Humic acid-cinnamon essential oil emulsion as well as preparation and application thereof

Abstract

The invention belongs to the technical field of emulsion, and discloses humic acid-cinnamon essential oil emulsion as well as preparation and application thereof. The preparation method comprises the following steps: adding a dried orange peel and citrus pulp fermentation product into an alkaline solution, uniformly stirring, sealing, heating and oscillating, centrifuging, taking supernate, acidifying and precipitating, and freeze-drying the precipitate, thereby obtaining the dried orange peel source humic acid freeze-dried powder. The dried orange peel source humic acid freeze-dried powder is used as an emulsifier and can form a humic acid-cinnamon essential oil emulsion under the neutral condition that the pH value is 5-9. The preparation process of the humic acid-cinnamon essential oil emulsion sourced from the dried orange peel and citrus pulp leavening is simple, the storage stability at normal temperature is high, and the humic acid-cinnamon essential oil emulsion has excellent antibacterial performance and can be applied to the fields of medicine, cosmetics, food and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of emulsions, and particularly relates to a humic acid-cinnamon essential oil emulsion and a preparation method and application thereof. Background Art

[0002] Cinnamon essential oil is a natural, renewable antibacterial agent, in which the active ingredient is cinnamaldehyde (75-90%). Cinnamaldehyde plays an antibacterial role by destroying cell walls and damaging intracellular substances. At present, cinnamon essential oil has been gradually applied to food preservation, animal husbandry, pest control and other fields. However, cinnamon essential oil is volatile, sensitive to light, oxygen and temperature, has poor stability, and has low water solubility, which limits the practical application of cinnamon essential oil. In order to solve the above problems, the prior art proposes to use encapsulation and emulsification methods to carry cinnamon essential oil.

[0003] The Chinese invention patent publication (CN114869805A) discloses a method for preparing cinnamon essential oil microcapsules by mixing chitosan, quaternary ammonium salt, gum arabic, acetic acid and water as a composite wall material solution. The microcapsules prepared by the invention have excellent antibacterial properties against a variety of bacteria and maintain good antibacterial properties for a long time, but their antibacterial activity is lower than that of pure cinnamon essential oil, and the preparation process is complicated.

[0004] The Chinese invention patent publication (CN111589385A) discloses a method for preparing cinnamon essential oil microcapsules using chitosan and sodium alginate as wall materials, sodium chloride as a promoter, and calcium chloride as a curing agent. The microcapsules prepared by this method are more evenly distributed and have improved the controlled release of microcapsules obtained by the traditional preparation method, but the preparation process is complicated and the antibacterial effect needs to be explored.

[0005] Although the method of encapsulating cinnamon essential oil in microcapsules can improve the stability of cinnamon essential oil, its antibacterial activity is reduced and the preparation process is complicated and cumbersome. By preparing an emulsion to carry cinnamon essential oil, the water solubility of the essential oil can be improved, the influence of environmental factors on the essential oil can be reduced, and the oxidation of the essential oil can be delayed, thereby improving its stability.

[0006] A large number of tea-juice oranges are planted every year in Xinhui, Jiangmen, my country. The skin of tea-juice oranges is peeled, dried, stored and aged to make the world-famous Xinhui dried orange peel. However, the peeled orange flesh is large and cheap, and only a small amount of orange flesh is used for development and utilization such as feed and beverages, and most of it is directly discarded. The orange flesh piled up for a long time becomes sour and smelly, and the leachate pollutes water bodies and groundwater, affecting the environmental sanitation of cities and towns. Composting and fermenting the orange peel flesh, and extracting humic acid from the fermentation product for application in the preparation of emulsion is conducive to promoting the resource utilization of orange peel, but there are currently no relevant technologies and research reports.

[0007] Based on the above situation, we invented a method for preparing cinnamon essential oil emulsion using humic acid derived from tangerine peel pulp fermentation product as an emulsifier. Summary of the invention

[0008] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for extracting humic acid from tangerine peel pulp fermentation, which method is a resource-based and high-value utilization of tangerine peel pulp, which is beneficial to the sustainable development of the environment.

