A compound cinnamon essential oil microcapsule, its preparation method and application

Abstract

This invention proposes a novel process for preparing cinnamon oil-loaded microcapsules using a Pickering emulsion stabilized by sugarcane bagasse nanofibers as a template via spray drying. Nanocellulose is prepared using a green, low-cost solvent. Maltodextrin and sugarcane bagasse nanocellulose are used as wall materials, and cinnamon oil is used as the core material, resulting in microcapsules with good stability and strong antibacterial properties. In this invention, sugarcane bagasse and acidified ethanol are mixed at a mass ratio of 1:(8-12) to prepare nanocellulose. The sugarcane bagasse nanocellulose is then mixed with cinnamon oil and maltodextrin at a mass ratio of (8-40):(40-72):20. After ultrasonic emulsification to obtain a Pickering emulsion, the emulsion is spray-dried to obtain composite cinnamon oil microcapsules. The cinnamon oil microcapsules prepared by this method exhibit improved antibacterial properties and retain good antibacterial activity even after 180 days of storage, making them suitable for the food and cosmetic industries.

Description

Technical Field

[0001] This invention belongs to the field of microcapsule production technology, and mainly relates to a compound cinnamon essential oil microcapsule, its preparation method and application. Background Technology

[0002] Cinnamon essential oil is a natural essential oil extracted from the bark of the cinnamon tree. It has a unique aroma and a variety of potential health benefits, including antibacterial, antioxidant, anti-inflammatory, and medicinal value. The main components of cinnamon essential oil include cinnamaldehyde, cinnamic acid, and other esters. However, its practical applications are limited due to its volatility and instability.

[0003] Sugarcane is an important sugar crop in my country, accounting for over 90% of the country's total sugar production. Guangxi province alone produces nearly 7 million tons of bagasse annually. However, most of this bagasse is used only for papermaking, with the remainder burned or discarded, resulting in resource waste.

[0004] Microcapsules are prepared using methods such as complex coagulation, spray drying, and freeze drying, and are typically spherical. Microencapsulation can improve the stability of unstable bioactive substances such as essential oils and curcumin, expanding their application scenarios. Currently, research using bagasse as a wall material to encapsulate essential oils usually requires acid, alkali, or carbonization treatment of the bagasse, followed by physical processing to prepare bagasse fiber. These methods use environmentally unfriendly reagents, involve complex steps, are costly, and yield low encapsulation rates for the essential oil capsules. For example, CN 109864983 B discloses a slow-release antibacterial capsule for essential oils using bagasse as a wall material, which requires high-temperature carbonization of the bagasse, resulting in high processing costs and low microcapsule encapsulation rates. CN114869805 A discloses a cinnamon essential oil microcapsule, its preparation method, and its application, using chitosan quaternary ammonium salt, gum arabic, and acetic acid as a composite wall material to prepare cinnamon essential oil microcapsules via complex coagulation, but the resulting microcapsule encapsulation rate is low, and the essential oil retention rate is low after long-term storage.

[0005] Therefore, there is an urgent need to provide a mild and efficient method for preparing cinnamon essential oil microcapsules in order to improve their encapsulation rate and essential oil retention rate. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a novel process for preparing cinnamon oil-loaded microcapsules using a Pickering emulsion stabilized by bagasse nanofibers as a template via spray drying. Nanocellulose is prepared using a green, low-cost solvent, with maltodextrin and bagasse nanocellulose as wall materials and cinnamon oil as the core material, resulting in microcapsules with excellent stability and strong antibacterial properties.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing compound cinnamon essential oil microcapsules, characterized by comprising the following steps:

[0009] S1. Sugarcane bagasse and acidified ethanol are mixed at a mass ratio of 1:(8-12) and heated to react. After the reaction is completed, sodium hydroxide solution is added, the solid is filtered and freeze-dried, then reconstituted with water, dispersed and homogenized to obtain nanocellulose. The mass ratio of ethanol, acid and water in the acidified ethanol is 160:(0.5-5):39.

[0010] S2. The nanocellulose obtained in S1 is mixed with maltodextrin and cinnamon essential oil in a mass ratio of (8-40):(40-72):20. After ultrasonic emulsification to obtain Pickering emulsion, the emulsion is spray-dried to obtain composite cinnamon essential oil microcapsules.

[0011] Preferably, the mass ratio of sugarcane bagasse to acidified ethanol in S1 is 1:10.

