Preparation and Application of a Microcapsule Emulsion

Abstract

The present invention belongs to the fields of food and chemical engineering, and specifically relates to the preparation and application of a microcapsule emulsion. Sodium alginate and calcium ions form a network structure in an aqueous solution; then the temperature of the system is raised to increase the exposure degree of the lipophilic groups in the sodium alginate molecules, and cinnamaldehyde is added and dispersed into the network structure formed by sodium alginate and calcium ions; finally, the temperature is lowered under high-speed stirring to embed cinnamaldehyde into the sodium alginate and calcium ion system, forming a stable microcapsule emulsion system. The emulsion realizes the slow release of cinnamaldehyde, improves the antibacterial cycle of cinnamaldehyde, and the method used is simple, environmentally friendly and low-cost. The denser hydrogel structure in the emulsion can improve the oil repellency of the paper after coating the emulsion, and expands the application of the paper in the preservation of high-oil-content foods. The food packaging material or preservative prepared from the emulsion can increase the preservation period of fruits, vegetables and meat products.

Description

Technical Field

[0001] The present invention belongs to the fields of food and chemical engineering, and particularly relates to the preparation and application of a microcapsule emulsion. Background Art

[0002] Food safety directly affects people's physical health and has always been a widely concerned issue. The antibacterial agent cinnamaldehyde used in the present invention exists in large amounts in plants such as cinnamon. Cinnamon has a long history of application in improving the flavor of food in cooking, which ensures the safety and acceptability of cinnamaldehyde from the aspect of traditional diet. The safe and reasonable use of food additives is an effective way to improve food safety. Cinnamaldehyde is a food additive certified by the state and has good antibacterial and antioxidant properties. Using cinnamaldehyde as a food preservative can not only improve the taste quality of food but also extend the shelf life of food. However, relevant research shows that cinnamaldehyde has certain toxicity. Although the addition amount is limited, long-term consumption still poses a risk to human health. In addition, cinnamaldehyde is unstable under high temperature and light conditions and will degrade, thereby affecting the bactericidal and antioxidant effects. On the premise of not affecting the antibacterial and anti-corrosion properties of cinnamaldehyde, reducing its addition amount and improving its stability have become the research focus of the application of cinnamaldehyde in the fields of food antibacterial and antioxidant.

[0003] The commonly used method is to use molecular embedding technology to prepare a microcapsule shell to improve the stability of cinnamaldehyde. Under suitable conditions, cinnamaldehyde can be slowly released to achieve antibacterial and antioxidant effects. However, since cinnamaldehyde is a lipophilic compound, common shells such as cellulose are usually difficult to achieve encapsulation. Therefore, in order to ensure the stability of the microcapsule, those skilled in the art often choose to add surfactants. This operation prolongs the process route, increases the preparation cost of the product, and some components may also have an adverse impact on the food flavor. Sodium alginate is a natural polysaccharide with the stability, solubility, viscosity, and safety required for pharmaceutical excipients. It is commonly used in the production of suspensions, gels, and concentrated emulsions based on fats and oils and is an ideal material for preparing the microcapsule shell of cinnamaldehyde. However, the hydrocolloid formed by sodium alginate has a poor encapsulation effect on cinnamaldehyde, and the product has poor storage resistance, and surfactants often need to be added to improve the stability of the system. How to prepare sodium alginate into the shell of cinnamaldehyde microcapsules in the simplest way has become a problem worthy of research.