[0009] Another object of the present invention is to provide a method for preparing a cinnamon essential oil water-in-oil emulsion using humic acid derived from the fermented tangerine peel pulp prepared by the above method as an emulsifier. The preparation method of the humic acid-cinnamon essential oil emulsion derived from the fermented tangerine peel pulp provided by the present invention is simple, has good storage stability, and the emulsion uses humic acid as an emulsifier, is green and environmentally friendly, has low cost, and has certain functionality.

[0010] Another object of the present invention is to provide an application of the humic acid-cinnamon essential oil emulsion. The humic acid-cinnamon essential oil emulsion provided by the present invention has a good antibacterial effect on Escherichia coli and Staphylococcus aureus, and its antibacterial effect is better than that of pure cinnamon essential oil.

[0011] The purpose of the present invention is achieved through the following solutions:

[0012] A method for extracting humic acid from tangerine peel pulp fermentation product, comprising the following steps:

[0013] The fermented tangerine peel pulp is added into an alkaline solution, stirred evenly, sealed and heated and shaken, then centrifuged to obtain the supernatant, acidified and precipitated, and the precipitate was freeze-dried to obtain the tangerine peel-derived humic acid freeze-dried powder.

[0014] The tangerine peel pulp fermented product can be purchased from the market, or can be prepared by the following method: Chinese medicine residue, dust-removed rice husk, wood bran and fermentation bacteria agent are uniformly mixed and sent into a fermentation tank as bedding, soy sauce residue, tangerine peel pulp and water are mixed into a slurry liquid, and then the slurry liquid is sprayed on the bedding, and under natural ventilation conditions, the pile is mechanically turned 1 to 3 times every 1 to 3 days, and the tangerine peel pulp fermented product is continuously fermented for 1 to 3 months to obtain the tangerine peel pulp fermented product;

[0015] In the preparation of the fermented dried orange peel pulp, the Chinese medicine residue is at least one of yam, codonopsis, tuckahoe, white hyacinth bean, dried orange peel, amomum villosum, atractylodes macrocephala and quinquefolius oleraceus; preferably, it is quinquefolius oleraceus residue.

[0016] In the preparation of the tangerine peel pulp fermentation product, the fermentation bacteria agent is at least one of Pseudocanthomonas, Tauerella, Bacillus siamensis, halophilic Bacillus theridi, Bacillus subtilis, Lactobacillus acidophilus and fertilizer fermentation bacteria; preferably, it is a composite bacteria agent composed of Pseudocanthomonas, Tauerella, Bacillus siamensis, halophilic Bacillus theridi, Bacillus subtilis and Lactobacillus acidophilus; more preferably, it is the fermentation bacteria of Guangzhou Rongxin Technology Development Co., Ltd.

[0017] In the preparation of the fermented tangerine peel pulp, the volume ratio of wood chaff, dust-removed husk and Chinese medicine residue in the bedding is (1-6): (4-10): (0-2.5), and the amount of fermentation agent added is 1m 3 Add 150 to 450 g of fermentation agent to the litter.

[0018] In the preparation of the fermented tangerine peel pulp, the volume ratio of the soy sauce residue, tangerine peel pulp and water is (0.3-1): (1-20): 90;

[0019] In the preparation of the tangerine peel pulp fermented product, the water content in the fermentation tank is adjusted to 60%-70% by controlling the spraying amount of the slurry liquid, and the carbon-nitrogen ratio is (20-30):1.

[0020] In the method for extracting humic acid from fermented tangerine peel pulp, the alkaline solution is preferably a mixed aqueous solution of sodium pyrophosphate and alkali, wherein the alkali is at least one of sodium hydroxide and potassium hydroxide, and the molar ratio of sodium pyrophosphate to alkali is (0.5-2):(0.5-2).