[0012] Preferably, the mass ratio of nanocellulose to maltodextrin and cinnamon oil in S2 is (30-40):(40-50):20.

[0013] Preferably, the acid in the acidified ethanol in S1 is sulfuric acid, and the mass ratio of ethanol, sulfuric acid and water is 160:1:39.

[0014] Preferably, the heating reaction conditions in S1 are 170±20℃, 300±50rpm, and 0.5±1h; the water addition for redissolution is carried out at a solid-liquid mass ratio of 1:100.

[0015] Preferably, the bagasse mentioned in S1 is pretreated, which means drying at 80-120°C for 5-8 hours.

[0016] Preferably, in S1, the dispersion refers to processing at a rotation speed of 12000±200 rpm for 10±5 min; the homogenization refers to homogenization cycles of 5±1 times at a pressure of 1500±100 bar; and in S2, the ultrasonic emulsification conditions are 180±50 W for 3±1 min.

[0017] Preferably, the spray drying in S2 uses a 0.5 mm atomizing nozzle, with inlet and outlet air temperatures of 150±5℃ and 60±5℃, respectively, and the emulsion feed rate is 2 mL / min.

[0018] The compound cinnamon essential oil microcapsules prepared by the above method.

[0019] The above-mentioned compound cinnamon essential oil microcapsules are used in antibacterial applications in food and cosmetics.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] (1) Green and environmentally friendly with low cost: This invention uses sugarcane bagasse as raw material and acidified ethanol to prepare nanocellulose. Compared with traditional acid or alkali methods and carbonization, the acidified ethanol used in this invention has an extremely low acid content (less than 3%), the reagents are cheaper, and the preparation method is simpler and milder. This feature makes this invention green, environmentally friendly, and low-cost, suitable for large-scale production.

[0022] (2) High encapsulation rate and long-term stability: This invention utilizes bagasse nanofibers and maltodextrin as wall materials to successfully prepare a novel microcapsule loaded with cinnamon essential oil through spray drying technology. The encapsulation rate of this microcapsule can reach 97%, and it has long-term stability, effectively improving the antibacterial properties of cinnamon essential oil.

[0023] (3) Significant antibacterial effect: The cinnamon oil microcapsules of the present invention exhibit good antibacterial effects against Escherichia coli, Vibrio parahaemolyticus, Salmonella, and Staphylococcus aureus. Even after 180 days of storage, their antibacterial performance remains at a good level. Attached Figure Description

[0024] Figure 1 The image shows a TEM image of the prepared bagasse nanocellulose.

[0025] Figure 2 The images show the appearance of the microcapsules in Examples 1-4.

[0026] Figure 3 The images are SEM images of the microcapsules from Examples 1-4.

[0027] Figure 4 The results are the thermogravimetric analysis results of the microcapsules in Examples 1-4.

[0028] Figure 5 The diagram shows a comparison of the antibacterial properties of the microcapsules prepared in Examples 1-7 and cinnamon essential oil.

[0029] Figure 6 This is a comparison chart of the antibacterial ability of the microcapsules prepared in Example 3 after 7 days and 180 days.

[0030] Figure 7 From left to right, these are images of the appearance of the nanocellulose prepared in Examples 5-7.

[0031] Figure 8 The images show TEM images and diameter distribution diagrams of the nanocellulose prepared in Examples 5-7; where A, B, and C correspond to the TEM images of the nanocellulose in Examples 5-7, and D, E, and F correspond to the diameter distribution diagrams of the nanocellulose in Examples 5-7.

[0032] Figure 9 XRD images and crystallinity of the nanocellulose prepared in Examples 5-7.

[0033] Figure 10 The contact angles of the nanocellulose prepared in Examples 5-7 are shown; where A corresponds to Example 5, B corresponds to Example 6, and C corresponds to Example 7. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments, but the embodiments are not intended to limit the present invention.

[0035] Example 1

[0036] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethanol, which contained 160g of anhydrous ethanol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0037] Weigh 200g of ultrapure water and add 2g of lyophilized pretreatment reactant. Shear at 12000rpm for 10 minutes to obtain a pre-dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose.

[0038] 1.6g of nanocellulose (1% wt), 14.4g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0039] Example 2

[0040] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethanol, which contained 160g of anhydrous ethanol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0041] Weigh 200g of ultrapure water and add 2g of lyophilized pretreatment reactant. Shear at 12000rpm for 10 minutes to obtain a pre-dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose.