[0004] For the storage of fatty foods, the outer packaging is also required to have good oil repellency. The Kit value of the paper coated with sodium alginate itself in the grease resistance test (Tappi T559 cm-02) is about 9. After sodium alginate encapsulates cinnamaldehyde, due to the lipophilicity of cinnamaldehyde itself, the oil repellency of the coated paper will be further reduced. When using the microcapsules of sodium alginate-encapsulated cinnamaldehyde to prepare oil-proof fresh-keeping paper, on the one hand, it is necessary to solve the problem of the stability of the system after embedding, and on the other hand, it is necessary to improve the oil repellency of the paper coated with the coating. The present invention studies the stability of the microcapsules formed by sodium alginate encapsulating cinnamaldehyde and the application of the microcapsule emulsion of sodium alginate-encapsulated cinnamaldehyde in the preparation of oil-proof paper. A preparation process of cinnamaldehyde microcapsules with simple components, high stability, simplified process flow, and high oil repellency of the coated paper is developed. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention prepares a microcapsule emulsion system with oil repellency and antibacterial properties and applies it to the field of food preservation. Specifically, a network structure is formed by sodium alginate and calcium ions in an aqueous solution; then the temperature of the system is raised to increase the exposure degree of the lipophilic groups in the sodium alginate molecules, and cinnamaldehyde is added and dispersed into the network structure formed by sodium alginate and calcium ions; finally, the temperature is lowered under high-speed stirring to encapsulate cinnamaldehyde into the sodium alginate and calcium ion system to form a stable microcapsule emulsion system. On the one hand, sodium alginate and calcium ions can form a stable and dense network structure. On the other hand, when the initial concentration of the sodium alginate solution reaches 4.5 wt%, continuing to add a calcium ion solution (such as calcium chloride) still ensures that the system does not produce precipitation due to agglomeration, and cinnamaldehyde can uniformly penetrate into the network structure with sodium alginate as the main body to form a stable structure. In addition, after the emulsion is coated or sprayed on the surface of the substrate and dried, not only can food preservation be achieved through the slow release of cinnamaldehyde, but also the oil repellency of the surface can be improved by coating. The Kit value of the coated paper can reach 12.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a microcapsule emulsion, the emulsion comprising a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules include sodium alginate and calcium chloride; the core material of the microcapsules includes cinnamaldehyde; the solid content of the emulsion is 0.5-5 wt%; the particle size of the microcapsules is 0.1-1000 μm.

[0008] The microcapsules are mainly composed of sodium alginate and calcium chloride. By means of the complexation reaction between sodium alginate and calcium ions, the compactness of the sodium alginate network structure is adjusted by adding calcium ions to improve the oil repellency of the surface of the coated paper.

[0009] Preferably, polyethyleneimine is also included in the microcapsule system. Polyethyleneimine, as an auxiliary material for emulsion preparation, is only used in the paper coating process. Its main function is to improve the wet strength of the paper and the adhesion performance of the emulsion on the paper surface during the paper coating process. At the same time, since polyethyleneimine itself carries a positive charge, adding it can also increase the antibacterial property of the emulsion. For the oil repellency index of the emulsion, the Kit value can reach 12 after the emulsion is coated on the kraft paper surface tested by the Tappi T559 cm-02 method.

[0010] More preferably, the final mass fractions of the components in the microcapsule emulsion are respectively 0.01 - 2.5 wt% of sodium alginate, 0 - 2 wt% of polyethyleneimine, 0.001 - 0.2 wt% of calcium chloride, and 0.04 - 2 wt% of cinnamaldehyde.

[0011] The present invention also provides a preparation method of the above microcapsule emulsion, including the following steps:

[0012] (1) Prepare the sodium alginate hydrocolloid under the condition that the temperature is not lower than 20 °C;

[0013] (2) Add the calcium salt aqueous solution to the sodium alginate hydrocolloid, stir while adding, and mix evenly to obtain sol A;

[0014] (3) Heat sol A to 35 - 60 °C, add cinnamaldehyde under high-speed stirring, mix evenly, and cool to room temperature to obtain microcapsule emulsion B;

[0015] (4) Add the polyethyleneimine aqueous solution to emulsion B and mix evenly to obtain the microcapsule emulsion.

[0016] Preferably, the preparation method of the sodium alginate hydrocolloid in step (1): Dissolve sodium alginate in water at 20 - 50 °C to obtain a 0.1 - 5 wt% sodium alginate hydrocolloid.

[0017] Preferably, the solute of the calcium salt aqueous solution in step (2) is calcium chloride, and the initial concentration is 0.001 - 1.5 wt%.