[0021] In the method for extracting humic acid from fermented tangerine peel pulp, the concentration of sodium pyrophosphate in the alkaline solution is 0.05-0.2 mol / L, preferably 0.1 mol / L; the mass volume ratio of the fermented tangerine peel pulp and the alkaline solution is 1g:6-20mL, preferably 1g:10mL.

[0022] In the method for extracting humic acid from fermented tangerine peel pulp, the heating oscillation refers to heating to 45-60°C for oscillation, and the oscillation time is 18-24h; preferably, oscillation in a 60°C air bath constant temperature oscillator for 24h. Oscillation is to make the raw materials fully contact each other, and all oscillation speeds can achieve the technical effect of the present invention, so the oscillation speed is not limited.

[0023] For full extraction, after centrifugation to obtain the supernatant, the precipitate can be repeatedly washed with water until the liquid phase is clear, and the washing liquid obtained is combined with the supernatant and proceeded to the next step together.

[0024] In the method for extracting humic acid from fermented dried orange peel pulp, the acidification precipitation refers to making the pH of the filtrate 1-2, the acid used for acidification is dilute hydrochloric acid, and the concentration of dilute hydrochloric acid is 3-6 mol / L, preferably 6 mol / L. The freeze drying is preferably liquid nitrogen freeze drying.

[0025] After the acidification treatment, the precipitate is preferably washed with water at least three times to remove the remaining soluble matter and leave the precipitate that is insoluble in the acidic solution.

[0026] A tangerine peel-derived humic acid prepared by the method.

[0027] The above-mentioned tangerine peel-derived humic acid is used as an emulsifier in the preparation of cinnamon essential oil oil-in-water emulsion.

[0028] A method for preparing a cinnamon essential oil oil-in-water emulsion comprises the following steps:

[0029] (1) dispersing the prepared tangerine peel-derived humic acid freeze-dried powder in water to obtain a tangerine peel-derived humic acid solution;

[0030] (2) Cinnamon essential oil is added to the tangerine peel-derived humic acid solution, and the cinnamon essential oil oil-in-water emulsion is prepared by shearing.

[0031] The pH of the tangerine peel source humic acid solution described in step (1) is 5-9; the pH is adjusted by adding alkali, preferably by using sodium hydroxide solution; the concentration of the tangerine peel source humic acid solution is 5-20 mg / ml.

[0032] The relative amounts of the tangerine peel-derived humic acid solution and the cinnamon essential oil in step (2) satisfy: the volume ratio of the cinnamon essential oil to the tangerine peel-derived humic acid solution is 1:1-1:4;

[0033] The shearing in step (2) refers to shearing at 90000-150000 rpm for 3-5 min, preferably shearing at 10000 rpm for 4 min.

[0034] The invention discloses a cinnamon essential oil oil-in-water emulsion prepared by the method.

[0035] The cinnamon essential oil oil-in-water emulsion has high storage stability at room temperature and excellent antibacterial properties, and can be used in the fields of medicine, cosmetics, food, etc.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] (1) The emulsifier used in the present invention is humic acid derived from the fermented tangerine peel pulp, which is low in cost, easy to obtain, and environmentally friendly. In addition, the humic acid can form an emulsion under neutral conditions of pH = 5 to 9, and has a wide range of applications.

[0038] (2) The humic acid-cinnamon essential oil emulsion derived from the fermented dried orange peel pulp of the present invention has a simple preparation process, high storage stability at room temperature, and excellent antibacterial properties, and can be applied to the fields of medicine, cosmetics, food, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the appearance of the commercial humic acid-cinnamon essential oil emulsion prepared in Comparative Example 4.

[0040] Figure 2 The optical microscope images of the humic acid-cinnamon essential oil emulsion derived from the fermented dried orange peel pulp prepared in Examples 1-3 and Comparative Example 1. a, b, d, and e correspond to Comparative Example 1 and Examples 1-3, respectively, and c is a partial enlarged optical microscope image of the emulsion in Example 1.

