Cinnamon essential oil-bagasse cellulose microspheres with sustained-release antibacterial effect, preparation method and application thereof

Abstract

The present invention discloses a kind of cinnamon essential oil-bagasse cellulose microsphere with slow-release antibacterial effect and its preparation method and application. The method comprises the following steps: (1) crushing and sieving bagasse and adding it to a sodium carbonate solution for soaking, then washing and drying, and then adding it to a DES solvent consisting of choline chloride and urea for heating and extraction to obtain bagasse cellulose; (2) adding bagasse cellulose and maltodextrin to a urea alkaline solution, and then adding cinnamon essential oil and acrylic resin NE30D, homogenizing after mixing, spray drying, and obtaining cinnamon essential oil-bagasse cellulose microsphere. Bagasse cellulose in the present invention has a high porosity structure, can accommodate a larger amount of essential oil, and acrylic resin NE30D forms a membrane material as a wall material, can better encapsulate the essential oil, and the obtained microspheres have good microscopic morphology, high embedding rate, long sustained-release time, and good antibacterial effect.

Description

Technical Field

[0001] The present invention relates to the technical field of sustained-release antibacterial technology, and in particular to cinnamon essential oil-bagasse cellulose microspheres with sustained-release antibacterial effect, and a preparation method and application thereof. Background Art

[0002] Cellulose is the most abundant renewable resource on Earth and the most widely distributed natural polymer material. It is non-toxic, biodegradable, and biocompatible. Bagasse, a waste product from sugarcane, is typically incinerated after sugar extraction, which not only increases environmental pollution but also wastes a significant amount of natural resources. Bagasse has an extremely high cellulose content and can be processed for high-value utilization. Cellulose spheres with diameters ranging from micrometers to millimeters have been developed for applications such as water treatment, drug loading and release, chromatography, and protein immobilization. However, research into its use as an encapsulation wall material for volatile essential oils in the food industry is limited.

[0003] Plant essential oils, as natural antioxidants and antimicrobial agents, are green, safe, and biodegradable, with no side effects. They are gradually replacing chemical preservatives and becoming the preferred choice for food preservation. Domestic and international studies have demonstrated that natural plant extracts have strong inhibitory effects against common food bacteria such as Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Clostridium botulinum. For example, cinnamon has been used in Traditional Chinese Medicine for over 2,000 years as an insect repellent, bactericidal, and disinfectant. Its active ingredient, cinnamaldehyde, possesses excellent antioxidant and antimicrobial properties. It can inhibit or kill microorganisms at room temperature without direct contact with food, making it a promising antimicrobial agent for food preservation.

[0004] However, plant essential oils are easily oxidized, volatile, and poorly soluble in water. In particular, their strong volatility results in a short-lasting antibacterial effect, which greatly limits their application in food antibacterial preservation. How to efficiently release the active ingredients in trace amounts and maintain a long-term antibacterial effect is the primary problem faced by plant essential oils as food preservatives. Microspheres and encapsulation technology are important means to improve the chemical stability and thermal stability of plant essential oils, thereby improving their biological activity, functional activity, release, action time, and overall quality. However, the microspheres prepared by the existing technology have problems such as low content and encapsulation rate, the use of more solvents, complex preparation process, and short release time. Summary of the Invention

[0005] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a method for preparing cinnamon essential oil-bagasse cellulose microspheres.

[0006] Another object of the present invention is to provide cinnamon essential oil-bagasse cellulose microspheres prepared by the method.

