing gelatin peppermint oil microcapsules using the multi-spray device of this example are as follows:

[0048] Dissolve an appropriate amount of gelatin in distilled water at 50 °C to prepare a 5 wt% gelatin solution; add peppermint oil, control the mass ratio of peppermint oil to gelatin to be 1:2, adjust the pH value to 3.8 using acetic acid, emulsify for 2 min at 13,000 rpm, and sonicate for 3 min to obtain a peppermint oil gelatin emulsion; the frequency of sonication is 20 kHz and the power is 200 W.

[0049] Dissolve an appropriate amount of anhydrous sodium sulfate in water, control the concentration at 40 wt%, and adjust the pH value to 3.8 with acetic acid to obtain a concentrated anhydrous sodium sulfate solution; dissolve an appropriate amount of anhydrous sodium sulfate in water, control the concentration at 10 wt%, and adjust the pH value to 3.8 with acetic acid to obtain a dilute anhydrous sodium sulfate solution.

[0050] Inject the 10 wt% dilute anhydrous sodium sulfate solution into the spray tank G through the feed port J.

[0051] Start the driving device D, and the first stirring paddle M1 and the second stirring paddle M2 stir at a speed of 800 rpm respectively; start the nozzle spraying, and the two nozzles are arranged at the horizontal relative positions in the spray tank G as Figure 1 shown.

[0052] Spray the prepared gelatin emulsion into the spray tank G through the first nozzle P1, spray the concentrated anhydrous sodium sulfate solution into the spray tank G through the second nozzle P2. After the sprayed droplets collide and mix with each other, they are fully mixed under the action of the first stirring paddle M1. Under the action of gravity or the inertial force of the stirring paddle, the droplets settle or flow along the inner wall of the spray tank G to the dilute anhydrous sodium sulfate solution at the bottom of the spray tank G. At the same time, the second stirring paddle M2 fully mixes the above liquid, and continues to stir for 10 min;

[0053] Discharge the above liquid through the discharge port C into an intermediate storage device (not shown in the figure), continuously stir at a speed of 800 rpm, cool down to 5 °C, continue to stir, slowly add 12 M formaldehyde solution drop by drop, and then slowly add 20 wt% sodium hydroxide solution to adjust the pH value to 8.5, keep the temperature at 5 °C unchanged, and continue to stir for 2 h.

[0054] Filter, wash the filter cake with water until the filtrate no longer makes the hydroxylamine phosphate solution change from light yellow to pink, and freeze-dry to obtain the finished product of gelatin peppermint oil microcapsules. Its SEM image is as Figure 3 shown, and its particle size is 40 - 50 microns. The encapsulation efficiency measured is 80.4%.

[0055] Comparative example:

[0056] The preparation method is the same as the conventional single coacervation reported in the literature. The preparation methods of the 40 wt% and 10 wt% anhydrous sodium sulfate solutions, peppermint oil gelatin emulsion, formaldehyde, and sodium hydroxide solutions are the same as those in Example 1.

[0057] The steps are as follows: Take an appropriate amount of peppermint oil gelatin emulsion in a beaker, add an appropriate amount of acetic acid solution to adjust the pH value to 3.8, slowly dropwise add an appropriate amount of 40wt% anhydrous sodium sulfate solution, continuously stir for 5 min, add an appropriate amount of 10wt% anhydrous sodium sulfate solution, and stir for 5 min. Cool down to 5°C, continuously stir, slowly dropwise add 12M formaldehyde solution, and then slowly dropwise add 20wt% sodium hydroxide solution to adjust the pH value to 8.5, keep the temperature at 5°C unchanged, and continuously stir for 2 h. Filter, wash the filter cake with water until the filtrate cannot change the color of the hydroxylamine phosphate solution from light yellow to pink, and freeze-dry to obtain the finished gelatin peppermint oil microcapsules with a particle size of 10 - 80 microns. The encapsulation efficiency is measured to be 71.9%.