[0041] Figure 3 The appearance of the humic acid-cinnamon essential oil emulsion derived from the fermented dried orange peel pulp prepared in Examples 1-3 and Comparative Example 1 after storage at room temperature for 0h and 360h. Among them, ad corresponds to Comparative Example 1 and Examples 1-3 respectively, and e is an enlarged view of Comparative Example 1 after preparation for 360h.

[0042] Figure 4 The optical microscope images of Examples 4-7, the curves in the figure are the particle size distribution of the emulsion measured by a laser particle size analyzer (MALVERN MS3000). ad corresponds to Examples 4-7 respectively.

[0043] Figure 5 These are appearance diagrams of the humic acid-cinnamon essential oil emulsion derived from the fermented dried orange peel pulp prepared in Examples 4 and 5 and Comparative Example 2 after being stored at room temperature for different periods of time, wherein a corresponds to Example 5, b corresponds to Example 4, and c corresponds to Comparative Example 2.

[0044] Figure 6 These are appearance diagrams of Examples 6, 7 and Comparative Example 3 stored at room temperature for different periods of time, where a corresponds to Example 7, b corresponds to Example 6, and c corresponds to Comparative Example 3.

[0045] Figure 7 Figure 7 is a characterization of the antibacterial properties of Example 7. a is a graph showing the inhibitory effect of humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation on Escherichia coli, b is a graph showing the inhibitory effect of cinnamon essential oil on Escherichia coli, c is a graph showing the inhibitory effect of humic acid derived from tangerine peel pulp fermentation on Escherichia coli, d is a graph showing the antibacterial inhibition of humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation on Staphylococcus aureus, e is a graph showing the inhibitory effect of cinnamon essential oil on Staphylococcus aureus, and f is a graph showing the inhibitory effect of humic acid derived from tangerine peel pulp fermentation on Staphylococcus aureus. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0047] Example 1

[0048] A tangerine peel-derived humic acid-cinnamon essential oil emulsion with an oil-water volume ratio of 1:3 was prepared, wherein the tangerine peel-derived humic acid solution had a pH of 5 and a concentration of 5 mg / ml.

[0049] (1) Preparation of fermented tangerine peel pulp: Prunus mume residue, dusted rice husk and sawdust were mixed in a volume ratio of 2:7:3, and then 300 g / m 3 The composite fermentation bacteria agent of the bedding (the yeast bacteria of Guangzhou Rongxin Technology Development Co., Ltd.) is mixed and sent into the fermentation tank as the bedding. The soy sauce residue (from Lee Kum Kee), tangerine peel pulp and water are mixed into a slurry in a volume ratio of 1:20:90, and then the slurry is sprayed on the bedding. The moisture content of the material in the fermentation tank is 65%, and the carbon-nitrogen ratio is 25:1. Under natural ventilation conditions, the pile is mechanically turned once a day, and fermentation is continued for 1 month to obtain the tangerine peel pulp fermentation product.

[0050] (2) Preparation of humic acid derived from fermented dried orange pulp: 15 g of fermented dried orange pulp was added to 150 ml of a mixture of sodium pyrophosphate and sodium hydroxide (the molar ratio of sodium pyrophosphate to sodium hydroxide was 1:1, and the concentrations of both were 0.1 mol / L). After sufficient stirring, the mixture was transferred to a 250 mL conical flask, sealed with plastic wrap, and placed in an air bath constant temperature oscillator for oscillation at 60° C. for 24 h. After the oscillation was completed, the mixture was centrifuged at 8000 rpm for 5 min, and the supernatant was collected. The precipitate was repeatedly washed with deionized water until the liquid phase was clear to obtain a washing liquid. The washing liquid and the supernatant were combined and filtered, and the pH of the filtrate was adjusted to 1-2 with 6 mol / L hydrochloric acid to precipitate humic acid derived from fermented dried orange pulp. The precipitate was washed with deionized water and centrifuged at 8000 rpm for 5 min, and the supernatant was discarded. This was repeated three times to obtain a precipitate, which was humic acid. The precipitate was freeze-dried to obtain freeze-dried powder of humic acid derived from fermented dried orange pulp.