[0007] Another object of the present invention is to provide an application of the cinnamon essential oil-bagasse cellulose microspheres.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing cinnamon essential oil-bagasse cellulose microspheres comprises the following steps:

[0010] (1) Extraction of bagasse cellulose

[0011] The sugarcane bagasse is crushed and sieved, then soaked in a sodium carbonate solution, washed with water until neutral, and dried to obtain pretreated sugarcane bagasse; choline chloride and urea are mixed, heated and melted at 80-120° C. until clear and transparent to obtain a DES solvent (deep eutectic solvent); the pretreated sugarcane bagasse is then added to the DES solvent, heated and extracted at 80-120° C., and the precipitate is collected by centrifugation, washed, and dried to obtain bagasse cellulose;

[0012] (2) Preparation of cinnamon essential oil-bagasse cellulose microspheres

[0013] Urea and NaOH are added to water to prepare a urea alkaline solution; the bagasse cellulose and maltodextrin obtained in step (1) are then added to the urea alkaline solution, ultrasonically mixed, and cinnamon essential oil and acrylic resin NE30D (water-soluble dispersion) are added, mixed and homogenized to obtain an emulsion; and the emulsion is spray-dried to obtain cinnamon essential oil-bagasse cellulose microspheres.

[0014] Preferably, the sieving in step (1) is through an 80-mesh sieve.

[0015] Preferably, the concentration of the sodium carbonate solution in step (1) is 5 to 20% by mass.

[0016] More preferably, the concentration of the sodium carbonate solution in step (1) is 20% by mass.

[0017] Preferably, the soaking time in step (1) is 12 to 24 hours.

[0018] More preferably, the soaking time in step (1) is 24 hours.

[0019] Preferably, the molar ratio of choline chloride to urea in step (1) is 0.5 to 1:2.

[0020] More preferably, the molar ratio of choline chloride to urea in step (1) is 1:2.

[0021] Preferably, the heating in step (1) is carried out under oil bath conditions.

[0022] Preferably, the temperature of heating and melting in step (1) is 80°C.

[0023] Preferably, the mass ratio of the pretreated bagasse to the DES solvent in step (1) is 1:10 to 30.

[0024] More preferably, the mass ratio of the pretreated bagasse to the DES solvent in step (1) is 1:20.

[0025] Preferably, the temperature of the heating extraction in step (1) is 100°C.

[0026] Preferably, the heating extraction time in step (1) is 2 to 4 hours.

[0027] Preferably, the heating extraction time in step (1) is 3 hours.

[0028] Preferably, the centrifugal conditions in step (1) are: rotation speed 8000-10000 r / min, centrifugation 10-20 min.

[0029] More preferably, the centrifugal conditions in step (1) are: rotation speed 8000 r / min, centrifugation 15 min.

[0030] Preferably, the washing in step (1) is achieved by soaking the precipitate in anhydrous ethanol for 20 to 30 hours and then filtering.

[0031] More preferably, the washing in step (1) is achieved by soaking the precipitate in anhydrous ethanol for 24 hours and then filtering.

[0032] Preferably, the drying conditions in step (1) are: drying at 105° C. for 20 to 30 hours.

[0033] More preferably, the drying condition in step (1) is: drying at 105° C. for 24 hours.

[0034] Preferably, the water in step (2) is distilled water.

[0035] Preferably, the mass ratio of urea, NaOH and water in step (2) is 10-20:5-15:81.

[0036] More preferably, the mass ratio of urea, NaOH and water in step (2) is 12:7:81.

[0037] Preferably, the mass ratio of bagasse cellulose, maltodextrin and urea alkaline solution in step (2) is 10:7.5:70.

[0038] Preferably, the mass ratio of bagasse cellulose, maltodextrin, cinnamon essential oil and acrylic resin NE30D in step (2) is 10:7.5:15:5-10.

[0039] More preferably, the mass ratio of bagasse cellulose, maltodextrin, cinnamon essential oil and acrylic resin NE30D in step (2) is 10:7.5:15:10.

[0040] Preferably, the ultrasonic mixing conditions in step (2) are: 120W ultrasonic mixing for 10 min.

[0041] Preferably, the homogenization conditions in step (2) are: rotation speed 8000-12000 r / min, time 5-10 min.

[0042] More preferably, the homogenization conditions in step (2) are: rotation speed 10000 r / min, time 5 min.

[0043] Preferably, the spray drying conditions in step (2) are: temperature 100-180° C., vacuum degree 0.1 MPa, and wind speed 100 m / s.