[0018] More preferably, the volume of the calcium salt aqueous solution in step (2) accounts for 1 - 50% of the volume of the sodium alginate hydrocolloid.

[0019] In step (2), stir while adding to increase the shear force so that the sample does not agglomerate. The total addition time of the sample is controlled within 5 - 60 minutes, and the solution is evenly dispersed by stirring or homogenizer treatment. Lower the temperature to 15 - 30 °C, and drop the solution containing calcium ions into the sodium alginate hydrocolloid system, and make the sol form a uniform and stable system by increasing the stirring force or homogenization method.

[0020] Preferably, in step (3), cinnamaldehyde is added in the form of a mixed solution of cinnamaldehyde and water with a mass fraction of 0.5-20%, and the final concentration of cinnamaldehyde in the emulsion B system is 0.04-2 wt%. The addition process needs to be carried out under the conditions of homogenization or other high shear forces; the stirring time during mixing is not less than 0.5 h.

[0021] In the present invention, a homogenizer or high-speed stirring and dispersing method is used to make the liquid uniform.

[0022] The present invention also provides the application of the above microcapsule emulsion, which is used for food preservation, antibacterial coating, papermaking or coating.

[0023] The present invention also provides a preservative spraying agent for fruits, vegetables and meats, which is obtained by diluting the microcapsule emulsion 1-50 times. The content of polyethyleneimine in the microcapsule emulsion is 0. The spraying agent is edible.

[0024] The present invention also provides a coating composed of the above microcapsule emulsion. The content of polyethyleneimine in the coating is 0-2 wt%. The using method of the coating is spraying, coating or dipping. When coating, the coating amount on the substrate surface is 0.02 g / cm 2 .

[0025] Preferably, the substrate is paper. The paper is selected from any one of printing paper, packaging paper, etc.

[0026] More preferably, the paper is kraft paper.

[0027] The present invention has the following advantages compared with the prior art:

[0028] (1) Through a series of physical treatment methods, the present invention realizes the slow release of cinnamaldehyde by encapsulating cinnamaldehyde into sodium alginate hydrogel in an aqueous phase system, improves the antibacterial cycle of cinnamaldehyde, and the used method is simple, environmentally friendly and low-cost.

[0029] (2) By establishing a reasonable method for mixing calcium ions and sodium alginate solution, the present invention prepares a hydrogel structure with a denser network structure by using the complexation reaction of calcium ions and sodium alginate, thereby improving the oil repellency of the paper after coating the emulsion, and expanding the application of the paper in the preservation of high-oil-content foods.

[0030] (3) The present invention transfers the microcapsule emulsion encapsulating cinnamaldehyde to a suitable carrier, uses the microcapsules as food packaging materials, can also reduce the addition amount of food preservatives while ensuring the food shelf life, and improves the safety of food.

[0031] (4) After diluting the microcapsule emulsion encapsulating cinnamaldehyde and spraying it on the surfaces of fruits, vegetables and meat products, the present invention can also improve the preservation period of fruits, vegetables and meat products. Description of the Drawings

[0032] Figure 1 It is a comparison diagram of Sample 1 in Embodiment 1 of the present invention and water;

[0033] Figure 2 It is a comparison diagram of Sample 2 in Embodiment 2 of the present invention and water;

[0034] Figure 3 It is a comparison diagram of Sample 3 in Embodiment 3 of the present invention and water;

[0035] Figure 4 It is a comparison diagram of Sample 4 in Embodiment 4 of the present invention and water;

[0036] Figure 5 It is a diagram of the surface topography of the paper before and after coating with the emulsion described in Embodiment 6 of the present invention;

[0037] Figure 6 It is an effect diagram of inhibiting Escherichia coli on the paper before and after coating with the emulsion described in Embodiment 6 of the present invention;

[0038] Figure 7 It is an effect diagram of inhibiting Staphylococcus aureus on the paper before and after coating with the emulsion described in Embodiment 6 of the present invention;

[0039] Figure 8 It is a hydrophobic property diagram of the paper after coating with the emulsion described in Embodiment 6 of the present invention;