[0051] (3) Preparation of humic acid solution derived from fermented dried tangerine peel pulp: 0.06 g of the freeze-dried humic acid powder derived from fermented dried tangerine peel pulp obtained in step (2) was dispersed in 12 ml of deionized water to obtain a 5 mg / ml humic acid solution derived from fermented dried tangerine peel pulp, to which NaOH solution was added to adjust the pH of the humic acid solution to 5.

[0052] (4) Preparation of humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product: Take 12 ml of the humic acid solution derived from tangerine peel pulp fermentation product prepared in step (2), add 4 ml of cinnamon essential oil, and use a disperser to high-speed shear at 10,000 rpm for 4 minutes to obtain a humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product.

[0053] Example 2

[0054] The pH of step (3) in Implementation 1 was adjusted to 7, and the rest was kept consistent with Example 1 to prepare a humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product with an oil-water ratio of 1:3, wherein the humic acid solution derived from tangerine peel pulp fermentation product has a pH of 7 and a concentration of 5 mg / ml.

[0055] Example 3

[0056] The pH of step (3) in implementation 1 was adjusted to 9. The rest was consistent with Example 1, and a humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product with an oil-water ratio of 1:3 was prepared, wherein the humic acid solution derived from tangerine peel pulp fermentation product had a pH of 9 and a concentration of 5 mg / ml.

[0057] Example 4

[0058] Step (3) in Example 1 is adjusted as follows: 0.16 g of humic acid freeze-dried powder derived from tangerine peel pulp fermentation product is dispersed in 8 ml of deionized water to obtain a humic acid solution with a concentration of 20 mg / ml.

[0059] The pH of step (3) in implementation 1 was adjusted to 7.

[0060] Step (4) in Example 1 is adjusted as follows: 8 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 4 ml of cinnamon essential oil is added thereto.

[0061] The rest was consistent with Implementation 1, and a humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product with an oil-water ratio of 1:2 was prepared, wherein the humic acid solution derived from tangerine peel pulp fermentation product had a pH of 7 and a concentration of 20 mg / ml.

[0062] Example 5

[0063] Step (3) in Example 1 is adjusted as follows: 0.32 g of humic acid freeze-dried powder derived from tangerine peel pulp fermentation product is dispersed in 16 ml of deionized water to obtain a humic acid solution with a concentration of 20 mg / ml.

[0064] The pH of step (3) in implementation 1 was adjusted to 7.

[0065] Step (4) in Example 1 is adjusted as follows: 16 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 4 ml of cinnamon essential oil is added thereto.

[0066] The rest was consistent with Implementation 1, and a humic acid-cinnamon essential oil emulsion derived from dried orange peel pulp fermentation product with an oil-water ratio of 1:4 was prepared, wherein the humic acid solution derived from dried orange peel pulp fermentation product had a pH of 7 and a concentration of 20 mg / ml.

[0067] Example 6

[0068] Step (3) in Example 1 is adjusted as follows: 0.09 g of humic acid derived from fermented dried orange peel pulp is dispersed in 6 ml of deionized water to obtain a humic acid solution with a concentration of 15 mg / ml.

[0069] The pH of step (3) in implementation 1 was adjusted to 7.

[0070] Step (4) in Example 1 is adjusted as follows: 6 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 6 ml of cinnamon essential oil is added thereto.

[0071] The rest was consistent with Implementation 1, and a humic acid-cinnamon essential oil emulsion derived from dried orange peel pulp fermentation product with an oil-water ratio of 1:1 was prepared, wherein the humic acid solution derived from dried orange peel pulp fermentation product had a pH of 7 and a concentration of 15 mg / ml.

[0072] Example 7

[0073] Step (3) in Example 1 is adjusted as follows: 0.12 g of humic acid derived from fermented dried orange peel pulp is dispersed in 6 ml of deionized water to obtain a humic acid solution with a concentration of 20 mg / ml.