[0042] 3.2g of nanocellulose (1% wt), 12.8g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0043] Example 3

[0044] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethanol, which contained 160g of anhydrous ethanol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0045] Weigh 200g of ultrapure water and add 2g of lyophilized pretreatment reactant. Shear at 12000rpm for 10 minutes to obtain a pre-dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose.

[0046] 4.8g of nanocellulose (1% wt), 11.2g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0047] Example 4

[0048] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethanol, which contained 160g of anhydrous ethanol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0049] Weigh 200g of ultrapure water and add 2g of lyophilized pretreatment reactant. Shear at 12000rpm for 10 minutes to obtain a pre-dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose.

[0050] 6.4g of nanocellulose (1% wt), 9.6g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0051] Example 5

[0052] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethanol, which contained 160g of anhydrous ethanol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0053] Weigh 200g of ultrapure water and add 2g of lyophilized pretreated reactant. Shear at 12000rpm for 10 minutes to obtain a preliminarily dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose, named AE-LCNF.

[0054] Weigh out 1.0g of nanocellulose (1% wt), 9.0g of maltodextrin (15% wt) and 10g of cinnamon essential oil and mix them. Use an ultrasonic homogenizer to sonicate at 180W power for 3 minutes to obtain a homogeneous emulsion. Finally, spray dry the emulsion using a 0.5mm atomizing nozzle. Maintain the inlet and outlet air temperatures at 150±5℃ and 60±5℃, respectively, and maintain the emulsion feed rate at 2mL / min to obtain stable microcapsule powder.

[0055] Example 6

[0056] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified ethylene glycol. The 200g of acidified ethylene glycol contained 160g of anhydrous ethylene glycol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially. The mixture was then vacuum filtered, the solid was collected, and finally lyophilized to obtain the pretreated reactant.

[0057] Weigh 200g of ultrapure water and add 2g of lyophilized pretreated reactant. Shear at 12000rpm for 10 minutes to obtain a preliminarily dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose, named AEG-LCNF.

[0058] 1.6g of nanocellulose (1% wt), 14.4g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0059] Example 7

[0060] 20g of dried sugarcane bagasse was weighed and mixed with 200g of acidified glycerol, which contained 160g of glycerol, 1g of sulfuric acid, and 39g of ultrapure water. The mixture was placed in a reaction vessel and reacted at 170℃ and 300rpm for half an hour. After the reaction was complete, 600ml of deionized water and 600ml of 3% sodium hydroxide solution were added sequentially, followed by vacuum filtration. The solid was collected and finally lyophilized to obtain the pretreated reactant.

[0061] Weigh 200g of ultrapure water and add 2g of lyophilized pretreated reactant. Shear at 12000rpm for 10 minutes to obtain a preliminarily dispersed fiber suspension. Homogenize the fiber suspension 5 times under a pressure of 1500bar to obtain nanocellulose, named AG-LCNF.

[0062] 1.6g of nanocellulose (1% wt), 14.4g of maltodextrin (15% wt) and 4g of cinnamon essential oil were weighed and mixed. The mixture was ultrasonically broken down at 180W for 3 minutes to obtain a homogeneous emulsion. Finally, the emulsion was spray-dried using a 0.5mm atomizing nozzle. The inlet and outlet air temperatures were maintained at 150±5℃ and 60±5℃, respectively, and the emulsion feed rate was maintained at 2mL / min to obtain stable microcapsule powder.

[0063] Figure 5 The comparison shows the antibacterial properties of the microcapsules prepared in Examples 1-7 and cinnamon essential oil. It can be seen that the microcapsules in Examples 1-4 have good antibacterial effects against Escherichia coli (E. coli), Vibrio parahaemolyticus (Vp), Salmonella (Sal), and Staphylococcus aureus (Sa). Among them, the antibacterial radius of cinnamon essential oil in Examples 3-4 is significantly larger than that of cinnamon essential oil alone, proving that the cinnamon essential oil microcapsules in Examples 3-4 have a stronger antibacterial effect than cinnamon essential oil alone.

[0064] Figure 6 The diameters of the inhibition zones of the microcapsules prepared in Example 3 against Enterobacter (E. coli), Vibrio parahaemolyticus (Vp), Salmonella (Sal), and Staphylococcus aureus (Sa) after 7 days and 180 days of storage are shown. It can be seen that the cinnamon essential oil microcapsules of Example 3 still have good antibacterial properties after 180 days of storage.