[0040] Figure 9 It is an effect diagram of the paper before coating with the emulsion described in Embodiment 6 of the present invention for preserving cakes;

[0041] Figure 10 It is an effect diagram of the paper after coating with the emulsion described in Embodiment 6 of the present invention for preserving cakes;

[0042] Figure 11 It is an effect diagram of preserving small tomatoes without spraying the emulsion in Embodiment 5 of the present invention;

[0043] Figure 12 It is an effect diagram of preserving small tomatoes sprayed with the emulsion in Embodiment 5 of the present invention. Detailed Embodiments

[0044] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that without departing from the spirit and scope of the present invention, the details and forms of the technical solutions of the present invention can be modified or replaced, but these modifications and replacements all fall within the protection scope of the present invention.

[0045] Embodiment 1

[0046] A microcapsule emulsion, the emulsion comprising a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules are sodium alginate and calcium chloride, the core material raw material of the microcapsules is cinnamaldehyde, and the oleophobic index of the emulsion is measured by the following method: Drop 25 μL of the emulsion onto the surface of a glass slide, and after drying, drop 4 μL of an oil droplet onto the same position on the surface of the glass slide, and measure the contact angle. The contact angle of linseed oil on the surface of the glass slide after emulsion coating is about 100°. The food preservation microcapsule emulsion is edible.

[0047] The particle size of the microcapsules depends on the concentration of the calcium ion solution and the titration rate conditions, and is between 0.1 and 10 μm;

[0048] The preparation method of the above microcapsule emulsion includes the following steps:

[0049] (1) At 38 °C, add sodium alginate to water, and after fully dissolving, prepare a hydrocolloid with a solid content of 0.2 wt%, and use a homogenizer to process it evenly and then set aside;

[0050] Wait for the temperature of the sodium alginate hydrocolloid to cool to 30 °C, add the calcium chloride solution (0.5 wt%) to the sodium alginate hydrocolloid within 10 min, stir while adding, fully stir or use a homogenizer to process to make the system evenly dispersed, and obtain sol A;

[0051] (2) Heat the temperature of sol A to 40 °C, add a mixture of 8 wt% cinnamaldehyde and water to the system, stir fully for not less than 0.5 h, and disperse the cinnamaldehyde into the dense network structure microcapsule system formed by sodium alginate and calcium ions to obtain sample 1, as Figure 1 shown in.

[0052] The contents of each component in the final microcapsule emulsion system are: sodium alginate 0.18 wt%, calcium chloride 0.05 wt%, and cinnamaldehyde 0.8 wt%.

[0053] Example 2

[0054] A microcapsule emulsion, the emulsion comprising a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules are sodium alginate and calcium chloride, the core material raw material of the microcapsules is cinnamaldehyde, and the oleophobic index of the emulsion is measured by the following method: Drop 25 μL of the emulsion onto the surface of a glass slide, and after drying, drop 4 μL of an oil droplet onto the same position on the surface of the glass slide, and measure the contact angle. The contact angle of linseed oil on the surface of the glass slide after emulsion coating is about 130°. The microcapsule emulsion is edible.

[0055] The particle size of the microcapsules is between 1 and 100 μm;

[0056] The preparation method of the above microcapsule emulsion includes the following steps:

[0057] (1) At 35°C, sodium alginate was added to water. After being fully dissolved, a hydrocolloid with a solids content of 2 wt% was prepared. After being homogenized evenly, it was reserved for use;

[0058] (2) The temperature of the sodium alginate hydrocolloid was lowered to 25°C. A calcium chloride solution (0.2 wt%) was added to the sodium alginate hydrocolloid while stirring. The addition time was controlled within 30 min. After sufficient stirring or homogenization treatment, the system was evenly dispersed to obtain Sol A;

[0059] (3) The temperature of Sol A was raised to 45°C. A mixed solution of cinnamaldehyde with a mass fraction of 10 wt% and water was added to the system. After sufficient stirring or homogenization treatment, cinnamaldehyde was dispersed into the microcapsule system with a dense network structure formed by sodium alginate and calcium ions to obtain Sample 2, as Figure 2 shown.