[0044] More preferably, the spray drying conditions in step (2) are: temperature 180° C., vacuum degree 0.1 MPa, and wind speed 100 m / s.

[0045] Cinnamon essential oil-bagasse cellulose microspheres are prepared by any of the above methods.

[0046] The invention relates to an application of the cinnamon essential oil-bagasse cellulose microspheres in the preparation of antibacterial products.

[0047] The bacteria include Escherichia coli and Staphylococcus aureus.

[0048] The products include drugs (sustained-release drugs) and the like.

[0049] The present invention has the following advantages and effects compared to the prior art:

[0050] (1) The present invention first pre-treats bagasse by soaking it in a sodium carbonate solution, and then extracts it with a deep eutectic solvent (DES) (composed of urea and choline chloride) under suitable conditions to obtain bagasse cellulose; then ultrasonically dissolves the obtained cellulose and maltodextrin with an alkali-urea mixed aqueous solution; then adds cinnamon essential oil and acrylic resin NE30D, mixes them together and homogenizes to obtain an emulsion, and spray-dries to obtain a finished microsphere product.

[0051] (2) The high porosity structure of bagasse cellulose in the present invention can accommodate a larger amount of essential oil, and acrylic resin is used as a wall material to form a membrane material to better encapsulate the essential oil. It can not only embed a larger amount of cinnamon essential oil and control its slow release, but all ingredients are biodegradable. The production method using spray drying is economical, simple, and efficient, and at the same time realizes the high value utilization of bagasse.

[0052] (3) The present invention uses cinnamon essential oil as a functional antibacterial component. However, since cinnamon essential oil is easily oxidized and volatile, bagasse cellulose, maltodextrin, and acrylic resin NE30D are added as carriers to delay the release of cinnamon essential oil. The present invention combines bagasse cellulose with maltodextrin and acrylic resin NE30D for the first time to enhance the adsorption and embedding properties of cinnamon essential oil, solving the problems of easy volatility, poor antibacterial effect, and low utilization rate of plant essential oils in practical applications. The obtained microspheres have good microscopic morphology, high embedding rate, and long sustained-release time.

[0053] (4) The present invention uses sodium carbonate pretreatment + DES solvent to extract bagasse cellulose. Compared with bagasse cellulose extracted by other methods, the pore size is larger, the size is uniform and the arrangement is orderly, which is more conducive to the loading of plant essential oils.

[0054] (5) The cinnamon essential oil-bagasse cellulose microspheres prepared by the present invention have a large drug loading capacity (196.5 mg / g), a high embedding rate (94.3%), a high yield (83.1%), a long release time (continuous release for about 7 days at room temperature), high antibacterial sensitivity, and a significant long-term antibacterial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 : are scanning electron microscope images of bagasse and bagasse cellulose; wherein A1 and A2 are bagasse; B1 and B2 are bagasse cellulose prepared in Example 1; C1 and C2 are bagasse cellulose prepared in Comparative Example 1; D1 and D2 are bagasse cellulose prepared in Comparative Example 2.

[0056] Figure 2 The figures are scanning electron micrographs of cinnamon essential oil-bagasse cellulose microspheres; A is the microspheres prepared in Example 2; B is the microspheres prepared in Example 3; C is the microspheres prepared in Comparative Example 3; D is the microspheres prepared in Comparative Example 4; E is the microspheres prepared in Comparative Example 5; and F is the microspheres prepared in Comparative Example 6.

[0057] Figure 3 This is the release curve of cinnamon essential oil-bagasse cellulose microspheres. DETAILED DESCRIPTION

[0058] The present invention will be described in further detail below in conjunction with the examples, but embodiments of the present invention are not limited thereto. Unless otherwise stated, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. The test methods for which specific experimental conditions are not specified in the following examples are usually based on conventional experimental conditions or the experimental conditions recommended by the manufacturer. Unless otherwise stated, the reagents and raw materials used in the present invention can be obtained commercially.