[0074] The pH of step (3) in implementation 1 was adjusted to 7.

[0075] Step (4) in Example 1 is adjusted as follows: 6 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 6 ml of cinnamon essential oil is added thereto.

[0076] The rest was consistent with Implementation 1, and a humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product with an oil-water ratio of 1:1 was prepared, wherein the humic acid solution derived from tangerine peel pulp fermentation product had a pH of 7 and a concentration of 20 mg / ml.

[0077] from Figure 2 It can be seen from b, d, and e that under the conditions of pH = 5, pH = 7, and pH = 9, the humic acid derived from the fermented tangerine peel pulp can stabilize the oil-water interface and wrap the oil droplets to form an emulsion. Figure 3 From the appearance of the emulsion, it can be seen that the lower layer of the emulsions with pH = 5, pH = 7 and pH = 9 is milky white, and the water layer of the emulsion is precipitated, resulting in the phenomenon of emulsion stratification. This is because the density of cinnamon essential oil is greater than that of water, and the emulsion droplets settle in the system due to gravity, but this process does not destroy the emulsion structure.

[0078] Comparative Example 1

[0079] The pH of step (3) in implementation 1 was adjusted to 3. Other steps were the same as in implementation 1.

[0080] like Figure 2 As shown in a, under the condition of pH = 3, the humic acid particles derived from the fermented tangerine peel pulp were adsorbed on the surface of cinnamon essential oil, but no emulsion droplets were observed. Figure 3 It can also be seen from Figure 5 that after standing, the upper layer is a clear water phase, and the lower layer is a clear oil phase. The oil and water are completely separated and no emulsion is formed.

[0081] Comparative Example 2

[0082] Step (3) in Example 1 is adjusted as follows: 0.08 g of humic acid derived from fermented dried orange peel pulp is dispersed in 4 ml of deionized water to obtain a humic acid solution with a concentration of 20 mg / ml.

[0083] The pH of step (3) in implementation 1 was adjusted to 7.

[0084] Step (4) in Example 1 is adjusted as follows: 4 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 8 ml of cinnamon essential oil is added thereto.

[0085] Others are consistent with implementation 1, such as Figure 5 As shown in c, after the prepared emulsion was placed at room temperature for 24 hours, the oil and water separated and a stable emulsion could not be obtained.

[0086] Comparative Example 3

[0087] Step (2) in Example 1 is adjusted as follows: 0.02 g of humic acid derived from fermented dried orange peel pulp is dispersed in 8 ml of deionized water to obtain a humic acid solution with a concentration of 2.5 mg / ml.

[0088] The pH of step (2) in implementation 1 was adjusted to 7.

[0089] Step (3) in Example 1 is adjusted as follows: 8 ml of humic acid solution derived from fermented dried orange peel pulp is taken, and 8 ml of cinnamon essential oil is added thereto.

[0090] Others are consistent with implementation 1, such as Figure 6 As shown in (d), compared with Examples 6 and 7, Comparative Example 3 demulsified after being placed at room temperature for 480 hours, and oil-water separation occurred.

[0091] Comparative Example 4

[0092] Step (3) in Example 1 was adjusted as follows: 0.12 g of commercial humic acid (Shanghai Yuanye Biotechnology Co., Ltd.) was dispersed in 6 ml of deionized water to obtain a humic acid solution with a concentration of 20 mg / ml.

[0093] The pH of step (3) in implementation 1 was adjusted to 7.

[0094] Step (4) in Example 1 was adjusted as follows: 6 ml of commercial humic acid solution was taken and 6 ml of cinnamon essential oil was added thereto.

[0095] The other conditions were the same as those in Example 1, and a commercial humic acid-cinnamon essential oil mixture with an oil-water ratio of 1:1 was prepared, wherein the commercial humic acid solution had a pH of 7 and a concentration of 20 mg / ml. Figure 1 As shown, in Comparative Example 4, oil and water were separated, clear oil droplets were stained on the surface of the glass bottle, and the upper layer was a clear water phase, and no emulsion could be formed.