[0060] The contents of each component in the final microcapsule emulsion system were as follows: sodium alginate 1.6 wt%, calcium chloride 0.02 wt%, cinnamaldehyde 1 wt%.

[0061] Example 3

[0062] A microcapsule emulsion, the emulsion comprising a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules are sodium alginate and calcium chloride, the core material raw material of the microcapsules is cinnamaldehyde, and the microcapsule system further includes polyethyleneimine. The function of the polyethyleneimine is to increase the coating performance of negatively charged surface coatings such as paper. The oil repellency index of the emulsion was measured by the following method: Castor oil was dropped onto the surface of kraft paper coated with the emulsion, and the grease resistance test (Tappi T559 cm - 02) Kit value of the paper was detected. The Kit value of the paper was 11 or 12.

[0063] The particle size of the microcapsules is about 0.1 - 20 μm;

[0064] The preparation method of the above microcapsule emulsion includes the following steps:

[0065] (1) At 45°C, sodium alginate was added to water. After being fully dissolved, a hydrocolloid with a solids content of 0.5 wt% was prepared. After sufficient stirring and dispersion to be uniform, it was reserved for use;

[0066] (2) The temperature of the sodium alginate hydrocolloid was lowered to 15°C. A calcium chloride solution (1.5%) was added to the sodium alginate hydrocolloid while stirring. The addition time was controlled within 7 min. After sufficient stirring or homogenization treatment, the system was evenly dispersed to obtain Sol A;

[0067] (3) Heat sol A to 55 °C, add the mixed solution of cinnamaldehyde and water (mass fraction 1 wt%) to the system, stir well for no less than 0.5 h, and disperse cinnamaldehyde into the microcapsule system with a dense network structure formed by sodium alginate and calcium ions;

[0068] (4) Add the aqueous solution of polyethyleneimine (1 wt%) to the above-mentioned microcapsule system with a network structure, stir well, and treat it with a homogenizer to obtain Sample 3, as Figure 3 shown.

[0069] The contents of each component in the final microcapsule emulsion system are as follows: sodium alginate 0.35 wt%, calcium chloride 0.15 wt%, cinnamaldehyde 0.1 wt%, and polyethyleneimine 0.1 wt%.

[0070] Example 4

[0071] A microcapsule emulsion, the emulsion comprising a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules are sodium alginate and calcium chloride, the core material raw material of the microcapsules is cinnamaldehyde, and the microcapsule system further includes polyethyleneimine. The role of polyethyleneimine as an additive to increase the coating performance of the paper surface coating is polyethyleneimine. The oil repellency index of the emulsion is measured by the following method: Drop castor oil onto the surface of kraft paper coated with the emulsion, and detect the Kit value of the grease resistance test (Tappi T559 cm-02) of the paper. The Kit value of the paper is 12.

[0072] The particle size of the microcapsules is 20 - 1000 μm;

[0073] The preparation method of the above microcapsule emulsion includes the following steps:

[0074] (1) At 45 °C, add sodium alginate to water, fully dissolve it to prepare a hydrocolloid with a solid content of 3 wt%, and use a homogenizer to make it uniform and then set aside;

[0075] (2) Lower the temperature of the sodium alginate aqueous solution to 20 °C, add the calcium chloride solution (0.05 wt%) to the sodium alginate aqueous solution, stir while adding, and control the addition time within 50 min. Stir well or use a homogenizer to make the system uniformly dispersed to obtain sol A;

[0076] (3) Heat the solution A to 45 °C, add the mixed solution of cinnamaldehyde and water (2 wt%) to the system, stir well or use a homogenizer to treat for no less than 0.5 h, and disperse cinnamaldehyde into the microcapsule system with a dense network structure formed by sodium alginate and calcium ions;

[0077] (4) Add the polyethyleneimine aqueous solution (2 wt%) to the above-mentioned reticulated hydrogel system, stir well, and treat with a homogenizer to obtain Sample 4, as Figure 4 shown in

[0078] The contents of each component in the final microcapsule emulsion system are as follows: sodium alginate 2.1 wt%, calcium chloride 0.005 wt%, cinnamaldehyde 0.2 wt%, and polyethyleneimine 0.2 wt%.