[0059] The sugarcane bagasse (bagasse) involved in the examples and comparative examples of the present invention is the waste of sugarcane after sugar extraction.

[0060] The cinnamon essential oil involved in the examples and comparative examples of the present invention was purchased from Ji'an Huashuo Fragrance Essential Oil Co., Ltd.; acrylic resin (pH independent) NE30D (emulsion), acrylic resin (gastric soluble) EPO and acrylic resin L30D (aqueous dispersion 30%) were all purchased from Shenzhen Youpuhui Pharmaceutical Co., Ltd.

[0061] The crystallinity in the examples and comparative examples was measured using a multi-position automated X-ray diffractometer. X-ray diffraction crystallinity was calculated using Material Data Jade software. Scanning electron microscopy was performed using a Zeiss scanning electron microscope, and pore size was measured using Nano Measure software. All tests were repeated three times.

[0062] Example 1 Extraction of bagasse cellulose (sodium carbonate pretreatment + DES method)

[0063] The bagasse was first crushed and passed through an 80-mesh sieve. It was then soaked in a 20% by mass sodium carbonate solution for 24 hours, washed with water until neutral, and dried. Choline chloride and urea were mixed in a 1:2 molar ratio and melted in an 80°C oil bath until clear and transparent, yielding the DES solvent. The DES solvent was then mixed with the dried bagasse in a 20:1 (g / g) liquid-to-solid ratio and heated in a 100°C oil bath for 3 hours. The solution was collected and centrifuged at 8000 rpm for 15 minutes. The supernatant was removed, and the precipitate was retained. The precipitate was soaked in anhydrous ethanol for 24 hours, filtered, and oven-dried at 105°C for 24 hours to yield bagasse cellulose. The bagasse cellulose had an average pore size of 2.24±0.38 μm in its major diameter and 1.44±0.27 μm in its minor diameter, with a crystallinity of 65.95%.

[0064] Example 2 Preparation of cinnamon essential oil-bagasse cellulose microspheres

[0065] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare a urea alkaline solution in a mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0066] (2) Add 70g of urea alkaline solution, 7.5g of maltodextrin, and 10g of the bagasse cellulose extracted in Example 1 to a clean beaker and mix thoroughly (using 120W ultrasonic mixing for 10min, the same below), then add 15g of cinnamon essential oil and 10g of acrylic resin NE30D emulsion. After mixing evenly, homogenize with a homogenizer (speed of 10000r / min, time of 5min) to obtain a homogenized emulsion. The homogenized emulsion is connected to a spray dryer (Japan Yamato spray dryer ADL311S, the same below) for spray drying, and the sample is collected to obtain cinnamon essential oil-bagasse cellulose microspheres; wherein the spray drying conditions are: temperature 180℃, vacuum degree 0.1MPa, wind speed 100m / s. Take the sample collected in the collection tube after spray drying to measure the content, embedding efficiency, yield and release rate, and draw a release curve.

[0067] Example 3 Preparation of cinnamon essential oil-bagasse cellulose microspheres

[0068] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare a urea alkaline solution in a mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0069] (2) Add 70g of urea alkaline solution, 7.5g of maltodextrin, and 10g of the bagasse cellulose extracted in Example 1 to a clean beaker and mix thoroughly. Then, add 15g of cinnamon essential oil and 5g of acrylic resin NE30D emulsion. After mixing evenly, use a homogenizer to homogenize (speed of 10000r / min, time of 5min) to obtain a homogenized emulsion. The homogenized emulsion is connected to a spray dryer for spray drying, and a sample is collected to obtain cinnamon essential oil-bagasse cellulose microspheres; wherein the spray drying conditions are: temperature of 180℃, vacuum degree of 0.1Mpa, wind speed of 100m / s. Take the sample collected in the collection tube after spray drying to measure the content, embedding efficiency, yield and release rate, and draw a release curve.