[0096] Test method:

[0097] Elemental analysis: The N, C, H, and O content of commercial humic acid (Shanghai Yuanye Biotechnology Co., Ltd.) and humic acid derived from fermented dried orange peel pulp in Example 2 of the present invention were determined using an elemental analyzer (Elementar Vario EL cube) at pH = 7. The results are shown in Table 1 below.

[0098] Table 1

[0099]

[0100] The elemental composition and atomic ratio can reflect the molecular structure and source of humic acid. The elemental composition and atomic ratio of humic acid derived from tangerine peel pulp fermentation and commercial humic acid derived from lignite are shown in Table 1 above. Compared with commercial humic acid, humic acid derived from tangerine peel pulp fermentation has higher N, H, and O contents and lower C content, resulting in higher ratios of N / C, H / C, O / C and [(N+O) / C]. The higher N / C of humic acid derived from tangerine peel pulp fermentation is mainly due to the addition of more protein raw materials (soy sauce residue) during the composting fermentation process; the higher H / C ratio indicates that it has lower aromaticity; the high O / C ratio indicates that it contains more aliphatic groups; [(N+O) / C] is called the polarity index, and a higher ratio indicates that the humic acid derived from tangerine peel pulp fermentation is more polar.

[0101] Emulsion microstructure: A small amount of fresh emulsion was used to prepare a glass slide specimen, and the microstructure was observed under a Motic optical microscope (BA410EMotic) at 400× magnification.

[0102] Emulsion storage stability: Observe the changes in the appearance of the emulsion when stored at room temperature for different periods of time.

[0103] Characterization of antibacterial properties of emulsion:

[0104] Take 50 μL of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 43894) culture (OD600 = 0.1), transfer to LB solid agar medium (Guangdong Huankai Microbiological Technology Co., Ltd.), spread evenly, and let the bacterial solution dry naturally.

[0105] Place a filter paper (d = 0.6 cm) in the center of the plate, drip 10 μL of the humic acid-cinnamon essential oil emulsion from the fermented dried orange peel pulp prepared in Example 7 onto the filter paper, and incubate at 37°C for 24 h. Measure the diameter of the inhibition zone, measure each 3 times, and take the average value. Repeat the test for each bacterium at least 3 times. Take pure cinnamon essential oil and humic acid solution from the fermented dried orange peel pulp as controls, and drip 10 μL of each. The size of the inhibition zone is as follows: Figure 7 The diameters of the inhibition zones are shown in Table 2.

[0106] Table 2

[0107]

[0108] The measured data showed that the inhibition zone of the emulsion and cinnamon essential oil against Escherichia coli was smaller than that against Staphylococcus aureus. This is because the lipopolysaccharide on the cell wall of Escherichia coli can effectively limit the diffusion of hydrophobic substances. At the same time, Escherichia coli has a membrane, which can also resist the influence of adverse external environments. In contrast, the hydrophobic compound cinnamon essential oil can pass through the peptidoglycan layer of Staphylococcus aureus. In addition, the data showed that the humic acid-cinnamon essential oil emulsion derived from tangerine peel pulp fermentation product can reduce the volatilization of cinnamon essential oil and improve its antibacterial properties.

[0109] The above embodiments are preferred implementation modes of the present invention, but the implementation modes 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for extracting humic acid from tangerine peel pulp fermentation product, characterized in that The following steps are involved: The fermented tangerine peel pulp is added into an alkaline solution, stirred evenly, sealed and heated and shaken, then centrifuged to obtain the supernatant, acidified and precipitated, and the precipitate was freeze-dried to obtain the tangerine peel-derived humic acid freeze-dried powder.