[0079] Example 5

[0080] A fresh-keeping spraying agent for fruits, vegetables, and meats is obtained by diluting the microcapsule emulsion of Example 2 by 10 times with water. Fill the spraying agent into a spray vial and spray it three times on each of the four sides of the cherry tomatoes (about 0.5 mL each time), ensuring that the surface of the cherry tomatoes is completely wet each time. Wait for the water droplets to dry naturally before the next spraying. After spraying, let the water droplets on the surface of the cherry tomatoes dry naturally and then put them into a sealed bag and store them at room temperature.

[0081] Under visual conditions, there is no difference in the surface of the cherry tomatoes sprayed with the microcapsule emulsion and the control group of cherry tomatoes. After storing for a period of time, water loss and small mildew spots appear on the surface of the cherry tomatoes without the microcapsule emulsion spraying, and they increase rapidly with the extension of the storage time. The cherry tomatoes in the group sprayed with the microcapsule emulsion do not show water loss and small mildew spot phenomena during storage.

[0082] The state changes of the cherry tomatoes without the microcapsule emulsion spraying are as Figure 11 shown in Figure 12 shown in

[0083] Example 6

[0084] A paper with oleophobic, antibacterial, and food fresh-keeping properties is obtained by coating the microcapsule emulsion of Example 4 on the surface of kraft paper and drying it naturally. The coating thickness of the emulsion is 1 mm.

[0085] The surface morphologies of the paper with oleophobic, antibacterial, and food fresh-keeping properties and kraft paper in this example are as Figure 5 shown in, where (A) is the surface of kraft paper and (B) is the surface morphology of the paper with oleophobic, antibacterial, and food fresh-keeping properties in this example.

[0086] Perform an antibacterial experiment on the paper with oleophobic, antibacterial, and food fresh-keeping properties and kraft paper in this example. The specific operation steps are as follows:

[0087] (1) Coat the coating on the surface of kraft paper at a dosage of 0.02 g / cm 2 and dry it naturally. Cut it into circular pieces with a diameter of 1 cm using a tablet press for standby;

[0088] (2) The cultured Escherichia coli and Staphylococcus aureus were added at 10 7 The density of each piece / plate was evenly spread on the surface of the solidified peptone medium in the culture dish, and then the cut paper was pasted to a certain position of the solid medium. It was cultured in a 37℃ incubator overnight, taken out and photographed. The experimental results are as follows Figure 6 (E. coli antibacterial test) and Figure 7 As shown in (Staphylococcus aureus antibacterial experiment), (A) is kraft paper, and (B) is the paper of this embodiment with oleophobic, antibacterial and food preservation properties.

[0089] Depend on Figure 6 , Figure 7 It can be seen that the obtained paper has a good inhibitory effect on both Escherichia coli and Staphylococcus aureus.

[0090] The oleophobic performance of the paper and kraft paper with oleophobic, antibacterial and food preservation properties of this embodiment was tested, and the results are as follows: Figure 8 As shown in the figure, (A) is the surface of kraft paper, and (B) is the surface morphology of the paper with oleophobic, antibacterial and food preservation properties of this embodiment. Castor oil did not penetrate the surface of the paper coated with microcapsule emulsion, while castor oil immediately penetrated the paper without microcapsule emulsion after adding castor oil, which shows that the coating of microcapsule emulsion on the surface of paper can effectively improve the oleophobicity of paper.

[0091] The handmade cakes without any fresh-keeping and preservatives were packaged with kraft paper and the paper with oleophobic, antibacterial and food preservation properties of the present embodiment, and stored at room temperature. The results were as follows: Figure 9 and 10 As shown in the figure, for the wrapping paper not coated with microcapsule emulsion, mold spots began to appear on the cake on the first day after storage, and the mold spots increased rapidly over time. For the wrapping paper coated with microcapsule emulsion, mold spots began to appear on the cake on the third day after storage, indicating that the coating of microcapsule emulsion can effectively extend the shelf life of the cake by two days.