[0070] Comparative Example 1 Extraction of bagasse cellulose (acid method)

[0071] Nitric acid and anhydrous ethanol were mixed in a volume ratio of 1:4 to produce a nitric acid-ethanol mixture. The crushed, 80-mesh sieved bagasse was then mixed with the nitric acid-ethanol mixture at a material-liquid ratio of 1:25 (g / mL). The mixture was heated in a 100°C water bath under reflux for 1 hour, repeatedly heating until the bagasse turned white. The mixture was collected and centrifuged at 8000 rpm for 15 minutes. The supernatant was removed, and the precipitate was retained. The precipitate was washed repeatedly with distilled water until neutral and then dried in an oven at 105°C for 24 hours to obtain bagasse cellulose. The average pore size of the bagasse cellulose was 0.94±0.31 μm for the major diameter and 0.51±0.14 μm for the minor diameter, with a crystallinity of 47.30%.

[0072] Comparative Example 2 Extraction of bagasse cellulose (DES method)

[0073] Choline chloride and urea were mixed in a 1:2 molar ratio and melted in an 80°C oil bath until clear and transparent to obtain DES solvent. The DES solvent was then mixed with crushed, 80-sieve bagasse at a liquid-to-solid ratio of 20:1 (g / g) and heated in a 100°C oil bath for 3 hours. The liquid was collected and centrifuged at 8000 rpm for 15 minutes. The supernatant was removed and the precipitate was retained. The precipitate was soaked in anhydrous ethanol for 24 hours, filtered, and oven-dried at 105°C for 24 hours to obtain bagasse cellulose. The average pore size of the bagasse cellulose was measured to be 1.35±0.53 μm for the major diameter and 0.68±0.47 μm for the minor diameter, with a crystallinity of 60.27%.

[0074] Comparative Example 3 Preparation of Cinnamon Essential Oil-Sugar Bagasse Cellulose Microspheres (without NE30D)

[0075] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare urea alkaline solution in the mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0076] (2) Add 70g of urea alkaline solution, 7.5g of maltodextrin, and 10g of the bagasse cellulose extracted in Example 1 to a clean beaker and mix thoroughly. Then, add 15g of cinnamon essential oil. After mixing evenly, homogenize with a homogenizer (speed of 10000r / min, time of 5min) to obtain a homogenized emulsion. Connect the homogenized emulsion to a spray dryer for spray drying, collect samples, and obtain cinnamon essential oil-bagasse cellulose microspheres; wherein the spray drying conditions are: temperature of 180℃, vacuum degree of 0.1Mpa, wind speed of 100m / s. Take the sample collected in the collection tube after spray drying to measure the embedding yield and embedding efficiency, and draw a sustained release curve.

[0077] Comparative Example 4 Preparation of Cinnamon Essential Oil-Sugar Bagasse Cellulose Microspheres (Using EPO)

[0078] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare a urea alkaline solution in a mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0079] (2) Add 70g of urea alkaline solution, 7.5g of maltodextrin, and 10g of the bagasse cellulose extracted in Example 1 to a clean beaker and mix thoroughly. Then, add 15g of cinnamon essential oil and 10g of acrylic resin EPO. After mixing evenly, homogenize with a homogenizer (speed of 10000r / min, time of 5min) to obtain a homogenized emulsion. The homogenized emulsion is connected to a spray dryer for spray drying, and a sample is collected to obtain cinnamon essential oil-bagasse cellulose microspheres; wherein the spray drying conditions are: temperature of 180°C, vacuum degree of 0.1MPa, and wind speed of 100m / s. Take the sample collected in the collection tube after spray drying to measure the content, embedding efficiency, yield, and release rate, and draw a release curve.