2. The method for extracting humic acid from tangerine peel pulp fermentation product according to claim 1, characterized in that: The tangerine peel pulp fermented product is purchased from the market or prepared by the following method: Chinese medicine residue, dust-removed rice husk, wood bran and fermentation bacteria agent are uniformly mixed and sent into a fermentation tank as bedding, soy sauce residue, tangerine peel pulp and water are mixed into a slurry liquid, and then the slurry liquid is sprayed on the bedding, and under natural ventilation conditions, the pile is mechanically turned 1 to 3 times every 1 to 3 days, and the tangerine peel pulp fermented product is continuously fermented for 1 to 3 months to obtain the tangerine peel pulp fermented product.

3. The method for extracting humic acid from tangerine peel pulp fermentation product according to claim 2, characterized in that: In the preparation of the fermented tangerine peel pulp, the Chinese medicine residue is at least one of yam, codonopsis, tuckahoe, white hyacinth bean, tangerine peel, amomum villosum, atractylodes macrocephala and quinquefolius; In the preparation of the fermented tangerine peel pulp, the fermentation agent is at least one of Pseudocanthomonas, Tauerella, Bacillus siamensis, Bacillus halophilicus, Bacillus subtilis, Lactobacillus acidophilus and fertilizer fermentation bacteria, preferably a composite agent composed of Pseudocanthomonas, Tauerella, Bacillus siamensis, Bacillus halophilicus, Bacillus subtilis and Lactobacillus acidophilus; In the preparation of the fermented tangerine peel pulp, the volume ratio of wood chaff, dust-removed husk and Chinese medicine residue in the bedding is (1-6): (4-10): (0-2.5), and the amount of bacterial agent added is 1m 3 150-450g of fermentation agent is added to the litter; In the preparation of the fermented tangerine peel pulp, the volume ratio of the soy sauce residue, tangerine peel pulp and water is (0.3-1): (1-20): 90; In the preparation of the tangerine peel pulp fermented product, the water content in the fermentation tank is adjusted to 60%-70% by controlling the spraying amount of the slurry liquid, and the carbon-nitrogen ratio is (20-30):

1.

4. The method for extracting humic acid from tangerine peel pulp fermentation product according to claim 1, characterized in that: The alkaline solution is a mixed aqueous solution of sodium pyrophosphate and alkali, wherein the alkali is at least one of sodium hydroxide and potassium hydroxide, and the molar ratio of sodium pyrophosphate to alkali is (0.5-2):(0.5-2); The concentration of sodium pyrophosphate in the alkaline solution is 0.05-0.2 mol / L; the mass volume ratio of the orange peel pulp fermentation product and the alkaline solution is 1g:6-20mL.

5. The method for extracting humic acid from tangerine peel pulp fermentation product according to claim 1, characterized in that: The heating and shaking refers to heating to 45-60°C and shaking for 18-24h; The acidification precipitation refers to making the pH of the filtrate 1-2; the freeze drying is liquid nitrogen freeze drying.

6. Humic acid derived from dried tangerine peel prepared by the method according to any one of claims 1 to 5.

7. Use of the tangerine peel-derived humic acid according to claim 6 as an emulsifier in the preparation of cinnamon essential oil oil-in-water emulsion.

8. A cinnamon essential oil oil-in-water emulsion, characterized in that Prepared by the following method: (1) dispersing the tangerine peel-derived humic acid freeze-dried powder of claim 6 in water to obtain a tangerine peel-derived humic acid solution; (2) Cinnamon essential oil is added to the tangerine peel-derived humic acid solution, and the cinnamon essential oil oil-in-water emulsion is prepared by shearing.

9. The cinnamon essential oil oil-in-water emulsion according to claim 8, characterized in that: The pH of the tangerine peel source humic acid solution described in step (1) is 5-9; the concentration of the tangerine peel source humic acid solution is 5-20 mg / ml; The relative amounts of the tangerine peel-derived humic acid solution and the cinnamon essential oil in step (2) satisfy: the volume ratio of the cinnamon essential oil to the tangerine peel-derived humic acid solution is 1:1-1:4; The shearing described in step (2) refers to shearing at 90000-150000 rpm for 3-5 min.

10. Use of the cinnamon essential oil oil-in-water emulsion according to claim 8 or 9 in medicine, cosmetics and food.

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