[0092] Comparative Example 1

[0093] At 15°C, sodium alginate was added to water and fully dissolved to prepare a 2wt% hydrosol, and then 0.2wt% calcium chloride and 10wt% cinnamaldehyde and water were added respectively; the final concentrations of each component were 0.16wt% sodium alginate, 0.02wt% calcium chloride, and 1wt% cinnamaldehyde. The final prepared sample was agglomerated, and the preservation effect was poor due to insufficient wrapping of cinnamaldehyde droplets.

[0094] Comparative Example 2

[0095] At 40 °C, a mixture of 2 wt% sodium alginate hydrogel, 10 wt% cinnamaldehyde and water was mixed with 0.2 wt% calcium chloride solution, and then homogenized or stirred at high speed. The concentrations of the components in the obtained sample were the same as those in Example 2, but the uniformity was poor. Cinnamaldehyde floated on the surface of the aqueous phase system in an oily state, and granular agglomerates would block the channels, so spraying preservation could not be achieved.

[0096] Comparative Example 3

[0097] At 30 °C, a mixture of 3 wt% sodium alginate hydrogel, 2 wt% cinnamaldehyde and water was further mixed, and then a mixed liquid of 0.05 wt% calcium ions and 2 wt% polyethyleneimine was added, and then homogenized or stirred at high speed. The concentrations of the components in the obtained sample were the same as those in Example 4, but the stability of the obtained sample was poor. Cinnamaldehyde floated on the surface of the aqueous phase system in an oily state and could not be encapsulated.

Claims

1. A method for preparing a microcapsule emulsion, characterized in that, It includes the following steps: (1) Prepare sodium alginate hydrocolloid under the condition that the temperature is not lower than 20 °C; (2) Add calcium salt aqueous solution to the sodium alginate hydrocolloid, stir while adding, and mix evenly to obtain sol A; (3) Heat sol A to 35 - 60 °C, add cinnamaldehyde under high-speed stirring, mix evenly, and obtain edible microcapsule emulsion B after cooling to room temperature; (4) Add polyethyleneimine aqueous solution to emulsion B and mix evenly to obtain microcapsule emulsion; The emulsion includes a continuous aqueous phase and a microcapsule dispersed phase; the wall material raw materials of the microcapsules include sodium alginate and calcium chloride; the core material of the microcapsules includes cinnamaldehyde; the solid content of the emulsion is 0.5 - 5 wt%; the particle size of the microcapsules is 0.1 - 1000 µm; polyethyleneimine is also included in the microcapsule system; The final mass fractions of each component in the microcapsule emulsion are as follows: sodium alginate 0.01 - 2.5 wt%; polyethyleneimine 0 - 2 wt%; calcium chloride 0.001 - 0.2 wt%; cinnamaldehyde 0.04 - 2 wt%.

2. The preparation method of the microcapsule emulsion according to claim 1, characterized in that, The preparation method of the sodium alginate hydrocolloid in step (1): Dissolve sodium alginate in water at 20 - 50 °C to obtain a 0.1 - 5 wt% sodium alginate hydrocolloid.

3. The preparation method of the microcapsule emulsion according to claim 1, characterized in that, The solute of the calcium salt aqueous solution in step (2) is calcium chloride, and the initial concentration is 0.001 - 1.5 wt%.

4. The preparation method of the microcapsule emulsion according to claim 1, characterized in that, The volume of the calcium salt aqueous solution in step (2) accounts for 1 - 50% of the volume of the sodium alginate hydrocolloid.

5. The preparation method of the microcapsule emulsion according to claim 1, characterized in that, The addition method of cinnamaldehyde in step (3) is to add it in the form of a mixed solution of cinnamaldehyde and water with a mass fraction of 0.5 - 20%, and the final concentration of cinnamaldehyde in the emulsion B system is 0.04 - 2 wt%; the stirring time during mixing is not less than 0.5 h.

Images