[0080] Comparative Example 5 Preparation of Cinnamon Essential Oil-Sugar Bagasse Cellulose Microspheres (Using L30D)

[0081] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare a urea alkaline solution in a mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0082] (2) Add 70g of urea alkaline solution, 7.5g of maltodextrin, and 10g of the bagasse cellulose extracted in Example 1 to a clean beaker and mix thoroughly. Then, add 15g of cinnamon essential oil and 10g of acrylic resin L30D. After mixing evenly, homogenize with a homogenizer (speed of 10,000 r / min, time of 5 min) to obtain a homogenized emulsion. The homogenized emulsion is connected to a spray dryer for spray drying, and a sample is collected to obtain cinnamon essential oil-bagasse cellulose microspheres; wherein the spray drying conditions are: temperature of 180°C, vacuum degree of 0.1 MPa, and wind speed of 100 m / s. Take the sample collected in the collection tube after spray drying and measure the content, embedding efficiency, yield, and release rate, and draw a release curve.

[0083] Comparative Example 6 Preparation of Cinnamon Essential Oil Microspheres (without Bagasse Cellulose)

[0084] (1) Take urea (analytical grade) and NaOH (analytical grade) and prepare a urea alkaline solution in a mass ratio of urea: NaOH: distilled water of 12:7:81 for later use.

[0085] (2) Add 70g of urea alkaline solution and 7.5g of maltodextrin to a clean beaker and mix thoroughly. Then add 15g of cinnamon essential oil and 10g of acrylic resin NE30D. After mixing evenly, use a homogenizer to homogenize (speed of 10000r / min, time of 5min) to obtain a homogenized emulsion. The homogenized emulsion is connected to a spray dryer for spray drying, and the sample is collected to obtain cinnamon essential oil microspheres; the spray drying conditions are: temperature 180℃, vacuum degree 0.1MPa, wind speed 100m / s. Take the sample collected in the collection tube after spray drying to measure the content, embedding efficiency, yield and release rate, and draw a release curve.

[0086] Effect Example 1

[0087] The scanning electron microscope images of the bagasse cellulose prepared in Example 1 and Comparative Examples 1-2, and the untreated bagasse are as follows: Figure 1 As shown. Based on the above data and Figure 1 Untreated bagasse has a dense surface and a relatively intact structure, while bagasse cellulose extracted using different methods exhibits an uneven surface with oval pores. However, bagasse cellulose pretreated with sodium carbonate and extracted with DES exhibits the largest pores, a dense structure, uniform size, and orderly arrangement, making it more suitable for the preparation of high-value-added products such as nanocellulose. This suggests that sodium carbonate pretreatment and DES extraction increase cellulose crystallinity. Sodium carbonate and DES can disrupt the rigid connection between lignin and hemicelluloses, thereby removing some hemicellulose and lignin, increasing cellulose content, and improving cellulose crystallinity.

[0088] The scanning electron microscope images of the microsphere samples prepared in Examples 2-3 and Comparative Examples 3-6 are as follows: Figure 2 shown.

[0089] Effect Example 2

[0090] 1. Determination of cinnamon essential oil content in samples

[0091] (1) Preparation of 10% citric acid ethanol solution: Add citric acid to anhydrous ethanol to prepare an ethanol solution containing 10% by mass of citric acid.

[0092] (2) First, take 100 μL of pure cinnamon essential oil solution and dilute it to 10 mL with the above-prepared 10% citric acid ethanol solution, then take 100 μL of the solution after dilution and dilute it to 10 mL. Take 100, 200, 400, 600, 800, and 1000 μL of the above-prepared solution respectively and dilute them to 10 mL. Use an ultraviolet spectrophotometer to perform a full wavelength scan on the above-mentioned concentration gradient solution, and the maximum absorption wavelength is located at λ=285 nm. Record the corresponding maximum absorption value and draw a standard curve of cinnamon essential oil content in 10% citric acid ethanol solution. The standard curve obtained is y=39.544x+0.216, R 2 =0.9993.