[0065] Table 1. Yield, encapsulation rate, and essential oil retention rate of the microcapsules prepared in Examples 1-7 after 180 days.

[0066]

[0067]

[0068] Nanocellulose composition analysis

[0069] The solids yield, chemical composition, and recovery rate of bagasse before and after pretreatment are listed in Table 2, referring to the National Renewable Energy Laboratory (NREL) method for detecting cellulose, hemicellulose, and lignin in Examples 5, 6, and 7. As shown in Table 2, the main components of the raw bagasse were 39% cellulose, 25% hemicellulose, and 25% lignin. After acid-catalyzed pretreatment with the three alcohols, the cellulose content increased significantly (from 39% to 85%), due to the removal of lignin and hemicellulose during the pretreatment reaction. The highest solids yield was obtained after glycerol pretreatment, because it contained the highest levels of xylan and lignin.

[0070] A comparison of the pretreatment results of different alcohols catalyzed by acid showed that ethanol and ethylene glycol were significantly better than glycerol pretreatment in removing lignin, which is consistent with previous research results. In this study, the product obtained by acid-catalyzed ethanol pretreatment had the highest dextran content (85.3%), while the xylan and lignin contents were the lowest, at 2.8% and 7.5%, respectively. Therefore, ethanol has the strongest ability to remove lignin and hemicellulose.

[0071] Table 2. Component analysis results of LCNF prepared in Examples 5-7

[0072]

[0073] The type and abundance of hydroxyl groups are important characteristics of lignin, affecting its solubility and hydrophilicity / hydrophobicity. 31P NMR was used to analyze the hydroxyl content of lignin. As shown in Table 3, the hydroxyl content of lignin pretreated with AE, AEG, and AG increased sequentially. The difference in hydroxyl content indicates that ethanol, ethylene glycol, and glycerol successfully entered the lignin structure and contributed to the differences in hydrophilicity / hydrophobicity.

[0074] Table 3. Hydroxyl content of lignin in nanocellulose prepared in Examples 5-7

[0075]

[0076] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing compound cinnamon essential oil microcapsules, characterized in that, Includes the following steps: S1. Sugarcane bagasse and acidified ethanol are mixed at a mass ratio of 1:(8-12) and heated to react. After the reaction is completed, sodium hydroxide solution is added, the solid is filtered and freeze-dried, then reconstituted with water, dispersed and homogenized to obtain a nanocellulose suspension. The mass ratio of ethanol, acid and water in the acidified ethanol is 160:(0.5-5):

39. S2. The nanocellulose suspension obtained in S1 is mixed with maltodextrin and cinnamon essential oil in a mass ratio of (8-40):(40-72):

20. After ultrasonic emulsification to obtain Pickering emulsion, the emulsion is spray-dried to obtain composite cinnamon essential oil microcapsules.

2. The preparation method according to claim 1, characterized in that, The mass ratio of sugarcane bagasse to acidified ethanol in S1 is 1:

10.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the nanocellulose suspension to maltodextrin and cinnamon oil in S2 is (30-40):(40-50):

20.

4. The preparation method according to any one of claims 1-3, characterized in that, The acid in the acidified ethanol described in S1 is sulfuric acid, and the mass ratio of ethanol, sulfuric acid and water is 160:1:

39.

5. The preparation method according to claim 4, characterized in that, The heating reaction conditions described in S1 are 170±20℃, 300±50rpm, and 0.5±1h; the water addition for redissolution is carried out at a solid-liquid mass ratio of 1:

100.

6. The preparation method according to claim 5, characterized in that, The bagasse mentioned in S1 has undergone pretreatment, which refers to drying at 80-120℃ for 5-8 hours.

7. The preparation method according to claim 6, characterized in that, The dispersion in S1 refers to processing at a speed of 12000±200 rpm for 10±5 min; the homogenization refers to homogenization cycles of 5±1 times at a pressure of 1500±100 bar; the ultrasonic emulsification conditions in S2 are 180±50 W for 3±1 min.

8. The preparation method according to claim 7, characterized in that, The spray drying described in S2 uses a 0.5mm atomizing nozzle, with inlet and outlet air temperatures of 150±5℃ and 60±5℃, respectively, and an emulsion feed rate of 2mL / min.

9. The composite cinnamon oil microcapsules prepared by the method according to any one of claims 1-8.

10. The application of the compound cinnamon essential oil microcapsules according to claim 9 in antibacterial applications in food and cosmetics.

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