[0058] Example 2

[0059] The multi-spray device used in this example is the same as that in Example 1, the difference is that there are four nozzles, and the four nozzles are arranged in the spray tank G, and all the nozzles are arranged in a horizontal plane, and this plane is parallel to the bottom of the spray tank G, as Figure 2 shown in the top view. After the droplets sprayed by the four nozzles collide and mix with each other, they are further mixed under the action of the first stirring paddle M1, and then under the action of gravity or the inertial force of the paddle blades of the stirring paddle, the droplets settle or flow along the inner wall of the spray tank G to the bottom of the spray tank G and mix with the dilute anhydrous sodium sulfate solution. Others are the same as in Example 1. The particle size of the obtained gelatin peppermint oil microcapsules is measured to be 40 - 50 microns, and the encapsulation efficiency is 82.5%.

[0060] Example 3

[0061] The multi-spray device used in this example is the same as that in Example 1. The composition and concentration of the raw materials are the same as those in Example 1, the difference is that the fragrance is perilla oil. The encapsulation efficiency of the obtained finished gelatin perilla oil microcapsules is 80.8%.

[0062] Example 4

[0063] The multi-spray device used in this example is the same as that in Example 2. The composition and concentration of the raw materials are the same as those in Example 2, the difference is that the fragrance is citronella oil. The encapsulation efficiency of the obtained finished gelatin citronella oil microcapsules is 82.7%.

[0064] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for continuously preparing microcapsules using a multi-spray device, characterized in that, The multi-spray device includes the following components: a spray tank (G); a plurality of nozzles (P) arranged at the upper part of the inner wall of the spray tank (G); each nozzle is externally connected to a spray pipe (T) respectively; a plurality of stirring paddles (M), where at least one stirring paddle is arranged above or below the plurality of nozzles, and at least one stirring paddle is arranged at the lower part of the spray tank (G); the nozzles are arranged in an even number in the same horizontal plane and are opposite to each other in pairs; the plurality of stirring paddles are two, the stirring paddle arranged above or below the plurality of nozzles is the first stirring paddle (M1), and the one arranged at the lower part of the spray tank (G) is the second stirring paddle (M2); the first stirring paddle (M1) and the second stirring paddle (M2) share a stirring shaft (M), and a driving device (D) is connected to the stirring shaft (M); there is a feed port (J) in the middle of the spray tank (G) and a discharge port (C) at the bottom; It includes the following steps: ① Prepare an emulsion containing a flavor substance and a wall material, and connect the emulsion to the nozzle through a spray pipe; ② Prepare two salt solutions, one with a higher concentration and the other with a lower concentration; connect the salt solution with a higher concentration to the nozzle through a spray pipe; the nozzle connected to the salt solution with a higher concentration is opposite to the nozzle connected to the emulsion; ③ Inject the salt solution with a lower concentration prepared in step ② into the spray tank (G) through the feed port (J); ④ Start the driving device (D) to turn on the stirring paddle (M), turn on the nozzle (P), and adjust the droplet size for spraying; ⑤ Fully mix the solution at the bottom of the spray tank (G) and discharge it into an intermediate storage tank through the discharge port (C); ⑥ The materials continue to be mixed in the intermediate storage tank; ⑦ Filter and freeze-dry to obtain the microcapsules.

2. The method according to claim 1, characterized in that The flavor substance in step ① is one or more of peppermint oil, perilla oil or citronella oil; the wall material is gelatin.

3. The method according to claim 1, characterized in that The salt solution in step ② is one or more of sodium sulfate, potassium sulfate, sodium chloride or potassium chloride salt solutions; the concentration of the salt solution with a higher concentration is 20 - 40 wt%; the concentration of the salt solution with a lower concentration is 10 - 15 wt%.

4. The method according to claim 1, wherein In step ④, the rotation speed of the stirring paddle (M) is 500 - 1000 rpm.

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