[0093] (3) The oil content and total oil content on the surface of the microsphere samples prepared in Examples 2-3 and Comparative Examples 3-6 were measured to determine the embedding rate and embedding efficiency. The specific steps are as follows: Weigh 2 groups of 0.1g samples respectively, one of which is placed in a centrifuge tube containing 10mL of 10% citric acid ethanol solution, ultrasonically crushed for 15 minutes, and then placed in a centrifuge at 6000r / min for 15 minutes to determine the total oil content; the other group of solutions was washed with 5mL of 10% citric acid ethanol solution for 5 minutes, the surface oil content was determined, and finally the washing solution was diluted to 10mL. Take 200μL of the supernatant or washing solution after centrifugation and dilute it to 10mL with 10% citric acid ethanol solution. The absorbance of the diluted solution was measured at a wavelength of 285nm, and the content of cinnamon essential oil in different samples was calculated based on the absorbance value obtained and the standard curve obtained in step (2). Repeat three times and take the average value. Then calculate the embedding rate and yield of cinnamon essential oil in microspheres according to the following formula:

[0094] Microsphere embedding efficiency (%) = (1-cinnamon essential oil content on sample surface (g) / total cinnamon essential oil in sample (g)) × 100%.

[0095] Microsphere yield (%) = total oil content of sample (g) / total amount of cinnamon essential oil in emulsion (g) × 100%.

[0096] 2. Determination of the release curve of cinnamon essential oil sample

[0097] Microsphere samples prepared in Examples 2-3 and Comparative Examples 3-6 were placed in a dry iodine-containing flask. The total amount of cinnamon essential oil in the samples was measured every 1, 2, 3, 4, 5, 6, and 7 days according to the above method. The release rate was calculated according to the formula [release (%) = (1 - total cinnamon essential oil content (g) measured at the interval) / total cinnamon essential oil content (g) of the original sample) × 100%]. The average of three replicates was calculated, and release curves for the different samples were plotted and compared.

[0098] The oil content, embedding rate, yield and release days of each embodiment and comparative example are shown in Table 1. The release situation (0-7 days) is shown in Table 2, and the release curve is shown in Table 2. Figure 3 shown.

[0099] Table 1

[0100] Experiment number Content (mg / g) Embedding rate (%) Yield (%) Release days Example 2 196.5 94.3 83.1 7 days Example 3 114.7 74.5 76.4 5 days Comparative Example 3 52.9 48.2 37.8 <2 days Comparative Example 4 72.3 69.8 55.4 <2 days Comparative Example 5 68.1 65.6 52.7 <2 days Comparative Example 6 48.6 32.4 30.9 <2 days

[0101] Table 2

[0102]

[0103]

[0104] From Table 1, Table 2 and Figure 3As can be seen, the microspheres prepared in Example 2 have a high cinnamon essential oil content, embedding efficiency, and yield, and a long release time, indicating that the appropriate ratio of bagasse cellulose, acrylic resin NE30D, and maltodextrin can form tightly packed microspheres with good sustained-release effects. The results of Example 3 show that, when other conditions remain unchanged and the amount of acrylic resin NE30D is reduced, the cross-linking reaction between acrylic resin NE30D, bagasse cellulose, and maltodextrin is insufficient, resulting in a thin and brittle microsphere membrane with pores and cracks on the surface, which makes the microspheres easily damaged and the cinnamon essential oil easily released. The process indicators and release days are lower than those of Example 2. In Comparative Example 3, acrylic resin NE30D was removed, in Comparative Example 4, acrylic resin NE30D was replaced with acrylic resin EPO, in Comparative Example 5, acrylic resin NE30D was replaced with acrylic resin L30D, and in Comparative Example 6, bagasse cellulose was removed. The cinnamon essential oil content, embedding rate, and yield were all reduced, and the release was fast. The formed microspheres had obvious cracks and huge pores, the wall material was adhered, and the coating effect was poor. In Comparative Example 6, microspheres could not even be formed after the bagasse cellulose was removed due to the lack of the skeleton support of bagasse cellulose.

[0105] 3. The prepared products were tested for antibacterial activity. Samples of the microspheres prepared in Examples 2-3 and Comparative Examples 3-6 at the same dosage were added to nutrient agar plates containing Escherichia coli ATCC25922 and Staphylococcus aureus RN4220 (purchased from the Guangdong Institute of Microbiology), respectively. Blank controls were set up and incubated in a 37°C incubator for 24 hours. The diameters of the inhibition zones were measured. The experiment was repeated three times. The results are shown in Table 3.

[0106] Table 3

[0107]

[0108] Note: The criteria in Table 3 are: inhibition zone ≥15 mm is highly sensitive, 10-15 mm is moderately sensitive, 7-9 mm is lowly sensitive, and no inhibition zone is insensitive.

[0109] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing cinnamon essential oil-bagasse cellulose microspheres, characterized in that: The steps include: (1) Extraction of bagasse cellulose The sugarcane bagasse is crushed and sieved, then added to a sodium carbonate solution for soaking, washed with water until neutral, and dried to obtain pretreated sugarcane bagasse; choline chloride and urea are mixed, heated and melted at 80-120° C. until clear and transparent to obtain a DES solvent; the pretreated sugarcane bagasse is then added to the DES solvent, heated and extracted at 80-120° C., and the precipitate is collected by centrifugation, washed, and dried to obtain bagasse cellulose; (2) Preparation of cinnamon essential oil-bagasse cellulose microspheres Urea and NaOH are added to water to prepare a urea alkaline solution; then the bagasse cellulose and maltodextrin obtained in step (1) are added to the urea alkaline solution, ultrasonically mixed, and then cinnamon essential oil and acrylic resin NE30D are added, mixed and homogenized to obtain an emulsion; finally, the emulsion is spray-dried to obtain cinnamon essential oil-bagasse cellulose microspheres.

2. The method according to claim 1, wherein: The mass ratio of urea, NaOH and water in step (2) is 10-20:5-15:81; The mass ratio of bagasse cellulose, maltodextrin, cinnamon essential oil and acrylic resin NE30D described in step (2) is 10:7.5:15:5-10.

3. The method according to claim 2, wherein: The mass ratio of urea, NaOH and water in step (2) is 12:7:81; The mass ratio of bagasse cellulose, maltodextrin, cinnamon essential oil and acrylic resin NE30D described in step (2) is 10:7.5:15:

10.

4. The method according to claim 1, wherein: The concentration of the sodium carbonate solution in step (1) is 5 to 20% by mass; The molar ratio of choline chloride to urea in step (1) is 0.5 to 1:2; The mass ratio of the pretreated bagasse to the DES solvent in step (1) is 1:10 to 30.

5. The method according to claim 4, characterized in that: The concentration of the sodium carbonate solution in step (1) is 20% by mass; The molar ratio of choline chloride to urea in step (1) is 1:2; The mass ratio of the pretreated bagasse to the DES solvent in step (1) is 1:

20.

6. The method according to claim 1, wherein: The spray drying conditions in step (2) are: temperature 100-180° C., vacuum degree 0.1 MPa, and wind speed 100 m / s.

7. The method according to claim 6, characterized in that: The spray drying conditions in step (2) are: temperature 180° C., vacuum degree 0.1 MPa, and wind speed 100 m / s.

8. The method according to claim 1, wherein: The sieving in step (1) is through an 80-mesh sieve; The soaking time in step (1) is 12 to 24 hours; The temperature of heating and melting in step (1) is 80°C; The temperature of the heating extraction in step (1) is 100° C. The heating extraction time in step (1) is 2 to 4 hours; The centrifugal conditions in step (1) are: a rotation speed of 8000 to 10000 r / min, and a centrifugal time of 10 to 20 min; The washing in step (1) is achieved by soaking the precipitate in anhydrous ethanol for 20 to 30 hours and then filtering; The drying conditions described in step (1) are: drying at 105° C. for 20 to 30 hours; The ultrasonic mixing conditions described in step (2) are: 120W ultrasonic mixing for 10 min; The homogenization conditions in step (2) are: rotation speed 8000-12000 r / min, time 5-10 min.

9. A cinnamon essential oil-bagasse cellulose microsphere, characterized in that: It is prepared by the method according to any one of claims 1 to 7.

10. Use of the cinnamon essential oil-bagasse cellulose microspheres according to claim 9 in the preparation of antibacterial products.

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